Background: Staphylococcus aureus is one of the most frequently isolated pathogens in the respiratory tract of CF patients. Recently, we characterized peculiar mucoid S. aureus isolates, which are excessive biofilm formers and which carried a 5bp-deletion within the intergenic region of the ica operon. In this prospective study, we determined the prevalence of mucoid S. aureus-isolates in the airways of CF-patients during a 3-months period.

Methods: We analyzed specimens (sputa, throat swabs) from 81 CF patients who attended two CF centers in Münster, Germany. Ten S. aureus isolates were randomly picked from every S. aureus-positive airway specimen and evaluated for mucoidy using Congo Red agar and phenotypic tests. Mucoid isolates were characterized by spa sequence typing, biofilm production and sequencing of the intergenic region of the ica operon to screen for the 5bp-deletion.

Results: In 7 of 81 examined patients (8.6%), we detected mucoid S. aureus phenotypes (37 out of 1050 isolates; 3.5%). Twenty-five mucoid isolates carried the 5bp-deletion. Mucoid isolates produced excessive biofilm and were significantly more resistant to certain antibiotics.

Conclusions: In our prospective study, mucoid S. aureus was present in 8.6% of S. aureus–positive CF-patients. In 6 of 7 patients, mucoid isolates carried the 5bp-deletion, indicating that also other so far not identified mechanisms cause excessive biofilm formation. Further studies are necessary to ascertain the clinical impact of mucoid S. aureus phenotypes on the severity of the CF disease.

背景：金黄色葡萄球菌是CF患者呼吸道中最常见的病原体之一。最近，我们表征了独特的黏液状金黄色葡萄球菌分离物，它们是过量的生物膜形成物，并在ica操纵子的基因间区域内带有5bp的缺失。在这项前瞻性研究中，我们确定了3个月内CF患者气道中的黏液状金黄色葡萄球菌分离株的患病率。

方法：我们分析了81名CF患者的标本（痰液，咽喉拭子），这些患者曾在德国明斯特的两个CF中心就诊。从每个金黄色葡萄球菌阳性气道标本中随机抽取十个金黄色葡萄球菌分离株，并使用刚果红琼脂和表型测试评估粘液性。通过spa序列分型，生物膜生产和ica操纵子基因间区域测序筛选5bp缺失来表征粘液样分离物。

结果：在81位接受检查的患者中，有7位（8.6％）检测到了粘液状金黄色葡萄球菌表型（1050种分离物中的37种； 3.5％）。25个粘液样分离物进行了5bp的缺失。粘液样分离物产生过量的生物膜，并且对某些抗生素的抵抗力明显更高。

结论：在我们的前瞻性研究中，在金黄色葡萄球菌阳性CF患者中，有8.6％存在黏液状金黄色葡萄球菌。在7名患者中的6名中，粘液样分离物带有5bp的缺失，这表明迄今为止尚未发现的其他机制也导致了过度的生物膜形成。需要进一步的研究以确定粘液状金黄色葡萄球菌表型对CF疾病严重程度的临床影响。