Objectives:

Extended-spectrum beta-lactams are commonly included in empirical antibiotic regimens for the treatment of Gram-negative infections. The emergence of extended spectrum beta-lactamase (ESBL)-producing bacteria poses a serious threat to the continued use of this family of antibiotics. To date, ESBL-producing bacteria have been reported worldwide, mainly in hospital settings. The aim of this study is to ascertain the level of ESBL-producing bacteria in clinical samples submitted from patients outside of hospital.

Methods:

Over a 3-month period, we saved all cefradine-resistant Enterobacteriaceae collected from urine samples submitted to our laboratory for microbiological analysis. Isolates were provisionally identified by their colonial appearances on CLED medium and confirmed using the API 20E system. Antibiotic susceptibility to a range of antibiotics was determined using Stoke's disk diffusion method. All the isolates were screened for ESBL production using the standard Disc Synergy Testing (DST) and the commercially available MAST DD test. Polymerase chain reaction (PCR) using specific primers was used to screen for the presence of blaSHV and blaTEM in the isolates scoring positive for ESBL production. Nucleotide sequence analysis was used to determine the identity of the resistance determinants.

Results:

Eighty-four isolates from 78 patients were obtained during the study period. Forty-two (54%) were community-based patients. ESBL production was detected in 16 isolates from 10 patients (13%): nine Klebsiella species, five Enterobacter species, one Escherichia coli and one Citrobacter freundii. Three of the ESBL+ patients were community-based, only one of whom had recently been discharged from hospital. PCR showed that eight isolates harboured blaSHV while two isolates harboured blaTEM. Nucleotide sequence analysis of an internal fragment of the blaSHV showed the isolates to produce an SHV-2 like ESBL (five isolates). Identity of the ESBLs in the remaining isolates has not been determined yet.

Conclusion:

This is the first report describing the presence of extended-spectrum beta-lactamases in UK community-based patients. This highlights the continuing global emergence of these clinically important enzymes and the importance of screening for their presence not only in hospitalised patients, but in the community as well.