Background and purpose: Hospital-acquired pneumonia (HAP) remains an important cause of morbidity and mortality despite advances in antimicrobial therapy. The emergence of multidrug resistant (MDR) Pseudomonas aeruginosa  (PA) is of major concern. Our aim was to evaluate the risk factors and prognosis of HAP due to MDR-PA infection.
Patients and methods: In a retrospective observational study, we collected data on all episodes of HAP caused by PA (PA-HAP) occurring from January 2013 to December 2016. Characteristics of patients with drug-sensitive PA were compared with those with MDR-PA. Data of demographic, underlying conditions, peripheral neutrophil-to-lymphocyte ratio (NLR), and clinical outcomes were collected and analyzed.
Results: One hundred fifty-seven patients with PA-HAP were included, of which 69 (43.9%) patients were diagnosed with MDR-PA infection. There were significant differences between MDR-PA group and non-MDR-PA group on the following variables: initial inappropriate antibiotic therapy (P <0.001, OR 0.103, 95% CI 0.044–0.244), admission in more than two departments in previous 30 days (P <0.001, OR 0.186, 95% CI 0.072–0.476), and NLR level (P =0.020, OR 0.911, 95% CI 0.843–0.985). The effect of antibiotic treatment was significantly different (P <0.001, OR 4.263, 95% CI 2.142–8.483). The 30-day mortality was higher in MDR-PA group than that in non-MDR-PA group (P <0.001).
Conclusion: We have shown that lower NLR level was identified as a clinical predictor of MDR-PA infection in HAP patients. Even with goal-directed therapy, MDR-PA infection implicates poor outcomes in patients with HPA.
Keywords: risk factors, prognosis, multidrug-resistant Pseudomonas aeruginosa , hospital-acquired pneumonia