Kawada-Matsuo Miki, Shammi Fariha, Oogai Yuichi, Nakamura Norifumi, Sugai Motoyuki, Komatsuzawa Hitoshi
Department of Oral Microbiology.
Department of Oral Maxillofacial Surgery, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
Microbiol Immunol. 2016 Mar;60(3):139-47. doi: 10.1111/1348-0421.12360.
Exfoliative toxin (ET) produced by Staphylococcus aureus is closely associated with the onset of bullous impetigo. To date, three ETs (ETA, ETB and ETD) have been identified. The gene encoding ETB is located in a plasmid designated pETB. Bacteriocin synthesis genes are also located in this plasmid and pETB-positive strains reportedly produce the C55 bacteriocin. In this study, the antibacterial activity against S. aureus strains of the bacteriocin produced by the pETB-positive strain TY4 was investigated. This bacteriocin demonstrated antibacterial activity against all pETB-negative but not pETB-positive strains, including TY4. Additionally, a TY4- strain from which the pETB plasmid had been deleted exhibited susceptibility to the bacteriocin. Further experiments revealed that two immunity factors (orf 46-47 and orf 48) downstream of the bacteriocin synthesis genes in the pETB plasmid are associated with immunity against the bacteriocin produced by TY4. The TY4- with orf46-47 strain exhibited complete resistance to bacteriocin, whereas the TY4- with orf48 strain exhibited partial resistance. Whether bacteriocin affects the proportion of each strain when co-cultured with S. aureus strains was also investigated. When TY4 or TY4- was co-cultured with 209P strain, which is susceptible to the bacteriocin, the proportion of 209P co-cultured with TY4 was significantly less than when 209P was co-cultured with TY4-, whereas the proportion of TY4- with orf46-48 co-cultured with TY4 was greater than with TY4-. These results suggest that the C55 bacteriocin produced by pETB-positive strains affects the proportion of each strain when pETB-positive and -negative strains co-exist.
金黄色葡萄球菌产生的剥脱毒素（ET）与大疱性脓疱病的发病密切相关。迄今为止，已鉴定出三种ET（ETA、ETB和ETD）。编码ETB的基因位于名为pETB的质粒中。细菌素合成基因也位于该质粒中，据报道pETB阳性菌株会产生C55细菌素。在本研究中，对pETB阳性菌株TY4产生的细菌素对金黄色葡萄球菌菌株的抗菌活性进行了研究。这种细菌素对所有pETB阴性菌株具有抗菌活性，但对包括TY4在内的pETB阳性菌株没有活性。此外，缺失了pETB质粒的TY4-菌株对该细菌素敏感。进一步的实验表明，pETB质粒中细菌素合成基因下游的两个免疫因子（orf 46 - 47和orf 48）与对TY4产生的细菌素的免疫有关。带有orf46 - 47的TY4-菌株对细菌素表现出完全抗性，而带有orf48的TY4-菌株表现出部分抗性。还研究了细菌素与金黄色葡萄球菌菌株共培养时是否会影响各菌株的比例。当TY4或TY4-与对该细菌素敏感的209P菌株共培养时，与TY4共培养的209P的比例显著低于与TY4-共培养时，而带有orf46 - 48的TY4-与TY4共培养的比例高于与TY4-共培养时。这些结果表明，当pETB阳性和阴性菌株共存时，pETB阳性菌株产生的C55细菌素会影响各菌株的比例。
