Official website of the Johns Hopkins Antibiotic (ABX), HIV, Diabetes, and Psychiatry Guides, powered by Unbound Medicine. Johns Hopkins Guide App for iOS, iPhone, iPad, and Android included. Explore these free sample topics:
-- The first section of this topic is shown below --
- Facultatively anaerobic, gram-negative bacillus
- Genus has 2 species, Salmonella eterica and Salmonella bongori; most of the clinically important sub-species are within Salmonella enterica.
- Non-typhoidal strains: Foodborne acquisition (95% cases: outbreaks linked to multiple vehicles including eggs, poultry, meats, dairy or vegetables) or acquisition as zoonotic pathogen (such as reptiles).
- Infection with "typhoidal strains" (S. typhi [typhoid fever; serogroup D] and S. paratyphi [paratyphoid fever]) implies contact with person who is infected or a chronic carrier, or with contaminated food or water.
- Humans are the only reservoirs for typhoid strains.
- Non-typhoidal strains classified by agglutination reactions to O antigens identifying serogroups A-E; approximately 2,500 serovars/serotypes exist. Most common in US are S. Typhimurium, S. Enteriditis, S. Newport.
- S. enterica or S. choleraesuis sometimes used as single name for clinically familiar serovars (e.g., S. enterica Typhimurium).
- Serotyping usually only performed in reference/state labs
- Diagnosis is via culture (of blood, stool, etc)
- Typhoidal species more difficult to Cx. Increased yield when blood, bone marrow and intestinal secretions Cx’d before or soon after ABx initiated
- Recovery of organism possible from almost any site, but most commonly stool followed by blood
- Oxidase and lactose negative.
- Grows easily under both anaerobic and aerobic conditions on standard media for stool. Fresh stool specimen preferred; rectal swabs inferior. Using a Salmonella-Shigella agar allows for identification of hydrogen sulfide, which is produced by most Salmonellae.