Shigella – causes, symptoms and treatment of Shigella infection

Shigella is gram-negative rods that are one of the pathogens causing infections of the digestive system (bacterial dysentery). Shigella flexneri strains (in addition to Salmonella, Yersinia, Campylobacter, Mycoplasma and Chlamydia trachomatis) may elicit a Reiter syndrome response. Bacterial dysentery manifests as blood in the stools, fever and stomach pains.

What is Shigella Bacteria?

Shigella is a gram-negative bacterium that causes bacterial dysentery, also known as dysentery. This bacterium has been known for a long time. It was isolated by the Japanese scientist Kiyoshi Shiga in 1897. It is from his surname that the name of the microorganism comes from. In Poland, infections with sonnei and flexneri sticks are the most common. Bacterial dysentery is a specific form of diarrhea characterized by severe abdominal pain, passing bloody stools, and fever. Children under five are most often affected. Shigella sticks are related to E. coli sticks. Shigella attacks when basic hygiene is lacking, and its characteristic feature is high contagiousness and a predisposition to tissue invasion.

Causes of Shigella infection

Shigella reservoirs are patients who in the acute phase of bacterial dysentery excrete a large amount of bacteria along with their stools. Therefore, in order to effectively protect against infection, patients should be isolated. A small amount of microorganisms (about a hundred) is enough for infection. It occurs as a result of direct contact with a sick person, although some dysentery epidemics have been caused by contact with contaminated food and water. Please note that Shigella can also be transmitted by fleas and sexual contact. Dysentery is a threat to people traveling to and working in highly endemic countries. Sporadic infections among tourists, even those staying in reputable hotels, are brought to Poland every year.

The period of incubation of the disease is 24-72 hours, less frequently up to 7 days, its duration – on average from 48 to 120 hours. If left untreated, the disease may persist for several weeks, causing:

1. dehydration,
2. cachexia,
3. death (especially in children and patients with AIDS).

In summary, transmission of Shigella infection occurs:

1. in the fecal-oral route, directly from the sick, convalescent or healthy carrier of the pathogen (asymptomatically infected),
2. indirectly through water contaminated with human faeces (for drinking or recreation, epidemics in France and the USA),
3. through food (dairy products, fruits, raw vegetables),
4. through objects (doors, handles, bedding, walls in flush-flush toilets – splashes),
5. by flies.

The genus Shigella is divided into 4 species / groups marked with letters, differing in biochemical and antigenic properties, and 47 types and serological subtypes:

S. dysenteriae (group A, 13 types),

S. flex neri (group B, 6 types, 15 subtypes),

S. boydii (group C, 20 types),

S. sonnei (group D, 1 type, two varieties).

The greatest incidence of bacterial dysentery occurs in the following areas:

1. Chin,
2. Pakistan,
3. Thailand,
4. Bangladesh,
5. Indonesia,
6. Witnamu.

Symptoms of bacterial dysentery

The symptoms of bacterial dysentery mainly depend on the condition of the patient’s immune system and whether it is adequately nourished. Inadequate hygiene, malnutrition and poor social conditions make the course of the disease much more severe. Normally, the course of bacterial dysentery can be divided into four phases:

1. hatching – it can last up to 8 days; initially, patients develop a high temperature and watery diarrhea. Moreover, patients complain of malaise and lack of appetite;
2. watery diarrhea – its symptoms are more severe in contrast to the brooding period. The fever can be as high as 40-41 degrees Celsius;
3. dysentery diarrhea;
4. recovery period.

Abdominal discomfort in the course of bacterial dysentery is very diverse. They may present as mild abdominal discomfort or cramp pains, vomiting, diarrhea and a painful urge to stool. Bacterial dysentery in many people ends at the hatching stage, and in the remaining people, after a few days, characteristic symptoms of dysentery begin to appear in the form of painful, blood-mucus-purulent stools, often passed.

Bacterial dysentery resolves in a few days or weeks without major consequences.

Complications of bacterial dysentery

Complications of bacterial dysentery are usually observed in young children under the age of five (especially those who have poor sanitary conditions on a daily basis, are malnourished and live in developing countries). The most important complications are:

1. intestinal perforation
2. rectal prolapse
3. the presence of disseminated infection,
4. hemolytic uremic syndrome,
5. hypoglycemia,
6. hiponatermia,
7. toxic distention of the colon (a very dangerous and common complication),
8. sometimes disturbed consciousness and seizures,
9. confusion, coma.

Toxic colonic distension occurs as a result of taking anti-diarrheal agents such as loperamide.

Shigella – bacterial dysentery, diagnosis and treatment

Bacterial dysentery is diagnosed based on a bacteriological examination of the feces. In some cases, fecal occult blood tests are recommended to help determine the amount of blood that comes out of the body during a bowel movement. In turn, the most important thing in the treatment of Shigella is to prevent the patient from becoming dehydrated. For this purpose, you should systematically replenish electrolytes and carbohydrates in the body (even 4 liters a day). Many patients are administered antibiotics. Patients with severe bacterial dysentery are referred to the hospital.

Shigella – prevention

Shigella infection cannot be completely prevented. However, there are ways to reduce your risk of contamination:

1. basic hygiene rules should be followed,
2. remember to wash your hands before eating,
3. when preparing meals, remember to wash vegetables or fruit,
4. food should be stored properly (keep away from insects carrying Shigella),
5. direct contact with people suffering from bacterial dysentery should be avoided.

Lit.: [1] Jennison A.V., Verma N.K.: Shigella flexneri infection: pathogenesis and vaccine development. FEMS Microbiol Rev 2004, 28(1); 43-58. [2] Muytjens H.L., Eggink C.A., Dijkman F.C. i wsp.: Keratitis due to Shigella flexneri. J Clin Microbiol 2006, 44(6); 2291-4.

Source: A. Kaszuba, Z. Adamski: “Lexicon of dermatology”; XNUMXst edition, Czelej Publishing House