Mortality and microbiological clearance among critically ill patients receiving Polymyxin B in a Malaysian ICU: A 10 years retrospective study

Abstract

Background: In the era of increasing bacterial resistance, Polymyxins became the choice to treat infection by multidrug resistant organism. This study aimed to observe the microbiological outcome and all-cause mortality among patients receiving Polymyxin B (PolyB) in Intensive Care Unit (ICU). Methods and materials: In this retrospective observational study, patients who were prescribed PolyB were identified from the hospital electronic prescribing system. Only patients who were prescribed in ICU were included. Culture and sensitivity (C&S) before and after initiation of PolyB therapy was retrieved to determine microbiological clearance. Results: Since year 2008 to 2018, a total of 572 patients were prescribed PolyB. After excluding non-ICU cases and missing data, 31 patients were included. The median age of patients was 59 (5–68) y old and 15 (48.4%) were female. The comorbidities were hypertension (14, 45.2%), diabetes mellitus (11,35.5%) and/or dyslipidemia (9, 29%). Almost all patients (96.8%) were on inotropes. The length of ICU stay was median 20 (15–25) d. The average weight were 73.7 ± 21.8 kg with a median cumulative dose of 750 (385–1225)mg or average 2.2 ± 0.6 mg/kg/day, given intravenously for the median duration of 7 (4–12) d. The documented indications were pneumonia (15, 48.4%) and sepsis (14; 45.2%). Common infection sites were respiratory tract (16; 51.6%) and bloodstream (7; 22.6%). Among all the bacteria isolated in 28 cultures, Acinetobacter baumannii was the most common (25, 80.6%), followed by Pseudomonas aeruginosa (3, 9.7%). Minimum inhibitory concentration (MIC) were determined in 61.3% of cases and found to be ≤2 mg/L. Cultures were repeated in 21 cases which showed microbiological clearance in 14 (66.7%) patients but not in 7 patients (33.3%). During therapy, acute rise of serum creatinine was observed in 14 (45.2%) patients. Since the initiation of PolyB, 18 (58.1%) patients died during therapy. Overall, 21 patients (67.7%) died within 14 d and 29 patients (93.5%) died within 30 d. The commonest documented cause of death was septic shock (25; 83.3%). Conclusion: There was a high rate of mortality seen among patients receiving PolyB in ICU despite microbiological clearance in two thirds of patients. Further investigations and interventions are warranted to improve these outcomes.