season with high temperature and humidity in Japan starts in June.
And bacteriae can easily propagate in this environment and foods
themselves become tainted, too. Then, bacterial enteritis (food
poisoning) often breaks out. The infected enteritis breaks out
in winter, too, but the main cause of the enteritis is ROTA virus,
SRV (Small Round shape Virus) and CORONA virus etc. This page
shows the cause of the bacterial enteritis (food poisoning), the
features by each bacteria, diagnosis, therapy and how to prevent
of major food poisoning
２．Major bacteriae of the infectious food poisoning
３．Diagnosis of food poisoning
４．Treatment of food poisoning
５．Prevention of bacterial food poisoning
１．The classification of food poisoning
There are a few sorts of food poisoning. They are the enteritis due to the chemical agents such as alcohol, and due to the poisonous matter in the nature such as globefish poison and poisonous mushrooms etc. And others are the infectious gastroenteritis by virus and bacteriae etc. Further, bacterial enteritis occurs by bacteriae themselves and by toxin from bacteriae. Food poisoning due to the chemical agents and the poisonous matter in the nature account for less than 2% of whole food poisoning (by cause), but they occupy 6-8% of total number of food poisoning cases, and the death rate in cases by poisonous mushrooms and globefish poison is higher than other bacterial food poisoning. The cause of more than 90% of food poisoning is bacteriae, and they are salmonella, staphylococcus, Vibrio parahaemolyticus, enteropathogenic Escherichia coli (haemorrhagic Escherichia coli; O-157 etc), Campylobacter, Welch bacillus, Bacillus cereus, Botulinus bacillus, Dysentery bacillus, Cholera vibrio, Listeria monocytogenes etc, and the bacteriae printed in italics are increasing recently. Food poisoning by Listeria monocytogenes are often seen in Europe and America by cheese, and Vibrio vulnificus infection to a person with hepatic disturbance may bring the serious disorder, and this bacteria is called "the man-eater bacteria".
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２．Bacteriae of food poisoning (bacterial enteritis)
The anaerobic Gram positive bacillus of 0.5-2μm, and it has flagellum around body and moves actively in the intestine. More than one million bacteriae can bring disorder. This bacteria is seen lot in the nature (river, pond and drains etc) and it has no spore so it will die by heating easily. Especially eggs and chicken meat will often be tainted by this bacteria.
（２）Vibrio parahaemolyticus（microscope image）
Gram negative bacillus with one flagellum and some thin cilii. It has no spore as salmonella so it will die by heating easily, too. It propagates in sea water (3% of salt content), and it cannot live in water without salt content or in acids. Seafoods are often tainted, and it propagates in room temperature, so the preservation of seafoods needs much care in this rainy season.
Staphylococcus is a major pyogenic bacteria of1μm size and it swarms like a grape bunch. They can be found usually on skin or hair (fur), in nasal cavity and larynx etc. It produces enterotoxin and 100 degrees centigrade heating cannot activatethe the enterotoxin. So it is important not to make foods be contaminated.
（４）Haemorrhagic Escherichia coli（O-157）・Enteropathogenic E.coli（microscope image）
These bacteriae are Gram negative bacilli living in the intestines of animals, and ther is no definite difference except pathogenesis between these bacteriae and other indigenous bacterial flora of colibacillus. Drinking water may be contaminated by excrement and urine, or raw meat may be contaminated through dealing process. It has no spore so it will die by heating but very little volume (only 100 bacilli!) can make a person become ill. O-157, O-26, O-111 and O-128 are known and they produce verotoxin and it can be a cause of HUS (Hemolytic Uremia Syndrome) which may bring death to a patient.
This is a Gram negative bacillus with cord-like flagella at both ends and usually live in the intestine of domestic animals and domestic fowls. Meat especially chicken, viscera and drinking water are often tainted. And it is important as a cause of children's diarrhea. It is very weak to heating and dryness.
（６）Botulinus bacillus（microscope image）
Gram positive anaerobic bacillus living in the nature such as soils and in the intestine of domestic animals. It has a spore and is resistant to heat. Botulinus toxin which has very strong toxicity to nerve system, and it needs 80 degrees centigrade heating for more than 20 minutes to inactivate this toxin. Food poisoning by botulinus is important because its death rate is high (25%).
（７）Welch bacillus（microscope image）
Gram positive anaerobic bacillus usually seen in the intestines of human and animals, soils and sewages. It forms a spore and produces toxin according to increasement. More than 1 million bacilli can bring disorder to human body, and it is known as a cause of gas gangrene at wartime. Heating by 100 degrees centigrade for 1 - 2 hours is necessary to inactivate it.
（８）Bacillus cereus（microscope image）
Gram positive aerobic bacillus widely seen in the nature such as soils, sewages and rivers. It exists as a spore form which is resistant to heat, and it produces toxin. Heat tolerance is strong and heating by 100 degrees centigrade for 30 minutes cannot kill this spore, but it can be a cause of mild food poisoning as diarrhea type and vomiting type.
Gram negative bacillus which belongs to the vibrio group. It has one flagella at one side and makes no spore. It will die soon in gastric juice, but when it reaches to the intestine, it produces cholera toxin and brings diarrhea. Cholera vibrio O-1 and O-139 infection are specified to the infectious disease designated by law, and non-O-01 and non-O-139 are related with food poisoning.
