Document Type: Original Article
Assistant Professor, Department of Microbiology, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
Assistant Professor, Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Professor, Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Associate Professor, Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Background & Aims: The production of extended-spectrum-β-lactamases (ESBLs) is the main mechanism of resistance to β-lactam antibiotics. The outbreak of isolates simultaneously possessing several resistance mechanisms to β-lactam antibiotics caused a decrease in sensitivity of the confirmatory tests for ESBL. The aim of this study was the evaluation of the β-lactamase disk test method in the detection of ESBLs in clinical isolates of multidrug-resistant Pseudomonas aeruginosa.
Methods: A total of 100 multidrug-resistant P. aeruginosa isolates were recovered from burn patients. The sensitivity of the isolates to different antibiotics was determined using the standard disk diffusion method. ESBL-producing isolates were detected through the combination disk test with clavulanic acid, double disk synergy test, and β-lactamase disk test. Carbapenemase-producing isolates were detected using the Modified Hodge Test (MHT). The ESBLs genes (blaTEM, blaOXA, blaPER, blaSHV, blaCTX-M and blaPSE) were determined through polymerase chain reaction (PCR).
Results: All isolates were multidrug resistant. Only 3 isolates were detected as ESBL-producing isolates through combination disk test. No ESBL-producing isolates were detected through double disk synergy test. Among the 100 studied isolates, 87% were detected as ESBL-producing isolates and 68% as carbpenemase-producing isolates through β-lactamase disk test. . The prevalence of bla
, and bla
among isolates were 97%, 61%, and 13%, respectively. All isolates were negative for bla
, and bla
Conclusion: According to the results obtained in this study, the β-lactamase disk test is suitable for the detection of ESBLs in multidrug resistant isolates. However, further investigation is required.