ABSTRACT

Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphylococcus aureus may affect up to 100% of these patients. Virulent and resistant isolates can worsen AD patient clinical condition and jeopardize the treatment. We aimed to detect virulence genes and to evaluate the biofilm production of S. aureus isolates from infected skin lesions of children with AD. Methicillin resistance was detected by phenotypic and molecular tests and the virulence genes were detected by PCR. Biofilm formation was assessed by bacterial growing on microtiter plates and later stained with safranin. Genotyping was performed by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Among 106 AD patients, 55 (51.8%) had developed S. aureus cutaneous infections and 23 (41.6%) were methicillin-resistant (MRSA). All 55 isolates carried the fnbA, hla, icaA, sasG, and seu genes, and more than 70% presented cna, eap, ebpS, hlg, and pvl genes. Clonal complex (CC) 30 was the main lineage found (34.5%), especially among MRSA isolates (52.2%). The egc cluster and the bbp gene were significantly the most frequent in MRSA isolates and in USA1100/ST30/CC30 lineage. Most of the isolates (74.5%) were non-biofilm producers and many of them only started to produce it in the presence of fibrinogen. There was no significant association between S. aureus isolates features and the AD severity. This study demonstrated a high frequency of CC30 MRSA isolates presenting several virulence genes in infected skin lesions of AD children in Brazil, that may influence the severity of the disease and the treatments required.

摘要

特应性皮炎 (AD) 是一种慢性炎症性皮肤病，金黄色葡萄球菌的定植可能影响多达 100% 的这些患者。毒性和耐药性分离株会使 AD 患者的临床状况恶化并危及治疗。我们的目的是检测毒力基因并评估来自 AD 儿童感染皮肤病变的金黄色葡萄球菌分离株的生物膜产生。通过表型和分子试验检测甲氧西林耐药性，并通过PCR检测毒力基因。生物膜形成通过细菌在微量滴定板上生长并随后用番红染色来评估。通过脉冲场凝胶电泳和多位点序列分型进行基因分型。在 106 名 AD 患者中，55 名 (51.8%) 患有金黄色葡萄球菌皮肤感染和 23 (41.6%) 是耐甲氧西林 (MRSA)。所有 55 个分离株都携带fnbA、hla、icaA、sasG和seu基因，并且超过 70% 的菌株携带cna、eap、ebpS、hlg和pvl基因。克隆复合体 (CC) 30 是发现的主要谱系 (34.5%)，尤其是在 MRSA 分离株中 (52.2%)。在EGC集群和BBP基因是显著最常见的MRSA菌株和USA1100 / ST30 / CC30血统。大多数分离株 (74.5%) 是非生物膜生产者，其中许多分离株仅在存在纤维蛋白原的情况下才开始生产。金黄色葡萄球菌之间没有显着关联隔离功能和 AD 严重性。该研究表明，在巴西 AD 儿童受感染的皮肤病变中，CC30 MRSA 分离株的高频率呈现出几种毒力基因，这可能会影响疾病的严重程度和所需的治疗。