Antibiotic Resistance in Clinical Isolates of Pseudomonas aeruginosa: A New Viewpoint for Antibiotic Prescription

  A growing number of resistant Pseudomonas aeruginosa isolates have been reported. To make better choice of antibiotic, reporting and analyzing the recent antibiotic resistance patterns of the bacterium are of crucial importance. The purpose of the present study was to survey antibiotic resistance status in clinical isolates of P. aeruginosa and to make more options for antibiotic prescription by revisiting antibiogram results. A total of 138 molecularly identified P. aeruginosa strains isolated from clinical specimens were tested for sensitivity to 10 antibiotics using Kirby-Bauer disk diffusion method. In addition, phenotypic combined disk diffusion test (CDDT) was applied to screen metallo-beta-lactamase (MBL) producing P. aeruginosa isolates among imipenem-resistant isolates. To find the most suitable antibiotic against P. aeruginosa infections, a new analytical way was employed using SPSS and chi-square test. Ceftizoxime showed the highest rate of resistance (78.9%) and amikacin showed the lowest (33.3%). 51.4% of the isolates showed resistance to Imipenem, 78.8% of which were positive for MBL production. Multidrug-resistant strain (MDR) isolates were observed in 67.3% of all isolates, 74.6% of Imipenem resistant isolates showed multidrug resistance and 83.9% of MBL positive isolates showed MDR. There was positive correlation between specimen source and resistance or susceptibly of P. aeruginosa isolates to some antibiotics in some specimens, and non-significant similarities in resistance or sensitivity to antibiotics in P. aeruginosa isolates (P<0.05). Resistance rate of imipenem, meropenem, gentamicin, tobramycin, ceftazidim, cefotaxime and ticarcillin was more than reported rates in previous studies. A higher proportion of MDR isolates and MDR-MBL producing strains suggest drastic dissemination of resistant isolates in the healthcare centers. Site specificity and non-significant similarity of the responses to antibiotics in P. aeruginosa isolates can provide a new sight for antibiotic prescription and better control of antimicrobial drug resistance