Plasmid Derived AmpC Genotypes among the Multidrug Resistant Enterobacteriaceae Strains Isolated from Urine Samples in Southern India

Abstract

Introduction: The most common pathogens causing Urinary Tract Infections (UTI) in community and hospital settings are Enterobacteriaceae. Antibiotic resistance is a major problem worldwide because of an increase in the use of antibiotics. Production of Extended Spectrum Beta-Lactamases (ESBLs) and AmpC beta-lactamases is the most common cause of resistance among Enterobacteriaceae (AmpC). Initially, AmpC b-lactamases received less attention globally, but now it has become a rising problem. Detection of AmpC β-lactamases expressing microbes is a requirement for addressing surveillance, for problems of hospital infection control, and for choosing optimal antimicrobial therapy. Aim: To study the genotype distribution of plasmid mediated AmpC β-lactamase produced in Enterobacteriaceae strains isolated from urine samples. Materials and Methods: A cross-sectional study based on clinical laboratory surveillance was conducted from July 2019 to February 2020. Sixty Enterobacteriaceae isolates were identified by standard biochemical reactions. AmpC screening were done by cefoxitin disk diffusion and confirmed by an inhibitor-based assay using boronic acid. The presence of six plasmid mediated AmpC genes was determined by multiplex Polymerase Chain Reaction (PCR). Statistical Package for the Social Science (SPSS) version 20.0 was used to obtain descriptive data. Results: Among 60 Enterobacteriaceae isolates, 23 (38.3%) were cefoxitin-resistant isolates which contain Escherichia coli strain (n=17) while the remaining samples consist of Klebsiella pneumoniae (n=5) and Proteus mirabilis strains (n=1). AmpC β-lactamase production was phenotypically confirmed in 12 (20%) isolates and genotypically confirmed by PCR analysis in 16 (26.6%) of all the urine isolates. In the present study, 3 (13%), 2 (8.6%) of cefoxitin resistant isolates harboured the DHA, EBC gene and 1 (4.3%) each harboured FOX and CIT gene, and 9 (39.1%) harboured a combination of the genes. Conclusion: The present study suggested the predominant existence of plasmid mediated AmpC producers in multi-drug resistant Escherichia coli and Klebsiella pneumoniae. We suggest continuous surveillance is important to effectively control the spread of these strains and for optimal clinical outcome.

Keywords

• boronic acid
• cefoxitin
• klebsiella pneumoniae
• multiplex polymerase chain reaction