title: Resistant Strains of Enterotoxigenic Staphylococcus aureus; Unknown Risk for Multiple Sclerosis Exacerbation.
abstract: BACKGROUND
  Despite all advances in neurological sciences, there are unknown aspects in the epidemiology of multiple sclerosis (MS). Based on this hypothesis, the enterotoxigenic strains of Staphylococcus aureus (S. aureus) are possible risk factors for exacerbations of MS.
  
  
  OBJECTIVE
  The present study was carried out to investigate the role of resistant strains of enterotoxigenic S. aureus in MS exacerbation.
  
  
  METHODS
  Two-hundred nasal swab samples were collected from non-MS (n = 80), MS stable (n = 60) and MS exacerbation (n = 60) groups. Samples were cultured and those that were S. aureus-positive were analyzed for the presence of enterotoxins, using polymerase chain reaction (PCR). Antimicrobial susceptibility was performed using disk diffusion method.
  
  
  RESULTS
  Ninety out of 200 nasal samples (45%) were positive for S. aureus. The highest levels of nasal colonization were seen in MS exacerbation group (68.33%). The most commonly detected enterotoxins were sea (30%), sec (15.55%) and seb (11.11%). There were significant differences between S. aureus colonization and type of samples (P = 0.026) and, also, between type of samples and prevalence of enterotoxins (P = 0.022). The highest levels of enterotoxigenic genes were seen in MS exacerbation group. The S. aureus strains had the highest levels of resistance against tetracycline (80%), ampicillin (72.22%), methicillin (66.66%), erythromycin (66.66%), oxacillin (63.33%), trimethoprim-sulfamethoxazole (61.11%) and cotrimoxazole (55.55%).
  
  
  CONCLUSIONS
  Our findings should raise awareness about the role of sea and sec enterotoxins, in resistant strains of S. aureus, as a risk factor for MS exacerbation. It is better to keep MS patients away from polluted environments of hospitals and health centers.
authors.affiliation: Department of Neurology, AJA University of Medical Sciences, Tehran, IR Iran.
authors.forename: Farzad
authors.initials: F
authors.lastname: Mehrabi
authors.affiliation: Department of Infectious Diseases, AJA University of Medical Sciences, Tehran, IR Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Asgari
keywords: Antibiotic Resistance; Enterotoxins; Iran; Multiple Sclerosis; Staphylococcus aureus