Infectious Disease and Microbiology – Kyasanur Forest Disease Virus

Overview

Kyasanur Forest disease virus (KFDV) is a tick-borne flavivirus that causes Kyasanur Forest disease (KFD), an acute febrile illness that may progress to hemorrhagic manifestations and neurologic complications.

The disease was first recognized in the Kyasanur Forest region of Karnataka, India, and is primarily associated with forested areas of India.

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Classification

Virus: Kyasanur Forest disease virus

Genus: Flavivirus

Family: Flaviviridae

KFDV belongs to the tick-borne flavivirus group.

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Microbiologic Characteristics

Kyasanur Forest disease virus is:

• Positive-sense, single-stranded RNA virus

• Enveloped

• Approximately spherical

• A member of the family Flaviviridae

Its envelope contains viral proteins important for attachment and entry into susceptible host cells.

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Epidemiology

Kyasanur Forest disease is primarily a zoonotic tick-borne infection associated with forest environments.

The disease is most strongly associated with India, particularly regions where infected ticks, wild animals, and humans come into contact.

Related viruses within the KFDV group have also been recognized elsewhere in Asia and the Arabian Peninsula.

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Transmission

Transmission to humans occurs primarily through the bite of infected hard ticks, particularly Haemaphysalis species.

The virus is maintained in nature through interactions between:

Ticks

Small mammals and other vertebrate hosts

Monkeys

Humans are generally accidental hosts.

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Monkey Association

KFD is sometimes called “monkey fever.”

Monkeys can develop severe or fatal infection, and monkey deaths in forested regions may serve as an epidemiologic warning of viral circulation.

Humans may become infected when they enter areas containing infected ticks.

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Incubation Period

The incubation period is approximately:

3–8 days

Symptoms generally begin abruptly following the incubation period.

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Clinical Infection

Kyasanur Forest disease typically begins as an acute febrile illness.

Common manifestations may include:

• Sudden high fever

• Severe headache

• Myalgia

• Generalized weakness

• Chills

• Nausea and vomiting

Hemorrhagic manifestations may develop in more severe cases.

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Hemorrhagic Manifestations

Patients may develop:

• Petechiae

• Epistaxis

• Gastrointestinal bleeding

• Other mucosal or systemic hemorrhage

Thrombocytopenia and other hematologic abnormalities may accompany severe disease.

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Biphasic Illness

Some patients experience a biphasic course.

After an initial febrile illness and apparent improvement, fever may recur.

The second phase may be accompanied by neurologic manifestations such as:

• Severe headache

• Tremor

• Altered mental status

• Meningoencephalitic features

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Important Terminology Correction

The supplied source describes KFDV as causing:

“Hemorrhagic fever with renal syndrome.”

This terminology should be interpreted cautiously.

Hemorrhagic fever with renal syndrome (HFRS) classically refers to disease caused by hantaviruses, not Kyasanur Forest disease virus.

KFDV instead causes Kyasanur Forest disease, a tick-borne viral hemorrhagic febrile illness.

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Diagnosis

The source lists:

• Cell culture

• Serologic testing

• PCR

Modern diagnosis commonly relies on molecular and serologic methods.

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PCR

RT-PCR can detect viral RNA, particularly during the acute viremic phase.

It provides specific evidence of active infection.

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Serology

Serologic testing can detect the host immune response to KFDV and may be particularly useful after antibodies have developed.

Interpretation depends on the timing of specimen collection and the specific assay used.

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Treatment

Treatment is primarily:

Supportive and symptomatic

There is no routinely established specific antiviral therapy for KFD.

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Supportive Management

Management may include:

• Adequate hydration

• Fever and pain management

• Monitoring of blood counts

• Management of bleeding complications

• Hemodynamic support when required

• Neurologic monitoring in severe disease

Severe cases may require hospitalization and intensive supportive care.

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Prevention

Because KFDV is primarily transmitted by ticks, prevention focuses on reducing tick exposure.

Measures include:

• Protective clothing in forested areas

• Appropriate tick repellents

• Regular examination for ticks

• Avoidance of heavily tick-infested areas when outbreaks occur

• Public-health surveillance in endemic regions

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High-Yield Clinical Pattern

Person exposed to forested areas in endemic India

Tick exposure

Incubation of approximately 3–8 days

Acute fever, severe headache, and myalgia

Possible hemorrhagic manifestations

→ Think Kyasanur Forest disease virus

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Biphasic Pattern

Initial hemorrhagic febrile illness

Temporary improvement

Recurrence with neurologic manifestations

→ Classic potential pattern of Kyasanur Forest disease

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Exam Essentials

Virus: Kyasanur Forest disease virus

Genus: Flavivirus

Family: Flaviviridae

Genome: Positive-sense single-stranded RNA

Envelope: Present

Vector: Tick, particularly Haemaphysalis

Geographic association: Primarily India

Human role: Accidental host

Important animal association: Monkeys

Alternative name: Monkey fever

Incubation: 3–8 days

Disease: Acute febrile illness with possible hemorrhagic and neurologic manifestations

Course: May be biphasic

Diagnosis: RT-PCR and serology; culture historically described

Treatment: Supportive

Important distinction: HFRS is classically a hantavirus syndrome, not the usual name for KFD

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Key clinical pearl: Kyasanur Forest disease virus is a tick-borne flavivirus associated primarily with forest exposure in India and produces an acute febrile illness that may become hemorrhagic and sometimes biphasic with neurologic involvement; do not confuse it with hantavirus-associated hemorrhagic fever with renal syndrome.

Infectious Disease and Microbiology – Flavobacterium Species

Overview

Flavobacterium species are aerobic Gram-negative bacilli historically associated with a variety of opportunistic and healthcare-associated infections. Important manifestations described in older literature include neonatal meningitis and bacteremia, prosthetic-valve endocarditis, contaminated-solution-associated bacteremia, and wound infection.

The taxonomy of this group has changed substantially, so several organisms formerly classified as Flavobacterium now belong to other genera.

Important Species

Historically recognized species include:

• Flavobacterium indologenes

• Flavobacterium meningosepticum

• Flavobacterium odoratum

• Other Flavobacterium species

Several of these names are now considered older taxonomic designations.

Important Taxonomic Changes

A major point when reading older infectious-disease literature is that:

Flavobacterium meningosepticum → now Elizabethkingia meningoseptica

Flavobacterium indologenes → now Chryseobacterium indologenes

Thus, older reports of Flavobacterium infection may actually describe organisms currently classified as Elizabethkingia or Chryseobacterium.

Microbiologic Characteristics

Historically classified Flavobacterium organisms are:

• Aerobic

• Gram-negative bacilli

• Generally environmental organisms

• Capable of causing opportunistic and healthcare-associated infection

The source correctly notes that the taxonomy was unsettled; subsequent reclassification has substantially reorganized these organisms.

