Epidemiology of MDR, XDR and PDR Microbial Isolates from Patients admitted in Critical Care Units of a Tertiary Care Private Hospital of Kolkata - One-year Study Based on Phenotypic and Genotypic Data

Abstract

Introduction

Incidence of MDR (multi-drug resistant), XDR (extensively drug resistant) and PDR (pan-drug resistant) microbes is increasing across Indian hospitals, complicating antimicrobial therapy, especially in the critical care units.

Objectives

The present study focuses on the prevalence of MDR, XDR and PDR microbes in the Critical Care units of a tertiary care private hospital of Kolkata for one-year period: 1.9.2022 – 31.8.2023, based on microbiological (phenotypic) and molecular testing (genotypic) data.

Materials and methods

10,911 samples received from all the Critical Care units of the hospital were processed for culture and sensitivity by manual and automated methods. 1520 samples (13.9%) yielded growth of 1565 isolates. All the isolates were processed for antimicrobial resistance gene (carbapenem-resistance/ methicillin-resistance/ vancomycin-resitance) detection by Real-time Multiplex PCR (open system) on the day the growth was identified. The phenotypic sensitivity reports followed on the following day.

Results

73% of the isolates were obtained within 48 hours of admission. 27% were hospital-acquired. BSI caused 31% of the infections, followed by UTI (22%), RTI (16%), SSTI (6.5%), IAI and others (6%), while 18.5% of the isolates were colonizers. Among bacterial isolates, 1207 (86%) isolates were Gram-negative bacilli (Klebsiella sp.: 36%, E. coli: 31%, other Enterobacteriaceae: 9%; Pseudomonas sp.: 9%, Acinetobacter sp.: 10%), 192 (14%) Gram-positive cocci (S. aureus: 28%, CONS: 27%, Enterococcus faecium: 22.5%, E. faecalis: 9.5%, Pneumococci: 6%). 166 fungal isolates were obtained (Candida: 151: non-albicans: 67.5%, albicans: 32.5%). 85% of the 436 Klebsiella isolates were MDR (ESBL: 9%, Carbapenem resistant: 72%), 4% XDR (Polymixins-resistant). 74% of the 371 E. coli isolates were MDR (ESBL: 47%, Carbapenem-resistant: 21.5%). 75% of the 104 other Enterobacteriaceae were MDR (ESBL: 5%, Carbapenem-resistant: 51%), 1% XDR (Polymixins-resistant) and 2% PDR. 57% of the 107 Pseudomonas isolates were Carbapenem-resistant (MDR/ XDR), 5% Polymixins-resistant (XDR), 4% PDR. 88% of the 125 Acinetobacter isolates were carbapenem-resistant (MDR/ XDR). Real Time Multiplex PCR identified 568 (47%) of the 1207 GNB isolates as Carbapenemase producers: NDM: 50%, NDM+OXA48: 26%, OXA48: 19%. 37% of the 54 S. aureus isolates and 65% of the 51 CONS isolates were methicillin-resistant (all mecA mediated, identified by PCR). 34% of the 62 Enterococcus isolates were VRE - PCR identified VanA + VanB genes in 62% of VRE isolates, VanA in 33% and VanB in 5%. 11% of the Candida isolates were Fluconazole-resistant, 10.5% Amphotericin-B-resistant, 1% Echinocandin-resistant.

Discussions

The data shows a high prevalence of MDR and XDR bugs in the Critical care units of the hospital, which matches with data from other hospitals across India. This calls for judicious use of antimicrobials, an effective antimicrobial stewardship programme, and earnest implementation of infection control practices.