Colonization, Infection, and Molecular Typing of Methicillin-Resistant Staphylococcus Aureus (MRSA) in Children.
Condition: Methicillin Resistance; Staphylococcus Aureus
MeSH terms: Staphylococcal Infections
Study type: Observational

Summary: 
      The intent of this study is to:

        1. Define the prevalence of MRSA carriage in the pediatric population in Kansas City.

        2. Systematically define patient risk factors for MRSA carriage and infection.

        3. Characterize the unique genetic characteristics of MRSA strains, both community acquired
           (CA) and healthcare associated (HCA) that are present in the different pediatric
           populations.
    

Detailed description: 
      Staphylococcus aureus (SA) are responsible for both localized and invasive infections
      including carbuncles, cellulitis, lymph node abscess, and wound infections among others. SA
      is a ubiquitous environmental organism that colonizes 30-50% adults and more than 50% of
      children with underlying skin disorders. Hematogenous seeding can result in fulminant
      infection, and sites as diverse as bone, joint, lung, muscle, pericardium, endocardium, and
      other vascular structures can be involved. Factors which are known to increase the risk for
      colonization include the presence of underlying skin disorders and history of frequent needle
      use which occur in the setting of diabetes, or hemodialysis. Health care workers have
      traditionally been noted to have higher carriage rates.

      MRSA strains emerged in the last two decades in the US and similarities to the evolution of
      penicillin resistant S. aureus were noted with colonization and infection in the hospital
      based setting noted first. Again, risk factors for MRSA colonization or infection in the
      hospital were noted to include prior antibiotic exposure, admission to an intensive care
      unit, surgery, and exposure to an MRSA-colonized patient. Emergence of CA-MRSA strains has
      been noted in the last decade having resistance to methicillin and erythromycin but
      susceptibility to clindamycin. These strains have challenged the practitioner's approach to
      the treatment of common skin and soft tissue infections as well as the management of invasive
      disease. The importance of such strains was underscored by the 1999 report detailing the
      deaths of 4 US children with invasive MRSA infection, none of whom had identifiable MRSA risk
      factors. Pulsed field typing of the isolates confirmed that these community strains were
      distinct from nosocomial strains isolated from patients in local hospitals.

      This study seeks to more clearly define the prevalence of MRSA carriage; better identify risk
      factors through personal interview; and further identify resistance patterns and molecular
      strains. This data will guide physicians at Children's Mercy and in the community at large in
      choosing the best treatment option for children with MRSA infections.

      The absence of traditional risk factors for MRSA infection has been noted in children with CA
      infections. Many studies that describe risk factors in MRSA patients do so by retrospective
      review of the medical record. Misclassification of patients may occur as physicians do not
      routinely document the presence or absence of such risk factors, particularly among household
      contacts.

      This study will look at nasal colonization for 500 children in the Kansas City area to
      determine prevalence of MRSA colonization. During the study period, all invasive MRSA
      isolates will also be collected. Pulsed field typing will be done to determine whether the
      strains are community or healthcare associated and both groups will be compared.
    

Time perspective: Other
Keywords: Methicillin Resistant Staphylococcus aureus; Children; Colonization; Risk Factor