Unit 5 Pathogens

Agrobacterium Tumefaciens

• plant pathogen

• T-DNA from Ti plasmid transferred via conjugation

• cause crown gall tumors

zenobacteria

• entirely lab grown

• used to breakdown pesticides, herbicides, and fungicides

Norovirus

• RNA+ virus, very low dosage required

• self-limiting, but very contagious

• passed from infected service workers

• “stomach bug”

salmonella

• Gm-, facultative

• grows inside phagocytes- make endo,exo, and enterotoxins

• shed for multiple weeks, long term carriers

Clostridium perfringens

• Gm +, strict anaerobe, sporulates

• targets small intestine (diarrhea and cramps)

Camplyobacteria

• Gm-, spiral shape, microaerophile

• poultry

• self-limiting

• more susceptible if you’re taking an antacids or if you’re eating a lot of food

staphylococcus aureus

• Gm+ cocci

• heat stable enterotoxin, “superantigen”

• inflammation, nausea, vomiting, diarrhea

Food Poisoning

Ingestion of food with a toxin, the toxin is the cause of the symptoms not the pathogen itself (the pathogen is typically dead).

typically self-limiting

aka “food intoxication”

Food infection

food carries the pathogen, the pathogen grows in the host, causes disease.

May or may not be self limiting (long lasting or severe cases), treat with antibiotics

Clostridium botulinum

• spore former, causes paralysis

• high mortality if not treated quickly (treatment = ventilation and antitoxin)

• Food poisoning in adults, food infection in infants

  • Due to immature immune systems/microflora

Escherichia coli

• Gm-, facultative

• mostly non-pathogenic, but there are four main pathogenic types

EHEC

• strain of E. coli

• verotoxin

• causes bloody diarrhea, kidney failure, lead to hospitalization

• comes from undercooked ground meat, fruits and veggies w/ feces or contaminated runoff

ETEC

• strain of E. coli

• “travelers diarrhea”

• heat labile

EPEC

• strain of E. coli

• intracellular, attaches to the lining of small intestine

EIEC

• strain of E. coli

• invasive, survives in phagocytes

• watery to bloody diarrhea

• mainly in developing countries

Listeria monocytogenes

• acid, salt, and cold tolerant

• intracellular (phagocytes)

• polymerizes host actin to drive motility

Yersinia enterocolitica

causes foodborne infections due to contaminated meat and dairy

lead to life threatening enteric fever

Bacillus cereus

grows in food that is cooked and left to cool slowly, heat stable toxin

diarrhea and vomiting

shigella spp.

severe foodborne invasive gastroenteritis, shiga toxin

Vibrio spp

vibriosis, gastroenteritis

*also waterborne

Coliforms

• Gm-, aerobic or facultative, non-spore forming, ferment lactose

• E. coli

Vibrio Cholera

• curved rods

• attaches to epithelial cells, release enterotoxin [AB toxin]

• causes severe diarrhea- lead to death from dehydration if untreated

• El tor or classic

• waterborne, also from raw shellfish and veggies

Giardia Intestinalis (lamblia)

• protozoan/ trophozoite

• produce cysts that resists chlorine

• acute gastroenteritis, foul smelling diarrhea, no blood/ mucus

• found in surface waters, beavers and muskrats are common carriers

Cryptosporidium parvum

• produce highly chlorine resistant oocytes and cysts,

• causes mild diarrhea, normally self-limiting (dangerous to at risk populations)

• recreational water infections (caused the largest outbreak in America)

Legionella pneumophila (“legionellosis”)

• aka “the disease of built environments.”

• resistant to heat and chlorine, intracellular (monocytes, macrophages, and amobae)

• asymptomatic to mild Pontiac fever to pneumonia

• transmitted through aerosols; outbreaks via hot tub displays, American Legion Convention (1976)

Mosquito-borne illness

Yellow fever, dengue fever, zika, west nile fever (aka flavivirus), malaria, and plasmodium

standing water is a reservoir for water borne illness