Detection of Plasmid Mediated AmpC-β lactamases Among Gram-Negative Uropathogens at a Tertiary Care Hospital, Dhaka City.

Plasmid-mediated AmpC β-lactamase (PMABL) resistance among gram negative bacilli is an emerging problem worldwide. They likely originate from chromosomal AmpC of certain Gram-negative bacterial species and subsequently are mobilized to transmissible plasmids. There are reports of unfavorable clinical outcomes in patients infected with these organisms and treated with broad-spectrumcephalosporins. The present cross sectional study was designed to detect PMABL genes among gram negative uropathogens in a tertiary care hospital, Dhaka city, Bangladesh from January 2014 to December 2014. Total 138 gram negative uropathogens were identified by the conventional methods and were screened for AmpC production using cefoxitin discs. Confirmatory phenotypic identification was done by modified three dimensional test (MTDT). The common AmpC genotypes ACC, FOX, MOX, DHA, CIT and EBC types were determined by a multiplex PCR.PMABL genes were detected by PCR in 90% of cefoxitin resistant isolates and the molecular types of the genes detected predominantly were CIT, DHA followed by EBC and ACC types. Overall, PMABL genes were detected in 32.61% (45/138) of the studied gram negative uropathogens which is alarming. All (100%) the plasmid mediated AmpC β-lactamase producers showed resistance to amoxicillin-clavulanic acid, ceftazidime, ceftriaxone, cefotaxime and cefoxitin. These results emphasize that clinical laboratories should consider the tests for the detection of PMABL genes for infection control and formulation of effective antibiotic policy.