INTRODUCTION: National obesity rates are leading to higher rates of Type 2 Diabetes, increasing the number of people at risk of invasive infections with Methicillin Resistant Staphylococcus aureus (iMRSA) upon onset of ESRD and hemodialysis. However, an association between adiposity and risk of iMRSA has not been researched. AIM: The purpose of this study is to describe the epidemiological characteristics of an iMRSA cohort in the Atlanta metro area between 2005-2008; to examine BMI-related health outcomes within the cohort; and to compare proportions of BMI categories in this cohort to BRFSS data. METHODS: Surveillance data collected by the CDC EIP program on iMRSA in Atlanta, Georgia was used. BMI was calculated for each eligible case. Statistical analysis was carried out in SPSS. Univariate and multivariate binary logistic regression analysis was performed on select variables. A p-value of < 0.05 and a 95% confidence interval (CI) were used to determine significance. BRFSS BMI data for Georgia was compared to the study population. RESULTS: Overweight and obese cases were more likely to be diagnosed with diabetes by regression analysis. Cases with diabetes were at greater odds of having undergone dialysis within the previous year (univariate OR=2.3, p=0.000; multivariate OR=2.5, p=0.000). The proportion of iMRSA patients with diabetes is much greater (42.8%) than in the general population of the United States (7.8-10.7%). DISCUSSION: The results indicate that there may be a higher risk for iMRSA in overweight and obese individuals, particularly if other adiposity-related health problems are present.

Streptococcus pyogenes (Streptocoque du Groupe A (SGA)) est un germe humain responsable d’un large éventail de pathologies invasives et non-invasives, mais aucun attribut génétique ne rend compte à lui seul de cette diversité. Notre objectif a été de rechercher des liens entre génotype, présence de gènes de virulence et caractère invasif des souches par une approche d’épidémiologie moléculaire. Une association entre génotypes et présence de certains gènes de virulence a été établie sur une collection de souches françaises de SGA responsables d’infections invasives chez des adultes. De même, la présence du locus sil, codant un système de quorum-sensing, est liée au génotype des souches, mais non à leur caractère invasif. Concernant la réponse immunitaire innée, contrairement aux souches emm1, emm4 et emm28, les souches invasives emm3 et emm89 sont plus phagocytées par les macrophages que leurs homologues non-invasives. Les souches emm89 sont plus phagocytées et survivent plus longtemps dans les macrophages que les souches des autres génotypes. Par ailleurs, les souches emm3 induisent l’apoptose des macrophages. Enfin, la cinétique de production des médiateurs pro et anti-inflammatoires est dépendante du génotype. La souche de colonisation d’un cas groupé, incluant aussi une souche invasive, présente une mutation originale dans covS (codant le senseur d’un système de régulation à deux composants). La protéine CovSY39H répond peu aux signaux de l’environnement, correspondant à une protéine CovS constitutive. Le phénotype de ce mutant, résultant de l’expression de certains gènes de virulence, est favorable à la colonisation. Sa survie dans les macrophages et sa virulence sont altérées. / Streptococcus pyogenes (Group A Streptococcus (GAS)) is a human pathogen responsible for a wide range of diseases including non-invasive and invasive infections. To date no specific GAS attribute has been associated with a type of infection although a link between genetic background and tissue tropism has been demonstrated. Our objective was to investigate the relationship between genotype, the presence of genes encoding virulence factors and invasive strains by molecular epidemiology approach. An association between genotypes and the presence of genes encoding virulence factors has been established among a collection of French strains responsible for invasive GAS infections in adults. Similarly, the presence of sil locus, encoding a quorum sensing system, is related to genotype, but not to the invasive status of the GAS strains. Regarding the innate immune response, unlike emm1, emm4 and emm28 strains, invasive emm3 and emm89 strains are more phagocytosed by macrophages than their non-invasive counterparts. The emm89 strains are phagocytosed and survive longer in macrophages than strains belonging to any other genotype. Moreover, emm3 strains induce macrophage apoptosis. Finally, the kinetics of production of pro- and anti-inflammatory mediators are genotype-dependent. A colonization strain belonging to a cluster that also includes an invasive strain, has a unique mutation in covS (encoding the sensor of a two-component system). The CovSY39H protein responds less to some environmental signals, corresponding to a constitutive CovS protein. The phenotype of the mutant, resulting in the expression of certain genes encoding virulence factors, favors a colonization state. Survival in macrophages and virulence are also altered.