Nosocomial Pneumonia Epidemiology Common hospital-acquired infection Occurs at a rate of approximately 5-10 cases per 1000 hospital admissions Incidence increases by 6-20 fold in patients being ventilated mechanically. One study suggested that the risk for developing VAP increases 1% per day Another study suggested, highest risk occur in the first 5 days after intubation

Nosocomial Pneumonia

Epidemiology Nosocomial pneumonia is the leading cause of death due to hospital acquired infections Associated with substantial morbidity Has an associated crude mortality of 30-50% Hospital stay increases by 7-9 days per patient Estimated cost > 1 billion dollars/year

Nosocomial Pneumonia Hence, the importance of focusing on: Accurate diagnosis Appropriate treatment Preventive measures

Nosocomial Pneumonia Pathogenesis Risk factors Etiologic agents Differential diagnosis Treatment Prevention

Pathogenesis

Nosocomial Pneumonia Microaspiration may occur in up to 45% of healthy volunteers during sleep Oropharynx of hospitalized patients is colonized with GNR in 35-75% of patients depending on the severity and type of underlying illness Multiple factors are associated with higher risk of colonization with pathogenic bacteria and higher risk of aspiration

Nosocomial Pneumonia Pathogenesis Invasion of the lower respiratory tract by: Aspiration of oropharyngeal/GI organisms Inhalation of aerosols containing bacteria Hematogenous spread

Colonization Aspiration HAP MRSA*

Risk Factors

Nosocomial Pneumonia Risk Factors Host Factors Extremes of age, severe acute or chronic illnesses, immunosupression, coma, alcoholism, malnutrition, COPD, DM Factors that enhance colonization of the oropharynx and stomach by pathogenic microorganisms admission to an ICU, administration of antibiotics, chronic lung disease, endotracheal intubation, etc.

Nosocomial Pneumonia Risk Factors Conditions favoring aspiration or reflux Supine position, depressed consciousness, endotracheal intubation, insertion of nasogastric tube Mechanical ventilation Impaired mucociliary function, injury of mucosa favoring bacterial binding, pooling of secretions in the subglottic area, potential exposure to contaminated respiratory equipment and contact with contaminated or colonized hands of HCWs Factors that impede adequate pulmonary toilet Surgical procedures that involve the head and neck, being immobilized as a result of trauma or illness, sedation etc.

Etiologic Agents

Nosocomial Pneumonia Etiologic Agents S.aureus Enterobacteriaceae P.aeruginosa Acinetobacter sp. Polymicrobial Anaerobic bacteria Legionella sp. Aspergillus sp. Viral

Diagnosis

Nosocomial Pneumonia Diagnosis Not necessarily easy to accurately diagnose HAP Criteria frequently include: Clinical fever ; cough with purulent sputum, Radiographic new or progressive infiltrates on CXR, Laboratorial leukocytosis or leukopenia Microbiologic Suggestive gram stain and positive cultures of sputum, tracheal aspirate, BAL, bronchial brushing, pleural fluid or blood Quantitative cultures

Nosocomial Pneumonia Problems All above criteria fairly sensitive, but very non- specific, particularly in mechanically ventilated patients Other criteria/problems include Positive cultures of blood and pleural fluid plus clinical findings (specific but poor sensitivity) Rapid cavitation of pulmonary infiltrate absent Tb or cancer (rare) Histopathologic examination of lung tissue (invasive)

Nosocomial pneumonia Bronchoscopically Directed Techniques for diagnosis of VAP and Quantitative cultures Bronchoscopy with BAL/bronchial brushings (10,000 to 100,000 CFU/ml and less than 1% of squamous cells) Protected specimen brush method (>10³ CFU/ml) Protected BAL with a balloon tipped catheter (>5% of neutrophils or macrophages with intracellular organisms on a Wright-Giemsa stain)

Nosocomial pneumonia Multiple studies looked into the accuracy of quantitative culture and microscopic examination of LRT secretions as compared to histopathologic examination and tissue cultures (either lung biopsy or immediate post mortem obtained samples) Several trials conclude that use of FOB techniques and quantitative cultures are more accurate At least 4 studies concluded that bronchoscopically directed techniques were not more accurate for diagnosis of VAP than clinical and X-ray criteria, combined with cultures of tracheal aspirate Therefore no gold standard criteria exist

Nosocomial Pneumonia Differential diagnosis ARDS Pulmonary edema Pulmonary embolism Atelectasis Alveolar hemorrhage Lung contusion

Treatment

Nosocomial Pneumonia Antimicrobial Treatment Broad spectrum penicillins 3 rd and 4 th generation cephalosporins Carbapenems Quinolones Aminoglycosides Vancomycin Linezolid

Inadequate Antibiotic Therapy Antibiotic Resistance

Nosocomial Pneumonia Duration of antimicrobial treatment Optimal duration of treatment has not been established Most experts recommend days of treatment Recent data support shorter treatment regimens (8 days)

Prevention

Nosocomial Pneumonia Preventive Measures Incentive spirometry Promote early ambulation Avoid CNS depressants Decrease duration of immunosupression Infection control measures Educate and train personnel

Nosocomial Pneumonia Preventive Measures Avoid prolonged nasal intubation Suction secretions Semi-recumbent position( 30-45°head elevation) Do not change ventilator circuits routinely more often than every 48 hours Drain and discard tubing condensate Use sterile water for respiratory humidifying devices Subglottic secretions drainage

Craven, et al. Chest. 1995;108:s1-s16.

Nosocomial Pneumonia Preventive Measures Remove NGT when no longer needed Avoid gastric overdistention Stress ulcer prophylaxis: sulcrafate; antacids; H2 receptor antagonists Acidification of enteral feedings Prophylactic antibiotics Inhaled antibiotics Selective digestive decontamination Chlorexidine oral rinses Vaccines ( Influenza; Strep.pneumoniae)