MIC determination of Pseudomonas aeruginosa strains were isolated from clinical specimens of patients admitted to educational hospitals in Hamedan (90-91)

Pseudomonas aeruginosa is an important opportunistic pathogen, particularly in immuno compromised patients and is one of the main bacteria that cause nosocomial infections. The aim of this study was to evaluate the antibiotic sensitivity and determine the MIC levels for clinical isolates of Pseudomonas aeruginosa to antibiotics commonly used. In this study, 100 Pseudomonas aeruginosa strains from different infections occurring in Hamadan city hospitals were isolated. Thirty one samples were selected based on antibiotic susceptibility testing by disk diffusion test for aminoglycoside antibiotics (gentamicin, tobramycin, amikacin, kanamycin), and quinolone (ciprofloxacin, levofloxacin and ofloxacin) and carbapenem (imipenem and meropenem). Microdilution tests were performed to determine the MIC levels towards ciprofloxacin, gentamicin and imipenem. Out of the 31 samples, the highest resistance was seen towards levofloxacin (61.2%) and the least to imipenem (9.6%). Two of the isolates (6.5%) were resistant to all of these eight antibiotics. The MIC results for the three antibiotics were as follows. Gentamicin: (58.06%) resistant, (25.8%) intermediate and (16.12%) sensitive. Ciprofloxacin: (90.32%) resistant and (9.67%) intermediate. Imipenem: (30.7%) resistant, (41.93%) intermediate and (19.35%) sensitive. In comparison with other studies, there were not any significant differences in antibiotic resistance rates which shows similar patterns in different regions. Imipenem was the most effective antibiotics against clinical isolates. Amikacin and ofloxacin was the most effective antibiotic in the next order.