Association of blaCTX-M-15 and qnr genes in multidrug-resistant Salmonella Typhimurium and Shigella spp from India

Dear Editor, Acute infectious diarrhoea continues to be a significant cause of morbidity and mortality in children in low income countries. Among bacterial isolates, Shigella spp and Salmonella spp are known to contribute to the high burden of this illness in children. Recent literature survey reveals a sharp declining of prevalence of S. Typhi, while non-typhoidal Salmonella (NTS) and Shigella flexneri are increasing [1]. Among the Shigella isolates, > 90% are resistant to ampicillin and sulfonamides [2], 4%–10% of isolates are resistant to at least one of the thirdgeneration cephalosporins (ceftriaxone/cefotaxime) [3,2], and 7%–33% to fluoroquinolones [2]. Whereas in NTS, 86% are resistant to ampicillin, 33%–48% to sulfonamides [4,5], 34% to third-generation cephalosporins [3], and 24%-35% to fluoroquinolones [4,5]. Monitoring of cephalosporins and fluoroquinolones resistance is particularly important because these antibiotics are among the few therapeutic options commonly used for moderate to severe Salmonella and Shigella infections. The objective of this study was to determine the co-existence of qnr and extended-spectrum β lactamase (ESBL) genes in clinical isolates of multidrug-resistant (MDR) Shigella spp and Salmonella spp. (defined here as isolates resistant to ≥ 3 drugs)