Clinical Infections

Reported infections include:

• Meningitis

• Bacteremia

• Prosthetic-valve endocarditis

• Healthcare-associated outbreaks

• Wound infection

Clinical manifestations vary considerably according to the species and host.

Neonatal Meningitis

The organism historically called F. meningosepticum is particularly associated with:

Meningitis in newborns

Neonatal infection can be severe and may occur in healthcare settings.

This organism is now known as Elizabethkingia meningoseptica.

Neonatal Bacteremia

In addition to meningitis, E. meningoseptica can cause neonatal bacteremia and sepsis.

Premature and medically complex newborns may be particularly vulnerable to invasive infection.

Endocarditis

Organisms historically included in the Flavobacterium group have occasionally caused infective endocarditis.

The source particularly emphasizes infection involving:

Prosthetic heart valves

This represents a rare but serious invasive manifestation.

Nosocomial Bacteremia

Healthcare-associated outbreaks of bacteremia have been reported.

A particularly important epidemiologic association is:

Contaminated solutions

Such outbreaks demonstrate the ability of these environmental Gram-negative organisms to contaminate healthcare materials and cause invasive disease in susceptible patients.

Wound Infection

Flavobacterium-group organisms have also been associated with wound infections.

Their clinical significance should be interpreted according to the specimen source, evidence of tissue inflammation, and the patient’s underlying condition.

Diagnosis

Diagnosis is established by:

Culture of the pathogen

Accurate identification is particularly important because:

• Taxonomy has changed

• These are uncommon organisms

• Antimicrobial susceptibility may be unusual

• Resistance to multiple conventional Gram-negative antibiotics can occur

Antimicrobial Susceptibility

A major clinical feature of organisms such as Elizabethkingia meningoseptica is their unusual antimicrobial susceptibility pattern.

They may be resistant to several antibiotics ordinarily used against Gram-negative bacteria.

Therefore, treatment should be based on:

Accurate species identification + antimicrobial susceptibility testing

Treatment

The source lists:

Ciprofloxacin

as a treatment option.

Because susceptibility can vary substantially, modern management of serious infection should be guided by isolate-specific susceptibility testing rather than assuming that a particular agent will always be effective.

Historical Vancomycin Treatment

The source describes reports of successful treatment of neonatal meningitis with:

Vancomycin

This was historically notable because vancomycin ordinarily has little or no useful activity against Gram-negative bacteria.

However, the statement that Flavobacterium is uniquely susceptible to vancomycin reflects older literature and should not be treated as a modern general treatment rule.

Why Vancomycin Is Unusual

Normally:

Gram-negative outer membrane

→ prevents effective penetration of vancomycin

→ intrinsic lack of useful vancomycin activity

Therefore, historical reports involving F. meningosepticum were microbiologically unusual and became a memorable feature of older teaching material.

High-Yield Clinical Pattern

Newborn

• ●

Meningitis or bacteremia

• ●

Unusual aerobic Gram-negative bacillus

• ●

Healthcare-associated setting

→ Think Elizabethkingia meningoseptica

(formerly Flavobacterium meningosepticum)

Nosocomial Pattern

Cluster of bloodstream infections

• ●

Hospitalized patients

• ●

Possible contaminated medical solution

→ Consider an environmental Gram-negative organism historically classified among Flavobacterium

Exam Essentials

Historical genus: Flavobacterium

Type: Aerobic Gram-negative bacilli

Important old species: F. meningosepticum

Current name: Elizabethkingia meningoseptica

Old F. indologenes: Now Chryseobacterium indologenes

Classic severe infection: Neonatal meningitis and bacteremia

Other infection: Prosthetic-valve endocarditis

Nosocomial outbreaks: May involve contaminated solutions

Additional infection: Wound infection

Diagnosis: Culture

Important issue: Unusual and potentially multidrug-resistant susceptibility patterns

Treatment in source: Ciprofloxacin

Historical treatment observation: Vancomycin was reported for neonatal meningitis

Modern treatment principle: Susceptibility-guided antimicrobial therapy

Key clinical pearl: The most important association in older literature is Flavobacterium meningosepticum + neonatal meningitis/bacteremia. Remember that this organism has been reclassified as Elizabethkingia meningoseptica and has an unusual antimicrobial resistance profile, making accurate identification and susceptibility-guided therapy particularly important.

Infectious Disease and Microbiology – Flavimonas oryzihabitans

Overview

Flavimonas oryzihabitans is a rare aerobic Gram-negative bacillus that acts primarily as an opportunistic pathogen. Reported infections are often healthcare-associated and have a notable relationship with intravascular catheters and implanted prosthetic devices.

An important clinical presentation is catheter-associated bacteremia, which may be polymicrobial.

Microbiologic Characteristics

Flavimonas oryzihabitans is:

• An aerobic Gram-negative bacillus

• An uncommon human pathogen

• Primarily associated with opportunistic and healthcare-related infections

The organism has undergone taxonomic reclassification and is now generally known as Pseudomonas oryzihabitans.

Epidemiology

Human infection is rare.

When infection occurs, it is frequently associated with patients who have:

• Intravascular catheters

• Prosthetic devices

• Peritoneal dialysis catheters

• CNS shunts

• Significant underlying medical conditions

These associations suggest that foreign material and disruption of normal host barriers can facilitate infection.

Bacteremia

One of the most important manifestations is bacteremia.

Bloodstream infections may be:

• Polymicrobial

• Associated with intravascular lines

• Healthcare-associated

When the organism is repeatedly isolated from blood in a patient with an intravascular catheter, a catheter-related bloodstream infection should be considered.

Intravascular Line Infection

Intravascular catheters provide a potential surface for bacterial colonization and subsequent bloodstream invasion.

The clinical pattern may be:

Intravascular catheter

• ●

Fever or systemic illness

• ●

Positive blood cultures for F. oryzihabitans

→ Consider catheter-associated bacteremia

Peritoneal Dialysis-Associated Peritonitis

F. oryzihabitans has been reported as a cause of peritonitis in patients undergoing peritoneal dialysis.

Patients may develop:

• Abdominal pain

• Fever

• Cloudy peritoneal dialysis fluid

• Increased inflammatory cells in dialysate

The dialysis catheter may serve as an important portal or persistent source of infection.

CNS Shunt Infection

The organism can infect central nervous system shunts.

Such infections demonstrate its ability to cause disease involving implanted medical devices.

Depending on the clinical situation, management may require both antimicrobial therapy and evaluation of the infected shunt.

Prosthetic Joint Infection

F. oryzihabitans has occasionally been associated with prosthetic joint infection.

Possible manifestations include:

• Joint pain

• Swelling

• Reduced joint function

• Local inflammatory findings

Because prosthetic material is involved, antimicrobial therapy alone may not always provide adequate source control.

