Coagulase-negative staphylococci: incidence, pathogenicity, and treatment in the 1990s

Post-neurosurgical nosocomial bacterial meningitis in adults: microbiology, clinical features, and outcomes

The clinical data of 62 adult patients who suffered post-neurosurgical nosocomial bacterial meningitis, retrospectively collected over a 16-year period, were studied. Cases were divided into two groups based on the date of presentation, the first period being 1986-1993 and the second 1994-2001. Fever and progressive consciousness disturbance were the most consistent clinical features - signs that may also be attributed to other postoperative neurosurgical problems. The common pathogens included Staphylococcus aureus, coagulase negative Staphylococcus, Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii. An increase in polymicrobial infections and multi-antibiotic resistance during the second period was identified. In the first half of the study, mortality was 22%, and in the second half 36%. Adult post-neurosurgical nosocomial bacterial meningitis has become an important clinical problem. The choice of appropriate empirical antibiotics is challenging and must be guided by an awareness of the relative frequency of various pathogens and the increasing incidence of resistant strains. Although high mortality rates may, in part, be related to the primary brain pathology, early diagnosis and the timely use of antibiotics based on antimicrobial susceptibility testing are essential for survival.

Fever and 'negative' blood cultures in an elderly woman

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Update on clinical significance of coagulase-negative staphylococci

The clinical significance of coagulase-negative Staphylococcus species (CNS) continues to increase as strategies in medical practice lead to more invasive procedures. Hospitalized patients that are immunocompromised and/or suffering from chronic diseases are the most vulnerable to infection. Since CNS are widespread on the human body and are capable of producing very large populations, distinguishing the etiologic agent(s) from contaminating flora is a serious challenge. For this reason, culture identification should proceed to the species and strain levels. A much stronger case can be made for the identification of a CNS etiologic agent if the same strain is repeatedly isolated from a series of specimens as opposed to the isolation of different strains of one or more species. Strain identity initially can be based on colony morphology, and then one or more molecular approaches can be used to gain information on the genotype. Many of the CNS species are commonly resistant to antibiotics that are being indicated for staphylococcal infections, with the exception of vancomycin. The widespread use of antibiotics in hospitals has provided a reservoir of antibiotic-resistant genes. The main focus on mechanisms of pathogenesis has been with foreign body infections and the role of specific adhesins and slime produced by Staphylococcus epidermidis. Slime can reduce the immune response and opsonophagocytosis, thereby interfering with host defense mechanisms. As we become more aware of the various strategies used by CNS, we will be in a better position to compromise their defense mechanisms and improve treatment.

Antimicrobial activity of MDL 62,873, a semisynthetic derivative of teicoplanin, in vitro and in experimental infections

MDL 62,873 is an amide derivative of teicoplanin A2-2. Like those of natural glycopeptides, its antibacterial activity is mediated by inhibition of cell wall peptidoglycan synthesis. Against streptococci and enterococci, the in vitro activity of MDL 62,873 was similar to that of teicoplanin and greater than that of vancomycin. Against staphylococci, it has activity similar to that of vancomycin, and it was significantly more active than teicoplanin against coagulase-negative isolates. Like teicoplanin and vancomycin, MDL 62,873 had slow but significant bactericidal activity (99 to 99.9% killing in 24 h) against staphylococci at concentrations near the MIC. In murine septicemia studies with Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae, the 50% effective doses were lower than those of vancomycin. In staphylococcal endocarditis in rats, MDL 62,873 at 20 mg/kg of body weight and vancomycin at 40 mg/kg, both doses given intravenously twice daily, had similar efficacies in reducing the heart bacterial load. These results probably reflect the longer half-life of MDL 62,873, which has a pharmacokinetic profile in rats similar to that of teicoplanin.