Gram negative bacillus which shows pathogenesis to only humans and apes (Primates). It invades and destroys epithelium cells of the intestine and becomes a cause of bloody stool, so infection by this bacteria is regarded as the infectious disease designated by law.
（11）Pfeiffer bacillus (Yersinia)
It is widely seen in the nature and in the intestine of the animals, and edible meat and drinking water may be tainted by contaminated excreta. It can propagate in the low temperature of a refrigerator, so you should not be careless.
It is widely recognized in animals (both domestic animals and wild animals), fishes and in rivers. Edible meats, cheese (non-sterilized), salad, sashimi (raw fish) etc are often tainted. It is important in Europe because they deal much cheese. It can propagate in low temperature in a refrigerator but heating by 65 degrees centigrade for a few minutes can kill this bacteria.
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３．Diagnosis of food poisoning
The cause of bacterial enteritis is various bacteriae, so its diagnosis is done by detection of bacteriae in blood or stool and detection of toxin are diagnostic method. Practically, however, it take time to get the definite diagnosis by these examinations, and it is hard for a patient who is suffering from diarrhea, nausea, vomiting, fever and abdominal pain etc on coming. Therefore, blood and stool examination should be done and we should make diagnosis by the patient's symptoms, family history whether the patient's family complain of the same symptoms as the patient, history of eating and drinking, and history whether the patient has been abroad or not. And treatment should be started as soon as possible. The following table shows the feature of each bacterial enteritis;
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４．Treatment of Food Poisoning
Following therapeutic methods are common.
When a patient is suffering from severe nausea and vomiting, antiemetic drugs may be used, but its dose should be minimum amount.
When a patient is suffering from abdominal pain, analgesics can be used but its dose should be minimum amount, too.
Even in a case with severe diarrhea, antidiarrhoics should not be used because the use of this kind of drugs will make bacteriae be excreted and so recovery from disease may be delayed. Therefore the patient should understand the reason why antidiarrhoics should not be used in bacterial enteritis.
Putting a patient on a dietetic therapy is not always necessary except a case with severe symptoms. In a mild case, a patient may take digestible food little by little. Restriction to take water should not be done in order to prevent dehydration.
Ｅ．water (control of dehaydration)
In a case which restriction water as oral ingestion is necessary, urine volume should be kept by drip-infusion (fluid therapy). In a mild case, taking of the sports drinks which contain electrolytes. But please notice that the sports drink does not always contain salt enough.
Antibiotics is not always used to cases of bacterial enteritis, but antibiotics may be administered to some cases of salmonella infection (newquinolone, ampicillin and fosfomycin etc), some cases of Campylobacter infection (macrolides) and some cases of Enteropathogenic Escherichia coli infection (newquinolone and fosfomycin etc) with serious symptoms.
Ｇ．therapy to the botulinus toxin
The respiratory care by airway management should be done because nerve toxin will exacerbate the respiratory function. And polyvalent antitoxin serum must be administered at once.
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５．Prevention of Food Poisoning (bacterial enteritis)
About the prevention of food poisoning, knowledge about eachbacteria and infection route etc is important. About the infectious route, it can be devided into the primary infection and the secondary infection. Then it will be easy to understand.
（１）Prevention of the primary infection
enough washing、full thawing-out the frozen meat、sufficient heating
２．Sanitary control of kitchen, dresser and cooking instruments
keep clean the chopping board, kitchen knife and cooking instruments by boiling water and disinfectant soap or sodium hypochlorite is effective.
３．Sanitary control of cooks and staff
Keep hands clean by washing or taking gloves is effective.
４．Sanitary control of cooked foods
It makes cooked foods be bad to leave them long. Do not overestimate cooked foods in your refrigerator please.
（２）Prevention of the secondary infection
The bacteriae that may be the cause of the secondary infection (the bacteriae from the infected person will bring the same infection to others.) are dysentery, cholera and enterohaemorrhagic Escherichia coli. A case of botulinus infection sometimes becomes serious but there is no report about secondary infection case.
１．Washing hands・Strict enforcement of disinfection・Taking gloves
The bacteriae mentioned above spread through stools etc, so washing hands by enough flowing water and sodium hypochlorite or disinfectant soap. Of course washed hands must be dry and be kept clean. Medical staff should take glove when they contact patienets with food poisoning, and of course washing hands is indispensable. WHO reported the effectiveness of washing hands and taking gloves in cases of SARS.
２．Laundry of linen, bedclothes and clothes
Linen, bedclothes and clothes with excrement from a patient with bacterial enteritis (including secondary infection) should be washed with detergent and by hot water of 80 degrees centigrade for 10 minutes. In a case that hot water cannot be used, these clothes etc should be soaked in the sodium hypochlorite (0.01 - 0.1%) for more than 5 minutes at rinse.
３．Sanitary control of a washstand at a lavatory etc.
A lavatory and a place around the washstand are humid, and bacteriae will easily propagate in these area with suitable temperature. So it is necessary to keep these area dry and clean by soap and the sodium hypochlorite.
Japanese MInistry of Health, Labour and Welfare shows the six
points to prevent food poisoning for the household (1977), and
please check it if you are interested.
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