​Kembara Xtra - Medicine - Bacterial Pneumonia

​Kembara Xtra - Medicine - Bacterial Pneumonia 
A bacterial organism infects the pulmonary parenchyma to cause bacterial pneumonia.

Following categories can be used to categorize bacterial pneumonia:
 The degree of severity for community-acquired pneumonia (CAP) is as follows:
CAP in an outpatient environment CAP in an inpatient setting, but not severe CAP
- CAP in an intensive care unit (ICU) OR severe CAP is defined as the presence of one major criterion OR at least three minor criteria, and is based on established illness severity criteria.
Major requirements include respiratory failure requiring mechanical ventilation and septic shock requiring vasopressors.
 Minor criteria include hypothermia, hypotension, and hypotension requiring intensive fluid resuscitation (respiratory rate 30 breaths/min, PaO2/FiO2 ratio 250, multilobar infiltrates, disorientation, BUN 20, WBC 4, platelets 100,000).
Nosocomial pneumonia: contracted in medical facilities
Ventilator-associated pneumonia (VAP), which develops within 48 hours of endotracheal intubation, is a kind of hospital-acquired pneumonia (HAP) that did not appear to be incubating at the time of admission.

Epidemiology 
As of 2018, CAP is the ninth most prevalent cause of death in the United States (and considerably higher in people over 65).
African Americans have infection rates that are three times greater than those of white people, while Native Americans have infection rates that are five to ten times higher in adults and ten times higher in children. The most frequent causes of pneumonia that have been identified are respiratory viruses.
Incidence
HAP: 5 to 20 instances per 1,000 admissions; incidence rises 6- to 20-fold in ventilated patients. CAP: 5 to 6 cases per 1,000 people, with increasing incidence occurring in the winter.

Pathophysiology and Etiology 
Adults with outpatient CAP: Typical (85%) pathogens include Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, group A streptococcus, and Moraxella catarrhalis; atypical (15%) pathogens include Legionella species, Mycoplasma pneumoniae, and Chlamydophila pneumoniae.
Adults with non-severe or severe CAP, HAP, or VAP inpatients: Aerobic gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Acinetobacter sp.; Gram-positive bacteria such as Streptococcus sp. and S. aureus (including MRSA); Pediatric patients: Birth to 3 weeks: E. coli, S. pneumoniae is typical; C. pneumoniae and M. pneumoniae are atypical.

Immunosuppression: - Chronic steroid use (more than 20 mg/day or more than 2 mg/kg/day of prednisone for longer than 14 days)
Chronic health issues include asthma, COPD, type 2 diabetes mellitus (DM), chronic renal failure, CHF, liver illness, and cigarette use. - HIV/immunoglobulin deficiencies/solid organ transplant/TNF-inhibitor medication Other:
- Age >65 years, recent antibiotic therapy, or antibiotic resistance
hospitalization for less than two days within the last 90 days; poor functional status

Basic Prevention 
All children between the ages of 2 and 59 months should receive the pneumococcal conjugate vaccine (PCV13), which is administered at 2, 4, and 6 months of age. A fourth dose should be given between 12 and 15 months of age.
Adults over 65 who have never received a vaccine should only get PPSV23. Adults >65 years old in the high-risk group should have PCV13, then a one-year interval of pneumococcal polysaccharide (PPSV23).
After about a year, high-risk persons 65 years and older who have already had PPSV23 are advised to receive a dose of PCV13.
Adults aged 19 to 64 who smoke, have a chronic illness of the heart or lungs, drink excessively, or have chronic liver disease should receive a dosage of PPSV23, followed by PCV13 at age 65, and another dose of PPSV23 one year after PCV13 and at least five years after the first dose.
Adults at high risk who are under 19 and have immune-compromising conditions: According to the Centers for Disease Control, extra immunizations are needed in cases of asplenia, CSF leakage, cochlear implants, HIV infection, and immunodeficiencies.
 An annual influenza shot

Fever, chills, rigors, malaise, exhaustion, dyspnea, cough (with or without sputum), pleuritic chest discomfort, myalgias, and GI symptoms are used to diagnose the condition.
Lethargy, hypotonia, poor eating, dry mucous membranes, and vomiting in children

Alert CAP brought on by Legionella has been linked to high temperature (>104°F [40°C]), male sex, multilobar involvement, and GI and neurologic problems.
If a person has a history of advanced neurological illness or dementia and develops a sudden high fever and cough, aspiration pneumonia should be suspected.
Aspects of Geriatrics
In older persons with pneumonia, weakness, altered mental status, agitation, or a history of falls are common symptoms.

