Table of Contents:

• Taxonomy Information
• Lifecycle Information
• Genome Information
• Biosafety Information
• Culturing Information
• Epidemiology Information
• Diagnostic Tests Information
• Infected Hosts Information
• Phinet: Pathogen-Host Interaction Network
• Lab Animal Pathobiology & Management
• References
• Data Provenance and Curators

1. Species:
   1. Shigella. :
      1. Common Name: Shigella.
      2. GenBank Taxonomy No.: 620
      3. Description: In 1898, Japanese bacteriologist K. Shiga used bacterial culture to investigate an epidemic of acute dysentery in Japan. Using the serum from one of his patients, he was able to identify the epidemic agent in the feces of 34 out of 36 cases. Shiga characterized these bacteria by simple biochemical tests.The organism was named Shiga bacillus. Shigella spp. cause dysentery by invading the colonic mucosa. Shigella bacteria multiply within colonic epithelial cells, cause cell death and spread laterally to infect and kill adjacent epithelial cells, causing mucosal ulceration, inflamation and bleeding. Complications of Shigella infection are haemolytic-uraemic syndrome (HUS), seizures, sepsis, and toxic megacolon. Shigella infections are more severe in children who are malnourished and have a greater adverse effect on nutritional status than do infections with enteric pathogens that cause watery diarrhea. In several areas of the world, Shigella bacteria are resistant to available and affordable antibiotics(Website2).
      4. Variant(s):
         • Shigella flexneri. :
           • Common Name: Shigella flexneri.
           • GenBank Taxonomy No.: 623
           • Description: Simon Flexner, in the early 1900s, first isolated a mannitol-fermenting strain of Shigella from dysentery patients in the Philippines which has now been designated as Shigella flexneri. As it is a highly infectious pathogen, the infectious dose of S. flexneri is extremely low. Bacteria are spread by personal contact or exposure to contaminated food and water, creating severe outbreaks in areas of minimal sanitary conditions. S. flexneri is the predominant specie in endemic areas, accounting for approximately 50% of culture-positive disease(Website2).

1. Shigella Lifecycle Information
   1. Stage Information:
      1. Shigella lifecycle one stage(Website4, Website5, Website6):
         • Shape: Shigella cells are rod-shaped.
         • Picture(s):
           • SEM Image of Shigella dysenteriae (Website 63)
             
             
             
             Description: Scanning Electron Micrograph of Shigella dysenteriae - Gram-negative, enteric, facultatively anaerobic, rod prokaryote; causes bacterial dysentery. This species is most often found in water contaminated with human feces. Magnification: x2,200.
           • SEM Image of Shigella sonnei (Website 63)
             
             
             
             Description: Scanning Electron Micrograph of Shigella sonnei - Gram-negative, facultatively anaerobic, rod prokaryote; causes shigellosis (bacterial dysentery). This species is most often linked to infection from food. Magnification: x3,500.

1. Genome of Shigella flexneri.
   1. Shigella Chromosome
      1. GenBank Accession Number: AE005674
      2. Size: 4, 607 kb(Jin et al., 2002, Website40).
      3. Gene Count: 4,434 open reading frames(Jin et al., 2002, Website40).
      4. Description: There are several potential bacteriophage-transmitted PAIs (pathogenicity islands), many translocations, inversions and deletions of the corresponding E. coli DNA segments, and numerous pseudogenes. The presence of large numbers of pseudogenes has been postulated to be one of the main reasons that Shigella became a solely human pathogen(Jin et al., 2002).
   2. Shigella Plasmid pCP301
      1. GenBank Accession Number: AF386526
      2. Size: 221 618 bp(Jin et al., 2002).
      3. Gene Count: 267 open reading frames(Jin et al., 2002, Website41).
      4. Description: Shigella flexneri 2a strain 301 virulence plasmid pCP301(Jin et al., 2002, Website41).

1. General biosafety information
   1. Level: Biosafety Level 2.
   2. Precautions: Shigella may be present in feces, urine, and in food, feed, and environmental materials. Ingestion or parenteral inoculation are the primary laboratory hazards. The importance of aerosol exposure is not known. Recommended Precautions: Biosafety Level 2 practices, containment equipment, and facilities are recommended for activities with clinical materials and cultures known to contain or potentially contain the microorganism. Animal Biosafety Level 2 practices, containment equipment, and facilities are recommended for activities with experimentally or naturally infected animals(Website34).

