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Table of Contents:
Taxonomy Information
  1. Species:
    1. Salmonella enterica :
      1. Common Name: Salmonella
      2. GenBank Taxonomy No.: 28901
      3. Description: In 1885, pioneering American veterinary scientist, Daniel E. Salmon, discovered the first strain of Salmonella from the intestine of a pig. This strain was called Salmonella choleraesuis, the designation that is still used to describe the genus and species of this common human pathogen.Salmonella are a type of bacteria that causes typhoid fever and many other infections of intestinal origin. Typhoid fever, rare in the U.S., is caused by a particular strain designated Salmonella typhi. But illness due to other Salmonella strains, just called "salmonellosis," is common in the U.S. Today, the number of known strains (technically termed "serotypes" or "serovars") of these bacteria total over 2300(Website2).
      4. Variant(s):
        • Salmonella enterica serovar Typhi. :
          • Common Name: S. typhi
          • GenBank Taxonomy No.: 90370
          • Description: This bacterium is the causative agent of typhoid fever. Although typhoid fever is not widespread in the United States, it is very common in under-developed countries, and causes a serious, often fatal disease. The symptoms of typhoid fever include nausea, vomiting, fever and death(Website3).
Lifecycle Information
  1. Salmonella Lifecycle Information
    1. Stage Information:
      1. Salmonella lifecycle one stage(Krieg and Holt, 1984, Website4, Website5, Website9):
        • Shape: Salmonella cells are rod-shaped.
        • Picture(s):
          • SEM Image of Salmonella typhi (Website 53)



            Description: Scanning Electron Micrograph of Salmonella typhi - Gram-negative, enteric, rod prokaryote (dividing); causes typhoid fever. Magnification: x3,220.
          • SEM Image of Salmonella enteritidis (Website 53)



            Description: Scanning Electron Micrograph of Salmonella enteritidis - Gram-negative, enteric, rod prokaryote (dividing); note the flagella. This zoonotic microorganism causes salmonellosis (food poisoning) in humans when infected fowl, domestic mammals or turtles contaminate milk, eggs, meat, poultry or shellfish (which humans ingest). Magnification: x2,750.
          • SEM Image of Salmonella typhimurium (Website 53)



