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Mutations in grlA and norA Genes of Clinical Isolates of Staphylococcus aureus Resistant to Fluoroquinolone
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L Asadpour   1, S Veisi2 |
1- Young Researchers and Elite Club, Rasht Branch, Islamic Azad University, Rasht, Iran , l.asadpour@yahoo.com
2- Young Researchers and Elite Club, Rasht Branch, Islamic Azad University, Rasht, Iran |
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Abstract: (4635 Views) |
Abstract
Background and aim: Fluoroquinolones are group of antibiotics that are commonly used as broad-spectrum and resistance to them is expanding. The mechanisms of resistance to fluoroquinolones in S. aureus is important in mutation a subunit of topoisomerase type II grlA and efflux pump. This study was aimed was to investigate mutations in grlA and norA genes of clinical isolates of S. aureus resistant to fluoroquinolones
Methods: In the present cross-sectional study, 85 S. aureus isolates from different clinical samples using culture and molecular methods were identified. The resistant of these isolates to fluoroquinolones was determined by disc diffusion method and MIC ciprofloxacin method was tested by macro dilution broth. To examine the relationship between infection and the position of each drug resistance status the chi-square test was used. A P value of < 0.05 was considered statistically significant. Mutations in the quinolone resistance-determining regions (QRDR) in chromosomal grlA gene and norA gen mutations was investigated in quinolone-resistant S. aureus isolates, by PCR amplification of grlA and norA genes and sequencing.
Results: In this study, 20% of isolates were resistant to all antibiotics fluoroquinolones studied. Using statistical analysis revealed no significant differences between fluoroquinolone resistance in isolates of S. aureus infection in patients and location was observed. MIC ciprofloxacin resistant isolates to fluoroquinolones was ranged between 32-512 mg/ml. Two single mutations S80F and S80F and a pattern of P144S+ P144S in the grlA gene of fluoroquinolone resistant strains of S. aureus were identified, but no mutations were found in genes norA resistant strains. Also, no relationship between MIC of ciprofloxacin in resistant isolates and mutation in grlA was seen.
Conclusion: The obtained results demonstrated that grlA gene mutation is one of the most important mechanisms of resistance to ciprofloxacin in clinical isolates of S. aureus in Rasht and most of resistant isolates acquired common mutation in codon 80.
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| Keywords: Fluoroquinolone, S. aureus, grlA, norA |
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Full-Text [PDF 206 kb]
(1345 Downloads)
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Type of Study: Research |
Subject:
Microbiology
Received: 2016/12/4 | Accepted: 2017/02/22 | Published: 2017/03/15
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