described more frequently strong biofilm formers among S. aureus bloodstream isolates than commensal [20]. A possible explanation might be that all bloodstream isolates came from patients with peripheral Ferrostatin-1 intravenous devices, while this

was not an inclusion criterion in the study by Smith et al. Peripheral or central line intraluminal colonization might be associated with strains that easily attach to (catheter) surfaces and as a consequence these strains could be dominant in leading to bloodstream infections. Conclusion In summary, the present study reveals that the MLST CC8 associated genetic background was a predisposing factor for strong biofilm formation in vitro, under all tested glucose concentrations, i.e. 0%, 0.1%, 0.25% and 0.5%. At physiologic glucose concentration (0.1%), 0-7% of S. aureus from see more various Selleckchem MK1775 clonal lineages were defined as strong biofilm former, compared to 60% for the S. aureus associated MLST CC8. Methods Bacterial strains S. aureus

strains (72 MRSA and 156 MSSA) investigated were isolated during 2005 to 2008 in the Maastricht University Medical Center, a tertiary 715-bed hospital, and originate from surveillance cultures (commensal flora) from individual patients, recovered from nasal swabs. MRSA and/or MSSA strains associated with MLST CC1, CC5, CC8, CC22, CC30, CC45, CC7, CC12, CC15, CC25 and CC121, were randomly selected from our institutional collection (Table 1). All MRSA strains

were tested positive for the MRSA-specific mecA gene, by real-time PCR [34]. Additionally, 26 MSSA blood stream isolates from individual patients and associated with either MLST CC8 or CC7 were tested. These isolates were considered invasive. N-acetylglucosamine-1-phosphate transferase Characterization of the genetic background Typing of the spa locus was carried out as described previously [19]. The spa types were assigned through the Ridom SpaServer http://​spaserver.​ridom.​de and clustered into spa-CCs using the algorithm based upon repeat pattern (BURP) with Ridom StaphType 1.4 using the default settings [35, 36]. Although, spa typing alone sometimes lacks discriminatory power, due to related spa repeat patterns within different clonal lineages and the emergence of homoplasies among spa sequences [37], it has been shown that spa typing/BURP results are often in agreement with results obtained by MLST [36, 38]. Therefore, the associated MLST CCs were allocated through the SpaServer. To confirm the association between MLST and spa typing, in combination with BURP, MLST was performed on a representative set of 16 strains of each major spa type and associated MLST CC [39, 40]. Phenotypic detection of slime producing ability onto Congo red agar MRSA (n = 72), MSSA with MRSA associated MLST CCs (n = 75), i.e. CC1, CC5, CC8, CC22, CC30 and CC45, and MSSA with MSSA associated MLST CCs (n = 81), i.e.