Prosthetic Valve Endocarditis

Rare cases of prosthetic valve endocarditis have also been described.

This represents a serious invasive manifestation and should be considered when persistent bacteremia occurs in a patient with a prosthetic cardiac valve.

Meningitis

F. oryzihabitans can rarely cause meningitis.

Diagnosis depends on compatible clinical findings and microbiologic isolation from cerebrospinal fluid or other relevant specimens.

Wound Infection

The organism has also been recovered from wound infections.

Its significance should be interpreted according to the clinical appearance of the wound and the quality of the specimen because an unusual environmental organism recovered from a superficial specimen does not necessarily establish invasive infection.

Diagnosis

Diagnosis is established by:

Culture of the organism

Depending on the clinical syndrome, specimens may include:

• Blood

• Peritoneal dialysis fluid

• Cerebrospinal fluid

• Joint or prosthetic material

• Wound specimens

For significant infections, antimicrobial susceptibility testing can help guide therapy.

Treatment

The source lists an:

Antipseudomonal β-lactam

as a treatment option.

It also lists the carbapenems:

• Imipenem

• Meropenem

Treatment should be individualized according to the infection site, severity, and susceptibility results.

Additional Treatment

Additional agents listed in the source include:

• Ciprofloxacin

• Aminoglycosides

Because this organism is an uncommon pathogen, susceptibility-guided antimicrobial selection is particularly important.

Device-Associated Infection

A major clinical theme is the organism’s association with foreign or prosthetic material:

Intravascular line

Peritoneal dialysis catheter

CNS shunt

Prosthetic joint

Prosthetic heart valve

This association should raise consideration of device-related infection when the organism is recovered from an appropriate clinical specimen.

Source Control

When an implanted device is the suspected source, treatment may require consideration of:

• Catheter removal

• Shunt revision or removal

• Management of infected prosthetic material

• Drainage or debridement when appropriate

The need for device removal depends on the location, severity, persistence of infection, and clinical circumstances.

High-Yield Clinical Pattern

Hospitalized or medically complex patient

• ●

Intravascular catheter or implanted device

• ●

Gram-negative bacillus

• ●

Bacteremia, often polymicrobial

→ Consider Flavimonas oryzihabitans (Pseudomonas oryzihabitans)

Exam Essentials

Organism: Flavimonas oryzihabitans

Current name: Pseudomonas oryzihabitans

Type: Gram-negative bacillus

Oxygen requirement: Aerobic

Frequency: Rare human pathogen

Major infection: Catheter-associated bacteremia

Bacteremia: Frequently polymicrobial in the source

Other infections: Peritoneal dialysis-associated peritonitis, CNS shunt infection, prosthetic joint infection, prosthetic valve endocarditis, meningitis, wound infection

Major association: Indwelling and prosthetic medical devices

Diagnosis: Culture

Treatment in source: Antipseudomonal β-lactam or carbapenem

Additional agents: Ciprofloxacin or aminoglycoside

Management principle: Consider susceptibility-guided therapy and appropriate device/source control

Key clinical pearl: Flavimonas oryzihabitans, now generally called Pseudomonas oryzihabitans, is a rare opportunistic Gram-negative bacillus with a strong association with intravascular lines and other prosthetic devices; catheter-associated, sometimes polymicrobial, bacteremia is a particularly characteristic presentation.

Infectious Disease and Microbiology – Fasciolopsis buski

Overview

Fasciolopsis buski is a large intestinal trematode (fluke) that causes fasciolopsiasis. Unlike Fasciola species, which primarily involve the liver and biliary tract, F. buski primarily inhabits the small intestine.

Infection is concentrated in parts of South and Southeast Asia and usually produces gastrointestinal manifestations. Heavy worm burdens can rarely result in acute intestinal obstruction.

Microbiologic Characteristics

Fasciolopsis buski is:

• A trematode helminth

• An intestinal fluke

• Approximately 7 cm long as an adult

• One of the largest intestinal flukes infecting humans

Adult worms primarily inhabit the small intestine.

Epidemiology

Fasciolopsiasis occurs predominantly in:

• Rural Southeast Asia

• India and other parts of South Asia

Transmission is associated with areas where the parasite’s freshwater life cycle can be maintained.

Transmission

Humans acquire infection by ingesting metacercariae attached to raw or inadequately prepared aquatic vegetation.

Freshwater snails serve as intermediate hosts.

The general transmission cycle is:

Eggs reach freshwater

→

Freshwater snail intermediate host

→

Metacercariae develop on aquatic plants

→

Humans ingest contaminated aquatic vegetation

→

Adult flukes develop in the small intestine

Fasciolopsiasis

The disease caused by F. buski is known as:

Fasciolopsiasis

The severity of disease is related partly to the number of worms present.

Light infections may produce few or no symptoms, whereas heavier infections can cause significant gastrointestinal disease.

Gastrointestinal Manifestations

Clinical manifestations may include:

• Diarrhea

• Constipation

• Vomiting

• Anorexia

• Abdominal discomfort

The parasites can produce local irritation and inflammation of the intestinal mucosa.

Heavy Infection

Heavy parasite burdens can produce more severe gastrointestinal manifestations.

Large numbers of these relatively large flukes may interfere with normal intestinal function.

Acute Intestinal Obstruction

A rare but important complication is:

Acute intestinal obstruction

This is particularly associated with a heavy worm burden.

Thus:

Endemic-area exposure + gastrointestinal symptoms + intestinal obstruction

should raise consideration of heavy F. buski infection.

Diagnosis

Diagnosis is primarily established by:

Parasitologic examination of stool

Characteristic trematode eggs can be detected microscopically.

Stool Examination

Stool microscopy is the principal diagnostic method because adult worms residing in the intestine release eggs that are passed in feces.

The eggs may resemble those of Fasciola species, so clinical and epidemiologic context can assist with interpretation.

Treatment

The source recommends:

Praziquantel 25 mg/kg orally every 8 hours for 1 day

Praziquantel is the major antiparasitic agent associated with treatment of fasciolopsiasis.

Additional Treatment

The source lists:

Niclosamide 2 g orally as a single dose

as an additional treatment option.

Prevention

Prevention centers on interrupting transmission from contaminated freshwater environments.

