Diseases of the Digestive System & STDs - Ch.25 & 26

Streptococcus mutans

(a-hemolytic) primary agent in dental caries

• metabolizes sugar & tolerates acidity → biofilm & plaque formation

Rotaviruses (dsRNA virus)

gram-negative, highly infectious; can cause lethal dehydration

Norovirus: cruise ship outbreak

Invasive

type that invade cells of epithelial mucosa

Shigella dysenteriaee: enterotoxin producer

E.coli (EIEC)(enteroinvasive): shiga toxin via phage

Salmonella enterica: non-toxin producer

Non-invasive

types that remaining outside epithelial cells

E.coli (O157:H7)

• O157 = LPS serotype

• H7 = flagella serotype; produce shiga toxin

Shiga Toxin

blocks protein synthesis causing cell death

causes capillary damage, loss of blood

Staphylococcus aueues

secretes enterotoxins into prepared food

• food poisoning, ingest the enterotoxins not the pathogen

Giardia lamblia

cyst dissolved by acid pH; trophozoite attaches to intestine wall

contaminated drinking water

Treating GI tract infections

rehydration therapy (electrolytes/water)

Syphilis

caused by the spirochete Treponema pallidum

• Primary syphilis: chancre, painless if untreated → enters primary latent stage

• Secondary syphilis: generalized rash

• Tertiary syphilis: after several years; effects on heart and CNS

• Congenital syphilis: pregnant mother → fetus; congenital defects

Sexually Transmitted Disease (STDs)

require direct physical contact w/ mucous membranes for transmission