Both indicator strains did not show any alterations Obeticholic Acid in susceptibility to vancomycin, which confirmed the above result. Conclusions Although an increased transcription of the capsular gene cluster has been observed for several VISA strains, the type 5 capsule does not seem to play a significant role in the resistance mechanism of S. aureus 137/93G. It may therefore be assumed that – at least in the strain investigated here – an increased or uniform transcription of the capsule gene cluster is a phenomenon that accompanies vancomycin resistance, perhaps a by-product of a relatively high SigB activity in S. aureus 137/93G, indicated
by the intense yellow colour of this strain, that might contribute to glycopeptide resistance [50] or an overflow from an activated cell wall metabolism [1], rather than being the cause for vancomycin resistance. Acknowledgements This work was supported by the Bundesministerium für Wissenschaft und Forschung (PTJ-BIO/03U213B and PTJ-BIO/0313801 F) and the DFG (Bi504/8-1,2) to GB and the SFB766, project A7 to CW. click here V. Fuchs is thanked for expert technical assistance. We thank T. Roemer for supplying pEPSA5. Electronic supplementary material Additional file 1: Gene expression data.pdf. Table S1. Genes differentially expressed in the hVISA/MRSA strain SA137/93A and the related VSSA/MRSA control strain SA1450/94. Table S2. Genes differentially expressed
in the VISA/MSSA strain SA137/93G and the VSSA/MRSA control strain SA1450/94. Datasets of 4 microarray experiments (Full Genome Chip sciTRACER, Scienion AG, Berlin, Germany) were normalised by applying the LOWESS algorithm and subsequently consolidated using acuity 3.1 software (Axon instruments). Significant
changes in gene expression were identified with SAM (significance analysis of microarrays; www-stat.stanford.edu/~tibs/SAM/index.html) software using the one class response most type and a false discovery rate of <1%. (DOC 220 KB) References 1. Hanaki H, Kuwahara-Arai K, Boyle-Vavra S, Daum RS, Labischinski H, Hiramatsu K: Activated cell-wall synthesis is associated with vancomycin resistance in methicillin-resistant Staphylococcus aureus clinical strains Mu3 and Mu50. J Antimicrob Chemother 1998, 42:199–209.PubMedCrossRef 2. Cui L, Iwamoto A, Lian JQ, Neoh HM, Maruyama T, Horikawa Y: Novel mechanism of antibiotic resistance originating in vancomycin-intermediate Staphylococcus aureus . Antimicrob Agents Chemother 2006, 50:428–438.PubMedCrossRef 3. Cui L, Ma X, Sato K, Okuma K, Tenover FC, Mamizuka EM: Cell wall thickening is a common feature of vancomycin resistance in Staphylococcus aureus . J Clin Microbiol 2003, 41:5–14.PubMedCrossRef 4. Reipert A, Ehlert K, Kast T, Bierbaum G: Morphological and genetic differences in two isogenic Staphylococcus aureus strains with decreased susceptibilities to vancomycin. Antimicrob Agents Chemother 2003, 47:568–576.PubMedCrossRef 5.