Шигеллёз: возбудитель, симптомы, диагностика и профилактика.

Shigellosis is caused by four specific types of Shigella. These are typically spread by exposure to infected feces. Contamination may be spread by flies or when changing diapers (nappies). Commonly used antibiotics include ciprofloxacin and azithromycin. Onset time is 12 to 96 hours, and recovery takes 5 to 7 days. Infections are associated with mucosal ulceration, rectal bleeding, and drastic dehydration. Reactive arthritis and hemolytic uremic syndrome are possible sequelae that have been reported in the aftermath of shigellosis. The most common neurological symptom includes seizures.

Upon ingestion, the bacteria pass through the gastrointestinal tract until they reach the small intestine. There they begin to multiply until they reach the large intestine. In the large intestine, the bacteria cause cell injury and the beginning stages of Shigellosis via two main mechanisms: direct invasion of epithelial cells in the large intestine and production of enterotoxin 1 and enterotoxin 2.

The diagnosis of shigellosis is made by isolating the organism from diarrheal fecal sample cultures. Shigella species are negative for motility and are generally not lactose fermenters, but S. sonnei can ferment lactose. They typically do not produce gas from carbohydrates (with the exception of certain strains of S. flexneri) and tend to be overall biochemically inert. Shigella should also be urea hydrolysis negative. When inoculated to a triple sugar iron slant, they react as follows: K/A, gas , and H2S Indole reactions are mixed, positive and negative, with the exception of S. sonnei, which is always indole negative. Growth on Hektoen enteric agar produces bluish green colonies for Shigella and bluish green colonies with black centers for Salmonella.

Simple precautions can be taken to prevent getting shigellosis: wash hands before handling food and thoroughly cook all food before eating. The primary prevention methods are improved sanitation and personal and food hygiene, but a low cost and efficacious vaccine would complement these methods. Since shigellosis is spread very quickly among children, keeping infected children out of daycare for 24 hours after their symptoms have disappeared, will decrease the occurrence of shigellosis in daycares.

Currently, no licensed vaccine targeting Shigella exists. Several vaccine candidates for Shigella are in various stages of development including live attenuated, conjugate, ribosomal, and proteosome vaccines. Shigella has been a longstanding World Health Organization target for vaccine development, and sharp declines in age specific diarrhea/dysentery attack rates for this pathogen indicate that natural immunity does develop following exposure; thus, vaccination to prevent the disease should be feasible. Shigella species are resistant to many antibiotics,

Antibiotics should only be used in severe cases or for certain populations with mild symptoms (elderly, immunocompromised, food service industry workers, child care workers). For Shigella associated diarrhea, antibiotics shorten the length of infection, but they are usually avoided in mild cases because many Shigella strains are becoming resistant to common antibiotics. Furthermore, effective medications are often in short supply in developing countries, which carry the majority of the disease burden from Shigella. Antidiarrheal agents may worsen the sickness, and should be avoided. In most cases, the disease resolves within four to eight days without antibiotics. Severe infections may last three to six weeks. Antibiotics, such as trimethoprim sulfamethoxazole, ciprofloxacin may be given when the person is very young or very old, when the disease is severe, or when the risk of the infection spreading to other people is high. Additionally, ampicillin (but not amoxicillin) was effective in treating this disease previously, but now the first choice of drug is pivmecillinam.

Insufficient data exist, but it is estimated to have caused the death of 34,000 children under the age of five in 2013, and 40,000 deaths in people over five years of age. An estimated 500,000 cases of shigellosis occur annually in the United States. Infants, the elderly, and the critically ill are susceptible to the most severe symptoms of disease, but all humans are susceptible to some degree. Individuals with acquired immune deficiency syndrome (AIDS) are more frequently infected with Shigella. Shigellosis is a more common and serious condition in the developing world; fatality rates of shigellosis epidemics in developing countries can be 5–15%. Orthodox Jewish communities (OJCs) are a known risk group for shigellosis; Shigella sonnei is cyclically epidemic in these communities in Israel, with sporadic outbreaks occurring elsewhere in among these communities. "Through phylogenetic and genomic analysis, we showed that strains from outbreaks in OJCs outside of Israel are distinct from strains in the general population and relate to a single multidrug resistant sublineage of S. sonnei that prevails in Israel. Further Bayesian phylogenetic analysis showed that this strain emerged approximately 30 years ago, demonstrating the speed at which antimicrobial drug–resistant pathogens can spread widely through geographically dispersed, but internationally connected, communities."