1. Clostridium botulinum and perfringens

2. Characteristics of Clostridium
Gram positive rods in filaments or chains
Strict anaerobes (C. bot) to oxygen tolerant (C. perf)
Spore forming (endospores)
Vegetative cells motile
~55 (C. bot) to 965,000 (C. perf) cases/year in US (#2)
Diverse physiologically and biochemically
>100 species; only 5 human pathogens
C. difficile, C. tetani, C. sordellii
Image from Wikipedia

3. C. botulinum Historically, first recognized foodborne pathogen
1793, outbreak of blunzen in modern day Germany
Justinius Kerner, medical officer, identified several cases. Noted more often in larger sausages made with components other than muscle tissue
Coined term botulinum (botulus [Lt] = sausage)
1896; determined that this disease caused by toxin

4. Characteristics of endospores
Business end:
Low moisture
Proteins protecting DNA
Endospore stain

5. Ecology/reservoir Saprophyte
Soils (one study suggested 24% of soil samples in US are positive)
Aquatic muds (anaerobic, moist, nutrient rich)
Spores readily dispersed by dust, aerosols
Intestinal tract of animals
But not obligatory

6. Classification of C. botulinum
(proteolytic) (non-proteolytic)
Properties
C. botulinum group I
C. botulinum group II
C. botulinum group III
Neurotoxin
A, B, F
B, E, F
C, D
Min. growth temp
10oC
3oC
15oC
Opt. growth
35-40oC
18-25oC
Max. growth
48oC
45oC NA
Min. pH
4.6
5.0
Inhibitory aw
0.94
0.97
Inhibitory NaCl
10% 5% 3%
D100oC spores
25 min
<0.1 min
D121oC spores
0.21 min
<0.005 min
In US, ~60% due to type A, ~20% type B, 20% type E

7. Characteristics of toxin
Most potent toxin known; LD adult human ~0.01mg
Enters bloodstream, targets nerve cells
Neurotoxin (not enterotoxin)
Inhibits acetylcholine release at neuromuscular junctions
Only produced during vegetative growth

8. Disease Foodborne botulinum (intoxication)
Incubation period 8h to 8d; oft h
Double/blurred vision, dilated pupils, drooping eyelids
Dysphagia, dysphonia
Death by respiratory failure
Patient remains mentally aware
Infant (adult) botulinum (infection)
Honey not recommended to children under 1 yrs
FDA study suggests 13% are positive
Intestinal environment not fully developed
“Floppy baby syndrome”
Wound botulinum (infection)

9. Prevention: mostly a reminder!
Prevent growth and toxin production
Not possible to prevent contamination
Acid and water activity
“Potentially hazardous foods” (pH>4.6, aw>0.85)
12D process
Sodium nitrite in cured meats
Toxin infrequent in high acid foods unless:
Insufficient penetration of acid into food
Food contaminated with spoilage organisms that raise pH
Inactivate spores
D121oC of 0.21 min used as “golden rule”
Inactivate toxin
70 oC/1 h, boiling for 5 min
Study suggests standard pasteurization reduces % activity

10. 4 features of contaminated food
Food contaminated at source or during processing
Food receives treatment that restricts competitive microflora (yeasts, LAB) but permits Clostridium survival
Conditions of food are suitable for germination and outgrowth
Food consumed cold and/or after insufficient heat treatment to inactivate toxin

11. Clostridium perfringens

12. Notable differences from C. bot
Is considered an anaerobe, but is aerotolerant
Fast doubling time (<10 minutes)
Much more common
Less severe disease; “self-limiting”
14 toxin types (enterotoxins); 4 are “typing toxins”
Type
Alpha
Beta
Epsilon
Iota A + - B C D E

13. C. perfringens disease
Infection (not intoxication), high infectious dose (>108)
Incubation period ~8-18 hours
Some survive gastric transit, get to intestines
Vegetative cells sporulate
Synthesize toxin
Toxin binds to epithelial cells
Diarrhea and abdominal cramps
Usually resolves spontaneously ~12-24 hours
Death rare; elderly or some underlying condition

14. Characteristics of foodborne illness
Beef, poultry (meat, gravies, stews) primarily
pH ~5-8.3, temps >15 C
Food contaminated with vegetative cells
Cells not heat-killed
Food temperature abused, not cooled quickly
Often when cooking for large groups (group homes, large events)

15. Policy changing outbreaks
Sept 1985: Two sisters and mother develop peripheral weakness and respiratory troubles
Type B botulinum toxin in blood
Additional cases; link is Vancouver restaurant
Garlic was chopped, covered in soybean oil, and stored
pH seen in 15 bottles measured

16. Garlic in oil