Abstract
This study was designed to determine the molecular characteristic and antimicrobial resistance of enterococcal strains isolated from patients in an Iranian Hospital. Enterococcal strains were isolated from the burn patients. All strains were screened for genes encoding resistance to aminoglycoside [ aac(6')-Ie-aph(2'')-Ia, aph (3'), ant (4')], resistance to vancomycin (vanA, vanB), resistance to tetracycline (tetK, tetL, tetM, tetO), and resistance to erythromycin (ermA, ermB, ermC) by PCR and multiplex PCRâbased methods. Genetic diversity was evaluated using Random Amplified Polymorphic DNA (RAPD)-PCR. All enterococcal isolates showed complete sensitivity to vancomycin with MIC ≤ 0.5µg/ml. Resistance to gentamicin, tetracycline, erythromycin, ciprofloxacin or quinopristin-dalfopristin was detected, whilst more than 96.2% of isolates were high-level gentamicin-resistant (HLGR) and multiresistant. The most prevalent aminoglycoside resistance gene was aac(6')-Ie-aph(2'')-Ia, found in 96.2% (26/27) of the isolates. The most prevalent tetracycline resistance gene was tetM, found in 85.1% (23/27) of the isolates followed by tetL and tetO found in 7.4% (2/27) of the isolates. The ermA and ermB genes were detected in 33.3% (9/27) and 44.4% (12/27) of the isolates respectively. Random Amplified Polymorphic DNA (RAPD)-PCR analysis yielded 17 distinct profiles among 27 investigated isolates. One clusters of isolates shared the same RAPD patterns, while 16 isolates had unique RAPD patterns. we found that over the examined time period one RAPD genotype were common type and were disseminated among patients in the burn unit. Interestingly, most of these strains had an identical or very similar antibiotic and gene resistance pattern.
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