Infectious Disease

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  • Topic: Pneumonia, Streptococcus pneumoniae, Community-acquired pneumonia
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Community Acquired Pneumonia

Dora E. Wiskirchen, PharmD, BCPS
PHCY 836 – Day 5 PM

Learning Objectives
Identify risk factors for the development of pneumonia.
Explain the pathophysiology, signs and symptoms, most common bacterial etiologies and associated resistance patterns, severity of illness scoring systems, and diagnostic techniques for pneumonia. Define atypical pneumonia and characterize patients who may be at risk for developing this type of pneumonia. Evaluate pharmacologic therapies used for the empiric and definitive treatment of community acquired pneumonia by identifying the appropriate dose, adjustments for hepatic and renal impairment, duration of therapy, adverse events, contraindications, effectiveness, and monitoring parameters. Differentiate between currently approved fluoroquinolones and macrolides in terms of the antimicrobial spectra in the treatment of pneumonia. Select an appropriate antimicrobial regimen for the treatment of community acquired pneumonia based on clinical practice guidelines and other peer reviewed literature when given a patient case. CAP Clinical Practice Guidelines

Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults. Clin Infect Dis 2007;44:S27-72. Lower Respiratory Tract Infections

Lower Respiratory Tract
Tracheobronchial Tree
Lung parenchyma
Infections
Bronchitis
Bronchiolitis (RSV)
Pneumonia
Community-acquired
Healthcare-associated
Hospital-Acquired
Ventilator-associated
Pathophysiology
Occur when host defenses are hindered or overwhelmed
Humoral immunity, cellular immunity, anatomic mechanisms

Inoculation
Most common: colonization of upper airways, high concentrations, aspiration of oropharyngeal secretions Less common: via blood from an extrapulmonary source, or inhalation of infected aerosolized particles Epidemiology of Pneumonia

Most common infectious cause of mortality in the US

3 million cases diagnosed annually

$20 billion in healthcare costs
Diagnosis
Chest X-ray

Non-specific S&S
fever, respiratory rate, elevated WBC, lung sounds, hypoxia

Gram Stain and Microbiological culture
1 tracheal aspirate (expectorated sputum, BAL, PSB sample)
2 blood cultures
Most specific for finding causative pathogen
Often negative in up to 60% of patients
Ideally, collected prior to antibiotic administration
Not required for outpatients unless failure of therapy
Right Upper Lobe Infiltrate on Posterior and Lateral Chest X-ray Diagnosis
Chest X-ray

Non-specific S&S
fever, respiratory rate, elevated WBC, lung sounds, hypoxia

Gram Stain and Microbiological culture
1 tracheal aspirate (expectorated sputum, BAL, PSB sample)
2 blood cultures
Most specific for finding causative pathogen
Often negative in up to 60% of patients
Ideally, collected prior to antibiotic administration
Not required for outpatients unless failure of therapy
Diagnosis
Serology

Urinary Antigen Tests (CAP)
Rapid (15-30 minutes) turn around
Legionella pneumophila serogroup 1
Streptococcus pneumoniae

Severity-of-Illness Scores
Assist in determining risk of mortality, guidance for admission to hospital, ICU vs Ward Pneumonia Severity Index (PSI)
CURB-65
Confusion
Urea (BUN > 20mg/L)
Respiratory rate ≥ 30 breaths per minute
Blood pressure (systolic, 4 mcg/ml (nonmeningitis breakpoint)

North America (2004-2008): 27% intermediate (MIC=4), 15% resistant (>4)

When PRSP, there is often in-vitro resistance to some beta-lactams, macrolides, doxycycline, and trimethoprim/sulfamethoxazole

Antipneumococcal fluoroquinolones (levofloxacin, moxifloxacin), the ketolides (telithromycin), vancomycin, and linezolid are active against most PRSP

Risk Factors
Age 65 years
Beta-lactam therapy within past 3 months
Immune-suppressive illness (including treatment with corticosteroids) Multiple medical...
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