Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (Campus Pinheiral), Rio de Janeiro, Brazil.
Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Sci Rep. 2019 Aug 13;9(1):11736. doi: 10.1038/s41598-019-48248-4.
Staphylococcus hominis is part of the normal human microbiome. Two subspecies, S. hominis hominis (Shh) and S. hominis novobiosepticus (Shn), have clinical significance. Forty-nine S. hominis isolates were analyzed by the MicroScan automated system, SDS-PAGE and MALDI-TOF methods, followed by partial sequencing of the 16S rDNA gene. The trehalose fermentation test, disk diffusion and broth microdilution tests were used to identify (novobiocin test) and access the susceptibility to oxacillin and vancomycin of isolates. The SCCmec elements and genomic diversity were evaluated by PCR and PFGE methods, respectively. Profiles of 28 (57%; 8 Shh and 20 Shn) isolates corroborated with the results found in all the applied methods of identification. The remaining 21 (43%) isolates were phenotypically identified as Shh by MicroScan; however, they were identified as Shn by SDS-PAGE and mass spectral, and confirmed by 16S rDNA sequencing. Among 41 isolates identified as Shn by the molecular and mass spectrometry methods, 19 (41%) were novobiocin-sensitive, and the trehalose test indicated 11 positive isolates, which are considered atypical phenotypic results for this subspecies. In addition, 92.7% of the isolates identified as Shn by these methods carried mecA gene, while only 12.5% of the Shh isolates were positive. Together, the results highlighted the SDS-PAGE and MALDI-TOF MS methods as promising tools for discriminating S. hominis subspecies.
人葡萄球菌是人类正常微生物群的一部分。有两个亚种，人葡萄球菌人亚种（Shh）和人葡萄球菌新生物亚种（Shn），具有临床意义。对 49 株人葡萄球菌分离株进行了 MicroScan 自动化系统、SDS-PAGE 和 MALDI-TOF 方法分析，随后对 16S rDNA 基因进行了部分测序。使用海藻糖发酵试验、纸片扩散和肉汤微量稀释试验鉴定（新生霉素试验）并评估分离株对苯唑西林和万古霉素的敏感性。通过 PCR 和 PFGE 方法分别评估 SCCmec 元件和基因组多样性。28 株（57%；8 株 Shh 和 20 株 Shn）分离株的图谱与所有应用的鉴定方法的结果一致。其余 21 株（43%）分离株在 MicroScan 中被表型鉴定为 Shh；然而，它们在 SDS-PAGE 和质谱中被鉴定为 Shn，并通过 16S rDNA 测序得到证实。在通过分子和质谱方法鉴定为 Shn 的 41 株分离株中，19 株（41%）对新生霉素敏感，海藻糖试验表明有 11 株阳性分离株，这被认为是该亚种的非典型表型结果。此外，这些方法鉴定为 Shn 的 92.7%的分离株携带 mecA 基因，而 Shh 分离株中只有 12.5%携带 mecA 基因。总之，结果突出了 SDS-PAGE 和 MALDI-TOF MS 方法在区分人葡萄球菌亚种方面的潜力。