clinical assessment 
Vital signs include a temperature over 100.4°F (38°C), tachypnea, tachycardia, and hypoxemia in severe cases. Hypothermia, bradycardia, and hypotension may also be present.
 Pulmonary exam: asymmetric breath sounds, dullness to percussion, rales, rhonchi, decreased breath sounds unilaterally, increased fremitus, and abdominal discomfort
Examination results in children: groaning and retractions

Differential diagnoses include rheumatologic etiologies such sarcoidosis, viral pneumonia, bronchitis, asthma or COPD exacerbation, pulmonary edema, lung cancer, pulmonary tuberculosis, pneumonitis, and pulmonary edema.


Initial tests in the laboratory (lab, imaging)
There is no need for routine laboratory testing in the outpatient context.
The most effective and reliable biomarker for CAP diagnosis in an outpatient setting is CRP.
- No need for a chest x-ray based on the clinical diagnosis of fever, tachypnea, and physical exam findings.
- When influenza is present in the community, a quick influenza NAAT is favored over a rapid influenza antigen test in all CAP patients.
 Chest x-ray, CBC, and CRP in an inpatient context without critical care
- The use of procalcitonin is no longer advised.
- Urine Legionella antigen testing if exposure to a Legionella outbreak OR travel to a place where the disease is endemic
 Chest x-ray, CBC, CRP, inpatient or critical care environment, or severe CAP
- Blood cultures and sputum cultures are only advised for patients with severe CAP OR who have a history of MRSA or P. aeruginosa infections OR who are currently receiving treatment for MRSA/P. aeruginosa infections OR who have recently been hospitalized and received parental antibiotics.
- Testing for Legionella and pneumococcal antigens in urine should be done.
- The use of procalcitonin is no longer advised.
Evidence of necrotizing or cavitary pneumonia should make MRSA pneumonia suspect.
Tests in the Future & Special Considerations
 Influenza virus testing, as up to 80% of infants under 2 will have a viral cause.
 Only get blood cultures if there has been no improvement with antibiotics or if the CAP is severe.
Other Diagnostic Techniques For HAP and VAP Prior to starting/changing therapy, collect a lower respiratory tract sample for culture using bronchoscopy or non-bronchoscopy. Serial assessments might be required.


Management 

To assess the effectiveness of treatment and the need for hospitalization, use a risk calculator:
The Pneumonia Severity Index calculator may be found at https://www.thecalculator.co/health/Pneumonia-Severity-Index-(PSI)-Calculator- 977.html.
CURB-65: www.mdcalc.com/curb-65-score-pneumonia-severity

