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.