High Risk For Invasive Infections Research Articles

Multicenter, Prospective Surveillance Study of Staphylococcus aureus Nasal Colonization in 28 Italian Intensive Care Units: The ISABEL Study

The role of methicillin-resistant Staphylococcus aureus (MRSA) colonization as a predictor of invasive disease in intensive care unit (ICU) patients was established many years ago. The role of mefhicillin-susceptible Staphylococcus aureus (MSSA) colonization is more debated, although in a recent report patients who were carriers of MRSA or MSSA at ICU admission were found to be at increased risk. Whether carriage at ICU admission involves a higher risk of invasive infection than carriage acquired during an ICU stay has not been established. We report the results of a study aimed at estimating the frequency of S. aureus (MRSA and MSSA) colonization at admission and at discharge in patients admitted to several ICUs in Italy and at estimating the relationship between colonization status and infection by S. aureus.

The effects of interferon-γ and transforming growth factor-β on adherence and survival of group B Streptococcus type III strains in ECV304 cells

Group B streptococci (GBS) are an important cause of neonatal sepsis, pneumonia and meningitis. In some newborns, GBS sepsis may have a severe course, including septic shock with high mortality rate, whereas other newborns are colonized with GBS on their surfaces without any clinical signs of bacterial infections. Interferon (IFN)-gamma is produced in neonatal GBS sepsis, and transforming growth factor (TGF)-beta is also found in the uterus. The involvement of IFN-gamma and TGF-beta in the earliest phase of infection might be a determinant of susceptibility and/or progression of infection in vivo. The aim of this study was to assess the effect of IFN-gamma and TGF-beta on adherence and intracellular viability in ECV304 cells of GBS serotype III isolated from cerebrospinal fluid (CSF) and vagina (strains 90356 and 80340, respectively). Interaction of GBS-ECV304 cells showed that the CSF isolate exhibited a more efficient adherence mechanism than the vagina isolate (P<0.001). Intracellular viability was observed for the CSF 90356 isolate within 2 h incubation. Results suggest the expression of additional bacterial virulence factors that favor some GBS type III strains to cause invasive disease. Detection of genotypic virulence marker (162-kb) in the CSF 90356 isolate by PFGE emphasizes the high risk of invasive infection by some GBS-III strains. Treatment of ECV304 cells with IFN-gamma and/or TGF-beta increased adherence of both GBS strains (P<0.001). Intracellular survival of the CSF 90356 isolate was observed after 24 h incubation following treatment of ECV304 cells with IFN-gamma and TGF-beta. Our data suggest that both IFN-gamma and TGF-beta may favor virulence of GBS strains. Variation of IFN-gamma and TGF-beta producing capacity of host cells of different individuals may influence development of invasive disease by GBS-III.