Mechanism of drug resistance, characterization of plasmid-borne determinants and transformation study in P. aeruginosa from burn and ICU units-its susceptibility pattern.

The transfer of drug resistance between hospital pathogens has led to alarming increase of multidrug resistant strains imposing therapeutic challenges. These resistant isolates harbor various mechanisms to counteract the drugs administered and have been reported to deliver these factors to sensitive strains in hostile environment. The present study aimed to screen for multidrug resistant Pseudomonas aeruginosa strains for the production of extended-spectrum β-lactamases, metallo-β-lactamases, AmpC β-lactamase, drug efflux phenotypes and co-transfer the resistance for cephalosporin and other non-beta lactam antibiotics in CaCl2 treated drug sensitive E. coli strains. From the 87 samples processed about 23 isolates of P. aeruginosa were ESBL and MBL positive, 5 (20%) were found to be AmpC β-lactamase producers, efflux mechanism was observed in 8 isolates, 15 isolates had MIC of 16 μg/ml. A putative efflux mechanism was observed in 8 out of 23 isolates that showed decrease in the MIC of meropenem with reserpine. The plasmid profile was characterized for all the common isolates obtained from burn and ICU units. About 69.66% of E. coli recombinants scored positive for both beta lactam and non-beta lactam antibiotics is due to co transfer of resistant plasmid obtained from P. aeruginosa.