Term
|
Definition
Disease: cholera Characteristics: - Comma-shaped gram-negative rods
- Oxidase + (distinguished from Enterobacteriaceae)
Habitat and Trnasmission: Colon. Fecal-oral transmission Pathogenesis: - Enterotoxin
- stimulates Gs to always be on
- ↑ cAMP and results in massive watery diarrhea
- Mucinase
- enhances attachment to the intestinal
Clinical Features: - Watery diarrhea - no RBC's or WBC's
- no abdominal pain
- Dehydration and electrolyte loss leads to cardiac and renal failure
- Acidosis and hypokalemia
Lab Dx: - Gram negative rods culture
- agglutination confirms
Tx: Fluid and electrolyte replacement Prevention: Public health measures
|
|
|
Term
|
Definition
Disease: Food poisoning Characteristics: Aerobic gram + spore forming Habitat and Transmission: Habitat is grains like rice. Spores survie heating. Pathogenesis - Enterotoxin
- acts like cholera toxin
- other acts like antigen (i.e. like staph enterotoxin)
Clinical Features: - short incubation
- Long incubation
- 18 hrs
- water, nonbloody diarrhea (like clostridial gastroenteritis)
Lab Dx: Not done Tx: Sx tx only Prevention: No vaccine
|
|
|
Term
Salmonella enteritidis (Salmonella enterica) |
|
Definition
Disease: Enterocolitis. Sepsis with metastatic abscesses sometimes. Characteristics: - Facultative gram negative rods.
- Lactose Negative
- Motile (unlike Shigella)
Habitat and Transmission: enteric tract of humans and animals (Turtles). Fecal-oral transmission. Pathogenesis: - Invades mucosa
- requires 105 organisms for infection.
- inactivated by stomach acid
- Risk factors: low acid in stomach (PPI's), sickle cell anemia risk for osteomyelitis
Clinical Features: - 12-48 hr incubation
- Nausea and vomiting, abdominal pain and diarhea
- sef-limited
Lab Dx: - Gram stain and culture.
- Lactose Negative
Tx:Fluid and electrolytes Prevention: public health measures |
|
|
Term
Salmonella typhi or Salmonella paratyphi |
|
Definition
Disease: Typhoid fever Characteristics: - Facultative gram-negative rods.
- Lactose Negative
- H2S +
Habitat and Transmission: Human colon only. Fecal-oral transmission. Pathogenesis: - Infects retculoendothelial system (spleen and liver)
- chronic carrier in gallbladder
- Risks: low stomach acid
Clinical Features: - Slow onset fever and constipation
- 1st wk - high fever, delirium, tender abdomen, splenomegaly, Rose spots,
- Leukopenia and anemia, abnormal LFT's
Lab Dx: - Gram stain and culture
- Lactose Negative
Tx: ceftriaxone Prevention: Public health measures |
|
|
Term
Shigella (S. dysenteriae, S. sonnei) |
|
Definition
Disease: Enterocolitis (dysentery) Characteristics: - Facultative gram negative rods
- Lactose negative
- Non-motile (contrast to Salmonella)
Habitat and Transmission: Human colon only. No animal carriers. Fecal-oral transmission. Pathogenesis: - Invades the mucosa but not all the way through
- Low ID50
- Resistant to stomach acid
- At risk: Children and mental institutions
Clinical Features: - 1-4 day incubation
- fever, cramps, diarrhea (bloody)
- 2 Factors
- Species
- S. dysenteriae is most virulent
- S. sonnei most common in U.S.
- Age
- Children and elderly at increased risk
Lab Dx: - Gram stain and culture
- Lactose Negative
- No gas or H2S
Tx: Fluid and electrolytes Prevention: Public health measures |
|
|
Term
|
Definition
Disease: Enterocolitis Characteristics: - Comma-shaped gram negative rods
- Mecroaerophilic
- Grows well at 42°C
Pathogenesis: - Invades mucosa of colon - no penetration
- No enterotoxin
Clinical Features: - Watery, foul-smelling diarrhea followed by bloody stools with fever and severe abdominal pain
- Guillain-Barré syndrome association
- Cross rxn b/w Ab's for C. jejuni and neurons
Lab Dx: - Gram stain and culture
- grows at 42°C
Tx: Symptomatic tx only. Erythromycin for severe cases Prevention: Public health measures |
|
|
