Phenotypic detection of extended spectrum -lactamase and Metallo -lactamase production by Gram negative uropathogens after exposure to gamma radiation

Eighty-five uropathogen isolates were collected and differentiated on the basis of their Gram stain reaction. Among the collected isolates, 25 (29.4%) were Gram positive cocci and 60 (70.6%) were Gram negative bacilli. Antibiotic susceptibility profile towards 15 different antibiotics concluded that impenime (IMP), amikacin (AK) and Pipperacillin/tazobactam (TZP) were the most effective against Gram negative; while linezolid (LZD), and vancomycin (VA) were the most potent against Gram positive. The highly drug resistant isolates were identified as Pseudomonas aeruginosa and Klebsiella pneumoniae using 16srRNA; the two strains were subjected to different doses of gamma-radiation and the sub lethal dose of both strains was 5.0 kGy. The D10 values were recorded (1.2 and 1.1 kGy) for P. aeruginosa and K. pneumoniae), respectively. In addition, gamma-irradiation technique decreases the resistance of K. pneumoniae towards IMP and the resistance of P. aeruginosa towards more than one antibiotic (TZP, AZM and CIP). The results also, revealed that both of the tested strains had the ability to produce Extended Spectrum β-lactamase (ESBL) before and after gamma-radiation but only P. aeruginosa had the ability to produce Metallo β-lactamase (MBL), that is, ESBL and MBL co-production was detected in P. aeruginosa. So, these findings must be supported by other studies on the level of genes to prove the possibility for using gamma-irradiation technique to overcome microbial drug resistance problem.