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Detection of virulence genes in Staphylococus aureus isolates from dairy sheep, goats and cows mastitis, using single-dye DNA microarray

Abstract number: p1700

Vautor  E., Magnone  V., Rios  G., Pepin  M., Barbry  P.

Objectives: 

Staphylococcus aureus is a common cause of mastitis in dairy farms animals. Although many putative virulence factors have been identified in S. aureus genomes (Kuroda et al., 2001), the differences in pathogenic potential between naturally occurring isolates remain largely unaddressed. The relative importance of host (tissue) factors versus bacterial virulence determinants in disease pathogenesis is not well known, but it is widely accepted that bacterial factors including toxins, cell wall-associated adhesions, and secreted exoproteins are involved in the process. In this study, we use a single-dye DNA microarray assay to investigate the presence or absence of 196 putatives virulence genes in 75 S. aureus isolates recovered from cases of ovine, caprine and bovine mastitis.

Methods: 

Mastitis S. aureus isolates: sheep (n = 25), goats (n= 22), cows (n = 20).

DNA microarray: the arrays were spotted with long oligonucleotides (65-mer) representing 192 known virulence genes and new candidates identified in Mu 50 genome (a human strain) and other S. aureus genomes. Each gene were spotted four time. DNA extracted from the strains were labelled with fluorescent Cy5 using the BioPrime® Array CGH (Invitrogen). Control strains with known genetic and phenotypic characteristics were used to normalize the data.

Results: 

(i) The majority of the virulence gene was detected in all the isolates (e.g. coa, ica ADBC operon, htrA, hysA, nuc, sbi, sdrE, ssp, feoB, fnb, sib, spa). (ii) genes were not detected in the majority of the isolates (e.g. cna, edin, lukF-PV, SAV1999,...). (iii) genes were not found in isolates, depending on the herd (e.g. aur or SAV1038 absent in isolates from some dairy sheep farm), on the isolates whatever the species (i.g. bsaP, capH, entK, eta, fnbB, hsdS, lpl2, lukD, Map-ND2C,...). But we found gene mainly related to species (e.g. agrIII, SAV2496,...) Comprehensive results will be given in the poster.

Conclusions: 

The present study indicated that the prevalence of virulence genes among S. aureus isolates recovered from dairy farm species depends on the gene. These observations suggest a common occurrence of host-adapted (or tissue-adapted) S. aureus strains in which particular virulence genes may play a significant role. When taken with complementary methods such as PCR or/and Southern hybridisation, single-dye DNA microarrays may provide a powerful tool to type S. aureus strains for epidemiological and possibly pathogenesis studies.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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