Molecular Typing and Variations in Amount of tst Gene Expression of TSST-1-Producing Clinical Staphylococcus aureus Isolates

Abstract

The toxic shock syndrome toxin-1 (TSST-1), encoded by tst gene, has been proposed to cause staphylococcal toxic shock syndrome (TSS) in a susceptible host, which highlights the need to evaluate the level of tst gene expression and molecular genetic characteristics of the tst -positive isolates. A total of 916 S. aureus isolates collected from seven hospitals in China were screened for the tst gene. The tst positive isolates were characterized by spa , SCC mec , PFGE, and agr typing. Representative strains were also subjected to MLST typing. qRT-PCR was used to quantify tst and major virulence regulator genes expression. We also sequenced the regions of promoter and open reading frame (ORF) of tst to investigate whether they correlate with the variation in tst expression. We found 208 (22.7%) of surveyed isolates including 198 (29.8%) of MRSA and 10 (4.0%) of MSSA isolates harbored the tst gene. The most common clone among tst positive MRSA isolates belonged to ST5 (CC5)- agr 2-t002-SCC mec II. The amount of tst mRNA varied 8.4-folds among clinical S. aureus isolates. Sequencing the tst promoter revealed a base T deletion in tst high expressed isolates. As for major virulence regulators, srrA, sarT, RNAIII , and ccpA in four tst differentially expressed strains were detected to be highly expressed, respectively. Our study revealed high prevalence of ST5 (CC5)- agr 2-t002-SCC mec II clone among tst positive MRSA in hospitals from China. The levels of tst expression among clinical S. aureus isolates varied, which may be associated with tst promoter and variations in specific virulence regulators.

Multiple antibiotic resistance and virulence factors of Staphylococcus aureus strains isolated from dairy farms in South Sulawesi, Indonesia

“…The sea gene is the most commonly associated source of foodborne poisoning in humans due to improper handling and storage (Chen et al 2018) and cases of subclinical mastitis in cattle (Fursova et al 2018). The toxic shock syndrome toxin-1 (TSST-1), which is encoded by the tst gene, is a significant virulence factor in S. aureus infections which can trigger excessive and nonconventional T-cell activation and cytokines release and consequently interfere with the immune system function systemically (Zhao et al 2019). Moreover, the tst gene can cause food poisoning in humans (Pérez et al 2020).…”

Investigation of mec A and (tst-1) Genes Among Staphylococcus aureusIsolated from Skin Infection in Al- Diwaniyah Iraq

“…The nowadays-reports refer to increasing the worldwide distribution of the tst-1 gene to even higher levels than the already known elevated spreading 15 . It has been found that this gene has genetic variations which might suggest different virulence levels 16 .…”

Meat Borne Bacterial Pathogens

“…As these toxins are present on mobile genomic elements, these can easily be horizontally transferred to other non-virulent strains (Varshney et al 2009). SEs (A-E) are termed as classic enterotoxins, except SEF which is superantigen TSST-1 due to its sequence and structural homology to toxic shock syndrome toxin (Zhao et al 2019).…”