Vancomycin Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Vancomycin and links to relevant pages within the course.
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| Enterococcus faecium ID As a high percentage of Enterococcus faecium strains carry the Van A gene and are highly resistant to vancomycin. Species identifications are performed in some laboratories where MIC susceptibility testing may not be available.Methods for the phenotypic separation of E. faecium from E. faecalis are limited.Illustrated in this photograph are positive reactions for acid production from arabinose and melibiose (yellow color), characteristic of E. faecium. E. faecalis are negative for these reactions.A few preformed substrates such as beta galactosidase (E. faecium positive, E. faecalis negative) also serve to separate these two species, accomplished by certain commercial systems that include these substrates.E. faecium is not motile, an additional characteristic helpful to separate vancomycin-resistant Enterococcus species from E. cassiloflavus and E. gallinarum, both of which are motile, and carry the low level resistant gene VAN-c. | View Page |
| Vancomycin Resistance Vancomycin and ampicillin resistance among Enterococcus species, particularly E. faecium have been on a steady increase.The disk diffusion screening test is used in many laboratories to detect vancomycin resistant strains. Note in the upper photograph that no zone of inhibition is seen around either the vancomycin or the ampicillin disk, indicating resistance to both drugs.Vancomycin-resistant Enterococci (VRE) have been divided into three phenotypes--Van A, Van B, and Van C.Vancomycin-resistant strains of E. faecalis and E. faecium are commonly of the Van A phenotype, demonstrating high level resistance (MIC's higher than 64 ug/mL), as illustrated by total resistance of the test strain in the E test and the VA disk, as illustrated in the lower photograph.The strain shown in the lower photograph, however, is ampicillin susceptible at the level of 1 ug/ml (see lower set of yellow arrows), indicating that this drug may be effective in treating the urinary tract infection. | View Page |
| Illustrated in this photograph is a quadrant plate containing brain heart infusion agar plate supplemented with 6 ug/ml of vancomycin. The right upper quadrant was inoculated with the test strain of Enterococcus faecium. The presence of growth in the inoculated quadrant indicates resistance to vancomycin. | View Page |
| Review 1 Garbutt JM. Littenberg B. Evanoff BA. Sahm D. Mundy LM.
Enteric carriage of vancomycin-resistant Enterococcus faecium in patients tested for Clostridium difficile.
Infection Control & Hospital Epidemiology. 20(10):664-70, 1999OBJECTIVE: To identify independent risk factors for enteric carriage of vancomycin-resistant Enterococcus faecium (VREF) in hospitalized patients tested for Clostridium difficile toxin.PATIENTS: Convenience sample of 215 adult inpatients who had stool tested for C. difficile between January 29 and February 25, 1996.RESULTS: 41 (19%) of 215 patients had enteric carriage of VREF. Five independent risk factors for enteric VREF were identified: (1) history of prior C. difficile infection, (2) parenteral treatment with vancomycin for > or = 5 days, (3) treatment with antimicrobials effective against gram-negative organisms, (4) admission from another institution, and (5) age > 60 years. These risk factors for enteric VREF were independent of the patient's current C. difficile status.CONCLUSIONS: Antimicrobial exposures are the most important modifiable independent risk factors for enteric carriage of VREF in hospitalized patients tested for C. difficile. | View Page |
| Review 1 Piscitelli SC., Shwed J., Schreckenberger P., Danziger LH.
Streptococcus milleri group: renewed interest in an elusive pathogen.
European Journal of Clinical Microbiology & Infectious Diseases.11:491-8, 1992The following review examines the bacteriological characteristics, epidemiology, pathogenicity and antimicrobial susceptibility of the "Streptococcus milleri group". "Streptococcus milleri group" is a term for a large group of streptococci which includes Streptococcus intermedius, Streptococcus constellatus and Streptococcus anginosus.Usually considered commensals, these organisms are often associated with various pyogenic infections including cardiac, intra-abdominal, subcutaneous and central nervous system infections, particularly with the formation of abscesses.Organisms of the "Streptococcus milleri group" are often unrecognized pathogens due to the lack of uniformity in classifications and difficulties in microbiological identification. Penicillin G, cephalosporins, clindamycin and vancomycin all possess activity against these streptococci.Use of agents with poor activity may promote infections with "Streptococcus milleri group" and allow it to exhibit its pathogenicity. An understanding of these organisms may aid in their recognition and proper treatment. | View Page |