Phenotypic and genotypic identification of urinary tract infections caused by E. coli in the Leicestershire area.

Backgrounds Uropathogenic E. coli is one of the highest producers of ESBLs (Extended-spectrum β-lactamases), a major public health concern. Objectives This study aims to investigate the prevalence of ESBLs and plasmid types in Leicestershire. Methods 380 urinary E. coli ESBL producing isolates were collected from the Leicester Royal Infirmary. Phenotypic analysis involved the MAST ESBL detection kit. Genotypic prevalence was investigated by using a multiplex PCR assay. Primers for blaCTX-M, blaSHV, blaOXA and blaTEM were designed. A second multiplex PCR assay was designed to identify blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, blaCTX-M-9 and blaCTX-M-25. To investigate the relationship between plasmid type and ESBLs, a multiplex PCR-based replicon typing assay was designed[RR1] to detect IncFIA, IncI1, IncL/M, IncN and IncFII. Conclusions Phenotypic analysis showed blaCTX-M genes confer higher resistance to CTX, than CAZ and CPD. All isolates that showed resistance to CAZ and CPD, were also resistant to CTX. Prominence for ESBL genes was blaCTX-M (37%)> blaOXA (5%), blaTEM and blaSHV (2%). Associations between the ESBL groups were detected. In the second multiplex assay, the most prominent were blaCTX-M-1 (56%) and blaCTX-M-9 (11%), with associations between the blaCTX-M groups detected. blaCTX-M was found to be associated with all replicons other than L/M. This is the first study to analyse the prevalence of uropathogenic ESBLs in Leicestershire. blaCTX-M is the most prominent ESBL in Leicestershire. blaCTX-M can be associated with other ESBLs. blaCTX-M-1 is the most common subgroup. Multiple associated plasmids can increase the spread of resistance, causing the epidemic we see today.