Important measures include:

• Avoiding raw aquatic vegetation in endemic areas

• Thoroughly cooking aquatic plants

• Safe sanitation and disposal of feces

• Avoiding contamination of freshwater sources

Fasciolopsis vs. Fasciola

Fasciolopsis buski

→ Intestinal fluke

→ Adult worms live in the small intestine

→ Causes fasciolopsiasis

→ Diarrhea, vomiting, anorexia, and possible intestinal obstruction

→ Praziquantel is the classic treatment

Fasciola hepatica / F. gigantica

→ Liver flukes

→ Primarily involve the liver and biliary tree

→ Cause fascioliasis

→ Hepatic migration may produce RUQ pain and eosinophilia

→ Triclabendazole is the key treatment

High-Yield Clinical Pattern

Patient from rural Southeast or South Asia

• ●

Consumption of contaminated aquatic vegetation

• ●

Diarrhea, vomiting, anorexia, or abdominal symptoms

• ●

Large intestinal trematode eggs in stool

→ Think Fasciolopsis buski

Severe Infection Pattern

Heavy intestinal fluke burden

• ●

Acute abdominal symptoms

• ●

Mechanical intestinal obstruction

→ Consider severe Fasciolopsis buski infection

Exam Essentials

Organism: Fasciolopsis buski

Type: Trematode helminth

Common name: Large intestinal fluke

Adult size: Approximately 7 cm

Distribution: Rural Southeast Asia and South Asia

Primary site: Small intestine

Transmission: Ingestion of metacercariae on aquatic vegetation

Intermediate host: Freshwater snail

Disease: Fasciolopsiasis

Major symptoms: Diarrhea, constipation, vomiting, anorexia

Major rare complication: Acute intestinal obstruction

Diagnosis: Parasitologic stool examination

Treatment: Praziquantel 25 mg/kg every 8 hours for 1 day

Alternative in source: Niclosamide

Key clinical pearl: Fasciolopsis buski is a large intestinal fluke acquired from contaminated aquatic vegetation; remember small-intestinal disease + gastrointestinal symptoms + possible obstruction, in contrast to Fasciola species, which primarily cause hepatic and biliary disease.

Infectious Disease and Microbiology – Fasciola Species

Overview

Fasciola species are trematode helminths (liver flukes) that cause fascioliasis, a parasitic infection primarily involving the liver and biliary tract.

The two major species are Fasciola hepatica and Fasciola gigantica. Humans are accidental hosts, while the normal definitive hosts include sheep, cattle, and other herbivorous animals.

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Important Species

The principal human pathogens are:

• Fasciola hepatica

• Fasciola gigantica

F. hepatica is commonly known as the common liver fluke, whereas F. gigantica is generally larger and occurs predominantly in tropical regions.

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Microbiologic Characteristics

Fasciola species are:

• Trematodes (flukes)

• Helminthic parasites

• Leaf-shaped adult worms

• Approximately several centimeters in length

Adult Fasciola organisms inhabit the biliary system of their definitive hosts.

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Epidemiology

Fascioliasis occurs worldwide, although human infection is relatively uncommon.

The parasites naturally infect:

• Sheep

• Cattle

• Other grazing herbivores

Human disease is particularly associated with sheep- and cattle-raising regions where the parasite’s life cycle is maintained.

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Humans as Accidental Hosts

Humans are accidental definitive hosts.

Human infection occurs when infective metacercariae are ingested, classically on contaminated aquatic vegetation.

Ingestion → intestinal penetration → hepatic migration → biliary tract maturation

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Transmission

A classic source of human infection is consumption of raw aquatic plants, particularly watercress, contaminated with metacercariae.

Contaminated water can also serve as a source.

Freshwater snails participate as intermediate hosts in the parasite’s life cycle.

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Fascioliasis

The disease caused by Fasciola species is:

Fascioliasis

It primarily involves the:

Liver

and

Biliary tree

Disease can be divided conceptually into an early hepatic migratory phase and a later biliary phase.

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Acute Hepatic Phase

After ingestion, immature flukes penetrate the intestinal wall and migrate through the peritoneal cavity into the liver.

Migration through hepatic tissue may produce:

• Fever

• Right upper-quadrant abdominal pain

• Hepatomegaly

• Malaise

• Nausea

• Urticaria or other allergic manifestations

• Peripheral eosinophilia

This phase reflects tissue migration rather than established adult worms in the bile ducts.

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Chronic Biliary Phase

After reaching maturity, adult flukes enter the biliary ducts.

Chronic infection may produce:

• Biliary inflammation

• Recurrent right upper-quadrant pain

• Cholangitis

• Biliary obstruction

• Jaundice

Some infections remain relatively asymptomatic.

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Obstructive Cholangitis

Adult flukes may occasionally produce mechanical obstruction of the biliary tract, resulting in obstructive cholangitis.

In this situation, endoscopic intervention may be necessary in addition to antiparasitic treatment.

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Ectopic Fascioliasis

Rarely, Fasciola parasites migrate outside their usual hepatic and biliary locations.

Such ectopic infection has been described particularly with F. gigantica.

Clinical manifestations depend on the organ involved.

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Diagnosis

Diagnosis shares some features with other hepatobiliary fluke infections such as Clonorchis sinensis.

Methods include:

• Parasitologic examination for characteristic eggs

• Serologic testing

• Molecular testing such as PCR for species identification

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Stool Examination

Characteristic Fasciola eggs may be detected in stool once adult parasites have matured in the biliary tract and begun producing eggs.

However, during the early hepatic migratory phase, stool examination may be negative because immature parasites have not yet begun producing eggs.

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Serology

Serologic testing is particularly useful during early infection when clinical manifestations and eosinophilia are present but eggs are not yet detectable in stool.

Thus:

Acute hepatic symptoms + eosinophilia + exposure history + negative stool examination

→ Consider Fasciola serology

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PCR

PCR-based testing can assist with detection and differentiation of Fasciola species where available.

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Treatment

The source reflects older therapeutic information and states that satisfactory antiparasitic treatment was limited.

It describes:

Bithionol 30–50 mg/kg on alternate days for 10–14 doses

as having moderate effectiveness.

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Triclabendazole

The source describes triclabendazole 10 mg/kg as a single dose as a veterinary product that had occasionally been used in humans and was not FDA-approved at the time the source was written.

Importantly, that information is now historically outdated: triclabendazole subsequently became an approved human treatment for fascioliasis in the United States.

It is the key drug associated with treatment of Fasciola infection.

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Praziquantel

The source lists:

Praziquantel

as additional therapy.

However, a major high-yield distinction is that Fasciola species respond poorly to praziquantel, unlike several other trematode infections.

Therefore, the classic treatment association to remember is:

Fascioliasis → triclabendazole

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Endoscopic Treatment

When adult flukes produce significant biliary obstruction or obstructive cholangitis, ERCP (endoscopic retrograde cholangiopancreatography) can be used to identify and remove parasites from the biliary tract.

