JAC Advance Access published online on July 18, 2008
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkn293
Original research |
Faecal carriage of extended-spectrum β-lactamase-producing Escherichia coli: prevalence, risk factors and molecular epidemiology
1 Sección de Enfermedades Infecciosas, Hospital Universitario Virgen Macarena, Seville, Spain 2 Departamento de Medicina, Universidad de Sevilla, Spain 3 Servicio de Microbiología, Hospital Universitario Virgen Macarena, Seville, Spain 4 Departamento de Microbiología, Universidad de Sevilla, Spain
Received 29 April 2008; returned 27 May 2008; revised 20 June 2008; accepted 23 June 2008
* Correspondence address. Sección de Enfermedades Infecciosas, Hospital Universitario Virgen Macarena, Avda. Dr Fedriani, 3, 41071 Seville, Spain. Tel/Fax: +34-955-009-024; E-mail: jrb{at}nacom.es
Objectives: The aim of this study was to investigate the epidemiology of faecal carriage of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in the community.
Patients and methods: Faecal carriage with ESBL-producing E. coli was studied in 53 outpatients with urinary tract infection (UTI) due to these organisms, 73 household members, 32 non-household relatives and 54 unrelated patients. Clonal relatedness of the isolates was investigated using repetitive extragenic palindromic-PCR and PFGE, and ESBLs were characterized by PCR and sequencing. Multivariate analysis was performed to investigate risk factors for faecal carriage.
Results: The prevalence of faecal carriage was 67.9% in patients with UTI, 27.4% in household members, 15.6% in non-household relatives and 7.4% in unrelated patients. Being a relative of a patient with UTI was independently associated with an increased risk of being a carrier. Among the relatives, multivariate analysis showed that those eating their main meal outside their own home >15 days during the previous month were less likely to be faecal carriers (OR = 0.2; 95% CI: 0.06–0.6; P = 0.007). The faecal isolates of patients with UTI were CTX-M-producers in 66.6% and SHV-producers in 33.3% of the cases, while the percentages for other population groups were 40% to 55.5% and 50% to 75%, respectively. Of the 19 families with >1 carrier member, 8 families had 2 members who shared clonally related isolates, 8 families had 2 members carrying different clones producing the same enzymes and there were 3 families where all members had different enzyme-producing clones.
Conclusions: Our results suggest that both acquisition from a common source and person-to-person transmission might contribute to ESBL dissemination.
Key Words: urinary tract infections , antimicrobial resistance , community-acquired infections , cephalosporin resistance