Molecular characterisation of extended spectrum beta lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates from urinary specimens

Extended spectrum beta lactamase (ESBL) production is a major resistance mechanism of Gram-negative bacteria. Phenotypic tests for ESBL detection only confirm whether an ESBL is produced or not, but it cannot detect the ESBL subtype. There are various genotypes of ESBLs. Of these, the most common are the TEM, SHV and CTX-M types. Fifty phenotypically ESBL-producing Escherichia coli and Klebsiella pneumoniae urinary isolates were subjected to polymerase chain reaction to look for the presence of bla TEM , bla SHV and bla CTX-M genes. Forty-one isolates were positive for TEM gene, eleven isolates were positive for SHV gene and 10 isolates were positive for CTX-M gene. Both TEM and SHV genes were present in six isolates. Two isolates showed the simultaneous presence of CTX-M and TEM genes. All the three genes were present in two isolates.