Predominance of CTX-M–type extended-spectrum β-lactamase genes among enterobacterial isolates from outpatients in Brazil

Two hundred fifty-seven nalidixic acid-resistant enterobacterial isolates were collected in a Brazilian community from January 2000 to May 2005 to determine the prevalence of plasmid-encoded extended-spectrum β-lactamases. The blaCTX-M genetic environment was determined by polymerase chain reaction and sequencing. Eleven isolates (4.2%) harbored a blaCTX-M-2 gene, 3 isolates blaCTX-M-9, 2 isolates blaCTX-M-8, and 6 isolates blaSHV-5. Two novel blaCTX-M-2 variants, namely, blaCTX-M-74 and blaCTX-M-75, were identified.