Escherichia coli producing SHV-type extended-spectrum beta-lactamase is a significant cause of community-acquired infection.

OBJECTIVES: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBLEC) is an increasingly significant cause of community-acquired infection worldwide. The epidemiological features of CTX-M- and SHV-producing ESBLEC causing community-acquired infections are compared.

METHODS: A multicentre cohort study including all community-acquired infections caused by ESBLEC in four geographical areas of Spain was carried out. ESBL characterization was by isoelectric focusing, PCR and sequencing. Demographics, previous healthcare contact, co-morbidity, use of antimicrobials, invasive procedures and type of infection were collected for all patients. Patients with CTX-M- and SHV-producing isolates were compared using logistic regression.

RESULTS: One hundred and twenty-two cases (95% urinary tract infections) were included. ESBLs were characterized in 112 isolates; 77 isolates (69%) produced CTX-M, 36 (32%) produced SHV and 7 (6%) produced TEM enzymes (8 produced >1 ESBL). Patients with isolates producing CTX-M enzymes only (CTX-M group, n = 70) and SHV enzymes only (SHV group, n = 31) were compared. There were no differences in terms of underlying disease, previous healthcare contact, invasive procedures, antibiotic use or type of infection. Multivariate analysis including geographical area showed that a Charlson Index score of >2 (OR = 4.0; 95% CI = 1.2-12.6) was associated with SHV isolates, while age >60 (4.7; 1.7-12.5) was associated with CTX-M isolates.

CONCLUSIONS: SHV-producing ESBLEC is a significant cause of community-acquired infection in Spain; the clinical epidemiology of such isolates seems very similar to that of CTX-M-producing E. coli.