Multivariate analysis of risk factors for ESBL and AmpC producing Escherichia coli and Klebsiella pneumoniae at a Tertiary Care Hospital in Karnataka: A case control study

Abstract

Introduction: Extended spectrum β-lactamase (ESBL) and AmpC producing organisms pose unique challenges to clinical microbiologists, clinicians, infection control professionals. The objective of the present study was to analyze the risk factors that will help in identifying those at risk of acquiring infection by ESBL and/or AmpC producing organisms thereby making appropriate changes in the choice of antimicrobial therapy and minimizing treatment failures. Materials and Methods: Risk factors were evaluated using a retrospective Case control design. 100 patients with infections due to ESBL and/ or AmpC producing E.coli or K. pneumoniae were employed as cases. These were matched with 100 patients with non ESBL- non AmpC producing organisms (Controls). Univariate and Multivariate logistic regression analysis was performed to identify variables associated with becoming a case. Results: Out of the total 100 cases, E.coli 61 (61%) was the predominant ESBL and/or AmpC producer, followed by Klebsiella pneumonia 39 (39%). In the multivariate analysis, we found that duration of hospital stay for more than 5 days (OR=0.16, P=0), stay in ICU (OR=2.98, P=0.02) and prior treatment with antibiotics (OR=2.81, P=0.003) were statistically significant risk factors associated with acquisition of ESBL/AmpC producers. We also found invasive procedures like usage of urinary catheter (OR=3.34, P