Searching for West Nile virus (WNV) in Greece.

West Nile virus (WNV), a mosquito-borne flavivirus, has increasingly become a concern in both America and Europe due to its complex and unpredictable lifecycle. Transfusion-associated transmission of the WNV has been well documented during the last few years. This study aimed to detect the presence of WNV in: (i) cerebrospinal fluid (CSF) specimens derived from aseptic meningitis cases in Greece and (ii) Greek blood donations. A total of 115 CSF specimens from patients suffering from aseptic meningitis and 9590 blood samples were collected from seven Greek hospitals during the periods June to October 2006 and 2007 and tested for investigational purposes. Both blood and CSF samples were tested for the presence of WNV RNA by using the PROCLEIX WNV assay. None of 115 CSF and 9590 blood donor samples was found positive according to our testing algorithms. Despite the presence of WNV in Balkan countries, WNV has not reached significant levels in Greece.

Determinants of acquisition and carriage of Staphylococcus aureus in infancy.

Nasal carriage of Staphylococcus aureus is a major risk factor for invasive S. aureus disease. The aim of this study was to define factors associated with carriage. We conducted a prospective, longitudinal community-based study of infants and their mothers for a period of 6 months following delivery. The epidemiology of carriage was examined for 100 infant-mother pairs. Infant carriage varied significantly with age, falling from 40 to 50% during the first 8 weeks to 21% by 6 months. Determinants of infant S. aureus carriage included maternal carriage, breastfeeding, and number of siblings. Bacterial typing of S. aureus was performed by pulsed-field gel electrophoresis and multilocus sequence typing. The majority of individuals carried a single strain of S. aureus over time, and the mother was the usual source for colonizing isolates in infants. The effect of other components of the normal nasal flora on the development of S. aureus carriage was examined in 157 consecutive infants. Negative associations (putative bacterial interference) between S. aureus and other species occurred early in infancy but were not sustained. An increasing antistaphylococcal effect observed over time was not attributable to bacterial interference. S. aureus carriage in infants is likely to be determined by a combination of host, environmental, and bacterial factors, but bacterial interference does not appear to be an ultimate determinant of carrier status.

Fibronectin-binding protein A of Staphylococcus aureus has multiple, substituting, binding regions that mediate adherence to fibronectin and invasion of endothelial cells.

Invasive Staphylococcus aureus infection frequently involves bacterial seeding from the bloodstream to other body tissues, a process necessarily involving interactions between circulating bacteria and vascular endothelial cells. Staphylococcus aureus fibronectin-binding protein is central to the invasion of endothelium, fibronectin forming a bridge between bacterial fibronectin-binding proteins and host cell receptors. To dissect further the mechanisms of invasion of endothelial cells by S. aureus, a series of truncated FnBPA proteins that lacked one or more of the A, B, C or D regions were expressed on the surface of S. aureus and tested in fibronectin adhesion, endothelial cell adhesion and invasion assays. We found that this protein has multiple, substituting, fibronectin-binding regions, each capable of conferring both adherence to fibronectin and endothelial cells, and endothelial cell invasion. By expressing S. aureus FnBPA on the surface of the non-invasive Gram-positive organism Lactococcus lactis, we have found that no other bacterial factor is required for invasion. Furthermore, we have demonstrated that, as with other cell types, invasion of endothelial cells is mediated by integrin alpha5beta1. These findings may be of relevance to the development of preventive measures against systemic infection, and bacterial spread in the bacteraemic patient.