Asymptomatic neurocognitive disorders in patients infected by HIV: fact or fiction?

Neurocognitive disorders are emerging as a possible complication in patients infected with HIV. Even if asymptomatic, neurocognitive abnormalities are frequently detected using a battery of tests. This supported the creation of asymptomatic neurocognitive impairment (ANI) as a new entity. In a recent article published in BMC Infectious Diseases, Magnus Gisslén and colleagues applied a statistical approach, concluding that there is an overestimation of the actual problem. In fact, about 20% of patients are classified as neurocognitively impaired without a clear impact on daily activities. In the present commentary, we discuss the clinical implications of their findings. Although a cautious approach would indicate a stricter follow-up of patients affected by this disorder, it is premature to consider it as a proper disease. Based on a review of the data in the current literature we conclude that it is urgent to conduct more studies to estimate the overall risk of progression of the asymptomatic neurocognitive impairment. Moreover, it is important to understand whether new biomarkers or neuroimaging tools can help to identify better the most at risk population

[Adherence properties and production of slime by staphylococci: relation to pathogenicity]

Among the S. aureus 25/39 are non producing slime and non adherent isolates. These results did not allow a correlation between these properties and pathogenesis. Several different phenotyping systems (biotyping, phage typing, serotyping, antibiotic susceptibility profiling, and plasmid pattern analysis) have been used in an attempt to identify strains of CNS. There is still a need however, for a simple, rapid, and cost effective method of distinguishing true pathogens from simple contaminants. Our results suggest that testing isolates for slime positivity and for adherence property may fulfill this task

Effect of subinhibitory concentrations of cefamandole and cefuroxime on adherence of Staphylococcus aureus and Staphylococcus epidermidis to polystyrene culture plates

The ability of cefamandole and cefuroxime to inhibit adherence of staphylococci to polystyrene culture plates was tested in an in vitro assay using eight strains each of Staphylococcus aureus and Staphylococcus epidermidis. The results indicated that subinhibitory concentrations of cefamandole and cefuroxime altered the adherence ability of both staphylococcal species, inhibition of adherence being more marked in the presence of cefamandole. It may be important to consider antiadherence properties in association with bactericidal activity when selecting agents for antibiotic prophylaxis

Efficacy of subinhibitory concentration of pefloxacin in preventing experimental Staphylococcus aureus foreign body infection in mice

Adhesion is the first step leading to colonization and infection of a foreign body (FBI). To assess the ability of a subinhibitory concentration (subMIC) of pefloxacin (P) to prevent such infection, an experimental model was developed in Swiss albino mice. Subcuts of polyurethane catheters (Vygon) were placed in the peritoneal cavity of animals and 24 hours later, different inocula of an adherent strain of Staphylococcus aureus (SA) (MIC of P:0.8 mg/l) were injected i.p. Unexposed SA served as controls. Two days later the removed catheters, blood and spleen specimens were quantitatively cultured for bacterial content and identity. Infection was defined as more than 10 CFU/ml of SA recovered. Significant protection of mice, with lower dissemination, was found with inoculum sizes of 10(5) and 10(6). These results suggest that subMICs of P may confer protection against foreign body infection

[Effect of fibronectin on the adhesion of staphylococci and interaction with pefloxacin's anti-adherence properties]

Fibronectin (Fn) is recognized for its ability to mediate Staphylococcus aureus (SA) adhesion. The number of Fn receptors is dependent on the phase of growth, and type of media. Furthermore, it was of interest to examine SA and Staphylococcus epidermidis (SE) adherence to porcine Fn (IBF 10 ng/ml) immobilized on tissue culture plates. The aim of our study was to examine if removal of FN receptors by growing bacteria in an antibiotic containing medium decreased the ability to adhere and of pefloxacin (P) anti-adhesive properties were medium dependent. As SE usually lack Fn binding capabilities, it seemed of interest to investigate if the effects of subinhibitory concentrations of P were modified by medium or Fn. We found: a) For SA: whether Fn coated onto plastic substrata promoted adherence of strains, P's anti-adhesive properties were saved, non medium or phase of growth dependent. b) For SE: adherence properties were decreased if Fn was coated onto plates. P's anti-adhesive properties were not modified and non medium dependent. The number of Fn receptors on clinical isolates of SA correlates with the invasiveness of the isolates. As P reduced the binding of SA to Fn coated plates, this observation may have important implications for antimicrobial prophylaxis

Effects of subinhibitory concentrations of vancomycin and teicoplanin on adherence of staphylococci to tissue culture plates.

Bacterial adhesion is the first step in infection of medical devices. Staphylococcus aureus and Staphylococcus epidermidis are the pathogens recovered most often. The effects of subinhibitory concentrations of vancomycin and teicoplanin on the adherence of eight clinical strains of S. aureus and eight strains of S. epidermidis to tissue culture plates in vitro were tested. The mean relative inhibitions of adherence at one-fourth and one-eighth the MIC were statistically different for teicoplanin and vancomycin. Slime production seemed not to be involved in adherence

[Contribution of bacterial detachment by enzymatic or physical methods to the diagnosis of foreign material infections and chronic osteomyelitis]

Bacterial adhesion is a crucial factor in the pathogenicity of numerous bacterial species. This property plays such a great role in infections of foreign material that removal of the material is the only effective therapy. The electron microscopy studies performed by Christensen have demonstrated that infected foreign material harbors bacteria which are often coated with slime and therefore escape detection by conventional microbiological methods. in view of these properties, enzymatic or physical detachment of adherent bacteria was attempted. 231 specimens from a variety of materials (catheters, heart valves, drains, bone biopsies) which yielded negative results after 15 days culture in Schaedler medium were either exposed to trypsin or sonicated. Among catheter specimens, 44.7% yielded positive bacteriologic results; pathogens recovered included 8.3% micrococci, 5.1% nongroupable streptococci, 1.7% group D streptococci, 2.9% Enterobacteria, and 23.3% coagulase-negative staphylococci. Among the bone specimens, the improvement in yield was 64.7%; except in one case, the pathogens recovered were consistent with previously initiated treatments. This bacterial detachment method should be studied in a larger number of specimens to determine its diagnostic value as compared with conventional techniques