Abstract
Background: 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.
Methods: 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.
Results: 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).
Conclusions: 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.