Genomic and proteomic characterization ofStaphylococcus aureusmastitis isolates of bovine origin

Abstract

Staphylococcus aureus colonizes and infects humans as well as animals. In the present study, 17 S. aureus strains isolated from cows suffering from mastitis were characterized. The well-established multilocus sequence typing (MLST) technique and a diagnostic microarray covering 185 S. aureus virulence and resistance genes were used for genetic and epidemiological analyses. Virulence gene expression studies were performed by analyzing the extracellular protein pattern of each isolate on 2-D gels. By this way, a pronounced heterogeneity of the extracellular proteome between the bovine isolates has been observed which was attributed to genome plasticity and variation of gene expression. Merely 12 proteins were expressed in at least 80% of the isolates, i.e. Atl, Aur, GlpQ, Hla, LtaS, Nuc, PdhB, SAB0846, SAB2176, SAB0566, SspA, and SspB forming the core exoproteome. Fifteen extracellular proteins were highly variably expressed and only present in less than 20% of the isolates. This includes the serine proteases SplB, C, and F, and the superantigens SEC-bov, SEL and TSST-1. Compared to human isolates we identified at least six proteins with significantly different expression frequencies. While SAB0846 was expressed more frequently in bovine isolates, LytM, EbpS, Spa, Geh, and LukL1 were seen less frequently in these isolates.

The virulence of Staphylococcus aureus correlates with strain genotype in a chicken embryo model but not a nematode model

“…It was demonstrated that this subtype differed from avirulent strains in more that 400 ORFs [46]. Similarly, a proteomic approach indicated that multiple factors are involved in human and bovine host specificity [47]. In the present study the chicken embryo model clearly clustered poultry strains into virulent (ch3, ch5, ch8, ch9, ch21, ch23, ch25, and pa2), avirulent (ch22, ch24, pa3, ph1, ph2, and t2), and intermediate groups.…”

“…As Triplex PCR is based on co-amplification of fragments of spa, coa, and the hypervariable region adjacent to mecA [35], allelic variation in one of these regions may explain the unusual virulence of this strain. Another explanation is that despite close genetic relatedness, the exoproteome composition of ch21 and ch22 may vary significantly because of variability in gene expression [47,48]. These possibilities are currently being evaluated to identify the factors responsible for the observed differences in virulence of those two strains.…”

Improving the Safety of Staphylococcus aureus Polyvalent Phages by Their Production on a Staphylococcus xylosus Strain

“…The majority of these strains belongs to CC97 (47.5%) and CC151 (47.5%). Other studies showed that the latter CCs are distributed worldwide and constitute the major groups causing mastitis infection outbreaks, mainly in North and South America and Europe [50], [51]. However, CC126 is most predominant in Brazil, along with CC97 [52].…”

Differentiating Staphylococcus aureus from Escherichia coli mastitis: S. aureus triggers unbalanced immune-dampening and host cell invasion immediately after udder infection

“…b Originally isolated from clinical or sub-clinical cases of mastitis, cf ref. 65; c was shown to cause transient or persistent infection of udder cells, cf ref. 44.…”

“…That S . aureus strain has in addition been characterized at the genomic and proteomic level 65 together with the S . aureus strains RF122 (originally isolated from clinical mastitis), B and D. The latter two strains had been isolated from subclinical cases of mastitis.…”