gram negative curviform

What are the genera of Gram negative enteric pathogens?

Vibrio, Campylobacter, Helicobacter

Characteristics of Vibrio

comma shaped bacteria

monotrichous flagella

in marine environment (global warming aid in growth)

Most halophiles (like salt)

2 chromosomes (very unusual)

Some toxins + capsules

Characteristics and virulence of Vibrio cholera

Diversity of O Ags and H Ags

Cholera toxin: increases cAMP → fluid secretion

• rice water stool

Zonula occludens toxin: loosen tight junctions (of intestinal cells)

• Incr permeability and fluid leakage

Accessory cholera enterotoxin: increase fluid secretion

Pathology of Cholera and treatment/prevention

high I.D. (less on antacids since stomach acid is vital defense)

Cholera toxin: dehydration → muscle, circulatory, and neurological symptoms

Explosive onset

Oral rehydration

Tetracycline (protein synth)

Vaccine: live Attenuated (short and incomplete protection)

• for travelers in endemic areas

Bacteria from eating raw or undercooked shellfish

Vibro parahaemolyticus

What bacteria is from coastal water exposure and causes wound infection, often requiring amputation

Vibrio vulnificus

How to treat Vibrio vulnificus

Combo doxycycline (protein synth.) and cephalosporin

How to diagnose Vibrio bacteria

Curved Gram - rods in stool or wound

Collection must be handled carefully, bacteria can't survive dry or acidic environments

Bacteria culture from stool specimen, use TCBS Agar

Oxidase (+)

PCR

Characteristics of Campylobacter

gull wing rod, can look like short spirals

micro-aerophilic

Monotrichous flagella

common cause of bacterial gastroenteritis

hard to culture, idk virulence factors

Characteristics of Campylobacter jejuni or C. coli Gastroenteritis

poultry and unpasteurized milk

bacteria multiplies in cells of ileum or jejunum

Campy. jejuni toxin: heat labile exterotoxin incr cAMP → fluid secretion

• Not required for disease to occur tho

How to treat C. jejuni?

Rehydration + electrolyte balance therapy

Characteristics of Helicobacter pylori and what it causes

tight spirals

lophotrichous flagella

cause 90% stomach + duodenal ulcers

Associated with stomach cancer

Risk: Type O blood bc bacteria’s LPS can mimic Type O blood Ag (evade detection) and bind to carbohydrate receptors on gastric cells

• possesses LPS, which mimics to blood Ag on gastric cells -→ antigenic mimicry result in immune tolerance

• On the other hand, H. pylori colonize gastric mucosa by utilizing adhesins, which bind Lewis blood group antigen-related carbohydrates expressed on gastric epithelial cells

• (commonly these receptors expressed in type O blood people)

Produce Urease (urea→ ammonia and bicarbonate …helps neutralize stomach acid → spread)