RESUMEN
Aims: To determine resistance rates and patterns of certain uropathogens, including E. coli, Klebsiella spp. and Pseudomonas spp., isolated from hospitalized urinary tract infections patients, to aminoglycoside antibiotics and to detect the most prevalent plasmidmediated aminoglycoside modifying enzymes (AMEs). Methods: Uropathogenic isolates (150) were recovered from urine specimens of hospitalized UTI patients in Cairo, Egypt and identified by conventional methods. The recovered uropathogens (E. coli, Klebsiella spp. and Pseudomonas spp.) were tested for their susceptibility to gentamicin, tobramycin, amikacin, neomycin, netilmicin, and kanamycin by disc diffusion method. Plasmid-mediated aminoglycoside resistance was determined by transformation experiments as well as by using plasmids as templates for PCR screening of the AMEs-coding genes aph(3')-I, aac(6')-I, aac(3)-I, aac(3)-II and ant(2'')-I in all resistant isolates. Results: Of a total of 150 uropathogenic clinical isolates, 110 isolates were of the above mentioned genera and were selected for the current study. Sixty three isolates (57.2%) were resistant to at least one aminoglycoside antibiotic. Highest and lowest resistance rates were observed to kanamycin (53.6%) and amikacin (7.2%), respectively. The resistance rates to gentamicin, neomycin, tobramycin and netilmicin were 33.6%, 24.5%, 23.6% and 14.5%, respectively. AMEs-coding genes were detected on the plasmids of 93.6% of resistant isolates with prevalence rates of 53.9% for ant(2'')-I, 38% for both aac(6')-I and aac(3)-II and 33.3% for aph(3')-I, while aac(3)-I gene was not detected in any of the tested resistant isolates. Double and triple combinations of AMEs-coding genes were detected in ich49.2% of resistant isolates. Conclusion: A high prevalence of plasmid-mediated resistance to aminoglycoside antibiotics in Gram negative uropathogens from hospitalized patients was observed. Uropathogens may represent potential reservoirs of panaminoglycoside resistance in hospitals, having on their plasmids combinations of AMEs-coding genes. Good infection control measures in Egyptian hospitals together with periodic screening of prevalence rates of different resistance genes are required.