What are the diagnostic criteria for Hospital-Acquired Pneumonia (HAP)?

From the Guidelines

Hospital-acquired pneumonia (HAP) is diagnosed when a patient develops a new lung infection at least 48 hours after hospital admission that was not incubating at the time of admission, with qualifications including new or progressive radiographic infiltrates on chest imaging, along with at least two of the following clinical findings: fever above 38°C, leukocytosis (white blood cell count >12,000/mm³) or leukopenia (<4,000/mm³), purulent respiratory secretions, and declining oxygenation, as recommended by the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society 1. The diagnosis of HAP is based on a combination of clinical and radiographic findings, and the presence of at least two of the following clinical criteria: fever, leukocytosis or leukopenia, purulent respiratory secretions, and declining oxygenation.

• The clinical strategy emphasizes prompt empiric therapy for all patients suspected of having HAP, with the selection of initial antibiotic therapy based on risk factors for specific pathogens, modified by knowledge of local patterns of antibiotic resistance and organism prevalence, as stated in the guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia 1.
• The use of semiquantitative cultures of endotracheal aspirates or sputum with initial microscopic examination can help define the etiologic cause of pneumonia, and guide the modification of antibiotic therapy based on the clinical response and culture results, as recommended by the guidelines 1.
• Ventilator-associated pneumonia (VAP), a subset of HAP, occurs in mechanically ventilated patients at least 48 hours after intubation, and requires prompt empiric antibiotic therapy based on local antibiogram data and patient risk factors for multidrug-resistant organisms, as stated in the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society 1.
• Prevention strategies, such as elevation of the head of bed, oral care with chlorhexidine, and minimizing sedation to reduce ventilator days, can help reduce the risk of HAP and VAP, as recommended by the guidelines 1.
• The treatment duration for HAP is typically 7 days, though longer courses may be needed for complicated infections, and de-escalation of antibiotics should occur once culture results are available, as stated in the guidelines 1.
• HAP carries significant mortality (15-20%) and increases hospital length of stay, making prompt diagnosis and appropriate treatment essential, as emphasized in the guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia 1.

From the Research

Qualifications for Hospital-Acquired Pneumonia

• Hospital-acquired pneumonia (HAP) is a form of nosocomial pneumonia, distinct from ventilator-associated pneumonia (VAP) 2
• HAP can arise out of the ICU, or in the ICU, and can lead to severe illness, including the need for intubation and mechanical ventilation 2
• The American Thoracic Society (ATS) guidelines define patients at risk for multidrug-resistant (MDR) organisms on the basis of standardized criteria and time since admission (early <5 days; late ≥5 days) 3

Risk Factors for Multidrug-Resistant Organisms

• Prior hospitalization for at least 5 days 4
• Prior use of broad-spectrum antibiotics 4
• Prior colonization with resistant pathogens 4
• Admission to hospital settings with high rates of MDR pathogens 4
• Septic shock at the time of diagnosis with nosocomial pneumonia 4

Treatment Options

• Appropriate initial antibiotic therapy for presumed pneumonia in critically ill patients decreases the mortality rate 3
• An empiric algorithm supported by locally-driven analysis can predict more accurate coverage than one defined strictly by an unmodified guideline-driven approach 3
• Vancomycin with ciprofloxacin, cefepime, or piperacillin-tazobactam had predicted coverage of 95%, 94%, and 93%, respectively, for late HAP/VAP 3
• Linezolid has demonstrated favorable activity against Gram-positive bacteria, including MRSA, and is recommended in evidence-based guidelines as an alternative to vancomycin, particularly when MRSA is documented as the etiology 5

Antibiotic Combinations

• Combinations of antibiotics used in the empiric treatment of infections with suspected methicillin resistant Staphylococcus aureus etiology were investigated 6
• Vancomycin or teicoplanin + levofloxacin showed synergy in 16/50 and in 9/50 strains respectively, while vancomycin or teicoplanin + cefotaxime resulted synergic for 43/50 and 23/50 strains, respectively 6
• Triple combinations, involving teicoplanin, levofloxacin and ceftazidime or piperacillin/tazobactam gave synergy in 20/25 strains 6