Faecal carriage of extended-spectrum beta-lactamase-producing Escherichia coli: prevalence, risk factors and molecular epidemiology.
OBJECTIVE
The aim of this study was to investigate the epidemiology of faecal carriage of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in the community.


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.
Rodríguez-Baño
Jesús
J
Sección de Enfermedades Infecciosas, Hospital Universitario Virgen Macarena, Seville, Spain. jrb@nacom.es
López-Cerero
Lorena
L
Navarro
María D
MD
Díaz de Alba
Paula
P
Pascual
Alvaro
A
D000328:Adult; D000368:Aged; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D005192:Family Health; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D014552:Urinary Tract Infections / Q000382:microbiology; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D001618:beta-Lactamases