Hospital acquired pneumonia Flashcards
Impact of HAP?
• Second most common nosocomial (originating in a hospital) infection following UTI
- Second most common cause of bacteremia in nursing homes
- Contributed to 22,983 deaths in the US3
- Resulted in 5.0 extra hospital days per infection
- Cost $5,683 per infection
General risk factors for HAP? what if its due to legionella?
- General – Advanced Age – Prior surgery – Ventilator therapy3 – Serious underlying disease, often of lungs
- Due to Legionella – Cytotoxic chemotherapy – Corticosteroid use
Explain the gram negative and positive organisms causing pneumonia and the percentages?
Gram-negative bacilli 9097 (58.7) Pseudomonas aeruginosa 2666 (17.2) Enterobacter spp 1617 (10.4) Klebsiella pneumoniae 1140 (7.4) Escherichia coli 998 (6.4) Haemophilus influenzae 993 (6.4) Serratia marcsecens 695 (4.5) Proteus mirabilis 527 (3.4) Acinetobacter spp 461 (3.0)
Gram-positive bacilli
Staphylococcus aureus 2729 (17.6)
Streptococcus pneumoniae 461 (3.0)
Diagnosis of HAP?
- Physical findings and chest radiographs
- Sputum gram stain
- Cultures of pleural fluid and empyema
- Bronchoscopically directed protected specimen brush (PSB) with quantitative cultures*
- Bronchoalveolar lavage
- More invasive techniques generally reserved for immunosuppressed patients
What are common etiologies of localized alveolar infiltrates?
- Pneumococcal pneumonia – most common
- Klebsiella pneumonia – lobar enlargement evidenced by bowing or bulging of a fissure favors Klebsiella or pneumococcal Type III pneumonia
- Staphylococcal pneumonia – pneumatoceles may form
- Streptococcal pneumonia – empyema common
- Anaerobic pneumonia – favored if posterior segment right upper lobe or superior right lower lobe with cavitation
- Tuberculosis pneumonia
- Histoplasmosis – acute pneumonic form
- Legionnaire’s disease
Ddx for cavitary and cystic lesions?
- Necrotizing pneumonia with abscess formation – Pseudomonas and anaerobes most common
- Granulomas due to M. tuberculosis and fungi
- Bronchogenic carcinoma
- Metastatic neoplasm, especially squamous cell neoplasms of head and neck origin
- Bleb or bulla
- Cystic bronchiectasis
- Echinococcal cyst
- Pulmonsry infarcts
- Pneumatocele – staphylococcal pneumonia in children
- Rheumatoid granulomas
- Wegener’s granulomatosis
ddx of diffuse alveolar infiltrates?
- Pneumonia due to Pneumocystis jiroveci, cytomegalovirus, varicella-zoster, Aspergillus, etc.
- Pulmonary edema
- Pulmonary hemorrhage
- Alveolar proteinosis
- Alveolar cell carcinoma
- Shock lung
- Oxygen toxicity
- Uremia
Ddx for diffuse interstitial disease?
- Lymphangitic metastases
- Pneumoconioses
- Drug hypersensitivity
- Congestive heart failure
- Sarcoidosis
- Pneumocystis jiroveci, viral or mycoplasma pneumonia
- Collagen vascular disease
- Tuberous sclerosis
- Amyloidosis
- Desquamative interstitial pneumonia
Explain the incidence pathogenesis and host factors for Klebsiella Pneumonia?
- Incidence – 6-8% of all pneumonias – 18-64% of all community acquired GNBP – 30% of nosocomial GNBP
- Pathogenesis – Endogenous aspiration oropharyngeal secretions – Major vessel thrombosis with ling necrosis – Intrapulmonary bleed, pyopenumothorax, pericarditis
- Host factors – Debilitated (DM, alcohol, chronic heart, kidney, liver) – Carriage in debilitated higher – 29% – Binding sites on mucosa higher in debilitated – Polysaccharide capsule enhances virulence by retarding phagocytosis
What are the clinical features and diagnosis of Klebsiella Pneumonia?
• Clinical features – Fever, malaise, rigors, cough, hemoptysis – Currant jelly-like sputum
• Diagnosis
– Chest x-ray • Lobar consolidation of upper lobes (right) • Abscesses (15-50%) • Bulging interlobar fissures
– Sputum • Gram stain (gram-negative bacilli) • Culture (encapsulated non-motile rod) • Blood cultures (20-60%)
Explain the pathology seen in Pseudomonas Aeruginosa Pneumonia? Host factors? Virulence factors?
• Pathology
– Necrotizing pneumonia • Alveolar septal necrosis • Necrosis of arterial walls with thrombosis • Micro abscesses (nodular, hemorrhagic)
– Host factors • Granulocytes very important (neutropenics most susceptible) • Opsonizing antibody
– Virulence factors • Slime lover, lipopolysaccharide, released proteolytic enzymes and toxins
– Clinical • Confused, toxic appearing • Chills, fever with green sputum
Explain the incidence and pathogenesis of Pseudomonas Aeruginosa Pneumonia?
- Incidence – 22% of nosocomial GNBP • Mortality
- Pathogenesis – Endogenous aspiration from colonized oropharynx • 18-25% patients with malignancies are carriers • 50% hospitalized malignancy patients carriers – Exogenous inhalation from contaminated aerosol – Hematogenous seeding (neutropenics, severe burns)
Diagnosis of Pseudomonas Aeruginosa Pneumonia?
• Diagnosis
– Chest x-ray • Diffuse, bilateral, lower lobe bronchopneumonia • Infiltrates are nodular • Metapneumonic pleural effusions
– Sputum
– Culture (motile with single polar flagellum) • Blue-green pigment
– Oxidase positive
Treatment for HAP?
- Empiric therapy should begin after obtaining blood culture, gram stain, and culture of respiratory secretions (if available)
- Target antibiotics for the following pathogens: – Streptococcus pneumonia – Pseudomonas aeruginosa – Staphylococcus aureus – Klebsiella spp – Enterobacter spp – Other commonly implicated gram-negative bacteria
- Switch to oral therapy when patient is able to tolerate
