Genotypic Identification of Extended-Spectrum β-Lactamase (ESBL)Producing Enterobacteriaceae from Urinary Tract Infections in the Leicestershire Area, United Kingdom: A One Health Prospective

Objectives: Urinary Tract Infections (UTIs) are one of the most common infections diagnosed in the United Kingdom (UK). The prevalence of Extended-Spectrum-Β-Lactamase (ESBL) producing UTIs has dramatically risen, limiting treatment options. The emergence and spread of ESBLs is thought to be through the horizontal transmission of antibiotic resistance plasmids IncL/M, IncF, IncN and IncI1. These conjugative plasmids have been described as important vectors and directly linked to major outbreaks of antibiotic resistance. This study aimed to investigate the prevalence of ESBLs in Leicestershire, UK and their relationship with antibiotic resistance plasmids. Methods: 236 ESBL producing uropathogenic Enterobacteriaceae isolates were obtained from the Leicester Royal Infirmary (Leicestershire, UK). ESBL production was confirmed phenotypically via the MAST ID double disc synergy test. ESBL-producing genes (CTX-M, SHV, TEM and OXA) were identified by multiplex PCR. The CTX-M family was then further characterised into (CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9 and CTX-M-25) by multiplex PCR. The relationship between ESBL-producing genes and plasmid type was then investigated by multiplex PCRbased replicon typing to detect IncFIA, IncI1, IncL/M, IncN and IncFII. Results: ESBL genes were identified as follows: CTX-M (71.6%), OXA (7.6%), TEM (3.8%) and SHV (3.8%). Multiple resistance genes were detected in 16% of isolates. CTX-M genes were identified as follows: CTX-M-1 (84.1%), CTX-M-9 (12.5%), CTX-M-25 (1.7%), CTX-M-8 (1.1%) and CTX-M-2 (0.6%). Replicon typing results were as follows: IncL/M (29.2%), IncN (14.4%), IncI1 (5.1%), IncFII (27.5%) and IncFIA (23.3%). A combination of IncL/M, IncFII and IncFIA was the most common at 9.8%. A positive correlation between CTX-M and all plasmids except IncI1 was found. Conclusion: CTX-M harbouring Enterobacteriaceae are associated with multiple plasmids, which can be linked to its rapid spread across the world. Prevalence studies help to inform policy about antibiotic stewardship and resistance evolution, aiming to reduce resistance levels in the future.