Detection of Methicillin Resistance and Various Virulence Factors in Staphylococcus aureus Strains Isolated from Nasal Carriers

Prevalence of sea, seb, sec, sed, and tsst-1 genes of Staphylococcus aureus in nasal carriage and their association with multiple sclerosis

Background

Microbial superantigens might initiate or exacerbate autoimmune responses against particular tissues, organs or systems. This study aimed to examine the prevalence of sea, seb, sec, sed, and tsst-1 genes of Staphylococcus aureus in nasal carriage and their association with multiple sclerosis (MS).

Methods

Nasal swabs were collected from 150 MS patients and 150 healthy individuals (control group) to isolate S. aureus and investigate their superantigen genes (sea, seb, sec, sed and tsst-1) using PCR.

Results

A total of 300 participants were enrolled in the study, matched for age and gender (150 patients in the MS group and 150 in the control group). The prevalence of S. aureus colonization in MS patients and control groups was 42% and 23.3%, respectively. There was a statistically significant association between S. aureus colonization and MS disease (p<0.001; odds ratio 2.4; 95% confidence interval 1.4-3.9). No significant association was observed between the presence of S. aureus harboring sea, seb, sec, sed and tsst-1 genes with MS disease.

Conclusion

The rate of S. aureus nasal carriage is higher in patients with MS. Our study's results suggest that further investigation into whether there is a connection between MS and nasal exposure to staphylococcal superantigens is warranted.

Community-acquired methicillin-resistant Staphylococcus aureus carrying SCCmec type IV and V isolated from healthy children attending public daycares in northeastern Brazil

Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) have increasingly been reported in healthy communities. This study aimed to assess the rate of S. aureus in general and MRSA in particular from nasal secretion of children in daycare centers in Vitória da Conquista, Brazil. The isolates were identified based on morphology, biochemical tests and by PCR. Detection of virulence genes, biofilm production, and susceptibility test by disk diffusion agar were performed. MRSA isolates were characterized by spa, SCCmec, and multilocus sequence typing (MLST). S. aureus were recovered from 70 (47.3%) of 148 children. Among the 11 MRSA strains (15.7%), two SCCmec types (IV and V) were detected. MLST identified four STs related to three clonal complexes (CC): 5, 45, and 398. Four spa types were found circulating in this setting. Resistance of S. aureus isolates to ampicillin, erythromycin, ciprofloxacin, clindamycin, and tetracycline was 80%, 32.8%, 7.1%, 7.1% and 4.3%, respectively. One isolate presented intermediate resistance to vancomycin detected by Etest methodology. All strains were biofilm producers. The virulence genes seb, sec, spa, and pvl were detected in some isolates. This study revealed a high rate of children carrying MRSA among healthy attendees in daycare centers in Vitória da Conquista, Brazil.