VAP risk factors for MDR pathogens

Among the different risk factors associated with MDR pathogens in patients with VAP, the guidelines include: prior intravenous antibiotic use within 90 days, septic shock at the time of VAP, ARDS preceding VAP, 5 or more days of hospitalization prior to the occurrence of VAP, and acute renal replacement therapy prior to VAP onset. Therefore, in question D, a hospitalization for 2 days prior of VAP occurrence is not considered a risk factor for MDR pathogens.1

As outlined in the 2016 Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS) guidelines for management of hospital-acquired pneumonia (HAP) and VAP, established risk factors for multidrug-resistant pathogens in VAP are the following: acute renal replacement therapy prior to VAP onset (choice B is correct), prior IV antibiotic use within 90 days, septic shock at the time of VAP (choice C is incorrect), ARDS preceding VAP, or 5 or more days of hospitalization prior to occurrence of VAP.

VAP is defined as pneumonia that occurs at least 48 h after endotracheal intubation and mechanical ventilation. VAP can be diagnosed in the setting of a new or progressive infiltrate on chest imaging accompanied by leukocytosis or leukopenia, purulent tracheal secretions, fevers, or worsening oxygenation. The IDSA/ATS guidelines recommend obtaining a lower respiratory tract specimen in patients with suspected VAP. The most common etiologies of VAP are gram-negative bacilli and Staphylococcus aureus. Early and appropriate antimicrobial therapy is a cornerstone of management in VAP, and delays in the administration of appropriate antibiotics are associated with adverse outcomes. For these reasons, clinicians should be familiar with risk factors for multidrug-resistant infections.

Recommendations for antibiotic therapy have also been published in the 2016 IDSA/ATS guidelines for HAP and VAP. The choice for an initial empirical antibiotic regimen for clinically suspected VAP should be informed by local antibiotic resistance data, local distribution of pathogens, and risk factors for antimicrobial resistance. All regimens should empirically cover S aureus, Pseudomonas aeruginosa, and other gram-negative bacilli. If a patient has a risk factor for drug resistance, therapy against methicillin-resistant S aureus should be included. Risk factors for antibiotic resistance should also prompt clinicians to prescribe two antipseudomonal antibiotics from different classes. 

While poorly controlled type 2 diabetes is an independent risk factor for serious infections such as P aeruginosa skin and soft tissues infections and invasive fungal infections such as mucormycosis, it has not been identified as a risk factor for drug-resistant VAP (choice A is incorrect). Blood product transfusions are associated with risks including acute lung injury, circulatory overload, and very low risk of infection. However drug-resistant VAP is not associated with transfusions (choice D is incorrect).

Importantly, risk factors for drug resistance have low accuracy for the isolation of drug-resistant bacteria from lower respiratory tract cultures in patients with clinically suspected VAP. Clinicians must balance the limitations of risk-factor-based approaches with the potential harms of inadequate initial therapy for drug-resistant infections in patients who are critically ill.23456

Footnotes

  1. SEEK Questionnaires ↩

  2. Ang H, Sun X. Risk factors for multidrug-resistant gram-negative bacteria infection in intensive care units: a meta-analysis. Int J Nurs Pract. 2018;24(4):e12644. PubMed ↩

  3. Depuydt PO, Vandijck DM, Bekaert MA, et al. Determinants and impact of multidrug antibiotic resistance in pathogens causing ventilator-associated-pneumonia. Crit Care. 2008;12(6):R142. PubMed ↩

  4. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;63(5):e61-e111. PubMed ↩

  5. Palacios-Baena ZR, Giannella M, Manissero D, et al. Risk factors for carbapenem-resistant gram-negative bacterial infections: a systematic review. Clin Microbiol Infect. 2021;27(2):228-235. PubMed ↩

  6. Trouillet JL, Chastre J, Vuagnat A, et al. Ventilator-associated pneumonia caused by potentially drug-resistant bacteria. Am J Respir Crit Care Med. 1998;157(2):531-539. PubMed ↩