CTX-M-2 and a new CTX-M-39 enzyme are the major extended-spectrum beta-lactamases in multiple Escherichia coli clones isolated in Tel Aviv, Israel.
The rate of occurrence of the extended-spectrum beta-lactamase (ESBL)-producing phenotype among Escherichia coli isolates in Tel Aviv is 12% (22). The aim of this study was to understand the molecular epidemiology of E. coli ESBL producers and to identify the ESBL genes carried by them. We studied 20 single-patient ESBL-producing E. coli clinical isolates. They comprised 11 distinct nonrelated pulsed-field gel electrophoresis (PFGE) genotypes: six isolates belonged to the same PFGE clone, four other clones included two isolates each, and six unrelated clones included only one isolate. All isolates produced various beta-lactamases with pIs ranging from 5.2 to 8.2, varying within similar PFGE clones. The most prevalent ESBL gene was bla(CTX-M); 16 isolates carried bla(CTX-M-2) and three carried a new ESBL gene designated bla(CTX-M-39). Three strains carried bla(SHV) (two bla(SHV-12) and one bla(SHV-5)), and two strains carried inhibitor-resistant ESBL genes, bla(TEM-33) and bla(TEM-30); 18 strains carried bla(TEM-1) and eight strains carried bla(OXA-2). Plasmid mapping and Southern blot analysis with a CTX-M-2 probe demonstrated that bla(CTX-M-2) is plasmid borne. The wide dissemination of ESBLs among E. coli isolates in our institution is partly related to clonal spread, but more notably to various plasmid-associated ESBL genes, occurring in multiple clones, wherein the CTX-M gene family appears almost uniformly. We report here a new CTX-M gene, designated bla(CTX-M-39), which revealed 99% homology with bla(CTX-M-26), with a substitution of arginine for glutamine at position 225.
Chmelnitsky
Inna
I
Division of Epidemiology and Laboratory for Molecular Epidemiology and Antibiotic Research, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Carmeli
Yehuda
Y
Leavitt
Azita
A
Schwaber
Mitchell J
MJ
Navon-Venezia
Shiri
S
D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics*
C071167:beta-lactamase CTX-2; C039404:beta-lactamase OXA-2; D001618:beta-Lactamases