- Characteristics
- Facultative Anaerobic Gram Negative Rod in Enterobacteriaceae family
- Grouped with SS Gram Negative Bacteria (Salmonella, Shigella)
- Salmonella is distinguished from other Enterobacteriaceae
- Motile with flagella (unlike Shigella)
- Does not ferment lactose (unlike E. coli)
- Produces Hydrogen Sulfide or H2S (unlike Shigella)
- Facultative Anaerobic Gram Negative Rod in Enterobacteriaceae family
- Salmonellosis Pathogenesis
- Non-typhoid Salmonella is gastrointestinal colonizing flora in animals (reservoir)
- Natural Hosts (Ducks, birds)
- Pets (Reptiles, birds)
- All serotypes are pathogenic in humans
- More then 2000 serotypes have been identified (<100 are infectious in humans)
- Salmonellosis is most commonly caused by one of two Salmonella species
- Salmonella typhimurium (non-typhoid)
- Salmonella enteritidis
- Contrast with Salmonella typhi which causes Typhoid Fever
- Vi Antigen (Virulence Antigen)
- Surrounds the Salmonella Bacterial cell surface
- Protects surface Antigen O from immune response (Opsonization, Phagocytosis)
- Salmonella causes three distinct disease courses in humans
- Typhoid Fever (as well as chronic carrier state in up to 5%)
- Gastroenteritis
- Most common type of Salmonella infection (and described on this page)
- Invasive Disease and Sepsis
- Higher risk in children, esp. Asplenic (including Sickle Cell Anemia)
- Non-typhoid Salmonella is gastrointestinal colonizing flora in animals (reservoir)
-
Foodborne Illness Sources (95% of cases)
- Eggs
- Cheese
- Dry cereal
- Unpasterurized milk or juice
- Ice Cream
- Poultry
- Contaminated unpeeled fruit
- Contaminated vegetables
- See Acute Diarrhea
- Identification
- Enteric Pathogens Nucleic Acid Test Panels (or if unavailable, then routine Stool Culture)
- General
- See Acute Diarrhea
- See Traveler's Diarrhea
- Supportive Care
- Oral Rehydration
- Antibiotics are not indicated in uncomplicated non-typhi Salmonella Diarrhea
- Indications
- Severe infection or hospitalized
- Bacteremia or Sepsis
- Dysentery (Inflammatory Diarrhea)
- Disseminated disease (treat for 4-6 weeks)
- Age <12 months or >50 years
- Prosthesis (e.g. joint replacements)
- Valvular heart disease
- Severe Coronary Artery Disease
- Malignancy
- Uremia
- Liver disease
- Sickle Cell Anemia
- HIV or AIDS
- Immunocompromised (treat for 14 days)
- Precaution: Growing Antibiotic Resistance
- Third Generation Cephalosporin resistance increasing
- Fluoroquinolone resistance increasing (especially in Asia)
- Hohmann (2001) Clin Infect Dis 32:263-9 [PubMed]
-
Antibiotic course
- Typical duration: 7-10 days
- Immunocompromised: 14 days
- Adults with severe disease
- Infection not acquired in Asia
- Ciprofloxacin 500 mg twice daily OR
- Levofloxacin 500 mg once orally daily
- Infection acquired in Asia (Fluoroquinolone resistance)
- Azithromycin 500 mg orally daily OR
- Ceftriaxone 2 g IV every 24 hours (or Cefotaxime 2 g IV every 8 hours)
- Other alternatives
- Carbapenem (e.g. Imipenem)
- Trimethoprim-sulfamethoxazole (TMP-SMZ) 160/800 mg twice daily for 5-7 days
- Higher resistance rates
- Infection not acquired in Asia
- Children with severe disease
- Ceftriaxone every 24 hours (or Cefotaxime every 8 hours)
- Azithromycin
- Carbapenem (e.g. Imipenem)
- Trimethoprim-sulfamethoxazole 8-10 mg/kg/day of TMP component divided twice daily
- Higher resistance rates
- Gastrointestinal Bleeding
- Toxic Megacolon
- Bacteremia (5%)
- Cardiovascular (25% bacteremic patients over age 50)
- Abdominal aorta infection
- Endocarditis
- Focal infections in Immunocompromised patients
- Onset: 6 to 24 hours (up to 48 hours)
- Duration: 4 to 7 days (untreated)
- Infectious: Asymptomatic shedding for 3-4 weeks
- CDC Salmonella
- CDC Yellow Book - Salmonella
- (2014) Sanford Guide to Antimicrobials, accessed IOS app 5/8/2016
- Switaj (2015) Am Fam Physician 92(5): 358-65 [PubMed]