Prevalence of multidrug-resistant Salmonella typhi in typhoid patients and detection of blaCTX-M2 and blaCTX-M9 genes in cefetoxime-mediated extended spectrum β-lactamase-producing Salmonella typhi isolates

Abstract

Objectives: Prevalence of multidrug-resistant (MDR) S. typhi in typhoid-positive patients, phenotypic screening and molecular detection of blaCTX-M2, and blaCTX-M9 ESBL coding genes. Materials and methods: Sixty-six of the 650 clinical blood samples collected have turned out to be positive for S. typhi. Antimicrobial susceptibility and MIC was done as recommended by CLSI. Phenotypic screening of ESBL production and the PCR amplification ESBL coding genes blaCTX-M2, and blaCTX-M9 was also achieved. Results: Sixty-six out of 650 clinical blood samples have turned out to be positive for S. typhi with an incidence rate of 10.15%. Among 66 isolates (n=44) isolates were MDR. The significant increase in MIC was observed between 128-256 µg/ml to cefetoxime, among the isolates, 9 S. typhi isolates reported positive for cefetoxime-mediated ESBL production. The PCR amplification of ESBL coding genes blaCTX-M2 and blaCTXM-9 yielded amplicon size of 884 and 692 bp, respectively. The ciprofloxacin resistant and cefetoxime sensitive standard MTCC S. typhi 734 and S. typhi BST 63 strain showed absence of both blaCTX-M2 and blaCTXM-9 genes Discussion: The study shows an increase in the incidence rate of MDR S. typhi infection and ESBL production in S. typhi clinical isolates.