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%, P < 0.001). 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 (P < 0.001). Among the representative ceftriaxone-resistant isolates, bla TEM gene was detected among 88% (7/8) of the strains, whereas only one strain of S. Typhi was positive for both bla TEM and bla CTX-M genes. The study reflects higher prevalence of MAR Salmonella spp. and is the first to report the bla TEM gene mediated ESBL production among Salmonellae in Bangladesh. Emergence of MAR Salmonella spp. in particular ESBL strains should be considered a public health concern.