Early Detection of Drug Resistant Enterobacteriaceae in Urinary Tract Infections using Chromogenic Agar Medium in a Tertiary Care Hospital, Kakinada, Andhra Pradesh, India

Introduction: The irrational and inappropriate use of beta lactam antimicrobial drugs has led to the advent of Extended Spectrum Beta-Lactamase (ESBL) resistant strains. ESBL producing Enterobacteriaceae strains are frequent causative agents both in community and in acquired nosocomial infections and Urinary Tract Infections (UTI). The phenotypic confirmatory tests rarely identify all ESBLs. Chrom ID (Chromogenic identification Media) ESBL – Bx (bioMerieux) is a completely new and innovative chromogenic medium designed specifically for the screening of ESBL producing Enterobacteria directly from urine samples. It is a ready to use selective media which is sensitive and specific for rapid and presumptive identification of ESBL producing Enterobacteriaceae. Aim: Early detection of ESBL producing Enterobacteriaceae directly from urine samples on chromogenic medium (Chrom ID- ESBL- Bx) and confirmation of ESBL producing Enterobacteria using Disc Potentiation Test (DPT). Materials and Methods: The present cross-sectional study was conducted in the Department of Microbiology, Rangaraya Medical College, Kakinada, Andhra Pradesh, India from November 2019 to March 2020 (five months duration). The study was done on 70 urine samples from patients with UTI. All samples were subjected to wet mount, inoculated directly for culture on Chrom ID ESBL- Bx agar and MacConkey agar. Antibiotic Susceptibility testing of ceftazidime and cefotaxime was done by Kirby-Bauer disc diffusion method and conformation of ESBL production by DPT using Clinical and Laboratory Standards Institute (CLSI) method. The Statistical Package for the Social Sciences (SPSS) Statistical package version (18.0) was used. Results: A total of 56 (80%) isolates were obtained from 70 urine samples, out of them 28 (50%) were Escherichia coli, 21 (37.5%) were Klebsiella spp., 7 (12.5%) were Proteus spp., 23 (82.14%) isolates of Escherichia coli, 15 (71.43%) of Klebsiella spp., 6 (85.71%) of Proteus spp., isolated were screened positive using Chrom ID ESBL-Bx agar. About 44 (78.57%) of total Enterobacteria (56) were screened for ESBL production. 20 (86.96%) of Escherichia coli, 11 (73.33%) of Klebsiella spp., and 5 (83.33%) of Proteus spp., that were screened positive using Chrom ID ESBL agar were confirmed (by DPT) as ESBL producers and 2 (16.6%) of total (12) isolates that were screened negative by Chrom ID ESBL agar were confirmed as ESBL producers when screened and confirmed by DPT. So sensitivity and specificity CHRO Magar was 94.73% and 55.5%. Conclusion: ESBL continues to become a serious public health threat. Results from present study showed that CHROMagar ESBL has a high sensitivity and a convenient method for making provisional diagnosis of drug resistant Enterobacterial infections in 24 hours. Chrom ID ESBL- Bx agar medium allows easy differentiation of different bacteria based on colony colouration.