Clostridium botulinum

Author: Monica 

One of the feared microbe is Clostridium botulinum. This strain is very common in under-processed meat products. The toxins produced by the bacterium causes botulism, a condition that can lead to paralysis of the patient. Botulism in humans is always caused by toxin types A, B or E and occasionally by toxin type F. C. botulinum type E (group II) is one of the food-borne pathogenic bacteria that can survive in temperature of 3oC (Blackistore, 1998).

Clostridium botulinum is an anaerobic, Gram-positive, spore forming rod-shaped bacterium that is found widely in the environment such as soil and animal guts. It was first being isolated from salted raw ham in 1897. Clostridium botulinum type E , one of the food-borne pathogenic produce heat resistant spore of up to 90 oC. In addition, most food are pH 5 or pH6 and above. Clostridium botulinum grows from pH 4.5 and above and at water activity level (a w) of 0.94. Inactivation of Clostridium botulinum’s spores is done when the pressure is increased to 600-1400 Megapascal (MPa) and an increase in temperature of 90 oC to 110 oC, the use of pressure-temperature to inhibit the spores during vacuum packaging (Doyle, 2001). Clostridium botulinum can grow in a salt environment of lower than 7% (Sprenger, 2004). Clostridium botulinum causes the food-borne illness botulism. Botulism is caused by neuron toxins produced during the growth of the bacterium in food before eating.

Symptoms of this disease may occur within 12 to 36 hours or after 8 days of consuming the contaminated food. The initial symptoms include vomiting and nausea (Labbe, 2001). The toxin first affects the neuromuscular junctions in the head and neck area, causing the person to have symptoms like double vision, not being able to focus, drooping eyelids, dry mouth, difficulty in speaking clearly and the inability to swallow. The muscles of the body will continue to fail, resulting in paralysis and in severe cases, death (Labbe, 2001).

The growing of spores in food causes the bacterium to produce botulinum toxins. The spores of the bacteria grow best in the presence of oxygen, a pH environment of 4.6 or higher, a low salt environment of 7% and below and a high moisture environment of 95%. This factors suits especially well during the scenario whereby the ham was taken out from its packaging and left in the air for a relatively long time before being served. This could be so if the ham is left on a tray while waiting to be put into a sandwich order. This allows the conversion of the dormant spores from the curing to be reactivated into spores that proliferate. To avoid the production of the toxin in food, it is important to destroy the spores of the bacteria such as cooking the ham (Eco Lab website).As mentioned earlier, one of the ways to destroy the spores of the bacterium is by adding food preservatives such as sufficient sodium nitrite in food to inhibit the growth of C. Botulinum. The food product should also not be stored in the temperature of above 3oC.