1. Shigella Culturing Method :
   1. Description: Shigella Broth(Website35).
   2. Medium: BROTH BASE:Tryptone 20 g. K2HPO4 2 g. KH2PO4 2 g. NaCl 5 g. Glucose 1 g. Tween 80 1.5 ml. Distilled water 1.0 liter.Autoclave 15 min at 121 degrees celcius. Final pH, 7.0 0.2.NOVOBIOCIN SOLUTION:Weigh 50 mg novobiocin into 1 liter distilled water. Sterilize by filtration through 0.45 m membrane. Add 2.5 ml of this concentrated novobiocin solution to 225 ml base. Final concentration of novobiocin (0.55 g/ml).This broth is a specially formulated medium for Shigella, novobiocin is added to provide a selective environment.Pour supernatant into sterile 500 ml Erlenmeyer flask. Adjust pH, if necessary, to 7.0 0.2 with sterile 1 N NaOH or 1 N HCl. Place flask in anaerobic jar with fresh catalyst, insert GasPak and activate by adding water. Incubate jars in water bath for 20 h(Website35).
   3. Optimal Temperature: Incubate jars in 44 degrees celcius water bath(Website35).
   4. Optimal pH: Final pH 7.0 0.2(Website35).

1. Outbreak Locations:
   1. Shigella is the primary causative agent of bacillary dysentery throughout the developing world. According to the World Health Organisation, the annual number of Shigella episodes throughout the world was estimated to be 164.7 million, of which 163.2 million were in developing countries (with 1.1 million deaths) and 1.5 million in industrialized countries. A total of 69% of all episodes and 61% of all deaths attributable to shigellosis involved children under 5 years of age(Kotloff et al., 1999). Shigella infection in the USA. A total of 59,527 cases of laboratory-confirmed Shigella infection were reported to the US National Shigella Surveillance System over the 5-year period 1990-94 (average 11,900 per year)(Kotloff et al., 1999). Over the same period, an additional 27,899 cases were reported from states not participating in the US National Shigella Surveillance System, yielding a total number of 87,426 Shigella cases for the USA, i.e. an average of 17500-18000 cases per year(Kotloff et al., 1999, Website9). This corresponds to 6.5 cases per 100,000 population(Kotloff et al., 1999). Shigellosis, which continues to have an important global impact, cannot be adequately controlled with the existing prevention and treatment measures(Kotloff et al., 1999).
2. Transmission Information:
   1. From: Humans(Website9, Website10, Mead et al., 1999). , To: Humans(Website9, Website10, Mead et al., 1999).
      Mechanism: Shigella bacteria are spread from one infected person to another through fecal-oral transmition. Shigella cells are present in the diarrheal stools of infected persons while they are sick and for a week or two afterwards. Persons who have a Shigella infection have Shigella bacteria in their stool and frequently have Shigella bacteria on their hands. Vehicles - food and water. Food prepared by this person may easily become contaminated with Shigella bacteria. Water usually becomes contaminated with Shigella bacteria when sewage enters the drinking water supply. Approximately 20% of cases of shigellosis are transmitted via contaminated food or water(Mead et al., 1999).
3. Environmental Reservoir:
   1. Environmental Reservoir:
      1. Description: Humans are the only natural reservoir(Website22).
      2. Survival: Shigella may survive in faecally contaminated materials but not very long (Zaika, 2002). Shigella cells are known to survive in soiled linen for up to seven weeks, in fresh water from five to eleven days, in salt water for 12-30 hours, in dust at room temperature for six weeks, in sour milk for four weeks, and in kitchen refuse for approximately 1-4 days. Shigella survived for up to 14 days in tomato juice and apple juice stored at 7 degrees celcius. The shortest survival time (2-8 d) was observed in apple juice at 22 degrees celcius. Shigella cells were recovered after 48 h from strawberries and fruit salad kept at 4 degrees celcius (Bagamboula et al., 2002). Shigella organisms are killed by heat used in processing or cooking, and they do not survive well in acidic foods (pH below 4.5)(Website6, Website11, Zaika, 2002, Website17, Website26, Bagamboula et al., 2002).
4. Intentional Releases:
   1. Intentional Release Information:
      1. Description: Shigella infection.
      2. Emergency Contact: If you believe that you have been exposed to a biological or chemical agent, or if you believe an intentional biological threat will occur or is occurring, contact your local health department and/or your local police or other law enforcement agency. CDC Emergency Response Hotline (24 hours) 770-488-7100. Call communicable disease epidemiology 206-361-2914 or the food program 360-586-1249. Call USDA's Meat and Poultry Hotline at 1-800-535-4555, 10 a.m. to 4 p.m., Eastern Time. In the Washington, DC area, call (202) 720-3333. TTY: 1-800-256-7072(Website7, Website8).

1. Organism Detection Test:
   1. Gram Staining :
      1. Time to Perform: minutes-to-1-hour
      2. Description: Shigella cells are Gram (-) bacilli. Gram-staining is a four- part procedure which uses certain dyes to make a bacterial cell stand out against its background. The specimen should be mounted and heat fixed on a slide before you proceed to stain it(Website36, Website37).
      3. False Positive: Not using enough decolorizer may yield a false Gram (+) result(Website36).
      4. False Negative: Using too much decolorizer could result in a false Gram (-) result(Website36).
2. Nucleic Acid Detection Test: