Prevalence of an epidemic ESBL-producing Escherichia coli strain in LTCFs in Belfast

Abstract number: 1733_845

Loughrey A., Rooney P., O'Leary M., McCalmont M., Warner M., Karisik E., Donaghy P., Smyth B., Woodford N., Livermore D.

Objective: ESBL-producing E. coli (ESBLEC) were isolated rarely in the Belfast area prior to 2003, but have since increased, particularly from residents of long-term care facilities (LTCFs). We investigated the epidemiology of ESBLEC among LTCF residents.

Method: LTCFs in the Belfast area were invited to participate. Residents consented to supply medical data and a single sample of faeces for ESBLEC culture. To qualify for inclusion the LTCFs had to provide complete data plus a faecal sample from at least 10 residents between July 05 and September 06. Samples were screened on CLED agar containing 1 mg/L ciprofloxacin with a cefpodoxime disc. Suspected ESBLEC colonies were confirmed as E. coli on TBX agar and ESBL production was confirmed by double disc synergy testing. Antibiotic susceptibilities were determined and interpreted using BSAC guidelines. Isolates were grouped broadly by antibiogram. PCR was used to screen selected isolates for an IS26-blaCTX-M link, which is characteristic of CTX-M-15 ESBL-producing UK epidemic strain A.

Results: Overall, 120/307 (39%) samples from 13 homes yielded at least one ESBLEC; range, 0% (2 LTCFs) to 75% (18 of 24 positive samples from 1 LTCF). Sixty (50%) of 120 ESBLEC-positive residents had no hospital admissions since January 04. The majority of ESBLEC had phenotypes consistent with production of a CTX-M enzyme. Isolates assigned presumptively to strain A by PCR accounted for 59/120 (49%) ESBLEC. Although distinct from strain A, most of the other 61 isolates also produced a group 1 CTX-M ESBL; these isolates had varying antibiograms, suggesting multiple strains. In the eastern district of Belfast, 50/175 samples were ESBLEC-positive, and 38 (76%) of these were strain A; in the other districts 70/132 samples were positive, but only 22 (31%) were strain A. The proportion of strain A isolates varied widely in different LTCFs, ranging from 0/11 ESBLEC in one centre to 9/9 in another.

Conclusions: Epidemic strain A was the predominant ESBLEC strain among LCTF residents in Belfast. ESBLEC were found in many residents with no history of recent hospital admission. LTCF residents requiring hospital admission tended to be referred to their nearest hospital. Differences in the distributions of strain A and other ESBLEC in LTCFs from particular districts are consistent with acquisition in hospital and introduction into the LTCF on discharge. Our study highlights the importance of spread within LTCFs in the epidemiology of ESBLEC.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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