Thus, severe mechanical obstruction may require:

Antiparasitic treatment + endoscopic source control

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High-Yield Clinical Pattern

Sheep/cattle-raising region

Raw aquatic vegetation or watercress exposure

Right upper-quadrant pain and hepatomegaly

Marked eosinophilia

→ Think Fasciola hepatica or Fasciola gigantica

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Chronic Disease Pattern

Biliary colic or cholangitis

Adult liver fluke in the biliary tree

Characteristic eggs in stool

→ Think chronic fascioliasis

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Fasciola vs. Clonorchis

Fasciola

→ Infection classically from aquatic vegetation/watercress

→ Migrates through liver parenchyma

→ Acute phase commonly associated with eosinophilia

→ Treatment classically associated with triclabendazole

Clonorchis sinensis

→ Infection from raw or undercooked freshwater fish

→ Primarily inhabits the biliary ducts

→ Chronic infection associated with cholangiocarcinoma

→ Typically treated with praziquantel

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Exam Essentials

Genus: Fasciola

Species: F. hepatica, F. gigantica

Type: Trematode/liver fluke

Natural hosts: Sheep, cattle, and other herbivores

Human role: Accidental host

Intermediate host: Freshwater snail

Classic exposure: Raw aquatic vegetation, especially watercress

Primary organs: Liver and biliary tree

Acute phase: Hepatic migration

Important laboratory clue: Eosinophilia

Chronic phase: Biliary disease

Diagnosis: Stool examination, serology, and molecular methods where available

Early infection: Stool may be negative

Key treatment association: Triclabendazole

Praziquantel: Poor activity against Fasciola

Biliary obstruction: May require ERCP and parasite removal

⸻

Key clinical pearl: Think Fasciola when a patient with raw watercress/aquatic-plant exposure develops right upper-quadrant pain, hepatomegaly, and eosinophilia. Unlike many other trematodes, the key treatment is triclabendazole rather than praziquantel.

Infectious Disease and Microbiology – Exophiala Species

Overview

Exophiala species are dematiaceous (darkly pigmented) filamentous fungi that are distributed worldwide. They are uncommon causes of human disease but can produce cutaneous, subcutaneous, ocular, pulmonary, and invasive systemic infections.

Because of their melanin-containing cell walls and pigmented hyphae, infections caused by these organisms are generally classified among the phaeohyphomycoses.

Important Species

Clinically recognized species include:

• Exophiala dermatitidis

• Exophiala jeanselmei

• Exophiala moniliae

• Exophiala pisciphila

• Exophiala spinifera

Different species vary in their clinical associations and potential for invasive disease.

Microbiologic Characteristics

Exophiala species are:

• Dematiaceous fungi

• Filamentous molds

• Characterized by dark pigmentation related to melanin in the fungal cell wall

In infected tissue, they may appear as:

• Yeast-like forms

• Pseudohyphae

• Septate pigmented hyphae

Dematiaceous Fungi

The term dematiaceous refers to fungi with brown-to-black pigmentation in their cell walls.

When these pigmented fungi produce infection characterized by yeast-like cells, pseudohyphae, or irregular pigmented hyphae in tissue, the disease is generally termed:

Phaeohyphomycosis

Epidemiology

Exophiala species have a worldwide distribution.

Despite their environmental distribution, human infections are rare.

Disease may remain localized or, particularly in susceptible hosts, become invasive.

Clinical Infections

Reported infections include:

• Corneal infection

• Cutaneous and subcutaneous infection

• Prosthetic valve endocarditis

• Septic arthritis

• Brain abscess

• Pneumonia

• Other systemic infections

The clinical spectrum therefore ranges from localized superficial disease to potentially severe invasive infection.

Corneal Infection

Exophiala species can occasionally cause fungal keratitis.

Clinical manifestations may include:

• Eye pain

• Redness

• Photophobia

• Decreased vision

• Corneal inflammation or ulceration

A history of ocular trauma or environmental exposure may provide a clue to fungal infection.

Subcutaneous Infection

One of the better-recognized manifestations is subcutaneous phaeohyphomycosis.

Patients may develop:

• Slowly enlarging nodules

• Cysts

• Abscess-like lesions

• Chronic localized swelling

Traumatic implantation of environmental fungal material into the skin or subcutaneous tissue may initiate infection.

Pneumonia

Pulmonary infection due to Exophiala species is uncommon but has been reported.

Manifestations can range from chronic respiratory infection to invasive pneumonia, depending on the species and host factors.

Prosthetic Valve Endocarditis

Rare cases of Exophiala-associated prosthetic valve endocarditis have been reported.

This represents a serious invasive infection and may be difficult to eradicate because both fungal infection and infected prosthetic material are involved.

Septic Arthritis

Exophiala species have occasionally been associated with fungal arthritis.

Diagnosis generally requires demonstration of the fungus in synovial fluid or tissue together with compatible clinical findings.

Brain Abscess

One of the most serious manifestations is cerebral infection with brain abscess formation.

Certain dematiaceous fungi have a notable ability to cause central nervous system disease.

Neurologic manifestations may include:

• Headache

• Altered mental status

• Focal neurologic deficits

• Seizures

Systemic Infection

Although uncommon, disseminated or systemic Exophiala infection can occur and may involve multiple organs.

Invasive disease is potentially life-threatening and requires accurate species identification and antifungal management.

Diagnosis

Diagnosis is based on:

Culture of the fungus

and

Histopathologic examination of infected tissue

Using both methods can help establish that the recovered fungus represents true tissue infection.

Histopathology

Histopathologic examination may demonstrate:

Pigmented yeast-like cells

• ●

Pseudohyphae

• ●

Septate, darkly pigmented hyphae

These findings are characteristic of phaeohyphomycosis caused by dematiaceous fungi.

Culture

Fungal culture allows isolation and identification of Exophiala species.

Because treatment response may vary between species and isolates, accurate identification and, in severe disease, consideration of antifungal susceptibility information can be valuable.

Treatment

The source describes treatment with:

Amphotericin B

with or without:

Flucytosine

The optimal treatment depends on the site and severity of infection.

Additional Treatment

The source also lists:

Itraconazole

as an alternative antifungal agent.

Localized disease and invasive systemic infection may require substantially different therapeutic approaches.

Surgical Management

For localized subcutaneous lesions, abscesses, infected prosthetic material, or cerebral lesions, surgical management may sometimes be required in addition to antifungal therapy.

Management of invasive disease should therefore consider both antifungal treatment and appropriate source control.

