Perfringen Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Perfringen and links to relevant pages within the course.
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|Gas gangrene may be seen in infections with all the following clostridia EXCEPT:||View Page|
|The Gram stain shown in the image was prepared from a positive anaerobic blood culture bottle after 36 hours incubation. Based on the morphology of the bacterial cells (some with spores, noted by the blue arrows), what the most likely identification?||View Page|
|Clostridium Quad Plate|
Key reactions for the identification of Clostridium septicum are demonstrated in the two quadrant plates shown in the images to the right. Included in the upper image are reactions for milk (casein) proteolysis (12 o'clock quadrant), glucose fermentation, DNAse hydrolysis, and starch hydrolysis respectively reading clockwise. The media in the quadrant plate shown in the lower image include gelatin hydrolysis (2 o'clock quadrant) and fermentation of each of mannitol, lactose, and rhamnose respectively, reading clockwise. Milk (casein) hydrolysis and glucose fermentation are key reactions for the identification in the upper plate, including no proteolysis of milk, fermentation of glucose (yellow red color along the inoculation streak), positive DNAse (reddish clearing around the streak) ,and a negative reaction for starch. Key reactions in the lower plate include hydrolysis of gelatin, fermentation of lactose (yellow pigment), and negative reactions for mannitol and rhamnose (no pigment). Most strains of C. perfringens hydrolyze starch and produce proteolysins of milk, the key reactions that distinguish C. septicum (negative). Reactions to the other tests do not distinguish between the two.
Citron DM. Appelbaum PC.: How far should a clinical laboratory go in identifying anaerobic isolates, and who should pay? Clinical Infectious Diseases. 16 Suppl 4:S435-8, 1993 Identification of anaerobic bacteria in specimens from sites of infection due to mixed organisms can be time-consuming and expensive. Laboratories should limit anaerobic workups by testing only those specimens that have been properly collected and transported to the laboratory. Use of selective and differential media for initial processing can provide rapid and relevant information to the clinician. Anaerobes isolated from normally sterile sites and sites of serious infection should always be completely identified. Group-or genus-level identifications may suffice in other instances. The Bacteroides fragilis group of organisms should always be identified because of their virulence and resistance to many antimicrobial agents. Some of the other organisms that warrant identification include Clostridium septicum (associated with gastrointestinal malignancy); Clostridium ramosum, Clostridium innocuum, and Clostridium clostridioforme (which are resistant to antibiotics); Clostridium perfringens (a cause of myonecrosis and gas gangrene,potentially serious infection); anaerobic cocci (which may be resistant to metronidazole and clindamycin); and fusobacteria (which may be virulent and resistant to clindamycin and penicillin).
|Match the species of anaerobes and frequently associated conditions.||View Page|
|Category B Agents|
Category B agents include:Q Fever (Coxiella burnetii)Brucellosis (Brucella sp.)Glanders (Burkholderia mallei)Venezuelan encephalomyelitisEastern and western equine encephalomyelitisRicin toxin from castor beans (Ricinuscommunis)Epsilon toxin of Clostridium perfringensStaphylococcus enterotoxin B
|Which of the following organisms is most likely to be associated with gas gangrene:||View Page|