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Background & objectives: Nosocomial infections caused by multidrug-resistant, Pseudomonas species have become a major clinical and public health concern. The aim of this study was to characterize phenotypic and genotypic profile of antimicrobial resistance (AMR) in Pseudomonas spp. isolated from hospitalized patients. Methods: A total of 126 consecutive, non-duplicate isolates of Pseudomonas spp. isolated from various clinical samples were included in the study over a period of two years. Identification and antimicrobial sensitivity was performed using automated culture system according to the Clinical and Laboratory Standards Institute (CLSI) recommendations. Phenotypic detection of extended-spectrum ?-lactamases (ESBLs), Amp-C ?-lactamase (AmpC) and metallo-?-lactamases (MBLs) were done by various combinations of disc-diffusion and E-test methods, followed by polymerase chain reaction-based detection of ?-lactamase-encoding genes. Results: Among 126 clinical isolates, 121 (96.1%) isolates were identified as Pseudomonas aeruginosa. Most of the isolates were recovered from pus sample, 35 (27.8%) followed by urine, 25 (19.84%); endotracheal aspirate, 24 (19.04%); blood, 14 (11.11%) and sputum, four (3.17%). The highest rate of resistance was against ticarcillin-clavulanic acid, 113 (89.7%) followed by meropenem, 92 (72.5%) and ceftazidime, 91 (72.3%). Overall, ESBLs, AmpC and carbapenemase production was detected in 109 (96.4%), 64 (50.8%) and 105 (94.6%) isolates by phenotypic methods. The most prevalent ESBL gene was blaTEMin 72 (57.1%) and the least prevalent was blaSHVin 19 (15.1%) isolates. AmpC gene was seen less compared to ESBL gene. The most prevalent carbapenemases gene was blaNDM-141 (46.06%) followed by blaVIM and blaOXA-1. Interpretation & conclusions: Our findings suggested that a high rate of ESBLs and carbapenemases production was observed in Pseudomonas spp. Therefore, phenotypic and genotypic detection of AMR needs to be combined for better characterization of resistance patterns in Pseudomonas spp.
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Objective:To establish a new method to detect Amp C?-lactamase by PCR. Methods:The amp C and amp D gene fragments of E. cloacae were amplified by the amp C and amp D primers to detect Amp C ?-lactamase, especially the enduring and highly productive enzymes. Results:Totally 193 of 214 strains of E. cloacae were positive for amp C gene , implicating most strains of E. cloacae had the ability to produce the enzyme. Sixteen of the 193 strains (amp C positive) were negative for amp D genes, implicating these 16 strains could produce the enduring and highly productive enzymes. The results were confirmed by cefoxitin three-dimensional test. Conclusion:The new method to detect Amp C ?-lactamase, especially the enduring and highly productive enzymes,by amp C and amp D primers is a rapid and accurate method.