Abstract
The oral cavity may comprise a significant reservoir for Staphylococcus aureus but the data on molecular epidemiology and clonal distribution of oral strains are really scarce. This study aimed to evaluate the clonal relatedness in S. aureus isolated from oral cavity and their relationship with carriage of virulence genes, and antimicrobial resistance profiles. A total of 139 oral S. aureus isolates were obtained from 2327 analysed oral samples of dental patients. Antimicrobial susceptibility testing was performed. Isolates were characterized using protein A gene (spa) typing, spa-CC clonal complexes, toxin genes and SCCmec typing for MRSA. High resistance rates for penicillin, tetracycline and gentamicin were detected, respectively 58.3%, 42.4%, and 35.2%. Twelve (8.6%) S. aureus isolates were identified as MRSA. All of MRSA isolates were mecA-positive and mecC-negative. SCCmec IV was the most common type (66.7%), which was typical for community-acquired MRSA (CA-MRSA). Overall, the enterotoxin gene cluster (egc) was the most frequent detected virulence factor (44.9%), both in MSSA and MRSA isolates. Presence of genes encoding for the enterotoxins (sea, seb, sec, seh, sek), exfoliative toxin A (eta), and toxic shock syndrome toxin-1 (tst) was also observed. Strains carrying lukS-PV/lukF-PV genes belonged to SCCmecV- spa type t437. The most prevalent spa types were t091, t015, t084, t002, t571, and t026 among all 57 identified. Spa types, including 3 new ones, grouped in 6 different spa-CC clonal complexes, with four major dominated; CC45, CC30, CC5, and CC15. This study demonstrated that both methicillin-susceptible and methicillin-resistant major European clones of S. aureus could be isolated from the oral cavity of dental patients, with the emergence of PVL-positive CA-MRSA strains. The oral cavity should be considered as a possible source of toxigenic egc-positive S. aureus strains, in terms of potential risk of cross-infection and dissemination to other body sites.
Highlights
Staphylococcus aureus is responsible for a wide variety of human infections ranging from mild symptoms in superficial skin infections to life-threatening systemic disease, such as infective endocarditis and s epsis[1]
This study aimed to evaluate the clonal relatedness in S. aureus isolated from oral cavity and their relationship with carriage of virulence genes, as well as antimicrobial resistance profiles
A total 139 S. aureus were isolated from 2327 oral samples of 750 (18.5%) dental patients with symptoms of infection
Summary
Staphylococcus aureus is responsible for a wide variety of human infections ranging from mild symptoms in superficial skin infections to life-threatening systemic disease, such as infective endocarditis and s epsis[1]. Staphylococcus aureus may be associated with some oral conditions and infections in dentistry. These include angular cheilitis, mucositis, some endodontic infections, osteomyelitis of the jaw, and p arotitis[2,3,4]. Anterior nares are considered a primary ecological niche for S. aureus, it is estimated that 15–50% of persons colonized by these microorganisms are non-nasal carriers[9]. The oral cavity is frequently colonized by S. aureus, either as a primary location or as a consequence of migration from the anterior nares[10,11]. As the majority of these infections are endogenous, the risk among S. aureus colonized patients is 11.5 times higher than in non-colonized persons[22]
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