IV. Clostridium botulinumA. Anaerobic CellulitisEarly SymptomsNeuromuscular SymptomsConvalescence/ImmunityControl/PreventionSTATE UNIVERSITY OF NEW YORK AT BUFFALOSCHOOL OF MEDICINE AND BIOMEDICAL SCIENCESDEPARTMENT OF MICROBIOLOGY February 10, 2012 MICROBIOLOGY 301 D. Dombroski 829-2355CLOSTRIDIUM Genus: ClostridiumSpecies: Clostridium perfringensClostridium difficileClostridium tetaniClostridium botulinumMicroscopic Morphological AppearanceGram positive bacilliSpore formersMost are obligate anaerobesMost are motileGrowth ConditionsThioglycollate broth – anaerobic growthLitmus milk – stormy fermentationBlood agar – double zone of hemolysisEgg yolk agar – β-lecithinase – (α-toxin)Pathogenic Clostridia I. Histotoxic Clostridia C. perfringensII. Enterotoxigenic Clostridia C. perfringensC. difficileIII. Clostridium tetaniIV. Clostridium botulinumI. Histotoxic Clostridia - (gas gangrene) Causative agent - C. perfringens type A Opportunistic pathogens that require a special environment to initiate growth1. traumatized tissue2. vascular damage3. necrotic tissue4. decreased oxygenC. perfringens produces a large number of exotoxins and extracellular enzymes such as:1. collagenase2. proteinase3. deoxyribonuclease4. -toxin-(phospholipase C) - lecithinase5. -toxin- hemolysinClostridial wound infections A. Anaerobic myonecrosis (gas gangrene)B. Anaerobic cellulitisA. Anaerobic myonecrosis 2Ever widening expansion of necrotic lesion to adjacent healthy muscle tissues.Symptoms 1. local edema2. gas production - H2 and CO23. change of skin color to black4. generalized fever5. pain in infected tissueRisk Group Factors 1. traumatic injuries2. surgical procedures in close proximity to intestinal microflora - bowel surgery, abortions3. elderlyConvalescence/Immunity NO host defensePhagocytic cells uselessRepeated infections do not produce immunityTreatment 1. removal of dead tissue (debridement)2. application of antiserum (polyvalent antitoxin)3. broad spectrum antibiotic - penicillin or tetracycline4. hyperbaric O2 chamberA. Anaerobic Cellulitis Localized infection of necrotic muscle tissue only3Symptoms - similar to anaerobic myonecrosis but of a lesser severity *************************************************************************************II .A. Enterotoxigenic Clostridia - (food poisoning) Causative agent - C. perfringens type AMode of Infection 1. Ingestion of viable vegetative cells2. Synthesis of enterotoxin in small intestine3. Enterotoxin produced which breaks down intestinal mucosa  leakage of plasma membrane  disruption of osmotic equilibriumSymptoms watery diarrhea, abdominal crampsConvalescence/Immunity NO immunity - repeat attacksControl and Prevention cook food thoroughly initially - destroys sporesfood refrigeration after preparation - prevents enterotoxin productionreheating food - destroys toxin4II.B. Enterotoxigenic Clostridia - (antibiotic-associated colitis) Causative agent - C. difficile - drug resistant normal flora of intestine Antibiotic therapy - disrupts normal flora of intestine allowing a superinfection orsecondary infection with C. difficile Mode of Infection - (pseudomembranous colitis) 1. Antibiotic therapy2. Colonization of intestine by C. difficile3. Toxins produced - injure intestinal lining by inhibiting protein synthesis; produces hemorrhagic necrosis4. Leukocyte infiltration into colon due to toxin production5. Pseudomembrane - (white patch on colon) - mixture of fibrin, mucus, leukocytes and necrotic epithelial cells Symptoms abdominal pain, watery diarrhea , nausea Risk group patients receiving antibiotic therapy - primarily a disease of antibiotic induced colitishospitalized patients Treatment discontinue antibioticsmaintain fluid/electrolyte balanceadminister vancomycin5************************************************************************************III. Clostridium tetani - (tetanus) A. Generalized tetanus - initial involvement of neck and jaw muscles with progression to large muscle groupsB. Neonatal tetanus - initial infection of umbilical stump - progression to generalized tetanusConditions for infection (favor spore germination)1. small puncture wounds2. necrotic tissue at wound site3. decreased oxygenVariety of toxins produced1. Neurotoxin - tetanospasmin or spasmogenic toxin - toxin of primary importance accounts for classic symptoms Site of action - target neurons in the spinal columnFunction of Toxin Toxin binds to gangliosides in neural tissue  blocks release of neuroinhibitor glycine  continual contraction of muscles (tetany)Initial SymptomsCramping and twitching of muscle around wound6Later Symptomssweatingpain around wound arealockjaw or trismus - clenching of the jaw, muscle stiffness neck and jaw musclesrisus sardonicus - sarcastic grinopithotonos – arching of the backExtreme SymptomsProgression to other muscle groupsViolent spasms trunk and back  bone fracturesRisk Groups1. elderly2. intravenous drug abusers3. infants - neonatal tetanus (tetanus neonatorum)Death - paralysis of respiratory musclesConvalescence/ImmunityNo innate immunityRepeated infections do not produce immunity1 1. small amount of toxin in the circulation 2. toxins strong affinity for neural tissue7Convalescence - no permanent damage to musclesTreatment1. debridement of necrotic tissue2. anti-toxin3. unimmunized - human tetanus immune globulin (TIGH) - passive immunizationimmunized - received DPT series, may require a booster shot of tetanus toxoid 4. Antibiotics - metronidazole or penicillin5. Anti-spasmatic drugs or muscle relaxants - phenobarbital or chlorpromazineControl/PreventionActive immunization - DPT series (tetanus toxoid) **********************************************************************************IV. Clostridium botulinum - (botulism)Neurotoxins A, B, E and F - human diseaseNeurotoxin A- (Neurotoxin - hemagglutinin)Function of hemagglutinin - prevents deactivation of neurotoxin by gastric enzymes and lowered pH of stomach8Three Types of Botulism 1. Food-borne botulism 2. Infant botulism 3. Wound botulism1. Food-Borne Botulism (food poisoning or food intoxication)Mode of Infection1. Ingestion of poorly preserved food containing Botulin (Botulinum toxin)a. Spores not killedb. Improper food preservation created ideal environment for spores to germinate.1. anaerobic environment2 2.