Lecture 4 Part 3: Vibrio, Campylobacter, & Helicobacter Flashcards
What does Vibrio cholerae cause?
Vibrio cholerae is responsible for cholera outbreaks
Is Vibrio cholerae commensal?
Vibrio cholerae is NEVER commensal
What is required for V. cholerae to cause significant disease?
A large number of organisms must be ingested
Where is V. cholerae primarily found and what does it require for growth
V. cholerae is primarily found in water and requires NaCl (salt) for growth
Describe the shape and Gram stain of Vibrio bacteria
Vibrio bacteria are Gram-negative curved rods with polar flagella
Are Vibrio bacteria oxidase-positive or oxidase-negative?
A: Vibrio bacteria are oxidase-negative
What type of metabolism do Vibrio bacteria have?
Vibrio bacteria are facultative anaerobes
Name three medically relevant species of Vibrio?
- Vibrio cholerae
- Vibrio parahaemolyticus
- Vibrio vulnificus
What is the exotoxin associated with Vibrio cholerae?
The exotoxin is cholera toxin, which is carried on a bacteriophage (CTXΦ) that binds to Vibrio cholerae sex pili (toxin co-regulated pili – TCP)
How is cholera toxin genetic material integrated into the Vibrio cholerae genome?
The genetic material for cholera toxin is integrated into the Vibrio cholerae genome
What are the other pathogenicity genes associated with Vibrio cholerae? (hint; there is 3 of them)
ace genes – accessory cholera enterotoxin
zot genes – zonula occludens toxin
cep gene – chemotaxis proteins
Name the three virulence factors for vibro
- endotoxin
- cholera toxin
3, other pathogenicity genes
What type of toxin is cholera toxin?
exotoxin
What effect does cholera toxin have on cAMP levels in host cells
Cholera toxin causes an overproduction of cAMP
What is the mechanism of action of cholera toxin?
Cholera toxin is an exotoxin that overproduces cAMP and modifys the host’s adenylate cyclase
Which Vibrio cholerae strain has caused seven major pandemics?
The VO1 El Tor serotype is responsible for seven major pandemics
is endemic in Africa and Latin America
What new ability did the VO139 Bengal strain acquire?
The ability to produce a capsule
How was the mutation in the VO139 Bengal strain traced?
It was traced to the insertion of a new sequence into the O1 gene created new virulent strain.
Does previous exposure to VO1 strains provide immunity against the VO139 Bengal strain?
No, previous exposure to VO1 strains does not provide immunity against the VO139 Bengal strain
What are the four Campylobacter species associated with human disease?
- C. jejuni
- C. coli
- C. fetus
- C. upsaliensis
What is the shape and Gram reaction of Campylobacter?
Thin, curved, Gram-negative rods
What feature gives Campylobacter its motility?
Polar flagellum
What type of oxygen conditions does Campylobacter require?
Microaerobic (requires low oxygen conditions)
What are the primary diseases caused by Campylobacter?
Gastroenteritis and septicemia (mainly C. fetus)
True or False
Campylobacter infections are LESS common than Salmonella and Shigella.
False – Campylobacter infections are MORE common
What is the primary mode of transmission for Campylobacter?
Zoonotic – transmitted from animal reservoirs
What is the exotoxin produced by Campylobacter?
Cytolethal-distending toxin (CDT)
What bacterial components contribute to Campylobacter virulence?
LOS (lipooligosaccharide) and LPS (lipopolysaccharide)
What part of the gastrointestinal tract does C. jejuni affect?
Ulcerates the mucosal surface of the jejunum, ileum, and colon
What virulence factor does C. fetus have, and what is its function?
S protein – heat stable, blocks C3b binding, increases risk for systemic infections
Name 2 primary gastrointestinal infections caused by Campylobacter?
- Acute enteritis
- colitis
What autoimmune disorder is associated with C. jejuni and C. upsaliensis?
Guillain-Barré syndrome – an autoimmune disorder of the PNS leading to progressive, transient muscle weakness
How does Campylobacter contribute to Guillain-Barré syndrome?
antibodies against pathogen attack peripheral nerve tissue
What are the extraintestinal complications of Campylobacter infections?
Reactive arthritis and meningoencephalitis
What are the two major groups of Helicobacter?
Gastric and Enterohepatic
Which Helicobacter species is associated with gastric diseases?
H. pylori
Which Helicobacter species belong to the enterohepatic group?
H. cinaedi and H. fennelliae
What is the shape and Gram classification of Helicobacter pylori?
Curved or spiral, Gram-negative rods (mature coccoid form)
What enzyme is produced in high levels by gastric forms of Helicobacter pylori?
Urease is produced in high levels by gastric forms of Helicobacter pylori
What type of motility does Helicobacter pylori exhibit?
Helicobacter pylori are highly motile with polar flagella
What are the oxidase and catalase characteristics of Helicobacter pylori?
Helicobacter pylori are Oxidase(+) and Catalase(+)
Does Helicobacter pylori ferment or oxidize carbohydrates?
Helicobacter pylori do not ferment or oxidize carbohydrates
Where does Helicobacter pylori often establish chronic colonization?
Helicobacter pylori often establish chronic colonization of the stomach
What is the primary reservoir for H. pylori?
humans
What role does the bacterial acid-inhibitory protein play in Helicobacter pylori colonization?
clarifyyyy
The bacterial acid-inhibitory protein helps Helicobacter pylori survive in the acidic environment of the stomach by inhibiting acid production.
What virulence factor helps H. pylori neutralize stomach acid?
Urease activity, which converts urea into ammonia to neutralize acid
What is the role of adhesins in Helicobacter pylori infection?
Adhesins bind to the gastric epithelium
more info: so it can colonize and persist in stomach
What toxin does H. pylori produce and what does it do?
Vacuolating cytotoxin A (VacA)a toxin that primarily causes the formation of vacuoles within host cells, leading to cell damage and apoptosis
What is the function of cagA in H. pylori virulence?
It is a cytotoxin-associated gene delivered by the Type IV secretion system
more info: acts as a key virulence factor by being injected into host gastric epithelial cells, where it disrupts normal cell signaling pathways, leading to chronic inflammation and significantly increasing the risk of gastric cancer
What diseases can Helicobacter pylori cause in the stomach?
in other words Name the 4 dieases associated with Gastric helicobacter (H. pylori)
- Gastritis (acute and chronic)
- development of ulcers
- chronic infection- tissue replaced with fibrotic
growth (risk for cancer) - MALT lymphoma (stomach cancer)
What is the risk associated with chronic H. pylori infection?
Chronic H. pylori infection can lead to tissue damage, fibrosis, and an increased risk of cancer
Which Helicobacter species are associated with gastroenteritis and bacteremia?
Helicobacter cinaedi and Helicobacter fennelliae are associated with gastroenteritis and bacteremia
What type of cancer is associated with H. pylori infection?
MALT lymphoma
mucosa-associated lymphoid tissue (MALT)
