1. Prevalence of CTX-M-14 type in Welsh Hospitals
50th ICAAC
Sept , 2010
Boston
Prevalence of CTX-M-14 type in Welsh Hospitals
M. WOOTTON, J. M. TYRRELL, T. R. WALSH, R. A. HOWE
Introduction
CTX-M enzymes have become the dominant Extended Spectrum ß-lactamases (ESBL) in Enterobacteriaceae (E) from Europe. In the UK 44.7% of 3rd generation cephalosporin (3GC) resistant Enterobacteriaceae contain CTX-M, dividing into 96% group 1 (mainly CTX-M15) and 4% group 9 (CTX-M9, 14 or 27) (Potz et al. 2006). Wales is a rural area specialising in cattle and sheep farming and CTX-M-14 has been found in E. coli from Cattle suffering from scour (diarrhoea) in the northwest. This study aims to determine which CTX-M types are prevalent in Welsh hospitals plus sequence types prevalent in community isolates.
Methods cont.
Genotypic characterisation was investigated using a multiplex PCR and specific primers blaCTX gps 1, 2, 8, 9, 25.
CTX-M type was confirmed for isolates with positive results for CTX-M group 9 via sequencing of the whole gene.
Figure 1: Percentage of Community and Hospital isolates in CTX-M groups
Table 2: CTX-M sequence types within CTX-M gp 9 positive isolate
Figure 2: Percentage of Community and Hospital isolates in CTX-M-9, -14 & -27
Table 3: Characterisation of CTX-M-9, -14 & -27
Table 1: Prevalence of CTX-M gps in 3GC Enterobacteriaceae
Results
Of 580 isolates 346 (59%) harboured CTX-M genes. 312 (90.2%) isolates were found to contain CTX-M gp1 genes, probably CTX-M-15. CTX-M gp2, gp8 and gp25 genes were found in 5 (8.9%), 3 (0.9%) and 0 (0%) of Enterobacteriaceae respectively (Table 1). 26 isolates harboured CTX-M gp9 genes, of which 6 (23%), 19 (73%) and 1 (4%) were confirmed as CTX-M-9, CTX-M-14 and CTX-M-27 by sequence analysis (Table 2). Of the 19 isolates with CTX-M-14, 18 were E. coli and 1 K. pneumoniae (Table 3).
The percentage of community (C) and hospital (H) isolates harbouring CTX-M gps can be seen in Figure 1. Of the isolates with CTX-M-14, 16 originated from the community and 3 from hospital (Figure 2).
Methods
ESBL presence was determined in 580 3GC resistant Enterobacteriaceae from 10 Welsh hospitals. Enterobacteriaceae were collected from both hospital and community. ESBL phenotype was determined via agar dilution (AD) using a cefotaxime and ceftazidime with and without 4mg/L clavulanate. Isolates were considered ESBL positive if 3 Log2 drop in MIC was seen with clavulanate.
Conclusions
A high prevalence of CTX-M 14 type was seen in isolates in areas of North and West Wales. Also the unusual CTX-M gp 8 genes were found in Bangor only. CTX-M-14 appeared to be more prevalent in community isolates. The relationship between human and cattle CTX-M warrants further investigation.
Travel grant kindly funded by:
Specialist Antimicrobial Chemotherapy Unit, Public Health Wales, Cardiff, UK