High-Yield Clinical Pattern

Chronic subcutaneous cyst or nodule

• ●

Dematiaceous fungus

• ●

Pigmented septate hyphae in tissue

→ Think phaeohyphomycosis due to Exophiala species

Invasive Disease Pattern

Pigmented fungus

• ●

Pneumonia, prosthetic valve endocarditis, arthritis, or brain abscess

→ Consider invasive Exophiala infection

Exam Essentials

Genus: Exophiala

Type: Dematiaceous filamentous fungus

Pigment: Melanin-containing/dark fungal elements

Tissue morphology: Yeasts, pseudohyphae, and septate pigmented hyphae

Distribution: Worldwide

Frequency: Rare human pathogen

Disease category: Phaeohyphomycosis

Localized infections: Corneal and subcutaneous disease

Invasive infections: Pneumonia, arthritis, endocarditis, brain abscess

Diagnosis: Fungal culture + histopathology

Treatment in source: Amphotericin B ± flucytosine

Additional treatment: Itraconazole

Management consideration: Surgical intervention/source control may be necessary for selected localized or invasive lesions

Key clinical pearl: Exophiala species are dematiaceous fungi causing phaeohyphomycosis, recognized by pigmented septate hyphae, yeast-like forms, or pseudohyphae in tissue; although infection is usually rare and localized, these organisms can occasionally produce severe disease such as prosthetic valve endocarditis, pneumonia, and brain abscess.

Infectious Disease and Microbiology – Ewingella americana

Overview

Ewingella americana is a rare aerobic Gram-negative bacillus historically classified within the Enterobacteriaceae. It is infrequently recovered from clinical specimens, and because of its rarity, its overall clinical significance and pathogenic potential remain incompletely defined.

Reported infections have occurred particularly in immunocompromised patients and include bacteremia, wound infections, and occasional respiratory tract infections.

Microbiologic Characteristics

Ewingella americana is:

• An aerobic Gram-negative bacillus

• Historically classified within the Enterobacteriaceae group

• A rare opportunistic human pathogen

Its uncommon isolation makes it difficult to establish its precise role in many clinical settings.

Epidemiology

E. americana is rarely recovered in clinical cultures.

Consequently, considerably less is known about its epidemiology than about more common Gram-negative pathogens.

Clinical Significance

The clinical significance of E. americana can sometimes be uncertain, particularly when it is recovered from specimens that may contain colonizing organisms.

However, documented invasive infections indicate that it can function as an opportunistic pathogen, especially in susceptible hosts.

Risk Factors

Reported infections are particularly relevant in patients with:

• Immunocompromising conditions

• Significant underlying disease

• Wounds or disrupted tissue barriers

• Healthcare exposure

Because relatively few cases have been reported, the complete spectrum of risk factors remains uncertain.

Bacteremia

E. americana has been reported as a cause of bacteremia, particularly in immunocompromised patients.

Isolation from blood should therefore be evaluated carefully in conjunction with the patient’s clinical condition rather than automatically dismissed because the organism is uncommon.

Wound Infection

The organism has also been associated with wound infections, particularly in patients with impaired host defenses.

Clinical significance is more convincing when the organism is recovered from an infected wound together with compatible inflammatory findings.

Respiratory Tract Infection

E. americana has rarely been associated with respiratory tract infection.

Because respiratory specimens can contain colonizing organisms, recovery from the respiratory tract should be interpreted together with clinical and radiologic evidence of infection.

Diagnosis

Diagnosis is established by:

Culture of the organism

Because E. americana is unusual, accurate laboratory identification is important.

For clinically significant isolates, antimicrobial susceptibility testing is particularly valuable because predictable susceptibility patterns cannot always be assumed.

Treatment

There are limited clinical data regarding optimal antimicrobial therapy for E. americana infection.

The source reports activity with agents including:

• Cefotaxime

• Piperacillin–tazobactam

• Trimethoprim–sulfamethoxazole

However, antimicrobial susceptibility should ideally be determined for the individual isolate.

Multidrug Resistance

An important concern is that multidrug-resistant isolates have been reported.

Therefore:

Rare organism + uncertain susceptibility + possible multidrug resistance

→ Culture and susceptibility-guided therapy are particularly important

Combination Therapy

The source describes clinical use of combinations involving:

Trimethoprim–sulfamethoxazole

or

Cefotaxime

or

An antipseudomonal penicillin

combined with an:

Aminoglycoside

Because evidence is limited, these historical treatment approaches should not be considered universally appropriate for every isolate.

Treatment Principle

The most important therapeutic concept is:

Identify the organism

• ●

Perform antimicrobial susceptibility testing

• ●

Choose therapy according to susceptibility and infection severity

This is especially important because E. americana is uncommon and antimicrobial resistance has been reported.

High-Yield Clinical Pattern

Immunocompromised patient

• ●

Bacteremia or wound infection

• ●

Unusual aerobic Gram-negative bacillus

• ●

Potential multidrug resistance

→ Consider Ewingella americana

Exam Essentials

Organism: Ewingella americana

Type: Gram-negative bacillus

Oxygen requirement: Aerobic

Traditional classification: Enterobacteriaceae

Frequency: Very rare

Clinical significance: Incompletely defined

Important host: Immunocompromised patient

Major reported infections: Bacteremia and wound infection

Respiratory infection: Rare

Diagnosis: Culture

Important laboratory step: Antimicrobial susceptibility testing

Resistance: Multidrug resistance has been reported

Reported active agents in source: Cefotaxime, piperacillin–tazobactam, trimethoprim–sulfamethoxazole

Treatment principle: Susceptibility-guided therapy

Key clinical pearl: Ewingella americana is a rare opportunistic Gram-negative bacillus associated mainly with bacteremia and wound infection in immunocompromised patients; because clinical experience is limited and multidrug resistance can occur, antimicrobial susceptibility testing is central to treatment selection.

Infectious Disease and Microbiology – Eubacterium Species

Overview

Eubacterium species are anaerobic, pleomorphic Gram-positive bacilli that form part of the normal human microbiota. Because these organisms normally colonize the body, their recovery from a clinical specimen does not automatically establish that they are causing infection.

When pathogenic, Eubacterium species are commonly associated with polymicrobial infections, particularly abscesses, periodontal disease, and infections arising from sites containing anaerobic flora.

Important Species

Species described in this group include:

• Eubacterium lentum

• Eubacterium nodatum

• Eubacterium timidum

• Other Eubacterium species

Some organisms historically classified as Eubacterium have undergone taxonomic reclassification, so older names may still appear in infectious-disease literature.

Microbiologic Characteristics

Eubacterium species are:

• Anaerobic

• Gram-positive bacilli

• Pleomorphic in appearance

• Components of normal human flora

Their anaerobic nature means that specimens must be collected and transported appropriately if culture is required.

Epidemiology

Eubacterium species are members of the normal human microbiota.

They may inhabit sites such as the gastrointestinal tract and oral cavity.

Because colonization is common, isolation of an organism must always be interpreted in the context of the patient’s clinical syndrome and the specimen source.

Colonization vs. Infection

A particularly important principle is:

Positive culture ≠ necessarily active infection

Isolation from a normally colonized site may simply represent normal flora or contamination.

