Bacillary dysentery

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Bacillary dysentery
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Bacillary dysentery is a type of dysentery, and is a severe form of shigellosis. It is associated with species of bacteria from the family Enterobacteriaceae. [1] The term is usually restricted to Shigella infections. [2]

Contents

Shigellosis is caused by one of several types of Shigella bacteria. [3] Three species are associated with bacillary dysentery: Shigella sonnei, Shigella flexneri and Shigella dysenteriae . [4] A study in China indicated that Shigella flexneri 2a was the most common serotype. [5]

Salmonellosis caused by Salmonella enterica (serovar Typhimurium) has also been described as a cause of bacillary dysentery,[ citation needed ] though this definition is less common. It is sometimes listed as an explicit differential diagnosis of bacillary dysentery, as opposed to a cause. [6]

Bacillary dysentery should not be confused with diarrhea caused by other bacterial infections. One characteristic of bacillary dysentery is blood in stool, [7] which is the result of invasion of the mucosa by the pathogen.

Presentation

Pathogenesis

Transmission is fecal-oral and is remarkable for the small number of organisms that may cause disease (10 ingested organisms cause illness in 10% of volunteers, and 500 organisms cause disease in 50% of volunteers). Shigella bacteria invade the intestinal mucosal cells but do not usually go beyond the lamina propria. Dysentery is caused when the bacteria escape the epithelial cell phagolysosome, multiply within the cytoplasm, and destroy host cells. Shiga toxin causes hemorrhagic colitis and hemolytic-uremic syndrome by damaging endothelial cells in the microvasculature of the colon and the glomeruli, respectively. In addition, chronic arthritis secondary to S. flexneri infection, called reactive arthritis, may be caused by a bacterial antigen; the occurrence of this syndrome is strongly linked to HLA-B27 genotype, but the immunologic basis of this reaction is not understood.[ citation needed ]

Diagnosis

Specimen: Fresh stool is collected.

Culture: Specimen is inoculated on selective media like MacConkey's agar, DCA, XLD agar. Selenite F broth(0.4%) is used as enrichment medium which permits the rapid growth of enteric pathogens while inhibiting the growth of normal flora like E. coli for 6–8 hours. Subculture is done on the solid media from selenite F broth. All the solid media are incubated at 37 degrees for 24 hours.

Cultural characteristics: Colorless (NLF) colonies appear on MacConkey's agar which are further confirmed by gram staining, hanging drop preparation and biochemical reactions.

Treatment

Dysentery is initially managed by maintaining fluid intake using oral rehydration therapy. If this treatment cannot be adequately maintained due to vomiting or the profuseness of diarrhea, hospital admission may be required for intravenous fluid replacement. Ideally, no antimicrobial therapy should be administered until microbiological microscopy and culture studies have established the specific infection involved. When laboratory services are not available, it may be necessary to administer a combination of drugs, including an amoebicidal drug to kill the parasite and an antibiotic to treat any associated bacterial infection.

Anyone with bloody diarrhea needs immediate medical help. Treatment often starts with an oral rehydrating solution—water mixed with salt and carbohydrates—to prevent dehydration. (Emergency relief services often distribute inexpensive packets of sugars and mineral salts that can be mixed with clean water and used to restore lifesaving fluids in dehydrated children gravely ill from dysentery.)

If Shigella is suspected and it is not too severe, the doctor may recommend letting it run its course—usually less than a week. The patient will be advised to replace fluids lost through diarrhea. If the infection is severe, the doctor may prescribe antibiotics, such as ciprofloxacin or TMP-SMX (Bactrim). Unfortunately, many strains of Shigella are becoming resistant to common antibiotics, and effective medications are often in short supply in developing countries. If necessary, a doctor may have to reserve antibiotics for those at highest risk for death, including young children, people over 50, and anyone suffering from dehydration or malnutrition.

No vaccine is available. There are several Shigella vaccine candidates in various stages of development that could reduce the incidence of dysentery in endemic countries, as well as in travelers with traveler's diarrhea. [8]

History

The bacterium causing shigellosis is named after Kiyoshi Shiga, a Japanese researcher who discovered it in 1897.

