A total of 23 clinical isolates (15 Escherichia coli and 8 Klebsiella pneumoniae), resistant to cefotaxime and ceftazidime recovered during 2002 and 2003, were investigated for production of CTX-M extended spectrum β-lactamase (ESBL) by phenotypic and molecular methods. The presence of ESBL was tested by NCCLS phenotypic conÞ rmatory test using cephalosporin/clavulanate combination discs and E-test ESBL strips. Determination of MIC of cefotaxime and ceftazidime was done with and without the presence of clavulanic acid by agar dilution technique. Polymerase chain reaction revealed the presence of CTX-M type ESBLs in 19 isolates. Further sequencing resulted in identiÞ cation of CTX-M-15 ESBLs. This is the Þ rst report identifying CTX-M type ESBL from clinical isolates of E. coli and K. pneumoniae from a tertiary care hospital in south India.

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