title: Spread of epidemic MRSA-ST5-IV clone encoding PVL as a major cause of community onset staphylococcal infections in Argentinean children.
abstract: BACKGROUND
  Community-associated methicillin-resistant Staphylococcus aureus-(CA-MRSA) strains have emerged in Argentina. We investigated the clinical and molecular evolution of community-onset MRSA infections (CO-MRSA) in children of Córdoba, Argentina, 2005-2008. Additionally, data from 2007 were compared with the epidemiology of these infections in other regions of the country.
  
  
  RESULTS
  Two datasets were used: i) lab-based prospective surveillance of CA-MRSA isolates from 3 Córdoba pediatric hospitals-(CBAH1-H3) in 2007-2008 (compared to previously published data of 2005) and ii) a sampling of CO-MRSA from a study involving both, healthcare-associated community-onset-(HACO) infections in children with risk-factors for healthcare-associated infections-(HRFs), and CA-MRSA infections in patients without HRFs detected in multiple centers of Argentina in 2007. Molecular typing was performed on the CA-MRSA-(n: 99) isolates from the CBAH1-H3-dataset and on the HACO-MRSA-(n: 51) and CA-MRSA-(n: 213) isolates from other regions. Between 2005-2008, the annual proportion of CA-MRSA/CA-S. aureus in Córdoba hospitals increased from 25% to 49%, P<0.01. Total CA-MRSA infections increased 3.6 fold-(5.1 to 18.6 cases/100,000 annual-visits, P<0.0001), associated with an important increase of invasive CA-MRSA infections-(8.5 fold). In all regions analyzed, a single genotype prevailed in both CA-MRSA (82%) and HACO-MRSA(57%), which showed pulsed-field-gel electrophoresis-(PFGE)-type-"I", sequence-type-5-(ST5), SCCmec-type-IVa, spa-t311, and was positive for PVL. The second clone, pulsotype-N/ST30/CC30/SCCmecIVc/t019/PVL(+), accounted for 11.5% of total CA-MRSA infections. Importantly, the first 4 isolates of Argentina belonging to South American-USA300 clone-(USA300/ST8/CC8/SCCmecIVc/t008/PVL(+)/ACME(-)) were detected. We also demonstrated that a HA-MRSA clone-(pulsotype-C/ST100/CC5) caused 2% and 10% of CA-MRSA and HACO-MRSA infections respectively and was associated with a SCCmec type closely related to SCCmecIV(2B&5).
  
  
  CONCLUSIONS
  The dissemination of epidemic MRSA clone, ST5-IV-PVL(+) was the main cause of increasing staphylococcal community-onset infections in Argentinean children (2003-2008), conversely to other countries. The predominance of this clone, which has capacity to express the h-VISA phenotype, in healthcare-associated community-onset cases suggests that it has infiltrated into hospital-settings.
authors.affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica; Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sola
authors.forename: Hugo
authors.initials: H
authors.lastname: Paganini
authors.forename: Ana L
authors.initials: AL
authors.lastname: Egea
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Moyano
authors.forename: Analia
authors.initials: A
authors.lastname: Garnero
authors.forename: Ines
authors.initials: I
authors.lastname: Kevric
authors.forename: Catalina
authors.initials: C
authors.lastname: Culasso
authors.forename: Ana
authors.initials: A
authors.lastname: Vindel
authors.forename: Horacio
authors.initials: H
authors.lastname: Lopardo
authors.forename: José L
authors.initials: JL
authors.lastname: Bocco
mesh_terms: D017668:Age of Onset; D001118:Argentina / Q000453:epidemiology; D015373:Bacterial Typing Techniques; D002648:Child; D017714:Community-Acquired Infections / Q000453:epidemiology*; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D058872:Epidemics; D005260:Female; D006801:Humans; D007956:Leukocidins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000453:epidemiology*; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D007956:Leukocidins