Evidence for true infection is stronger when the organism is recovered from a normally sterile site, particularly when accompanied by compatible clinical findings.

Clinical Infections

When Eubacterium species cause disease, infections may include:

• Abscesses

• Periodontal infections

• Septic arthritis

• Gynecologic infections such as endometritis

• Other anaerobic infections

These infections are almost always polymicrobial, meaning other bacterial species are frequently present.

Abscesses and Mixed Infections

Eubacterium species may be recovered from abscesses and infections at various anatomical sites.

A typical pattern is:

Disruption of mucosal barrier

→

Normal anaerobic flora enters deeper tissue

→

Polymicrobial abscess or invasive infection

This is characteristic of many infections caused by endogenous anaerobic flora.

Periodontal Disease

Certain Eubacterium species have been associated with periodontal disease.

The oral cavity contains a complex anaerobic microbiome, so periodontal infections are usually polymicrobial rather than caused by a single organism.

Eubacterium lentum

The source associates Eubacterium lentum with:

Septic arthritis in patients with colonic lesions

This association suggests that disruption of the gastrointestinal mucosal barrier may permit organisms from intestinal flora to enter the bloodstream and subsequently involve a joint.

Eubacterium nodatum

The source associates Eubacterium nodatum with:

Endometritis in women using an intrauterine device (IUD)

This represents another example of an anaerobic organism associated with infection following alteration or disruption of normal mucosal environments.

Diagnosis

Diagnosis is established by:

Culture using appropriate anaerobic media

Successful isolation requires appropriate specimen collection and maintenance of anaerobic conditions during transport and processing.

Interpretation of Culture

Because Eubacterium species are normal flora, laboratory isolation should be interpreted together with:

• Clinical manifestations

• Anatomical source of the specimen

• Presence of abscess or tissue inflammation

• Recovery from a normally sterile site

• Presence of additional organisms

The organism’s presence alone does not prove causation.

Treatment

The source lists:

Penicillin G

or

A cephamycin

as treatment options.

It also lists:

Metronidazole

for anaerobic coverage.

Additional Treatment

Other antimicrobial agents described in the source include:

• Imipenem

• Meropenem

• Clindamycin

• Ureidopenicillins

For clinically significant infection, antimicrobial selection should take into account the susceptibility pattern and other organisms present in a polymicrobial infection.

Source Control

Because these organisms frequently occur in abscesses and mixed anaerobic infections, antimicrobial therapy may need to be combined with appropriate source control.

This can include drainage of an abscess, debridement of infected tissue, or management of an underlying anatomical source.

High-Yield Clinical Pattern

Anaerobic Gram-positive bacillus

• ●

Normally part of human flora

• ●

Recovered from an abscess or other polymicrobial infection

→ Think Eubacterium species

Important Interpretation Pattern

Eubacterium isolated from a colonized site

→ May represent normal flora

Eubacterium isolated from a sterile site + compatible infection

→ More supportive of true invasive infection

Exam Essentials

Genus: Eubacterium

Type: Pleomorphic Gram-positive bacillus

Oxygen requirement: Anaerobic

Normal habitat: Part of normal human flora

Major infection pattern: Polymicrobial anaerobic infection

Common manifestations: Abscesses and periodontal disease

E. lentum: Associated in the source with septic arthritis in patients with colonic lesions

E. nodatum: Associated in the source with endometritis in women using an IUD

Diagnosis: Anaerobic culture

Important diagnostic issue: Isolation does not necessarily indicate infection

Treatment in source: Penicillin G, cephamycins, or metronidazole

Additional agents: Carbapenems, clindamycin, or ureidopenicillins

Management principle: Consider source control for abscesses

Key clinical pearl: Because Eubacterium species are part of the normal human flora, a positive culture does not by itself establish disease; true infections are typically anaerobic, polymicrobial infections, especially abscesses and infections arising after disruption of normal mucosal barriers.

Infectious Disease and Microbiology – Erysipelothrix rhusiopathiae

Overview

Erysipelothrix rhusiopathiae is a Gram-positive bacillus that causes a characteristic occupational skin infection known as erysipeloid. Human infection is uncommon but occurs worldwide and is strongly associated with exposure to fish, shellfish, animals, animal products, or contaminated soil.

Although most infections remain localized to the skin, the organism can occasionally cause diffuse cutaneous disease, bacteremia, and infective endocarditis.

Microbiologic Characteristics

Erysipelothrix rhusiopathiae is an:

• Aerobic Gram-positive bacillus

• Zoonotic pathogen

• Environmental and animal-associated organism

It is especially notable for causing infection after inoculation through minor skin trauma during occupational exposure.

Incubation Period

The incubation period is:

Not clearly defined

Clinical infection usually follows direct inoculation of the organism into damaged skin.

Epidemiology

Human infection is rare but occurs worldwide.

Exposure is classically associated with people who handle:

• Fish

• Crustaceans and shellfish

• Meat or animal carcasses

• Livestock

• Animal products

• Soil contaminated by animals

Occupational risk is therefore increased in fish handlers, butchers, veterinarians, farmers, and similar workers.

Erysipeloid

The classic localized infection caused by E. rhusiopathiae is called:

Erysipeloid

This is a localized cutaneous infection that usually develops at the site of inoculation.

Clinical Features of Erysipeloid

Typical findings include:

• Painful or burning skin lesion

• Erythematous to violaceous discoloration

• Well-demarcated margins

• Gradual peripheral expansion

• Common involvement of the hands or fingers

Systemic symptoms are usually absent or mild in localized disease.

Diffuse Cutaneous Disease

Some patients may develop a more widespread cutaneous eruption accompanied by systemic symptoms.

Possible manifestations include:

• Fever

• Myalgias

• Arthralgias

• Multiple skin lesions

This represents a more extensive form of infection than classic localized erysipeloid.

Bacteremia

Rarely, E. rhusiopathiae can invade the bloodstream and cause:

Bacteremia

Bloodstream infection should raise concern for deeper or systemic involvement.

Infective Endocarditis

One of the most important severe manifestations is:

Infective endocarditis

Historically, E. rhusiopathiae bacteremia has had a notable association with endocarditis.

Patients with systemic infection may therefore require evaluation for cardiac involvement when clinically appropriate.

Diagnosis

Diagnosis is established by:

Culture of the organism

Specimens depend on the clinical syndrome and may include tissue or blood.

Because localized lesions can have relatively few organisms, obtaining an appropriate deeper specimen may improve diagnostic yield.

Treatment

The source recommends:

Penicillin G for 10 days

Penicillin has traditionally been considered an effective treatment for susceptible E. rhusiopathiae infection.

Additional Treatment Options

Alternative agents listed in the source include:

• Cephalosporins

• Clindamycin

• Ciprofloxacin

• Carbapenems such as imipenem or meropenem

Choice of therapy should depend on disease severity and susceptibility when available.

