Blomqvist Susanne, Leonhardt Åsa, Arirachakaran Pratanporn, Carlen Anette, Dahlén Gunnar
Department of Oral Microbiology and Immunology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Oral Medicine Clinic, Dental Faculty, Chulalongkorn University, Bangkok, Thailand.
J Oral Microbiol. 2015 Apr 23;7:26250. doi: 10.3402/jom.v7.26250. eCollection 2015.
The present study investigated phenotypes, virulence genotypes, and antibiotic susceptibility of oral Staphylococcus aureus strains in order to get more information on whether oral infections with this bacterium are associated with certain subtypes or related to an over-growth of the S. aureus variants normally found in the oral cavity of healthy carriers.
A total number of 157 S. aureus strains were investigated. Sixty-two strains were isolated from Swedish adults with oral infections, 25 strains were from saliva of healthy Swedish dental students, and 45 strains were from tongue scrapings of HIV-positive subjects in Thailand, and 25 Thai strains from non-HIV controls. The isolates were tested for coagulase, nitrate, arginine, and hemolysin, and for the presence of the virulence genes: hlg, clfA, can, sdrC, sdrD, sdrE, map/eap (adhesins) and sea, seb, sec, tst, eta, etb, pvl (toxins). MIC90 and MIC50 were determined by E-test against penicillin V, oxacillin, amoxicillin, clindamycin, vancomycin, fusidic acid, and cefoxitin.
While the hemolytic phenotype was significantly (p<0.001) more common among the Thai strains compared to Swedish strains, the virulence genes were found in a similar frequency in the S. aureus strains isolated from all four subject groups. The Panton-Valentine leukocidin (PVL) genotype was found in 73-100% of the strains. More than 10% of the strains from Swedish oral infections and from Thai HIV-positives showed low antibiotic susceptibility, most commonly for clindamycin. Only three methicillin-resistant S. aureus (MRSA) strains were identified, two from oral infections and one from a Thai HIV patient.
S. aureus is occasionally occurring in the oral cavity in both health and disease in Sweden and Thailand. It is therefore most likely that S. aureus in opportunistic oral infections originate from the oral microbiota. S. aureus should be considered in case of oral infections and complaints and the antibiotic susceptibility (including MRSA) should regularly be checked. The frequent presence of S. aureus, although in low numbers among students and staff, emphasizes the importance of standard infection control precautions and of using diagnostic test in the dental clinic.
本研究调查口腔金黄色葡萄球菌菌株的表型、毒力基因型和抗生素敏感性，以获取更多关于该细菌引起的口腔感染是否与某些亚型相关，或是否与健康携带者口腔中正常存在的金黄色葡萄球菌变体过度生长有关的信息。
共调查了157株金黄色葡萄球菌菌株。62株从患有口腔感染的瑞典成年人中分离得到，25株来自瑞典健康牙科学生的唾液，45株来自泰国HIV阳性受试者的舌拭子，以及25株来自泰国非HIV对照者。对分离株进行凝固酶、硝酸盐、精氨酸和溶血素检测，以及毒力基因hlg、clfA、can、sdrC、sdrD、sdrE、map/eap（黏附素）和sea、seb、sec、tst、eta、etb、pvl（毒素）的检测。通过E试验测定对青霉素V、苯唑西林、阿莫西林、克林霉素、万古霉素、夫西地酸和头孢西丁的MIC90和MIC50。
与瑞典菌株相比，溶血表型在泰国菌株中显著更常见（p<0.001），但在从所有四个受试者组分离的金黄色葡萄球菌菌株中，毒力基因的出现频率相似。Panton-Valentine杀白细胞素（PVL）基因型在73%-100%的菌株中被发现。来自瑞典口腔感染患者和泰国HIV阳性者的菌株中，超过10%显示出低抗生素敏感性，最常见的是对克林霉素。仅鉴定出3株耐甲氧西林金黄色葡萄球菌（MRSA）菌株，2株来自口腔感染患者，1株来自泰国HIV患者。
在瑞典和泰国，健康和患病个体的口腔中均偶尔会出现金黄色葡萄球菌。因此，机会性口腔感染中的金黄色葡萄球菌很可能源自口腔微生物群。对于口腔感染和不适病例应考虑金黄色葡萄球菌感染，并且应定期检查抗生素敏感性（包括MRSA）。尽管在学生和工作人员中数量较少，但金黄色葡萄球菌的频繁出现强调了标准感染控制预防措施以及在牙科诊所使用诊断检测的重要性。
