Expression of Staphylococcal Virulence Genes In Situ in Human Skin and Soft Tissue Infections

Abstract

Background: Staphylococcus aureus, the most common pathogen in skin and soft tissue infections (SSTI), harbors many well-characterized virulence genes. However, the expression of many of them in SSTIs is unknown. In this study, S. aureus virulence genes expressed in SSTI were investigated. Methods: Fifty-three subjects presenting to the outpatient’s care and emergency departments with a purulent SSTI at two medical centers in Wisconsin, USA, were enrolled in the study. Total mRNA was extracted from the purulent or swab materials, made into cDNA and sequenced on MiSeq platform. The relative cDNA counts to gmk and identifications of the transcripts were carried out with respect to USA300 reference genome and using SAMTOOLS v.1.3 and BWA, respectively. Result: A significantly higher cDNA count was observed for many of the virulence and regulatory gene transcripts in the pus samples compared to the swab samples relative to the cDNA counts for gmk, a housekeeping gene. They were for lukS-PV (18.6 vs. 14.2), isaA (13.4 vs. 8.5), ssaA (4.8 vs. 3.1), hlgC (1.4 vs. 1.33), atl (17.7 vs. 8.33), clfA (3.9 vs. 0.83), eno (6.04 vs. 3.16), fnbA (5.93 vs. 0.33), saeS (6.3 vs. 1.33), saeR (5.4 vs. 3.33) and agrC (5.6 vs. 1.5). Conclusions: A relative increase in the transcripts of several toxins, adhesion and regulatory genes with respect to a gmk in purulent materials suggests their role in situ during SSTIs, perhaps in an orchestrated manner.

The survival of epidemic and sporadic MRSA on human skin mimics is determined by both host and bacterial factors

“…In our study, we found that epidemic, but not sporadic, MRSA strains expressed pore-forming toxins, including alpha-hemolysin (Hla), gamma-hemolysin (HlgB), PVL (LukS) and LukED, upon interaction with NEMs. Upregulation of hla , hlgB , lukS-PV , LukF-PV , lukE and lukD genes by S. aureus strains has been shown earlier in skin explants and in drainage material of cutaneous abscesses, which strengthens our findings [ 28 – 32 ]. All these toxins exhibit cytotoxic activity towards leucocytes, i.e., monocytes and neutrophils [ 33 ].…”

Transcriptional adaptation of staphylococci during colonization of the authentic human environment: An overview of transcriptomic changes and their relationship to physiological conditions

“…However, one may assume that gene expression drastically changes once the bacteria enter deeper tissues or the blood stream. Pulia and colleagues demonstrated that gene expression was significantly different when comparing pus samples and wound swabs ( Pulia et al., 2022 ). For example, a relative increase in the expression of toxin genes and virulence regulators ( agr and sae ) was observed in purulent material ( Pulia et al., 2022 ).…”

“…Pulia and colleagues demonstrated that gene expression was significantly different when comparing pus samples and wound swabs ( Pulia et al., 2022 ). For example, a relative increase in the expression of toxin genes and virulence regulators ( agr and sae ) was observed in purulent material ( Pulia et al., 2022 ). Higher strain toxicity is also indicated by analyses of human cutaneous abscesses ( Loughman et al., 2009 ; Date et al., 2014 ).…”