Sequence analysis of bla [CTX-M] genes carried by clinically significant Escherichia coli isolates in Kuwait hospitals

ABSTRACT

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. Extended-spectrum beta-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. 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. This study confirms an explosive emergence of CTX-M-15 beta-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