Emergence of blaTEM Type Extended-Spectrum β-Lactamase Producing Salmonella spp. in the Urban Area of Bangladesh

Salmonellosis, an acute invasive enteric infection, is endemic in Bangladesh. We analyzed 128,312 stool samples of diarrheal patients to identify Salmonella spp. during 2005–2013. A total of 2120 (1.7%) Salmonella spp. were isolated and the prevalence of Salmonella spp. decreased significantly over time (2→1%, ). Among the typhoidal Salmonella (TS) serogroups, S. Typhi was predominant (404, [65.1%]) followed by S. Paratyphi B (139, [22.4%]) and S. Paratyphi A (78, [12.6%]). Of the nontyphoidal Salmonella (NTS) isolates, the serogroup C1 (560, [37%]) was predominant followed by B (379, [25%]), C2 (203, [14%]), E (127, [9%]), and D (94, [6%]). Most of the resistance was found towards nalidixic acid (40%), ampicillin (36%), cotrimoxazole (20%), chloramphenicol (13%), ciprofloxacin (4%), and ceftriaxone (4%). Interestingly, 32% of the isolates showed reduced susceptibility to Cip. Multiantibiotic resistance (MAR, ≥3 drugs) was more common among TS than NTS strains ( ). Among the representative ceftriaxone-resistant isolates, gene was detected among 88% (7/8) of the strains, whereas only one strain of S. Typhi was positive for both and genes. The study reflects higher prevalence of MAR Salmonella spp. and is the first to report the gene mediated ESBL production among Salmonellae in Bangladesh. Emergence of MAR Salmonella spp. in particular ESBL strains should be considered a public health concern. 1. Introduction Salmonellosis due to nontyphoidal Salmonella (NTS) infection is a global public health concern, particularly in Salmonella endemic low and middle income countries (LMICs). Treatment is critical for persons with severe disease, particularly children and immune compromised people. Treatment with an appropriate antibiotic can shorten the duration of symptoms, significantly reduce severity of disease and the risk of transmission, and prevent potentially lethal complications. Emergence of resistance to first-line therapy like ampicillin, chloramphenicol, and cotrimoxazole including ciprofloxacin among Salmonella spp. during the last decades has complicated the situation [1, 2]. For treatment of Salmonella infection resistant to these drugs, extended-spectrum cephalosporins (ESCs) are considered as an alternative therapeutic choice. With the increased use of β-lactam antibiotics to treat enteric infection, Salmonella spp. had acquired resistant to third generation cephalosporin antibiotics in different parts of the world and had been associated with clinical treatment failure [3, 4]. Extended-spectrum beta-lactamases (ESBL) are usually encoded by large