First Line of Medicine
Adults (1) - CAP, outpatient empiric treatment: no comorbidities or risk factors for MRSA or P. aeruginosa
 Doxycycline 100 mg twice daily OR amoxicillin 1,000 mg three times each day
 If local macrolide resistance is less than 25%, start with 500 mg of azithromycin on day 1 and subsequently 250 mg every day.
- CAP, outpatient empiric treatment: without risk factors for MRSA or P. aeruginosa but with comorbidities including alcoholism, asplenia, DM, cancer, or chronic heart, lung, liver, or kidney illness
Combination therapy may include cefpodoxime 200 mg BID, cefuroxime 500 mg BID PLUS amoxicillin/clavulanate 875 mg/125 BID.
 Doxycycline 100 mg BID OR azithromycin 500 mg on the first day, then 250 mg every day
Levofloxacin 750 mg daily or moxifloxacin 400 mg daily is the recommended monotherapy; the recommended minimum course of treatment is five days.
 CAP, inpatient: non-severe pneumonia without MRSA or P. aeruginosa risk factors
Initial IV antibiotics followed by a switch to oral antibiotics as symptoms improve; minimum course of treatment is five days.
Ampicillin/sulbactam (Unasyn), 1.5 to 3.0 g IV every six hours OR cefotaxime, 1 to 2 g IV every eight hours OR ceftaroline, 600 mg IV every twelve hours OR ceftriaxone, 1 to 2 g IV daily PLUS
CAP, inpatient: severe pneumonia without risk factors for MRSA or P. aeruginosa; azithromycin 500 mg PO/IV daily OR clarithromycin 500 mg PO q12h OR - Monotherapy with a respiratory fluoroquinolone: levofloxacin 750 mg PO/IV daily OR moxifloxacin 400 mg PO/IV daily
Combination of: - Ampicillin/sulbactam 1.5–3.0 g IV every six hours OR cefotaxime 1–2 g IV every eight hours OR ceftriaxone 1–2 g IV every day PLUS
CAP, inpatient: severe pneumonia with locally validated risk factors for MRSA or P. aeruginosa; azithromycin 500 mg PO/IV daily OR clarithromycin 500 mg PO q12h OR levofloxacin 750 mg PO/IV daily OR moxifloxacin 400 mg PO/IV daily
- Linezolid, 600 mg PO/IV q12h OR vancomycin, 15 mg/kg IV q12h (modify based on trough levels) for MRSA risk factors
Aztreonam, 2 g IV every eight hours; cefepime, 2 g IV every eight hours; meropenem, 1 g IV every eight hours; or piperacillin/tazobactam, 4.5 g IV every six hours. Routine use of corticosteroids is not advised, even in cases of severe CAP or HAP.
HAP, inpatient (2) - Patients who do not have MRSA risk factors and who do not have a high mortality risk should select one of the options below:
Piperacillin-tazobactam 4.5 mg IV every six hours (q.i.d.) or cefepime 2 g IV every eight hours (q.i.d.) or levofloxacin 750 mg IV every twenty-four hours (q.i.d.) or imipenem 500 mg IV every six hours (q.i.d.) or meropenem one g IV every eight hours (q.i.d.). Patients with MRSA
Inpatient VAP (2)
Cover MRSA if at risk for antibiotic resistance or if the prevalence of MRSA is unknown. - Empirically cover S. aureus, P. aeruginosa, and other gram-negative bacilli.
- Only use double Pseudomonas coverage from two separate classes in ICUs or with patients who are at high risk for developing antibiotic resistance.
Pediatric, outpatient (3 months) - Since viral infections are more prevalent in young children, antibiotic treatment is not typically necessary.
- The most researched duration of treatment is 10 days; if treating mild pneumonia as an outpatient, consider a shorter term.
- Suspected to have normal bacterial pneumonia
Amoxicillin 90 mg/kg/day given orally once every two hours (maximum dose: 4 g/day) OR amoxicillin-clavulanate
- Suspected to have unusual bacterial pneumonia
 Clarithromycin 15 mg/kg/day PO BID (max 1 g/day) or erythromycin 40 mg/kg/day PO daily Doxycycline 1 to 2 mg/kg/dose PO BID if >8 years old Azithromycin 10 mg/kg PO on day 1 (max 500 mg) and then 5 mg/kg/day (max 250 mg) on days 2 to 5
Pediatric inpatient (3 months): Typical bacterial pneumonia is thought to be the cause.
Not fully immunized: ceftriaxone 50 to 100 mg/kg/day IV q12-24h (maximum 2,000 mg) Fully immunized: ampicillin 200 mg/kg/day IV every six hours
If you think your patient has community-acquired MRSA, add vancomycin or clindamycin.
- Suspected to have unusual bacterial pneumonia
 Azithromycin, 10 mg/kg IV every day on days 1 and 2 (maximum 500 mg), and then 5 mg/kg PO every day on days 3 to 5 (maximum 250 mg).
Alternatives include levofloxacin (if reached growth maturity), erythromycin, doxycycline (if older than 8 years old), and clarithromycin.

Admission When suffering from CAP, patients with COPD or CHF are more likely to need to be admitted to the ICU.
Other factors include positioning to reduce the risk of aspiration, analgesia and antipyretics, chest physical therapy, IV fluids (and, if necessary, diuretics), pulse oximetry, and oxygen supplementation.

Child Safety Considerations
Infants under the age of three to six months, those with respiratory distress (tachypnea, dyspnea, retractions, grunting, nasal flaring, apnea, altered mental status, O2 saturation 90%), and those with CAP caused by a virulent pathogen such community-associated MRSA are all advised to have inpatient therapy.
 Clinical stability for 12 to 24 hours, including temperature 100°F (37.8°C), heart rate 100 beats per minute, respiratory rate 24 breaths per minute, systolic blood pressure 90 mm Hg, oxygen saturation 90% on room air, maintain oral intake, and normal mental condition


Continual Care 
Vaccinations and Smoking Cessation

Complications 
respiratory failure, sepsis, cavitation, bronchopleural fistula, empyema, abscesses, and necrotizing pneumonia

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