Vibrio Cholerae and Bordetella Pertussis

Vibrio Cholerae

Gram negative rod

Singular polar flagellum (highly motile water born diarrheal disease)

Two main serotypes O1 and O139

Three main strains: Classical, El Tor, Bengal

Inverse relationship between acute virulence and persistence in water

Cholera

Voluminous diarrhea (life threatening), fever, vomiting

Rice water stool because stool is relatively clear and has little particles of “rice” mucus from intestine

Death by dehydration in about 1 or 2 days, treatment is IV fluids

Transmission

Contaminated drinking water

Cholera is endemic in many regions and outbreaks can last weeks

Bacteria infect host, replicate, and return to water

Water purification is key

Could be stopped

Cholera Toxin

True AB toxin (1 A and 5 B proteins)

B binds to GM1 gangliosides

A binds to ribosylates G protein that regulates host adenylate cyclase enzyme (locks adenylate cyclase in active conformation and cause cAMP conc to increase)

Ion channels activated by cAMP open up and chloride and sodium flood cell

Water follows (osmoregulation) comes from blood to lumen

TagA

Virulence factor

Mucinase that degrades mucus and exposes underlying epithelial cells

Rice part of rice water

Mannos Sensitive Type IV pili

Virulence factor

Facilitates adherence

Assembled at base with rotating chamber

More pilin molecules are added pilus extends

Pili retracts by rotation in opposite direction that removes subunits

Drags cell across the surface

Works as a grappling hook

Flagella

Spin backwards slowly to assure good initial contact

Virulence factor

Zonula Occludence Toxin

Breaks down intercellular junctions of host cells

Allows rapid movement of water from blood vessels into lumen of intestines

Virulence factor

Hemaglutanin/protease/musinase

Helps clear mucus but also is important in bacterial release

Essentially cleaves off the host structure to which bacteria bind because binding is so strong

Diarrhea carries released bacteria away

Virulence factor

Darwinian Medicine of Cholera

Classical strain causes most severe disease but cannot persist in water long

El tor is not as severe but can persist in water

In parts of the world with Classical, El Tor was selected for when purification occurred

If treatment is not maintained classical will be selected

Related Vibrio Species

V. Parahaemolyticus and V. Vulnificus

Frequently cause milder diarrheal disease associated with seafood (shellfish)

ID tags were created to tract shipments

Bordetella Pertussis

Gram negative Coccobacillus

Produces LOS

Colonizes respiratory tract and bind to ciliate cells

Causative agent of pertussis

Pertussis

Whooping cough

Severe respiratory infection

Highly infectious R0 (5-6) transmitted through coughing

Cholera of respiratory tract where massive amounts of water efflux into airway

Causes distinctive paroxysmal cough (short coughs followed by inhalation)

Very dangerous in small children

Pertussis Toxin

AB toxin similar to Cholera

B subunit is S2-S5 and binds to carbohydrate moieties on host cell

S1 is A subunit which ribosylates G protein

Activates Adenylate cyclase and increase cAMP and ion movement

Some toxin molecules stay bound to bacterial membrane and function as adhesions

Adherence of Bordetella pertussis

Filamentous hemagglutinin with large, non-fimbrial adhesions that facilitates adherence to ciliary tufts

two distinct forms Fim 2 or Fim3 are main fimbriae subunits

Adherence is much less important

Toxins of B. pertussis

Invasive adenylate cyclase: Bacterial enzyme that enters host cell and produces cAMP

Tracheal cytotoxin: Derivative of peptidoglycan, Secreted by cells to stop ciliary movement

LOS: Lipid A and some have Lipid X

Vaccination

Formally DTP which used cell components (people reacted)

Now TDAP and uses Acellular pertussis with 5 antigens instead of cells (less effective but no reactions)

Little room for nonparticipation due to R0