Detection of Extended Spectrum Beta-lactamase Producing Serotype Typhi in a Tertiary Care Centre.

INTRODUCTION

Infections caused by are an important public health threat in tropical and subtropical countries. Due to the emergence of resistance to ampicillin, chloramphenicol and trimethoprim/sulfamethoxazole (multidrug resistant salmonellae) in the late 1980s, fluoroquinolones and extended spectrum cephalosporins became the drugs of choice. Resistance to cefotaxime and ceftriaxone due to the production of Extended Spectrum Beta-Lactamase (ESBL) and reduced susceptibility to ciprofloxacin have emerged resulting in treatment failure. The Cefotaximase (CTX-M) type ESBLs are the most widespread beta lactamase among Enterobacteriaceae including salmonellae.

AIM

To detect the presence of in salmonellae causing human infections. Detection of genes to identify the coexistence of and gene

MATERIALS AND METHODS

The study included 103 consecutive, non-repetitive salmonellae isolated from clinical specimens obtained from July 2015- June 2016 which were identified up to species level by conventional/automated methods. Susceptibility to various classes of antimicrobial agents was determined by disc diffusion method. Minimum Inhibitory Concentration (MIC) to cefotaxime and ceftriaxone was determined by agar dilution method. The results were interpreted in accordance with Clinical & Laboratory Standard Institute (CLSI) (guidelines 2015. Detection of the ESBL phenotype was performed by the combined disk method. Polymerase Chain Reaction (PCR) amplification of all isolates was performed using group specific primers to characterize the presence of and .

RESULT

Of the 103 study isolates two isolates of were resistant to cefotaxime and ceftriaxone and had a MIC of 128μg/ml. PCR amplification and sequencing detected the presence of in these two isolates. These two isolates exhibited resistance to ciprofloxacin in vitro but gene was not detected in these isolates.

CONCLUSION

Resistance to third generation cephalosporins among salmonellae is a cause for concern as it may lead to treatment failure. It is imperative to continuously monitor the susceptibility pattern as enteric fever is endemic in India.