School of Pharmacy and Pharmaceutical Sciences, University of Cape Coast, Cape Coast, Ghana.
College of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa.
Genes (Basel). 2022 Dec 29;14(1):104. doi: 10.3390/genes14010104.
The work aims to investigate biofilm formation and biofilm/adhesion-encoding genes in coagulase-negative staphylococci (CoNS) species recovered from blood culture isolates. Eighty-nine clinical CoNS were confirmed using the VITEK 2 system, and antibiotic susceptibility testing of isolates was conducted using the Kirby-Bauer disk diffusion method against a panel of 20 antibiotics. Isolates were qualitatively screened using the Congo red agar medium. Quantitative assays were performed on microtiter plates, where the absorbances of the solubilised biofilms were recorded as optical densities and quantified. In all, 12.4% of the isolates were strong biofilm formers, 68.5% had moderate biofilm capacity, and 17.9% showed weak capacity. A subset of 18 isolates, mainly methicillin-resistant , were investigated for adherence-related genes using whole-genome sequencing and bioinformatics analysis. The highest antibiotic resistance rates for strongly adherent isolates were observed against penicillin (100%) and cefoxitin (81.8%), but the isolates showed no resistance to linezolid (0.0%) and tigecycline (0.0%). The ABC genes involved in biofilm formation were detected in 50% of the screened isolates. Other adherence-related genes, including autolysin gene (88.8%), elastin binding protein gene (94.4%), cell wall-associated fibronectin-binding protein gene (66.7%), clumping factor A gene A (5.5%), and pili gene C (22.2%) were also found. The insertion sequence IS256, involved in biofilm formation, was found in 10/18 (55.5%) screened isolates. We demonstrate a high prevalence of biofilm-forming coagulase-negative staphylococci associated with various resistance phenotypes and a substantial agreement between the possession of biofilm-associated genes and the biofilm phenotype.
本研究旨在调查从血培养分离株中回收的凝固酶阴性葡萄球菌（CoNS）物种的生物膜形成和生物膜/黏附编码基因。使用 VITEK 2 系统确认了 89 株临床 CoNS，采用 Kirby-Bauer 纸片扩散法对分离株进行抗生素敏感性试验，共检测了 20 种抗生素。使用刚果红琼脂培养基对分离物进行定性筛选。在微量滴定板上进行定量测定，记录溶解生物膜的吸光度作为光密度并进行定量。共有 12.4%的分离株为强生物膜形成者，68.5%具有中度生物膜形成能力，17.9%则表现出较弱的能力。使用全基因组测序和生物信息学分析，对一组 18 个主要为耐甲氧西林的分离物进行了与黏附相关的基因研究。强黏附分离株对青霉素（100%）和头孢西丁（81.8%）的抗生素耐药率最高，但对利奈唑胺（0.0%）和替加环素（0.0%）无耐药性。在筛选出的 50%分离株中检测到参与生物膜形成的 ABC 基因。还发现了其他与黏附相关的基因，包括自溶素基因（88.8%）、弹性蛋白结合蛋白基因（94.4%）、细胞壁相关纤维连接蛋白结合蛋白基因（66.7%）、聚集因子 A 基因 A（5.5%）和菌毛基因 C（22.2%）。参与生物膜形成的插入序列 IS256 在 18 个筛选出的分离株中发现了 10 个（55.5%）。本研究表明，凝固酶阴性葡萄球菌形成生物膜的现象较为普遍，与各种耐药表型相关，并且生物膜相关基因的存在与生物膜表型之间具有高度一致性。
