Emergence and Dominance of CTX-M-15 Extended Spectrum Beta-Lactamase Among Escherichia coli Isolates from Children

Abstract

Of forty-seven extended-spectrum cephalosporin-resistant Escherichia coli isolates, collected from children at the Children's Hospital in 2006 (Tunis, Tunisia), we analyzed 32 isolates that were genotypically different by enterobacterial repetitive intergenic consensus -polymerase chain reaction. For all isolates, the double-disk diffusion test revealed synergy between clavulanate and cefotaxime and/or ceftazidime, suggesting the production of extended-spectrum beta-lactamases. Polymerase chain reaction experiments, performed on plasmid DNA, and sequencing revealed the presence of bla(TEM-1B) (26 isolates, 81%), bla(TEM-34(IRT-6)) (3 isolates, 9%), bla(SHV-12) (2 isolates, 6%), and bla(CTX-M-15) (31 isolates, 97%). Further, the insertion sequence ISEcp1 was found upstream from the bla(CTX-M-15) gene in 11 isolates. The bla genes were found alone or in various combinations in a single isolate. bla(TEM-1B) and bla(CTX-M-15) genes were detected in 26 out of the 32 isolates. Three isolates harbored both bla(TEM-34(IRT-6)) and bla(CTX-M-15). bla(SHV-12) was identified either alone or with bla(CTX-M-15) in a single isolate. Our investigation showed the dominance of CTX-M-type extended-spectrum beta-lactamases, with CTX-M-15 particularly common, and to our best knowledge, this is the first report of the coexistence of CTX-M-15 and IRT-6 in E. coli isolates from children in Tunisia.

Prevalence and characterisation of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates in healthy volunteers in Tunisia

“…In Tunisia, it has been reported that CTX-M-15 is the main type of ESBL in clinical E. coli isolates recovered in hospitals [7][8][9]23], and CTX-M-1 is the most frequent type among food E. coli isolates [3,4]. These data may suggest the potential food origin of the isolates recovered in the healthy human population, and the potential implication of the food chain in the transmission processes.…”

“…Similarities between the type of ESBLs and plasmids detected in E. coli isolates from humans, animals and food have suggested the potential transference of these ESBL genes from animals to humans, most likely through the food chain [6]. CTX-M-15 is the most frequent type of ESBL detected among clinical E. coli isolates in Tunisia [7][8][9]. However, this type of beta-lactamase has not been detected in food isolates in this country, in which the CTX-M-1 variant was frequently identified [3,4].…”

ESBL-producingEnterobacteriaceaein Africa – a non-systematic literature review of research published 2008–2012

“…In Tunisia, class A and D ESBLs, pAmpC, and carbapenemases were present, and the prevalence ranged from 11.7 to 77.8% in hospitals and was 0.7 and 7.3% in two communities (34–51). …”

Prevalence and molecular typing of extended-spectrum -lactamases in Escherichia coli, Enterobacter cloacae and Citrobacter freundii isolates from Laghouat Hospital, Algeria

“…The blaCTX-M-15 ESBL gene is considered to be the most prevalent ESBL worldwide, as it is found in a Tunisian study analyzed 32 ESBL E. coli isolates collected during a 10-month period, which reported the emergence of CTX-M-15 in 97% (31/32) of isolates; and 81% (26/32) also harbored TEM-1 (Réjiba et al, 2011).…”