            Description: Scanning Electron Micrograph of Salmonella typhimurium - Gram-negative, enteric, DT104, rod prokaryote (dividing); note the flagella. Zoonotic microorganism causing salmonellosis (food poisoning) in humans when infected fowl, domestic mammals or turtles contaminate milk, eggs, meat, poultry or shellfish (which humans ingest). Magnification: x3,200.
Genome Summary
  1. Genome of Salmonella enterica
    1. Salmonella Chromosome
      1. GenBank Accession Number: AE006468
      2. Size: 4,857kb(McClelland et al., 2001, Website34).
      3. Gene Count: 4,330 open reading frames(McClelland et al., 2001).
      4. Description: The chromosomes of enteric bacteria are mosaics, composed of colinear regions interspersed with 'loops' or 'islands' unique to certain species; the islands sometimes encode pathogenicity functions (called Salmonella pathogenicity islands, SPIs)(McClelland et al., 2001).
    2. Salmonella Plasmid pSLT
      1. GenBank Accession Number: NC_003277
      2. Size: 94 kb(McClelland et al., 2001, Website35).
      3. Description: Salmonella enterica serovar typhimurium LT2 plasmid pSLT(McClelland et al., 2001, Website35).
  2. Genome of Salmonella enterica serovar Typhi.
    1. S_typhi Chromosome
      1. GenBank Accession Number: AL513382
      2. Size: 4,809 kb(Parkhil et al., 2001, Website36).
      3. Description: S. typhi has hundreds of insertions and deletions, ranging in size from single genes to large islands. The genome sequence identifies over two hundred pseudogenes, several corresponding to genes that are known(Parkhil et al., 2001).
    2. S_typhi Plasmid pHCM1
      1. GenBank Accession Number: NC_003384
      2. Size: 218160 bp(Parkhil et al., 2001).
      3. Description: Salmonella enterica serovar Typhi plasmid pHCM1(Parkhil et al., 2001, Website37).
    3. S_typhi Plasmid pHCM2
      1. GenBank Accession Number: NC_003385
      2. Size: 106516 bp(Parkhil et al., 2001).
      3. Description: Salmonella enterica serovar Typhi plasmid pHCM2(Parkhil et al., 2001, Website38).
Biosafety Information
  1. General biosafety information
    1. Level: Biosafety Level 2.
    2. Precautions: The agent may be present in feces, blood, 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. Naturally or experimentally infected animals are a potential source of infection for laboratory and animal care personnel, and for other animals. 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 agents. Animal Biosafety Level 2 practices, containment equipment, and facilities are recommended for activities with experimentally or naturally infected animals(Website21).
Culturing Information
  1. Salmonella Culturing Method :
    1. Description: Rappaport-Vassiliadis (RV) medium is comparable to, or even more effective than, the other selective enrichments for recovery of Salmonella from all of the foods. Twenty-three laboratories participated in a collaborative study to compare the relative effectiveness of Rappaport-Vassiliadis (RV) medium(Hammack et al., 2001).
    2. Medium: BROTH BASE:Tryptone 5 g. NaCl 8 g. KH2PO4 1.6 g. Add distilled water to 1 liter.MAGNESIUM CHLORIDE SOLUTION (40%):MgCl2 6H2O 400 g. Add distilled water to 1 liter.MALACHITE GREEN OXALATE SOLUTION (0.4%):Malachite green oxalate 0.4 g. Add distilled water to 100 ml. To prepare the complete medium, combine 1000 ml broth base, 100 ml magnesium chloride solution, and 10 ml malachite green oxalate solution (total volume of complete medium is 1110 ml). Broth base must be prepared on same day that components are combined to make complete medium. Magnesium chloride solution may be stored in dark bottle at room temperature up to 1 year. To prepare solution, dissolve entire contents of MgCl2 6H2O from newly opened container according to formula, because this salt is very hygroscopic. Malachite green oxalate solution may be stored in dark bottle at room temperature up to 6 months. Merck analytically pure malachite green oxalate is recommended because other brands may not be equally effective. Dispense 10 ml volumes of complete medium into 16 x 150 mm test tubes. Autoclave 15 min at 115 degrees celcius. Final pH, 5.5 0.2. Store in refrigerator and use within 1 month.This medium must be made from its individual ingredients. Use of commercially available dehydrated media is not recommended. Users of this medium should be aware that there are formulations and incubation temperatures for this medium other than those recommended by U.S. Food and Drug Administration(Website22).
    3. Optimal Temperature: Incubate at 42 degrees celcius(Hammack et al., 2001, Website22).
    4. Optimal pH: Final pH 5.5 0.2(Website22).
Epidemiology Information:
  1. Outbreak Locations:
    1. Salmonella causes typhoid fever and other infections of intestinal origin. Typhoid fever, rare in the U.S., is caused by a particular strain designated Salmonella typhi. But illness due to Salmonella typhimurium, just called "salmonellosis," is common in the U.S. Non-typhoidal salmonellosis is a worldwide disease of humans and animals(Website8, Website9).
  2. Transmission Information:
    1. From: Humans(Website10). , To: Humans(Website10).
      Mechanism: Individuals who carry Salmonella in their intestines may transmit Salmonella to another individual if good personal hygiene is not followed. For example, an infected food handler may transmit Salmonella bacteria if he/she does not wash his/her hands after using the bathroom and before handling or preparing food(Website11).
    2. From: Poultry(Website11). , To: Humans(Website11).
      Mechanism: Salmonella bacteria live in the intestinal tracts of humans and birds, and are transmitted by the oral-fecal route. This means eating foods contaminated with feces. Contaminated foods usually look and smell normal. Contaminated food often originates from poultry, poultry products, or wild birds(Website11).
  3. Environmental Reservoir:
    1. Environmental Reservoir - Rural:
      1. Description: Rural areas represent a dangerous reservoir of disease, a particular threat to the nation's agriculturally dependent urban populations. Most countries need a more comprehensive public health system that addresses urban and rural problems(Casner, 2001).
      2. Survival: Salmonella can certainly survive, but may not actively grow, in many environmental waters. As Salmonella bacteria are present in the faeces of humans and birds they are often present in faecally polluted waters.SURVIVAL OUTSIDE HOST: Ashes - 130 days; rabbit carcass - 17 days; dust - up to 30 days; feces - up to 62 days; linoleum floor - 10 hours; ice - 240 days; skin - 10-20 min(Website12).
  4. Intentional Releases:
    1. Intentional Release Information:
      1. Description: Salmonella 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(Website6, Website7).
Diagnostic Tests Information
  1. Organism Detection Test:
    1. Gram Staining :
      1. Time to Perform: minutes-to-1-hour
      2. Description: Salmonella 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(Website23, Website24).
      3. False Positive: Not using enough decolorizer may yield a false Gram (+) result(Website23).
      4. False Negative: Using too much decolorizer could result in a false Gram (-) result(Website23).
  2. Immunoassay Test:
    1. Serobact Salmonella Test :
      1. Description: A simple one step latex slide agglutination test for both clinical and food laboratories.Serobact Salmonella is a rapid latex slide agglutination test for the identification of Salmonella from selective enrichment broths. Serobact latex technology is more sensitive than direct agglutination methods and the use of Serobact Salmonella permits the presumptive identification of Salmonella spp. at least 24 hours earlier than using conventional techniques. PRINCIPLE: Polyvalent H antisera prepared against a comprehensive range of Salmonella flagella antigens is coated onto latex particles. Additional information: http://www.diffchamb.com/(Website25).
      2. False Positive: Specificity 97.2%. Predictive negative value 100%(Website25).
      3. False Negative: Sensitivity 100%. Predictive positive value 98.2%(Website25).
    2. REVEAL for Salmonella :
      1. Description: The test is designed to screen one or several samples concurrently. Detectable levels of Salmonella are present within 20 hours of sample collection. Rappaport-Vassiliadis (RV) can also be used as a selective enrichment. When using RV, the sample is ready to test after four hours of sample incubation. To begin the test, a sample of the enriched culture is placed into the sample port. Contents of the sample are wicked through the pad to a specimen reaction zone containing colloidal gold-labeled antibodies specific to Salmonella. Reactive Salmonella combine with the gold-labeled antibodies and migrate through the support until they encounter a binding reagent zone which includes a second antibody specific to Salmonella. When this occurs, a line appears in the test window indicating a positive result. The rest of the sample continues to migrate until it encounters a second binding reagent zone. This results in the formation of a line in the control window. Regardless of whether or not the sample contains any Salmonella, a line will form, ensuring the test is working correctly. Additional information: http://www.neogen.com/revealsalmonella.htm(Website26).
    3. Transia Card :
      1. Description: Transia Card Salmonella: The Transia Card Salmonella is used directly on an enrichment broth. It is on a sandwich - type, immunochromatographic reaction using highly- specific antibodies immobilised onto a membrane and conjugated to a dye. This allows the detection of all Salmonella serotypes present in sample. Additional information: http://www.diffchamb.com/(Website27).
      2. False Positive: No cross - reaction with other enterobacteria(Website27).
      3. False Negative: Maximised sensitivity through lipopolysaccharide (LPS) detection(Website27).
  3. Nucleic Acid Detection Test: