CTX-M–Type β-Lactamases Affect CommunityEscherichia coliTreatment, Greece

To the Editor: In recent years, a new group of extended-spectrum βlactamases (ESBLs), the CTX-M-type enzymes, has emerged among Enterobacteriaceae (1).These enzymes are much more active against cefotaxime than against ceftazidime and exhibit greater susceptibilty to tazobactam than to clavulanate.Currently, the CTX-M family includes at least 30 alleles, which may be clustered on the basis of sequence similarity into four major evolutionary lineages (2).These enzymes were first detected in South America, Germany, and France, and subsequent reports found them to be in several European countries as well as in the Far East and North and South America (1-5).All of these studies have described the production of CTX-M-type β-lactamases in Enterobacteriaceae that have been isolated from patients with hospital infections, whereas surveys assessing countrywide prevalence of CTX-M clusters in community-acquired infections have not been carried out.We report the dissemination of various CTX-M-type enzymes in clinical isolates of Escherichia coli recovered from community-acquired infections in two large regions of Greece.The microbiology databases of two healthcare systems in Greece that serve as tertiary care centers for their region (University Hospital of Larissa and Hippokration University Hospital of Thessaloniki) were prospectively searched from January to September 2003.From almost 75,000 outpatient visits, we tested E. coli isolates that were recovered from patients with community-acquired infections and classified as ESBL producers by the E-test ESBL screen method with cefo-