Study of elevation of spdC gene expression with increased antibiotic resistance and virulence genes of Staphylococcus aureus isolated from diarrheal infections

Numerous clinical infections are caused by the opportunistic pathogen Staphylococcus aureus, including gastrointestinal diseases such as diarrhea. Frequent resistance to antibiotics makes S. aureus infections a problem. The surface protein displaying C encoded by (spdC) gene is an important virulence factor, which plays a role in anchoring virulence factors and antibiotic resistance genes in the cell wall. The objective of the current study is to investigate the significance of the relationship between expression spdC gene, resistance to different antibiotics and virulence S. aureus isolates collected from diarrheal patients. Thirty clinical samples were obtained from diarrhea patients at Al-Diwaniyah Teaching Hospital, Women and Children Hospital in Al-Diwaniyah city/Iraq during the period from June to October 2024. S. aureus isolates were cultured and identified on blood agar, mannitol salt agar using biochemical tests specific for S. aureus isolates, as well as antibiotic susceptibility testing by Vitek 2 device, and genetic detection by RT-qPCR for 16S rRNA, spdC, icaA & mecA genes. Twelve S. aureus isolates were diagnosed at a rate of 40%. The isolates showed resistance to different types of antibiotics (I, II & III & IV) by the Vitek 2. The expression (icaA 21.93, spdC 13.02 & mecA 5.03) genes was higher in the (IV) types, followed by types (III, II& I), respectively in expression. Strains of diarrheal S. aureus showed different resistance to multiple classes antibiotics. Expression analysis genes spdC, icaA & mecA was higher in isolates that showed multiple resistance to different types of antibiotics.