Important Antibiotic Pearl

A useful microbiology distinction is that Erysipelothrix rhusiopathiae is characteristically resistant to vancomycin.

This is clinically important because vancomycin is often used empirically for Gram-positive infections, but it is not a reliable treatment for this organism.

Occupational Exposure Pattern

A classic exposure history is:

Fish or animal handler

• ●

Minor cut or puncture wound

• ●

Painful violaceous hand lesion

→ Think Erysipelothrix rhusiopathiae

Differential Diagnosis

Localized erysipeloid may resemble:

• Cellulitis

• Erysipelas

• Contact dermatitis

• Other occupational skin infections

The exposure history is often the major clue.

High-Yield Clinical Pattern

Handling fish, shellfish, meat, or animals

• ●

Localized painful violaceous skin lesion on the hand

• ●

Gram-positive bacillus

→ Think Erysipelothrix rhusiopathiae

Severe Disease Pattern

Systemic symptoms or bacteremia

• ●

Possible cardiac murmur or persistent bloodstream infection

→ Evaluate for infective endocarditis

Exam Essentials

Organism: Erysipelothrix rhusiopathiae

Type: Gram-positive bacillus

Distribution: Worldwide

Frequency: Rare

Classic disease: Erysipeloid

Typical exposure: Fish, crustaceans, animals, meat, or soil

Common site: Hands and fingers after occupational inoculation

Systemic manifestations: Fever, myalgias, arthralgias

Serious complications: Bacteremia and endocarditis

Diagnosis: Culture

Traditional treatment: Penicillin G

Alternative agents: Cephalosporins, clindamycin, ciprofloxacin, carbapenems

Important resistance clue: Vancomycin resistance

Key clinical pearl: Erysipelothrix rhusiopathiae should be suspected in a fish or animal handler with a painful violaceous hand lesion, and severe bacteremic disease is particularly important because of its association with infective endocarditis.

Infectious Disease and Microbiology – Epidermophyton floccosum

Overview

Epidermophyton floccosum is a dermatophyte mold that causes superficial fungal infections of keratinized tissues. It is an important cause of tinea (dermatomycosis) worldwide.

Unlike some other dermatophytes, E. floccosum typically infects skin and nails but not hair, which helps explain why it does not cause tinea capitis.

⸻

Microbiologic Characteristics

Epidermophyton floccosum is a filamentous fungus characterized by:

• Septate hyaline hyphae

• Growth as a mold

• Dermatophyte behavior with affinity for keratinized tissues

It primarily involves the stratum corneum and nails.

⸻

Epidemiology

E. floccosum is a common cause of dermatophyte infection worldwide.

Transmission is generally associated with contact with infected skin, contaminated surfaces, clothing, towels, or other fomites.

⸻

Clinical Infections

E. floccosum causes superficial dermatophyte infections of the skin and nails.

Important manifestations include:

• Tinea cruris

• Tinea corporis

• Tinea pedis

• Inguinal dermatophytosis

• Onychomycosis

A major distinguishing feature is that it generally does not cause tinea capitis.

⸻

Tinea Cruris

Tinea cruris involves the groin and upper medial thighs.

Typical findings may include:

• Pruritic erythematous plaques

• Scaling

• Well-defined advancing borders

• Central clearing

E. floccosum is an important dermatophyte associated with this syndrome.

⸻

Tinea Corporis

Tinea corporis is dermatophyte infection of glabrous skin.

Lesions are often:

• Annular

• Scaly

• Pruritic

• Expanding outward with a more active border

⸻

Tinea Pedis

Tinea pedis affects the feet and may present with:

• Interdigital scaling and fissuring

• Plantar scaling

• Pruritus

• Maceration

E. floccosum is one of the dermatophytes capable of causing this infection.

⸻

Onychomycosis

E. floccosum can also infect the nails and produce onychomycosis.

Affected nails may become:

• Thickened

• Discolored

• Brittle

• Irregular or dystrophic

Nail infection generally requires a longer course of therapy than localized skin disease.

⸻

Why Tinea Capitis Is Absent

A useful distinguishing feature is:

Epidermophyton floccosum infects skin and nails, but not hair

Therefore:

Tinea capitis is not a typical infection caused by this organism.

This helps distinguish Epidermophyton from dermatophytes in the genera Trichophyton and Microsporum.

⸻

Diagnosis

Diagnosis is based on demonstrating the fungus in appropriate clinical specimens.

Specimens may include:

• Skin scrapings

• Nail material

The organism can be identified by:

• Direct microscopic examination

• Fungal culture

⸻

Microscopy

Direct examination of infected keratinized material may reveal:

Septate hyaline fungal hyphae

This supports the diagnosis of dermatophytosis.

⸻

Culture

Growth in fungal culture allows identification of the dermatophyte and can help distinguish E. floccosum from other causes of tinea.

⸻

Treatment – Extensive or Inflammatory Disease

For extensive or inflammatory manifestations, the source recommends:

Itraconazole 200 mg orally daily for 2–4 weeks

Systemic treatment is generally more appropriate when disease is widespread or difficult to manage with topical therapy alone.

⸻

Treatment – Localized Disease

For localized, noninflammatory infection, the source recommends topical:

Ciclopirox olamine, applied approximately every 12 hours.

Localized dermatophyte infections are commonly treated with topical antifungal agents.

⸻

Onychomycosis Treatment

For nail infection, the source recommends:

Itraconazole 200 mg orally daily for 3–6 months

The prolonged duration reflects the slow growth of nails and difficulty eradicating fungi from the nail plate.

⸻

High-Yield Clinical Pattern

Pruritic scaly dermatophyte infection

Skin or nail involvement

No hair infection

→ Think Epidermophyton floccosum

⸻

Dermatophyte Comparison

Epidermophyton

→ Infects skin and nails

→ Does not infect hair

Trichophyton

→ Can infect skin, hair, and nails

Microsporum

→ Typically infects skin and hair, but not nails

This tissue tropism is a useful exam distinction.

⸻

Exam Essentials

Organism: Epidermophyton floccosum

Type: Dermatophyte mold

Hyphae: Septate, hyaline

Distribution: Worldwide

Main infections: Tinea cruris, corporis, pedis, and onychomycosis

Hair involvement: Absent

Tinea capitis: Not typical

Diagnosis: Direct fungal examination + culture

Localized disease: Topical antifungal therapy

Extensive/inflammatory disease: Systemic itraconazole may be used

Onychomycosis: Requires prolonged systemic treatment

⸻

Key clinical pearl: Epidermophyton floccosum infects skin and nails but not hair, so it can cause multiple forms of tinea and onychomycosis, but not tinea capitis.