QUINOLONES RESISTANCE IN GRAM NEGATIVE BACTERIA

Abstract

This study was carried out to detennine the resistance of different isolated Gram-negative bacteria to quinolone antibiotics, detennination of cross resistance with other chemically unrelated antibiotics, in addition to studying the possible mechanism(s) of resistance among the commonly encountered pathogen.

In this study, 342 different clinical strains were isolated and identified from 436 clinical samples. Out of the 342 clinical strains, Ps. aeruginosa was the most prevalent (32.74%) followed by E. coli (27.48%), Kl. Pneumoniae (17.83%), Pr. mirabilis (8.77%), Ent. aerogenes (6.14%), Kl. oxytoca (3.21%), Morg. morganii (2.04%) and Prov. rettgeri (1.75%).

All recovered isolates were tested for their susceptibility to tested quinolone antibiotics. Ps. aeruginosa isolates showed high resistance to the tested quinolones even to the new ones as gatifloxacin, where 75% were resistant to nalidixic acid, 55.35% were resistant to ofloxacin, 49.10% were resistant to norfloxacin, 47.32% were resistant to levofloxacin, 41.96% were resistant to ciprofloxacin while only 22.32% were resistant to gatifloxacin.

E. coli isolates showed also high resistance to the tested quino1ones, where 43.61% were resistant to nalidixic acid, 36.17% were resistant to ciprofloxacin, 31.91% were resistant to ofloxacin, 11.70% were resistant to both norfloxacin and levofloxacin. Only 9.57% were resistant to gatifloxacin.