perfringens 1 Characteristics of Clostridium Gram positive rods in filaments or chains Strict anaerobes C bot to oxygen tolerant C perf Spore forming endospores Vegetative cells ID: 1043920
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1. Clostridium botulinum and perfringens1
2. Characteristics of ClostridiumGram positive rods in filaments or chainsStrict anaerobes (C. bot) to oxygen tolerant (C. perf)Spore forming (endospores)Vegetative cells motileImage from Wikipedia2~55 (C. bot) to 965,000 (C. perf) cases/year in US (#2)Diverse physiologically and biochemically>100 species; only 5 human pathogensC. difficile, C. tetani, C. sordellii
3. C. botulinumHistorically, first recognized foodborne pathogen1793, outbreak of blunzen in modern day GermanyJustinius Kerner, medical officer, identified several cases. Noted more often in larger sausages made with components other than muscle tissueCoined term botulinum (botulus [Lt] = sausage)1896; determined that this disease caused by toxin3
4. Characteristics of endospores4Endospore stainBusiness end:Low moistureProteins protecting DNA
5. Ecology/reservoirSaprophyteSoils (one study suggested 24% of soil samples in US are positive)Aquatic muds (anaerobic, moist, nutrient rich)Spores readily dispersed by dust, aerosolsIntestinal tract of animalsBut not obligatory 5
6. Classification of C. botulinum6In US, ~60% due to type A, ~20% type B, 20% type EPropertiesC. botulinum group IC. botulinum group IIC. botulinum group IIINeurotoxinA, B, FB, E, FC, DMin. growth temp10oC3oC15oCOpt. growth35-40oC18-25oC35-40oCMax. growth48oC45oCNAMin. pH4.65.0NAInhibitory aw0.940.97NAInhibitory NaCl10%5%3%D100oC spores25 min<0.1 minNAD121oC spores0.21 min<0.005 minNA(proteolytic) (non-proteolytic)
7. Characteristics of toxinMost potent toxin known; LD adult human ~0.01mgEnters bloodstream, targets nerve cellsNeurotoxin (not enterotoxin) Inhibits acetylcholine release at neuromuscular junctionsOnly produced during vegetative growth7www.hopkins-gi.org
8. Disease Foodborne botulinum (intoxication)Incubation period 8h to 8d; oft 12-48 hDouble/blurred vision, dilated pupils, drooping eyelidsDysphagia, dysphoniaDeath by respiratory failurePatient remains mentally awareInfant (adult) botulinum (infection)Honey not recommended to children under 1 yrsFDA study suggests 13% are positiveIntestinal environment not fully developed“Floppy baby syndrome”Wound botulinum (infection)8
9. Prevention: mostly a reminder!Prevent growth and toxin productionNot possible to prevent contaminationAcid and water activity“Potentially hazardous foods” (pH>4.6, aw>0.85)12D process Sodium nitrite in cured meatsToxin infrequent in high acid foods unless:Insufficient penetration of acid into foodFood contaminated with spoilage organisms that raise pHInactivate sporesD121oC of 0.21 min used as “golden rule”Inactivate toxin70 oC/1 h, boiling for 5 minStudy suggests standard pasteurization reduces 99.95-99.99% activity 9
10. 4 features of contaminated foodFood contaminated at source or during processingFood receives treatment that restricts competitive microflora (yeasts, LAB) but permits Clostridium survivalConditions of food are suitable for germination and outgrowthFood consumed cold and/or after insufficient heat treatment to inactivate toxin10http://extension.psu.edu/food-safety/food-preservation/safe-methods
11. Clostridium perfringens11
12. Notable differences from C. botIs considered an anaerobe, but is aerotolerantFast doubling time (<10 minutes)Much more commonLess severe disease; “self-limiting”14 toxin types (enterotoxins); 4 are “typing toxins”12TypeAlphaBetaEpsilonIotaA+---B+++-C++--D+-+-E+--+
13. C. perfringens diseaseInfection (not intoxication), high infectious dose (>108)Incubation period ~8-18 hoursSome survive gastric transit, get to intestinesVegetative cells sporulateSynthesize toxinToxin binds to epithelial cellsDiarrhea and abdominal crampsUsually resolves spontaneously ~12-24 hoursDeath rare; elderly or some underlying condition13
14. Characteristics of foodborne illnessBeef, poultry (meat, gravies, stews) primarilypH ~5-8.3, temps >15 C Food contaminated with vegetative cellsCells not heat-killedFood temperature abused, not cooled quicklyOften when cooking for large groups (group homes, large events)14
15. Policy changing outbreaksSept 1985: Two sisters and mother develop peripheral weakness and respiratory troublesType B botulinum toxin in bloodAdditional cases; link is Vancouver restaurantGarlic was chopped, covered in soybean oil, and stored pH 4.6-5.7 seen in 15 bottles measured15
16. Garlic in oil16