Department of Microbiology, Escuela Nacional de Ciencias Biológicas-Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N. Col. Santo Tomas. Deleg. Miguel Hidalgo. CP 11340 Mexico City, Mexico.
Instituto de Oftalmología Fundación Conde de Valenciana, Chimalpopoca No. 14, Col. Obrera, Deleg. Cuauhtémoc. CP 06800 Mexico City, Mexico.
J Med Microbiol. 2013 Oct;62(Pt 10):1579-1587. doi: 10.1099/jmm.0.055210-0. Epub 2013 Jul 16.
In ocular infections (OIs) caused by Staphylococcus epidermidis, biofilms composed mainly of poly-N-acetylglucosamine (PNAG) have been widely studied, but PNAG-independent biofilms have not. Therefore, we searched for a relationship between the ica operon (involved in PNAG-biofilm) and the biochemical composition of biofilms in isolates from OI. Isolates from OI (n = 62), from healthy conjunctiva (HC; n = 45) and from healthy skin (HS; n = 53), were used to detect icaA and icaD genes, and the insertion sequence 256 (IS256) using PCR. The compositions of the biofilms were determined by treatment with NaIO₄, proteinase K and DNase I. Multilocus sequence typing (MLST) was performed to characterize the isolates, and the expression of aap and embp genes was determined by real-time qPCR. A strong relationship between the icaA(-)/icaD(-)/IS256(-) genotype and protein- or protein/extracellular DNA (eDNA)-biofilm composition was found in the isolates from OI (53.6%), whereas the icaA(+)/icaD(+)/IS256(-) genotype and carbohydrate-biofilm was most prevalent in isolates from HC (25%) and HS (25%). Isolates with an icaA(-)/icaD(-)/IS256(-) genotype and protein-biofilm phenotype were predominantly of the ST2 lineage, while carbohydrate-biofilm-producing strains were mainly of the ST9 lineage. The protein-biofilm-producing strains had higher expression levels of aap gene than carbohydrate-biofilm-producing strains; while embp gene did not have the same pattern of expression. These results suggest that S. epidermidis strains with icaA(-)/icaD(-)/IS256(-) genotype and protein- or protein/eDNA-biofilms have a stronger ability to establish in the eye than S. epidermidis strains with icaA(+)/icaD(+)/IS256(-) genotype and PNAG-biofilms.
在表皮葡萄球菌引起的眼部感染（OIs）中，已广泛研究了主要由聚-N-乙酰葡糖胺（PNAG）组成的生物膜，但尚未研究 PNAG 非依赖性生物膜。因此，我们在 OI 分离株中寻找ica 操纵子（参与 PNAG-生物膜）与生物膜生化组成之间的关系。使用聚合酶链反应（PCR）检测 OI 分离株（n=62）、健康结膜（HC；n=45）和健康皮肤（HS；n=53）中的icaA 和 icaD 基因以及插入序列 256（IS256）。用 NaIO₄、蛋白酶 K 和 DNase I 处理来确定生物膜的组成。进行多位点序列分型（MLST）以表征分离株，并通过实时 qPCR 确定 aap 和 embp 基因的表达。在 OI 分离株中发现，icaA(-)/icaD(-)/IS256(-)基因型与蛋白或蛋白/细胞外 DNA（eDNA）-生物膜组成之间存在很强的关系（53.6%），而 icaA(+)/icaD(+)/IS256(-)基因型和碳水化合物-生物膜最常见于 HC（25%）和 HS（25%）分离株中。具有 icaA(-)/icaD(-)/IS256(-)基因型和蛋白生物膜表型的分离株主要为 ST2 谱系，而产生碳水化合物生物膜的菌株主要为 ST9 谱系。产生蛋白生物膜的菌株 aap 基因的表达水平高于产生碳水化合物生物膜的菌株；而 embp 基因没有相同的表达模式。这些结果表明，与具有 icaA(+)/icaD(+)/IS256(-)基因型和 PNAG 生物膜的 S. epidermidis 菌株相比，具有 icaA(-)/icaD(-)/IS256(-)基因型和蛋白或蛋白/eDNA 生物膜的 S. epidermidis 菌株在眼部的定植能力更强。
