From Different Units in Jeddah Hospitals, Saudi Arabia Abstract
Proteus mirabilis isolates had undergone considerable alteration in susceptibility to aminoglcosides with a gradual increase to resistance in gentamycin and tobramycin. Fortunately, amikacin have a broad spectrum of activity and is particularly valuable in treating nosocomial infections so this study aimed at obtaining data on susceptibility patterns of Pr. mirabilis isolates responsible for hospital infections in Jeddah, Saudi Arabia to the currently used aminoglcoside agents in their treatment.
Results showed that the most predominant organisms isolated from hospital-acquired infection were Gram-negative (60.93%), mostly isolated from urine (45.73%), where, Pr. mirabilis isolates accounted for 162 out of 1383 (11.7%) Enterobacteriaceae.About 89.6%, 84.3% and 82.8% of Pr. mirabilis isolates were sensitive to amikacin, tobramycin and gentamycin respectively by disk diffusion method. The highest level of resistance was found in Pr. mirabilis strains isolated from pus. The resistance of Pr. mirabilis isolates to aminoglycosides was allocated in 6 different patterns, and the most predominant pattern was pattern III (49.5%). MICs of most Pr. mirabilis isolates when detected by broth dilution method gave higher readings than when detected by agar dilution method and the disk diffusion method gave results similar to that of agar dilution. Only 30 out of 192 (15.6%) of Pr. mirabilis isolates harboured one plasmid on each strain and about 90% of Pr. mirabilis isolates resistant to gentamycin, tobramycin and amikacin were containing plasmid. Sixty percent of plasmid-containing Pr. mirabilis isolates were able to transfer their antibiotic resistance to the standard E.coli at a frequency ranged between 3×10-8 and 1.2×10-7. The resistance to amoxicillin, ampicillin, cephalothin, neomycin, streptomycin, kanamycin, gentamycin, tobramycin and amikacin was transferred in 100% of isolates due to presence of plasmids with molecular weight 180, 170 and 25 Kb.