Carriage frequency, phenotypic, and genotypic characteristics of methicillin-resistant Staphylococcus aureus isolated from dental health-care personnel, patients, and environment

Hossam M Ashour,Reham Wasfi,Ahmed S Khairalla

doi:10.1038/s41598-017-07713-8

Abstract

There is limited data on methicillin-resistant Staphylococcus aureus (MRSA) carriage in dental clinics. 1300 specimens from patients, health personnel, and environmental surfaces of a dental clinic in Egypt were tested for MRSA. Antibiotic susceptibility, biofilm formation, Staphylococcal protein A (spa) typing, SCCmec typing, and PCR-based assays were used to detect mecA, mecC, vanA, Panton-Valentine Leukocidin toxin (PVL), and toxic shock syndrome toxin-1 (tst) genes. Among 34 mecA-positive MRSA isolates, five (14.7%) were PVL-positive, seventeen (50%) were tst-positive, ten (29.4%) were vanA-positive, while none harboured mecC. MRSA hand carriage rates in patients, nurses, and dentists were 9.8%, 6.6%, and 5%. The respective nasal colonization rates were 11.1%, 6.7%, and 9.7%. 1.3% of the environmental isolates were MRSA-positive. Strong and moderate biofilm-forming isolates represented 23.5% and 29.4% of MRSA isolates. 24 MRSA isolates (70.6%) were multi-resistant and 18 (52.9%) harboured SCCmec IV. Among eight spa types, t223 (26.5%), t267 (23.5%), and t14339 (23.5%) were predominant. We noted an alarming genetic relatedness between 7 (20.6%) MRSA isolates and the epidemic EMRSA-15 clone, as well as a combined occurrence of tst and PVL in 3 (8.8%) isolates. Results suggest high MRSA pathogenicity in dental wards highlighting the need for more efficient surveillance/infection control strategies.

Highlights

Staphylococcus aureus is an infectious human pathogen that can survive on inanimate environmental surfaces[1]
It has to be highlighted that while mecA gene is located on a mobile staphylococcal cassette chromosome (SCC) element known as SCCmec, twelve different types of SCCmec (I to XII) have been defined to date, five of which (I to V) are globally distributed[12,13,14,15,16]
Various molecular typing techniques have been developed for effective epidemiological surveillance and control of Methicillin-resistant Staphylococcus aureus (MRSA), the most common of which are SCCmec typing, multilocus sequence typing (MLST), Staphylococcus protein A typing, pulsed-field gel electrophoresis (PFGE) typing, and Panton-Valentine leukocidin (PVL) typing

Summary

Introduction

Staphylococcus aureus is an infectious human pathogen that can survive on inanimate environmental surfaces[1]. MRSA infections, especially its biofilm-forming variants, are often difficult to treat for a variety of reasons. Various molecular typing techniques have been developed for effective epidemiological surveillance and control of MRSA, the most common of which are SCCmec typing, multilocus sequence typing (MLST), Staphylococcus protein A (spa) typing, pulsed-field gel electrophoresis (PFGE) typing, and PVL typing. In this regard, studies have already shown the cost-effectiveness and the efficacy of spa, SCCmec, and PVL techniques compared to PFGE and MLST23, 24. It is likely that dental clinic surfaces and dental health-care personnel (DHCPs) contribute to MRSA transmission to patients or other DHCPs28, 29

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