Comparative Study of CTX-M-15 Producing ST131 Clone Isolated from Urinary Tract Infections and Acute Diarrhoea.

BACKGROUND AND PURPOSE

The alarming increase in the prevalence of CTX-M-15 extended-spectrum β-lactamase (ESBL) producing has been significantly linked to the clonal expansion of emerging sequence type (ST131). This study aimed to screen for the O16/O25-ST131 clones among different phylogenetic types of strains isolated from urinary and diarrhoeal samples.

METHODS

A total of 205 strains isolated from patients with UTI and acute diarrhoea were investigated by phenotypic and genotypic methods for ESBL identification. Molecular methods were used for identification of O25/O16-ST131 clone and phylogenetic typing of isolates.

RESULTS

O25-ST131 clone was detected in 89/105 (84.8%) and 47/100 (47%) of urinary and intestinal isolates, respectively, with a significant difference (-value<0.001). There was a significant high rate of occurrence of ESBLs, MDR, and antibiotic resistance to most antibiotic classes among O25-ST131 than non-O25-ST131 isolates. CTX-M-15 gene was detected in 64/71 (90%) of ESBLs producing intestinal isolates and 54/79 (68.4%) of urinary ESBLs producing isolates. The O25-ST131 clone was reported among all phylogenetic groups. The O16-ST131 clone serotype was not detected in the study isolates.

CONCLUSION

High prevalence of the O25-ST131 clone was reported among extraintestinal and intestinal isolates. First detection of the O25-ST131 clone among phylogenetic groups other than group B2 draws attention of the ability of this clone to transfer among commensal groups. An increasing in the prevalence of CTX-M-15 among strains especially of intestinal origin is alarming as the intestine is the main reservoir for ExPEC strains causing UTI.