RESUMEN
BACKGROUND: Staphylococcus aureus may worsen already established atopic dermatitis (AD), but its primary role in the aetiopathogenesis and severity of AD is unclear. OBJECTIVES: To compare the prevalence of S. aureus colonization in early infancy in children who developed AD during the first 2â years of life with children who did not. METHODS: In this prospective birth cohort study, which included 450 infants, we analysed bacterial swabs collected from cheek skin at 0 and 2â months of age. The development of AD, and its severity, was diagnosed by a physician and monitored prospectively for 2â years. Information on parental atopy, filaggrin gene mutation status and use of antibiotics and emollients was included in the analyses. RESULTS: At birth, the occurrence of S. aureus colonization was similar in infants who developed subsequent AD and those who did not. At 2â months of age, S. aureus colonization was more common in children who later developed AD (adjusted hazard ratio 1.97, 95% confidence interval 1.21-3.19; P = 0.006). No association was found between S. aureus colonization and AD severity or age at onset. CONCLUSIONS: It remains unknown whether colonization with S. aureus may directly increase the risk of AD, or whether it should be considered as secondary to skin barrier impairment or a skewed immune activity, but according to our findings, S. aureus colonization is more commonly increased at 2â months of age in children who later developed AD.
Asunto(s)
Dermatitis Atópica , Infecciones Estafilocócicas , Lactante , Niño , Recién Nacido , Humanos , Dermatitis Atópica/complicaciones , Staphylococcus aureus , Estudios de Cohortes , Estudios Prospectivos , Cohorte de Nacimiento , Mejilla , Infecciones Estafilocócicas/complicaciones , Infecciones Estafilocócicas/epidemiologíaRESUMEN
BACKGROUND: The aim of this study was to investigate whether large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G can be adequately identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF). Previous studies show varying results, with an identification rate from below 50% to 100%. METHODS: Large colony beta-hemolytic streptococci containing Lancefield groups A, C, and G isolated from blood cultures between January 1, 2007 and May 1, 2012 were included in the study. Isolates were identified to the species level using a combination of phenotypic characteristics and 16s rRNA sequencing. The isolates were subjected to MALDI-ToF analysis. We used a two-stage approach starting with the direct method. If no valid result was obtained we proceeded to an extraction protocol. Scores above 2 were considered valid identification at the species level. RESULTS: A total of 97 Streptococcus pyogenes, 133 Streptococcus dysgalactiae, and 2 Streptococcus canis isolates were tested; 94%, 66%, and 100% of S. pyogenes, S. dysgalactiae, and S. canis, respectively, were correctly identified by MALDI-ToF. DISCUSSION: In most instances when the isolates were not identified by MALDI-ToF this was because MALDI-ToF was unable to differentiate between S. pyogenes and S. dysgalactiae. By removing two S. pyogenes reference spectra from the MALDI-ToF database the proportion of correctly identified isolates increased to 96% overall. MALDI-ToF is a promising method for discriminating between S. dysgalactiae, S. canis, and S. equi, although more strains need to be tested to clarify this.