Outcomes of adult patients in the intensive care unit with Pseudomonas aeruginosa pneumonia who received an active anti‐pseudomonal β‐lactam: Does “S” equal success in the presence of resistance to other anti‐pseudomonal β‐lactams?

STUDY OBJECTIVES: The most commonly prescribed antibiotics for patients with hospital‐acquired bacterial pneumonia (HABP) and ventilator‐associated bacterial pneumonia (VABP) due to Pseudomonas aeruginosa are the conventional anti‐pseudomonal β‐lactams (APBLs) (ie, ceftazidime, cefepime, meropenem, or piperacillin‐tazobactam). Similar resistance mechanisms in P. aeruginosa affect the APBLs, and it is unclear if resistance to one APBL can affect the effectiveness of other APBLs. This exploratory, hypothesis‐generating analysis evaluates the impact of APBL resistance among patients in the intensive care unit (ICU) with P. aeruginosa HABP/VABP who initially receive a microbiologically active APBL. DESIGN: A retrospective cohort [GJ1] [LT2] study. SETTING: Kaiser Permanente Southern California members (01/01/2011‐12/31/2017). PATIENTS: The study included adult patients admitted to the ICU with a monomicrobial P. aeruginosa HABP/VABP who received a microbiologically active APBL within 2 days of index P. aeruginosa respiratory culture. INTERVENTION: Patients were stratified by presence of resistance to APBL on index P. aeruginosa (0 vs. ≥1 resistant APBL). MEASUREMENTS: Primary outcomes were 30‐day mortality and discharge to home. MAIN RESULTS: Overall, 553 patients were included. Thirty‐day mortality was 28%, and 32% of patients were discharged home. Eighty‐eight patients (16%) had a P. aeruginosa HABP/VABP that was resistant to ≥1 APBL (other than active empiric treatment). Relative to patients with no APBL resistance, patients with resistance to ≥1 APBL had a higher 30‐day mortality (adjusted odds ratio (aOR) [95% confidence interval (CI)]: 1.65 [1.02–2.66]) and were less likely to be discharged home (adjusted hazard ratio (aHR) [95% CI]: 0.50 [0.29–0.85]). CONCLUSION: Further study is needed, but this exploratory analysis suggests that the full APBL susceptibility profile should be considered when selecting therapy for patients with P. aeruginosa HABP/VABP.