A retrospective cohort study of the risk factors and outcomes of antibiotic resistance in the intensive care unit

Background: Antibiotic resistance remains a major problem in the intensive care units (ICU). Various risk factors have been documented by various researchers. Similarly some factors have been identified to influence the outcome after the antibiotic resistance has been developed in the patients. This retrospective study aimed to identify and document the risk factors and outcomes in ICU of our hospital. Methodology: This retrospective, single-centre cohort study, involved 440 patients, treated in the ICU during January 2017 to December 2019. The medical records of the enrolled patients were reviewed to identify the risk factors and outcomes of antibiotic resistance. The data were analysed using the Statistical Package for the Social Sciences (SPSS) software version 26 (SPSS Inc., USA). Statistical tests used included chi-square test, Fisher's exact test, independent t-test, the Mann-Whitney test and simple or multiple logistic regression tests as per requirement. Results: The prevalence of antibiotic resistance was 22.3%. The odds for antibiotic resistance were increased 2.90 times with medical admission [Odds ratio (OR) 2.897; 95% confidence interval (CI) 1.560, 5.379; p = 0.01] and 3.42 times with carbapenem usage (OR 3.418; 95% CI 1.790, 6.526; p < 0.001). The odds were 73.2% lower with nitroimidazole usage (beta= -1.318, OR 0.268; 95% CI 0.131, 0.546; p < 0.001) and 62.2% lower with macrolide usage (beta = -0.973, OR 0.378; 95% CI 0.150, 0.950; p = 0.039). Each day of antibiotic usage increased the odds of antibiotic resistance by 1.07 times (OR 1.072; 95% CI 1.037, 1.111; p < 0.001), and each additional antibiotic prescribed increased the odds of antibiotic resistance by 1.72 times (OR 1.717; 95% CI 1.218, 2.423; p = 0.02). The antibiotic resistance mortality rate was 68.4%. Conclusions: Antibiotic resistance increased the mortality rate in the ICU, and the risk factors increased with medical-related admission, carbapenem usage, longer antibiotics duration and more antibiotic usage.