Enteric Bacterial Infections 4: Campylobacter, Helicobacter, and Listeria Flashcards
What are the cellular characteristics of Campylobacter?
- Comma/S-shaped
- Gram (-) Rods
- Motile
- Oxidase (+)
- Catalase (+)
- Microaerophilic
What is microaerophilia?
Bacterial lifestyle in which bugs need a little bit of oxygen to grow
What is the reservoir of Campylobacter?
Domestic animals (100% of poultry)
What are protective mechanisms against Campylobacter?
Stomach acid
What is the relative infectious dose of Campylobacter?
High due to stomach acid
What is the pathogenesis of Campylobacter jejuni?
- C. gets ingested and attaches to the brushborder
- C. gets endocytosed
- C. resists phagocytosis
- Has T4SS which injects proteins into epithelium and Cytolethal toxin which causes necrosis of the cells
What are Syx of Campylobacter infection?
Initially watery foul-smelling diarrhea follwed by bloody stools with fever and abdominal pain
What is the culture procedure for Campylobacter?
- Stool sample
- Blood agar with ABs to inhibit normal flora
- Two plates - 45C and 25C - Bugs should fail at low temperature
- Microaerophilic - 5% oxygen, 10% CO2
What is the Tx strategy for Campylobacter infection?
- Self-limited - rehydrate
- AB - if child, high fever, blood diarrhea, >8 stools/day, worsening Syx, illness > 1wk, pregnancy, HIV
What is a big no-no for Campylobacter Tx?
DO NOT use antimotility agents
What is different b/w vibrio and campylobacter ubiology?
- Reservoir
- Growth at room T
- Risk of reactive arthritis
What does Campylobacter strongly predispose a person to?
Guillain-Barre syndrome
What are the cellular characteristics of Heliobacter pylori?
- Curved Gram (-) rod
- STRONGLY urease (+)
What diseases are H. pylori associated with?
- PUD
- Mucosa-associatd lymphoid tissue (MALT) lymphomas, gastric lymphoma, adenocarcinoma of the stomach
What is the pathogenesis of H. pylori?
- Transmission unknown
- Bacteria attach to mucus-secreting cells of stomach w/ flagella
- Break down urea into ammonia w/ urease
- Ammonia neutralizes stomach pH, allowing bacterial growth and irritation of stomach lining
What other strategies does H. pylori utilize when infection its host?
- Causes infiltration by proinflamm. cells
- Upregulate caspases = apoptosis
- Vac-A cytotoxin (some strains)
- Cag-A chemotactic factor for neutrophils
Typical Syx of those with H. pylori?
Generally asymptomatic, but can result in gastric bleeding ulcers
What are the tests for H. pylori?
Radiolabeled Urea given to a patient. If H. pylori present, the patient will breathe off Radiolabeled CO2; PCR in the pipeline
Tx of H. pylori?
- Reduce irriation with bismuth salts
- PPIs
- Kill bacteria with triple AB therapies
What are the cellular characteristics of Listeria monocytogenes?
- Gram (+) rod
- Facultatively anaerobic
- Blue-green sheen on non-blood agar
- Forms Ls and Vs on agar
- Tumbling motility
- Beta hemolytic
- Grows well in cold
What is the route of transmission of Listeria?
Infection from environmentally-contaminated food
What are the serious complications of Liseria infection and the typical scenarios?
If immuncompromised, Listeria escapes GI tract, causing complications of pregnancy, meningitis, abscess, endocarditis, etc
Describe the pathogenesis of Listeria in pregnancy
Bacteria escapes GI and proliferates in placenta (especially in the 3rd trimester) resulting in preterm labor, abortion, stillbirth, and intrauterine infection
What does transmission of Listeria across the placenta cause? From the vaginia?
- Transplacental - Early-onset sepsis and premature birth with abscesses/granulomas
- Transvaginal - late-onset meningitis with sepsis
What laboratory tests are used to Dx Listeria?
- Blood culture
- Spinal Tap
Look for motile bacteria with tumbling motility
What area the Tx options for Listeria?
ABs are indicated if CNS manifestations or bacteremia; Ampicillin/Gentamicin combo
How to prevent Listeria?
- Cook food, wash hands, vegetables
- Avoid unpasturized milk
- IF PREGNANT - avoid leftover or read-to-eat mfoods until steaming (including deli meat); No soft cheeses
