Prevalence of Staphylococcal Superantigens and their association among bacteremic and Infective Endocarditis patients in Egypt

Aim Infective endocarditis (IE) is a major complication of Staphylococcus (S.) aureus infection in humans particularly those with bacteremia. Although Staphylococcus species are commensal on or in different parts of the human body, it is also known to be a serious pathogen causing bacteremia and sepsis that could lead to IE. Therefore, our aim was to assess the prevalence as well as phenotypic and genotypic association of the Staphylococcal superantigens (SAgs) among bacteremic and IE patients. Methods This study was conducted on Staphylococcus isolates recovered from bacteremic and IE patients. The isolates were screened phenotypically for the detection of SAgs including Staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin-1 (TSST-1). Molecular detection and analysis of sea, seb, sec, sed, see and tsst-1, the major SAgs coding genes were performed using PCR and agarose gel electrophoresis, respectively. The obtained findings were statistically analyzed using standard methods. Results Detection of SAgs using ELISA revealed that 12 (46%) isolates were positive for enterotoxin production. However, the PCR revealed that 19 (73%) isolates were positive for enterotoxin genes with the highest prevalence of the sea gene (79%), followed by the seb (63%), tsst-1 (21%). The least frequent gene was the sed (5.3%). Accordingly, phenotypic and genotypic screening for prevalence of SAgs among Staphylococcal isolates showed significant difference (P value =0.046703), however, no significant correlation could be observed among the coagulase negative Staphylococci (CoNS) isolates (P value =0.248213). Statistical correlations between bacteremic and IE isolates with respect to prevalence of SAgs, showed no significant difference (P-value = 0.139, Effect size = 0.572) indicating no specific association between any of the detected SAgs and IE. Conclusion no significant difference has been found between Staphylococcal IE and bacteremia isolates regarding both phenotypic and genotypic detection of the most commonly SAgs. Therefore, all Staphylococcal bacteremic patients are suspected for IE. Also, future work should be conducted for analysis of SAgs gene expression.