PHRM 541 Community Acquired Pneumonia: Diagnosis, Severity, Site of Care

Define pneumonia

Infection of the lung tissues via viruses, bacteria or fungi

Results in an inflammation of lung tissue and accumulation of inflammatory exudate

Define community acquired pneumonia (CAP)

Pneumonia acquired outside of the hospital setting or < 48 hours after hospital admission

Does not include immunocompromised patients

How can respiratory pathogens enter the lower respiratory tract?

1. Direct inhalation

2. Aspiration of oropharyngeal contents

3. Hematogenous spread

What are host defense mechanisms of the lungs?

Innate and adaptive immunity

Mucociliary transport

Normal bacteria flora

Cough reflex

Epiglottis

What can impair defenses of the lungs?

Respiratory viruses

Smoking

Chronic pulmonary disease (ex: cystic fibrosis)

Alterations in levels of consciousness

Immunocompromised comorbidities

What type of pathogens most commonly cause CAP?

Viral pathogens like influenza, rhinovirus, RSV, etc.

What are the most common bacterial pathogens that cause CAP?

Streptococcus pneumoniae

Haemophilus influenzae

Moraxella catarrhalis

Staphylococcus aureus (MSSA)

What are the most common atypical bacterial pathogens that cause CAP?

Mycoplasma pneumoniae

Legionella species (spp)

Chlamydia pneumoniae

Describe S. pneumoniae

Alpha hemolytic gram positive diplococci

Many serotypes

Describe H. influenzae

Gram negative diplococci

6 identifiable types

50% of strains produce beta-lactamase

What three factors make up a clinical diagnosis of CAP?

Clinical presentation (S/Sx, PE)

Laboratory data

Radiographic evidence

What are typical signs and symptoms of pneumonia?

Fever

Chills

Malaise

Productive cough

Dyspnea

Pleuritic chest pain

Increased sputum

Rust colored sputum

What are typical physical symptoms of pneumonia?

Tachypnea

Tachycardia

Diminished breath sounds

Dullness to percussion

Inspiratory crackles and wheezes

Chest wall reactions

What is typical laboratory data associated with pneumonia?

Increased leukocytosis

Decreased O2 saturation

Respiratory/blood culture and gram stain

S. pneumoniae urinary antigen

L. pneumophilia urinary antigen

Procalcitonin

Influenza virus NAAT

MRSA nasal swab

When should sputum cultures/blood cultures be obtained in non-severe CAP?

Obtain empirically in patients with strong risk factors for MRSA or PsA

When should Legionella urinary antigen be obtained in non-severe CAP?

Obtain in cases with epidemiological risk factors

When should Pneumococcal urinary antigen be obtained in non-severe CAP?

Not routinely recommended

What laboratory diagnostic tests are recommended in severe CAP?

Sputum cultures/blood cultures

Legionella urinary antigen

Pneumococcal urinary antigen

When should a MRSA nasal PCR be obtained in non-severe and severe CAP?

Obtain empirically in patients with prior respiratory isolation of MRSA and IV ABX in last 90 days

When should influenza & SARS-CoV2 rapid NAAT be obtained in non-severe and severe CAP?

When influenza/SARS-CoV2 viruses are circulating in the community

What are risk factors for isolation of MRSA or PsA?

Prior respiratory isolation of MRSA or PsA

Recent hospitalization AND receipt of IV ABX in the last 90 days

What is a MRSA nasal PCR used for?

Used to detect the COLONIZATION of S. aureus in the nares

Will NOT tell you if someone has an active infection

What has S. aureus colonization been shown to be a predictor of?

FUTURE clinical infection

What are MRSA nasal PCRs used for?

Used for antibiotic de-escalation ONLY

When should a MRSA nasal PCR be obtained?

Obtain test for patients with risk factors for MRSA infection

What should be done if a MRSA nasal PCR is positive?

Continue empiric coverage for MRSA

What should be done if a MRSA nasal PCR is negative?

Very low likelihood that the patient will have MRSA pneumonia

Would feel comfortable discontinuing empiric treatment for MRSA to avoid unnecessary treatment

De-escalate MRSA coverage if MRSA nares is negative

What is procalcitonin?

Peptide precursor to the hormone calcitonin

Rises in response to inflammation

What is the clinical utility of procalcitonin?

May help to shorten the duration of therapy when average CAP treatment duration exceeds 5 days with the use of serial levels

What are the limitations of procalcitonin?

Not recommended to determine INITIAL need for antibiotic therapy

Define severe CAP

Present in patients with either one major criteria or three or more minor criteria

What are the major criteria that define severe CAP?

Septic shock with need for vasodilators

Respiratory failure requiring mechanical ventilation

Define the pneumonia severity index (PSI)

Validated clinical prediction rule for prognosis upon CAP diagnosis, used to determine site of care

Stratifies patients into 5 mortality risk categories

Use in conjunction with clinical judgement

What are the benefits of the PSI?

Identifies larger proportions of patients at low risk

More comprehensive and requires laboratory and physiologic data

What are the limitations of the PSI?

Time consuming

Data may not be available at time of patient presentation

Describe the CURB-65

Designed to predict severity of illness more than mortality risk

Assign one point for each positive criteria

What does CURB-65 stand for?

C = Confusion

U = Uremia (BUN > 20 mg/dL)

R = Respiratory rate (≥ 30 rpm)

B = Blood pressure (SBP ≤ 90 or DBP ≤ 60 mmHg)

65 = Age ≥ 65 y/o

What does a CURB-65 score of 0-1 mean?

Outpatient management

What does a CURB-65 score of 2-5 mean?

Inpatient management

When should a patient be considered for ICU admission?

If one of the following criteria are met:

-septic shock requiring need for vasopressor support

-respiratory failure requiring mechanical ventilation