Genotyping of methicillin-resistant Staphylococcus aureus in the Sultan Qaboos University Hospital, Oman reveals the dominance of Panton-Valentine leucocidin-negative ST6-IV/t304 clone.

E.E. Udo,Z. Al-Muharmi,B.A.-H. Al-Lawati,S.S. Thukral

doi:10.1002/nmi2.47

Abstract

The objective of this study was to determine the prevalence and distribution of methicillin-resistant Staphylococcus aureus (MRSA) genotypes circulating at a tertiary hospital in the Sultanate of Oman. A total of 79 MRSA isolates were obtained from different clinical samples and investigated using antibiogram, pulsed-field gel electrophoresis (PFGE), staphylococcal chromosome cassette mec (SCCmec), Spa typing and multilocus sequence typing (MLST). The isolates were susceptible to linezolid, vancomycin, teicoplanin, tigecycline and mupirocin but were resistant to tetracycline (30.4%), erythromycin (26.6%), clindamycin (24.1%), trimethoprim (19.0%), ciprofloxacin (17.7%), fusidic acid (15.2%) and gentamicin (12.7%). Molecular typing revealed 19 PFGE patterns, 26 Spa types and 21 sequence types. SCCmec-IV (86.0%) was the dominant SCCmec type, followed by SCCmec-V (10.1%). SCCmec-III (2.5%) and SCCmec-II (1.3%) were less common. ST6-IV/t304 (n = 30) and ST1295-IV/t690 (n = 12) were the dominant genotypes followed by ST772-V/t657 (n = 5), ST30-IV/t019/t021 (n = 5), ST22-IV/t852 (n = 4), ST80-IV/t044 (n = 3) and 18 single genotypes that were isolated sporadically. On the basis of SCCmec typing and MLST, 91.2% of the isolates were classified as community-associated MRSA and 8.8% of the isolates (consisting of four ST22-IV/t852, one ST239-III/t632, one ST5-III/t311 and one ST5-II/t003) were classified as healthcare-associated MRSA. The study has revealed the dominance of a Panton–Valentine leucocidin-negative ST6-IV/t304 clone and provided insights into the distribution of antibiotic resistance in MRSA at the tertiary hospital in Oman. It also highlights the importance of surveillance in detecting the emergence of new MRSA clones in a healthcare facility.

Highlights

The burden of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) is increasing among different patient populations globally [1,2,3]
Thirty-five (44.3%) MRSA isolates were positive for the presence of lukS-PV-lukF-PV, mostly in isolates that were associated with skin and soft tissue infections and septicaemia but not in isolates recovered from colonization or respiratory tract specimens (Table 1)
Antibiotic resistance of MRSA isolates All 79 MRSA isolates were susceptible to vancomycin (MIC ≤ 2 mg/L), teicoplanin (MIC ≤ 2 mg/L), linezolid, tigecycline and mupirocin but were resistant to tetracycline (n = 24), erythromycin (n = 21), clindamycin (n = 19), kanamycin (n = 17), trimethoprim (n = 15), ciprofloxacin (n = 14) and fusidic acid (n = 12; 15.2%), gentamicin (n = 10) and streptomycin (n = 6)

Summary

Introduction

The burden of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) is increasing among different patient populations globally [1,2,3]. Previously restricted to healthcare facilities, especially large tertiary-care facilities [5], MRSA has been increasingly identified as a major cause of community-associated infections in previously healthy hosts since the late 1990s [6,7,8]. These new MRSA strains have been described as community-acquired or community-originated MRSA. New Microbes and New Infections published by John Wiley & Sons Ltd on behalf of the European Society of Clinical Microbiology and Infectious Disease

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