HOSPITAL-ACQUIRED PNEUMONIA AND VENTILATOR-ASSOCIATED PNEUMONIA
The long-awaited update to the IDSA’s hospital-acquired pneumonia (HAP)/ventilator-associated pneumonia (VAP) guidelines was finally revealed in summer 2016.8
Similar to the last version released in 2005, the update was co-endorsed by the American Thoracic Society and covers a range of topics from diagnosis to treatment.8,9
The new guidelines also provide additional remarks, “Rationale for the Recommendation,” which describe the panel’s “Values and Preferences” for each recommendation. Given the current healthcare landscape of increasing multidrug-resistant organisms(MDROs), the panel attempted to strike a balance between appropriate broad-spectrum antimicrobial use and minimizing unnecessary antimicrobial exposure. The updated guidelines have also incorporated the now common “Grading of Recommendations Assessment, Development and Evaluation” methodology used in other recent IDSA guidelines.
Perhaps one of the largest changes is the removal of the “healthcare-associated pneumonia” terminology. It was previously thought that a subset of patients would be at increased risk of resistant pathogens by virtue of frequent contact with the healthcare system. However, increasing evidence has shown that individual patient characteristics may better predict risk for MDROs than healthcare exposure alone.10
Therefore, these guidelines describe a more limited spectrum of patients compared to the prior version. The panel indicated that a forthcoming update to the Community-Acquired Pneumonia guidelines will likely incorporate a validated scoring tool to outline those who present from the community and are at risk for MDROs.
Generally, noninvasive sampling with semiquantitative cultures is recommended for a diagnosis of VAP, given insufficient evidence supporting invasive sampling methods, including protected specimen brush (PSB), blind bronchial sampling, or bronchoalveolar lavage (BAL). The value of obtaining culture data to deescalate or discontinue therapy is also addressed. For example, patients with suspected HAP should receive tailored treatment based on noninvasive respiratory sampling compared with a full course of empiric therapy (in the case that no cultures were obtained). Patients with suspected VAP and invasive quantitative culture results below the VAP diagnostic threshold (PSB <103
Colony-Forming Units(CFU)/mL; BAL <104 CFU/mL) can have their antimicrobials discontinued safely. Tracheobronchitis should not be treated to avoid unnecessary antimicrobial exposure.
The updated guidelines also highlight the importance of understanding local microbiology trends to optimize empiric therapy by minimizing exposure to unnecessary antimicrobials, such as decreasing empiric methicillin-resistant Staphylococcus aureus
(MRSA) coverage and avoiding dual gram-negative coverage when possible. For example, MRSA coverage for VAP is only recommended in units where >10% to 20% of S. aureus
isolates are methicillin-resistant or if the prevalence is not known. “Double-coverage” of Pseudomonas
spp. is only recommended if specific criteria for MDRO are met, if there is >10% resistance of gram-negatives to the agent being considered for monotherapy, or if local gram-negative susceptibilities are unknown. Resistance thresholds are less prescriptive for HAP, with the MRSA coverage threshold set arbitrarily at >20% methicillin resistance or if the patient has “high risk of mortality,” while “double-coverage” for gram-negatives is only recommended if “high risk of mortality” or risk factors, such as structural lung disease, are present. However, modification of resistance thresholds may be considered in an individual unit with the goal of ≥95% of patients receiving empiric therapy active against likely pathogens.