Sequence analysis of bla(CTX-M) genes carried by clinically significant Escherichia coli isolates in Kuwait hospitals.

Objective: To investigate the extent, distribution and sequence analysis of bla(CTX-M) genes carried by Escherichia coli isolated from patients admitted to all government hospitals in Kuwait.

Methods: Extended-spectrum β-lactamase (ESBL)-producing E. coli isolates were collected from the 8 major hospitals in Kuwait. CTX-M ESBLs were analyzed by PCR and sequenced. Clonality of the positive isolates was determined for genetic relatedness using pulsed-field gel electrophoresis (PFGE) with XbaI digestion of the genomic DNA.

Results: Of the 136 ESBL-positive isolates, 106 (77.9%) harbored bla(CTX-M) genes. Among these, bla(CTX-M-15) was the most frequent with a prevalence rate of 84.1%, followed by bla(CTX-M-14) (6.8%), bla(CTX-M-14b) (5.7%) and bla(TOHO-1) (3.4%). Ninety-three (87.7%) were isolated from Kuwaiti (35.9%), Egyptian (31.1%) and Indian (20.8%) nationals; the majority of isolates positive for bla(CTX-M-15) were mainly from these 3 nationalities. PFGE analysis did not demonstrate any clustering of positive isolates in any particular hospital.

Conclusions: This study confirms an explosive emergence of CTX-M-15 β-lactamase among E. coli isolates in Kuwait and shows that the strains were clonally heterogeneous with no evidence of inter- or intra-hospital spread. Thus Kuwait may represent an important source of CTX-M-15-positive E. coli.