Trimethoprim-/sulfamethoxazole-resistant small colony variants (SCVs) of Staphylococcus aureus, which are selected by use of trimethoprim/sulfamethoxazole, are involved in intractable biofilm-forming infection. This study aimed to determine the biofilm formation ability in trimethoprim-/sulfamethoxazole-resistant SCVs of S. aureus and investigate the bactericidal activity of differential antimicrobial agents to its biofilm-forming S. aureus. Between 32 S. aureus wild type (WT) and 32 SCVs selected from its WT, the amount of formed biofilm was compared. Vancomycin, daptomycin, rifampicin, and minocycline were exposed to biofilm-forming S. aureus to determine viable bacterial counts and its susceptibility. The biofilm-producing quantify of SCVs was approximately twice that formed by its WT. Vancomycin and daptomycin reduce 4 logs the bacterial counts of biofilm-forming WT at 24 hours, but did not affect SCVs. Rifampicin and minocycline considerably decreased both WT and SCVs; however, both bacterial counts recovered to an initial number 48 hours later. These survival strains showed resistance to each drug, and rpoB mutation or tet38 mRNA overexpression was confirmed.

中文翻译：

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生物膜形成甲氧苄啶/磺胺甲恶唑耐药金黄色葡萄球菌小菌落变体对各种抗菌剂的体外耐受性

通过使用甲氧苄啶/磺胺甲恶唑筛选的金黄色葡萄球菌的甲氧苄啶/磺胺甲恶唑耐药小菌落变异体 (SCV) 与难治性生物膜形成感染有关。本研究旨在确定对甲氧苄啶/磺胺甲恶唑耐药的金黄色葡萄球菌SCV 的生物膜形成能力，并研究不同的抗菌剂对其形成生物膜的金黄色葡萄球菌的杀菌活性。在 32 个金黄色葡萄球菌野生型 (WT) 和从其 WT 中选择的 32 个 SCV 之间，比较了形成的生物膜的数量。万古霉素、达托霉素、利福平和米诺环素暴露于形成生物膜的金黄色葡萄球菌以确定活细菌计数及其敏感性。SCV 的生物膜产生量大约是其 WT 形成的两倍。万古霉素和达托霉素在 24 小时使形成生物膜的 WT 的细菌计数减少 4 个对数，但不影响 SCV。利福平和米诺环素显着降低了 WT 和 SCV；然而，两个细菌计数在 48 小时后恢复到初始值。这些存活菌株对每种药物均表现出耐药性，并证实了rpoB突变或tet38 mRNA 过表达。