Salmonella spp
Gram Stain
- Gram negative bacilli - fermenter
Clinical Significance
These organisms are ubiquitous in animals (birds, reptiles, mammals).Human infections are most commonly caused by ingestion of contaminated food, water or milk, direct contact with animals (especially reptiles), or less frequently, by contact with infected humans.
These organisms are an important cause of various gastrointestinal syndromes including:
- gastroenteritis (mild-severe)
- enteric fever (typhoid fever)
- asymptomatic carrier state
Intestinal (non typhoid) infections tend to be self-limited and do not require therapy unless risk factors are present:
- age < 12 months or > 50 years
- immunosuppression
- hemoglobinopathy
- patient is food handler
Extraintestinal infections include urinary tract and skin/soft tissue infections, osteomyelitis, meningitis, endocarditis, abscesses, including parotid abscesses, intravascular infections, bacteremia, and septicemia.
Usual Susceptibility Pattern
Resistance to ampicillin is increasing.
Most strains remain susceptible to ceftriaxone. Ceftriaxone is recommended over cefotaxime as it achieves better intraluminal concentrations.
Although they typically test susceptible to aminoglycosides and 1st/2nd generation cephalosporins, these agents are not recommended due to their poor intracellular penetration.
Quinolone resistance is increasing especially if infections acquired in Asia.
S. typhi and S. paratyphi have significant resistance to ampicillin, TMP/SMX, and quinolones.
| Empiric Therapy |
|---|
| Diarrheal Illness: |
| Typically self-limited. |
| Risk factors: |
| TMP/SMX |
| or |
| Ciprofloxacin |
| or |
| Azithromycin |
| Bacteremia/Hospitalized: |
| Ceftriaxone Prolonged therapy (4-6 weeks) recommended for all extraintestinal infections (including urinary tract infections). |