title: Characterisation of virulence genes in methicillin susceptible and resistant Staphylococcus aureus isolates from a paediatric population in a university hospital of Medellín, Colombia.
abstract: Virulence and antibiotic resistance are significant determinants of the types of infections caused by Staphylococcus aureus and paediatric groups remain among the most commonly affected populations. The goal of this study was to characterise virulence genes of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains isolated from a paediatric population of a Colombian University Hospital during 2009. Sixty MSSA and MRSA isolates were obtained from paediatric patients between zero-14 years. We identified the genes encoding virulence factors, which included Panton-Valentine leucocidine (PVL), staphylococcal enterotoxins A-E, exfoliative toxins A and B and toxic shock syndrome toxin 1. Typing of the staphylococcal chromosome cassette mec (SCCmec) was performed in MRSA strains. The virulence genes were more diverse and frequent in MSSA than in MRSA isolates (83% vs. 73%). MRSA strains harboured SCCmec types IVc (60%), I (30%), IVa (7%) and V (3%). SCCmec type IVc isolates frequently carried the PVL encoding genes and harboured virulence determinants resembling susceptible strains while SCCmec type I isolates were often negative. PVL was not exclusive to skin and soft tissue infections. As previously suggested, these differences in the distribution of virulence factor genes may be due to the fitness cost associated with methicillin resistance.
authors.affiliation: Escuela de Microbiología, Universidad de Antioquia, Medellín, Colombia. judynatalia@yahoo.com
authors.forename: Judy Natalia
authors.initials: JN
authors.lastname: Jiménez
authors.forename: Ana María
authors.initials: AM
authors.lastname: Ocampo
authors.forename: Johanna Marcela
authors.initials: JM
authors.lastname: Vanegas
authors.forename: Erika Andrea
authors.initials: EA
authors.lastname: Rodríguez
authors.forename: Carlos Guillermo
authors.initials: CG
authors.lastname: Garcés
authors.forename: Luz Adriana
authors.initials: LA
authors.lastname: Patiño
authors.forename: Sigifredo
authors.initials: S
authors.lastname: Ospina
authors.forename: Margarita María
authors.initials: MM
authors.lastname: Correa
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003105:Colombia; D003430:Cross-Sectional Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D013203:Staphylococcal Infections / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors