Open Access

ARTICLE

Molecular typing of methicillin and vancomycin-resistant Staphylococcus aureus isolated from clinical specimens by doublelocus sequence typing (DLST) method

by SOHEILA HASANIAN, NOUR AMIRMOZAFARI, AHMAD FARAJZADEH SHEIKH, IRAJ MEHREGAN

1 Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
3 Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

* Address correspondence to: Ahmad Farajzadeh Sheikh. Email:

BIOCELL 2020, 44(3), 411-419. https://doi.org/10.32604/biocell.2020.08976

Received 30 October 2019; Accepted 11 May 2020; Issue published 22 September 2020

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) strains are the essential cause of infections in communities and hospitals. The present study was conducted to determine the molecular typing of MRSA, isolated from hospitalized patients, using the double-locus sequence typing (DLST). In total, 280 S. aureus isolated from clinical specimens by phenotypic (catalase, coagulase, DNase, oxacillin, vancomycin screening agar and antibiotic disk diffusion), and molecular methods (PCR for determining the mecA, vanA and nuc genes). The DLST and sequencing was performed for MRSA containing mecA. Out of 280 specimens, confirmed as Staphylococcus aureus (S. aureus), 123 (43.9%) strains were MRSA. The highest resistance toward the erythromycin (15 μg), followed by ciprofloxacin (5 μg), clindamycin (2 μg), tetracycline (30 μg), gentamicin (10 μg) and rifampicin (5 μg), was 98.3%, 97.5%, 94.3%, 90.2%, 83.7% and 41.4%, respectively. Also, the least resistance (0%) was observed in each of teicoplanin (30 μg), linzolide (30 μg), and vancomycin (30 μg). All (100%) of MRSA strains had the mecA, and none of them have had the vanA. The results of DLST showed that the most common sequence types were BPH 2003 and 0217. The DLST type 18-32 was a significant cluster of MRSA. By sequencing MRSA and comparing the dominant types via the DLST, it is possible to establish the etiology of the disease in a much shorter time, and prevent the complications of the disease. Therefore, the combination of partial sequences of clfB and spa can serve as useful genetic markers for MRSA typing. It concluded that the MRSA in our region was relatively high, but no vancomycin resistance was found. The majority of the MRSA DLST type was 18–32.

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