Objective: This study was aimed to determine the antibiotic resistance patterns of clinical Pseudomonas aeruginosa isolates and to detect the presence of PstS gene.
Methods: One hundred and ninety-two clinical isolates of P. aeruginosa were characterized using polymerase chain reaction (PCR) and 16S rDNA sequencing. Antibiotic resistance patterns were determined using the disk diffusion method, while the minimum inhibitory concentrations (MICs) of selected antibiotics against resistant isolates were determined by macro broth dilution and E-test strip methods. The resistant isolates were screened for the presence of PstS gene using PCR.
Results: Of 192 clinical isolates of P. aeruginosa, 136 (70.83%) were resistant to at least two antibiotics. Of these, 135 (99%) could be classified as multidrug-resistant P. aeruginosa (MDR-PA), 63 (46%) were extensively drug-resistant (XDR-PA), while 38 (28%) were pandrug-resistant (PDR-PA). The isolates exhibited high level of resistance to cefotaxime and ticarcillin, and low levels of resistance to meropenem and imipenem. The MIC values for meropenem against the resistant isolates were generally <32 mg/L, while the values for other antibiotics ranged from 32 to >128 mg/L. Multiple antibiotic resistance indexes of the MDR-PA ranged from 0.27 to 0.91 and the most prevalent pattern of resistance was PiperacillinR – TicarcillinR – Piperacillin/TazobactamR – CefotaximeR – CeftazidimeR – GentamicnR – TobramycinR– CiprofloxacinR. About 50% of the resistant isolates possessed the PstS gene.
Conclusions: The results confirmed the presence of XDR, PDRPA, and PstS gene in P. aeruginosa strains. There is an urgent need for healthcare practitioners to address the problem of multidrug resistance, by implementing a more rational and appropriate use of antibiotics.
Antibiotic Resistance Patterns and Genetic Diversity in Clinical Isolates of Pseudomonas aeruginosa Isolated From Patients of a Referral Hospital, Isfahan, Iran
