3.3-3.4.docx

3.3 ? Bacillus; 3.4 ? Clostridium Objectives: Describe the organisms comprising the genus Bacillus with respect to their habitat in nature, their morphological and cultural characteristics, their involvement in human disease and their importance in as biological moitors. Lecture Outline: Characterization of the genus Bacillus Microscopic morphology, cultural characteristics, habitat in nature B. anthracis ? anthrax; concern because spores are very stable, has potential to be used in biological warfare/terrorism; B. cereus ? gastroenteritis Geobacillus (Bacillus) sterothermophilus, B. aterophaeus ? biological monitors Objectives: Why are some microorganisms capable of only anaerobic growth and how must specimens be handled to endure successfully isolation? Describe the organisms comprising the genus Clostridium with respect to their habitat in nature and their morphological and cultural characteristics. List and describe the types of diseases caused by the clostridia. Discuss factors/conditions involved in the initiation of botulism, tetanus, gas gangrene and pseudomembranous colitis. Describe the histopathological features of the clostridial disease named above. Discuss methods used to treat or to prevent clostridial disease. Lecture Outline: Characterization of the genus Clostridium Microscopic morphology, cultural characteristics, habitat in nature: large, 3-8um, G+ rods, obligate anaerobes, form spores Clostridial diseases Botulism ? C. botulinum: intoxication type food poisoning; typically found in home-canned/home-processed food where spores are not completely eliminated and then grown in food; incubation period and severity of symptoms is proportional to the amount of toxin consumed Produces a neurotoxin affecting peripheral nerves Treat with antitoxin ? not antibiotics because it is a toxin Infant botulism ? need to neutralize toxin; wound botulism ? heroin users ?therapeutic? uses of botulism: botox injected to relax facial muscles and eliminate wrinkles Tetanus ? C. tetani ? lockjaw; 8th day disease; spores germinate in traumatized or devitalized tissue; vegetative cells then produce a potent neutotoxin, tetanospasmin which affects the CNS to produce tetany or spastic paralysis; death due to respiratory failure complicated by exhaustion; 50% mortality Produces a neurotoxin (tetanospasmin) affecting the CNS Lockjaw, 8th day disease Treat with antitoxin, penicillin, sedation (toxin: antitoxin, antibiotics will not be effective; infection: antibiotics and antitoxin at site of infection effective) Toxoid vaccine ? kinda looks like a toxin; made from a toxin that is altered; eliminate toxicity but keep immunogenicity (make provocative to immune system); DPT vaccine, boosters at 10 year intervals Gas gangrene ? an eating sore; myositis or myonecrosis C. perfrinogens, C. septicum, C. histolyticum, C. novyi Spores germinate in traumatized/devitalized tissue which has become anoxic Lecithinase (phospholipase) and collagenase ? vegetative cells produce a variety of tissue damaging enzymes Treatment ? debridement (removing tissue; more extreme: amputation), antibiotics, hyperbaric oxygen (force oxygen into tissue to further arrest growth of MO); death due to toxemia leading to major organ dysfunction Pseudomembranous colitis ? antibiotic-associated diarrhea C. difficile Importance of the normal intestinal microflora Treat with metronidazole or oral vancomycin Experimental toxoid vaccine