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<i>Escherichia coli</i> Enteric, rod shaped, gram-negative bacterium

Escherichia coli, also known as E. coli, is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes (EPEC, ETEC etc.) can cause serious food poisoning in their hosts, and are occasionally responsible for food contamination incidents that prompt product recalls. Most strains do not cause disease in humans and are part of the normal microbiota of the gut; such strains are harmless or even beneficial to humans (although these strains tend to be less studied than the pathogenic ones). For example, some strains of E. coli benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by pathogenic bacteria. These mutually beneficial relationships between E. coli and humans are a type of mutualistic biological relationship — where both the humans and the E. coli are benefitting each other. E. coli is expelled into the environment within fecal matter. The bacterium grows massively in fresh faecal matter under aerobic conditions for three days, but its numbers decline slowly afterwards.

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<span class="mw-page-title-main">Dysentery</span> Inflammation of the intestine causing diarrhea with blood

Dysentery, historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehydration.

<span class="mw-page-title-main">Shigellosis</span> Medical condition

Shigellosis is an infection of the intestines caused by Shigella bacteria. Symptoms generally start one to two days after exposure and include diarrhea, fever, abdominal pain, and feeling the need to pass stools even when the bowels are empty. The diarrhea may be bloody. Symptoms typically last five to seven days and it may take several months before bowel habits return entirely to normal. Complications can include reactive arthritis, sepsis, seizures, and hemolytic uremic syndrome.

<i>Shigella</i> Genus of bacteria

Shigella is a genus of bacteria that is Gram-negative, facultative anaerobic, non-spore-forming, nonmotile, rod-shaped, and genetically closely related to E. coli. The genus is named after Kiyoshi Shiga, who first discovered it in 1897.

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<i>Shigella dysenteriae</i> Bacterial species

Shigella dysenteriae is a species of the rod-shaped bacterial genus Shigella. Shigella species can cause shigellosis. Shigellae are Gram-negative, non-spore-forming, facultatively anaerobic, nonmotile bacteria. S. dysenteriae has the ability to invade and replicate in various species of epithelial cells and enterocytes.

<i>Shigella flexneri</i> Species of bacterium

Shigella flexneri is a species of Gram-negative bacteria in the genus Shigella that can cause diarrhea in humans. Several different serogroups of Shigella are described; S. flexneri belongs to group B. S. flexneri infections can usually be treated with antibiotics, although some strains have become resistant. Less severe cases are not usually treated because they become more resistant in the future. Shigella are closely related to Escherichia coli, but can be differentiated from E.coli based on pathogenicity, physiology and serology.

<span class="mw-page-title-main">Pathogenic bacteria</span> Disease-causing bacteria

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<i>Shigella sonnei</i> Species of bacterium

Shigella sonnei is a species of Shigella. Together with Shigella flexneri, it is responsible for 90% of shigellosis cases. Shigella sonnei is named for the Danish bacteriologist Carl Olaf Sonne. It is a Gram-negative, rod-shaped, nonmotile, non-spore-forming bacterium.

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Pathogenic <i>Escherichia coli</i> Strains of E. coli that can cause disease

Escherichia coli is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans. Unlike normal flora E. coli, the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by E. coli, and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens.

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References

  1. Dysentery,+Bacillary at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. " bacillary dysentery " at Dorland's Medical Dictionary
  3. Yang F, Yang J, Zhang X, et al. (2005). "Genome dynamics and diversity of Shigella species, the etiologic agents of bacillary dysentery". Nucleic Acids Res. 33 (19): 6445–58. doi:10.1093/nar/gki954. PMC   1278947 . PMID   16275786.
  4. "WHO | Diarrhoeal Diseases". Archived from the original on 15 December 2008. Retrieved 2008-12-19.
  5. Wang XY, Tao F, Xiao D, et al. (July 2006). "Trend and disease burden of bacillary dysentery in China (1991-2000)". Bull. World Health Organ. 84 (7): 561–8. doi:10.2471/BLT.05.023853. PMC   2627389 . PMID   16878230.
  6. "Bacillary Dysentery". Archived from the original on 27 December 2008. Retrieved 2008-12-19.
  7. "Enterobacteriaceae, Vibrio, Campylobacter and Helicobacter". Archived from the original on 24 December 2008. Retrieved 2008-12-19.
  8. Girard MP, Steele D, Chaignat CL, Kieny MP (April 2006). "A review of vaccine research and development: human enteric infections". Vaccine. 24 (15): 2732–50. doi:10.1016/j.vaccine.2005.10.014. PMID   16483695.