Introduction: To describe demographic aspects of a prospective multicentric nationwide study on Escherichia coli and Klebsiella pneumoniae producing extended spectrum b -lactamases (ESBL) in Spain, between March and June 2000.
Methods: 352 E. coli and K. pneumoniae strains showing a phenotype compatible to ESBL production were collected from 40 Spanish Hospitals. A form with demographic and clinical data was filled for every isolate. Identification and susceptibility testing (microdilution, NCCLS guidelines) were performed in a reference centre. RESULTS. 240 strains (170 E. coli and 70 K. pneumoniae) produced ESBL. E. coli ESBL (+) strains were isolated in 33 out of 40 participating hospitals, whereas K. pneumoniae were isolated in 17 hospitals. E. coli ESBL (+) prevalence ranged from 0% to 2.4% and K. pneumoniae ESBL (+) from 0% to 16.7%. Fifty-one percent of E. coli ESBL (+) were from outpatients, whereas 93% of K. pneumoniae ESBL (+) were from inpatients. E. coli ESBL (+) were mainly collected from Medicine and Surgery wards and K. pneumoniae from ICU and Paediatrics. ESBL (+) strains were isolated more frequently from urine samples. Patients' ages ranged from 0 to 93 years for E. coli (median 58 years) and 0 to 83 years for K. pneumoniae (median: 1 year). Paediatric cases excluded, these median values were 64 and 53 years, respectively.
Conclusions: E. coli and K. pneumoniae ESBL (+) were identificated in 90% of the participating hospitals. Although E. coli was more frequently isolated than K. pneumoniae, production of ESBL was more prevalent in K. pneumoniae. Fifty-one percent of ESBL producing E. coli were isolated from outpatients.