Bacterial gastroenteritis also known as summer flu is the infection of the stomach and intestine, particularly small intestine, caused by bacteria. The most common route of spread is feco-oral transmission meaning that fecal particles gain entry to the gut through the mouth. Most cases arise with ingesting contaminated food and water and is more frequently seen in developing nations where food handling procedures and sanitation are substandard. It is a very common disorder and ranges from mild to severe and can even be a life threatening condition.
Causes and Types Bacterial Gastroenteritis
Bacteria causing bacterial gastroenteritis include:
Campylobacter jejuni causes Campylobacter enteritis. It is a type of traveler’s diarrhea and most commonly affects the small intestine.
Escherichia coli (E. coli) causes E. coli enteritis. It is also a type of traveler’s diarrhea and sometimes referred to as hamburger disease because it is commonly transmitted through partially cooked ground meat.
Salmonella is a group of bacteria that causes Salmonella enteritis, an infection of small intestine, and also a type of food poisoning.
Shigella causes Shigella enteritis. Shigellosis is an acute bacterial infection of intestines and can lead to deadly outbreaks accompanied with blood and mucus in stools (dysentery).
Vibrio cholera causes cholera which is a type of infective watery diarrhea affecting the small intestines. It also causes outbreaks through contaminated water.
Staphylococci are a number of different bacteria which causes various types of food poisoning accompanied by diarrhea.
Yersinia enterocolitica is one species of the Yersinia family that causes a gastrointestinal infection. It more commonly occurs in children.
Bacterial gastroenteritis also known as summer flu more commonly arises in crowded public places like school cafeterias, large social functions and restaurants. The food can be contaminated with the bacteria by many ways particularly with improper handling or inadequate cooking. Personal hygiene is another key consideration as hands contaminated with fecal particles specifically after using the toilet may then contaminate foods. Raw meat and uncooked fruit and vegetables need to be kept separately. Any food that is to be eaten raw should be thoroughly disinfected with a suitable cleansing solution fit for human consumption. Washing food with contaminated water or using this water in cooking can also cause bacterial gastroenteritis. A lack of refrigeration particularly of cooked food, dairy, eggs and meat may also increase the risk of gastroenteritis especially in hot and humid environments.
The various bacteria employ different mechanisms to infect the body and damage or destroy the lining of the stomach and intestine. Salmonella, Shigella and enterohemorrhagic E. coli are invasive bacteria that ulcerates the mucosal lining of the intestine. Apart from the ulcers, abscesses may also form in the intestine . Some non-invasive bacteria like heat-labile and heat-stable enterotoxins of E. coli activate adenylate cyclase and ganylate cyclase which in turn causes watery diarrhea and electrolyte imbalances. Vibrio cholera produces enterotoxins which on reaching small intestine causes watery stools with severe vomiting. Some bacteria produce exotoxins that can contaminate the food even though the bacteria are not in the food. This may be seen with bacteria Staphylococcus aureus, Bacillus cereus and Clostridium perfringens. These exotoxins can cause gastroenteritis without the bacteria actually infecting the intestines. The most common complaints associated with these toxins include acute nausea, vomiting, and diarrhea. It tends to arise within 12 hours of eating contaminated food or drinking contaminated water. The symptoms abate within 36 to 48 hours as the toxins are flushed out and the stomach and intestinal lining heals.
Signs and Symptoms fo Ftomach Flu
Bacterial gastroenteritis is marked by the sudden onset of nausea, vomiting, bloating, abdominal cramps and loose stools with or without mucus. Prolonged gastroenteritis can lead to dehydration with low blood pressure (hypotension) and and rapid heart rate (tachycardia). Sometimes vomiting is the main symptom and if it is persistent then it can also lead to fluid loss. Infective diarrheas are associated with fever, malaise and muscle aches (myalgia). In severe cases the abdomen may be distended and associated with excessive gastrointestinal gas. In severe cases where there is persistent vomiting and diarrhea, the degree of dehydration can be very severe and lead to shock and even acute kidney failure.There may be associated metabolic disorders like hypokalemia (low blood potassium), hyponatermia (low blood sodium) and hypocholerimia (low blood chloride) which may be further aggravated if rehydration is insufficient or with an inappropriate rehydration solution.