Molecular characterization of extended spectrum βlactamase producing bacteria isolated from urinary tract infected patients, Bangladesh

The aims of the study were to examine the presence of extended spectrum βlactamase (ESBL) producing pathogen in urinary tract infected (UTI) patients and their respected molecular characterization and classification. The isolates collected from UTI patients attending a private hospital during the period between January and June, 2012, were biochemically identified and subjected to double disc synergy method for the detection of ESBL. ESBL genes were detected by multiplex PCR and antibiotic sensitivity test was performed. Thirty two percent of all Gram negative isolates were found as ESBL producer. Among 65 ESBL positive isolates, 77% were Escherichia coli, 20% Klebsiella pneumoniae and 3% were Pseudomonas spp. Around 48% isolates were found carrying at least one of the four ESBL genes, bla_CTX-M, bla_TEM, bla_SHV and bla_OXA, and were found in 32%, 23%, 18.5% and 3% of the isolates respectively. In antibiotic sensitivity assay, higher resistance was found in E. coli than K. pneumonia against ciprofloxacin and nalidixic acid. Interestingly, two E. coli and three K. pneumonia strains were found resistant to only 3^rd generation cephalosporines, but susceptible to all other antibiotics assessed. One E. coli strain was found resistant to ciprofloxacin but sensitive to nalidixic acid. Pseudomonas spp. was found resistant to most of the antibiotics. The susceptible rate to nitrofurantoin, amikacin, and gentamicin was also not satisfactory. Susceptibility (100%) to meropenem and imipenem render these as good alternatives to treat UTI. The majority of the isolates were positive for bla_CTX-M and adverted to molecular class A. Two strains carrying blaOXA gene along with bla_SHV/bla_TEM/bla_CTX-M, could not be included in any of the established ESBL classification.