Some cationic surfactants, present in disinfectants, cause the cell walls of bacteria to burst and subsequently die. However, two bacteria, Bacillus and Clostridium, will not die. They enter a “Resistant Resting Phase”. They produce an endospore. The spore forms inside the bacterial cell when the going gets tough, and the remainder of the cell disintegrates. Think of a spore as an ungerminated dry seed. Without moisture the spore will remain dormant. Provide moisture and the spore will germinate into a bacterial cell. Provide nutrients and a warm temperature and the cell will multiply. As they multiply they release exotoxins, which are heat stable.
We ingest spores on a daily basis, without any harm or consequence, as our digestive process is a very hostile environment for spores and they will not germinate, but pass straight through our system and are expelled with our faeces. They can germinate, and contaminate, after defecation. This is a major problem in hospitals where C difficile, a normal gut constituent, is causing major diarrhoeal cases, mainly with elderly patients. It has been estimated that tens of thousands of patients die from this every year. The blame is being apportioned to the over use of antibiotics, which kill all the body’s micro flora, and releases C difficile into the environment.
Infant botulism is a problem with children under 6 months, although warnings on some foods, such as honey, recommend children less than 12 months refrain from honey ingestion.
Spores will germinate in a very young child’s gastrointestinal tract. C botulinum, for example, are often present in untreated food products, such as honey. Bees inadvertently pick up spores from the environment, for example soil and vegetation. The spores are deposited into the honey during the production process. The spores germinate in the child, as their GI tract is not as acidic as somebody older. The germinated cells will now grow, excreting botox in the process, causing death of the child.
Some spores can resist temperatures in excess of 3500 degrees Celsius and below minus 150 degrees Celsius. Scientists have found spores in Egyptian tombs and revived them. Spores have been found in the intestines of bees which had been preserved in amber. The bees were aged at 42 million years. The spores were revived. Spores can survive in dry conditions indefinitely. Some further examples of spores include Bacillus anthracis (anthrax). There is no known antidote for the fatal disease caused by inhaled anthrax spores.
Clostridium tetani (tetanus) is a spore quite easily picked up from the environment (barbed wire, thorns) and infects the blood stream through a cut.
Botulism is a worrying problem in the canning industry. Why?
C botulinum produces spores. The bacteria are also anaerobes. They will only grow in vacuous conditions; air would kill them, or rather, turn them into spores until the conditions improve. If spores are present in a sealed can, along with cooked salmon, for example, then “we have a problem Houston”.
The spores will germinate into bacterial cells and start to grow. They are in a vacuum, they have a supply of protein and moisture and the temperature is conducive to active growth (we do not keep cans under refrigeration). As the bacteria grow they produce botox. When the can is opened, the contents looks, tastes and smells normal. However, ingestion will quickly cause death due to the concentration of the toxin.
Help is at hand. The canning industry has adopted a cooking system called the Botulinum Cook. It is another word for commercial sterilisation. If the can is heated to 121 degrees Celsius for 3 or more minutes, the spores are destroyed, together with any micro-organisms present.