1. Cytotoxin

2. A-B toxins

3.Superantigens

enzymatically attack cell contituents. lead to cell death/lysis.

Act on animal cytoplasmic membrane

aka- Hemolysins- lyse red blood cells in lab, create zone of clearing

2 covalently bound subunits

-B component binds to cell surface receptor

-Allows A to be transferred across membrane

B binds host cell receptor

A cleaved and enters cell

Shuts down protein synthesis

An A-B Toxin: Clostridium tetani-- sil born organism, normal soil organism

grows in deep puncture wounds, anaerobic enviornments, transported through motor neurons back to spinal cord, binds to ganglioside lipids on inhibitory motor neurons, prevents release of inhibitory signal, muscle stays contracted

gram +

anaerobic

spore-forming rod

toxoid vaccine effective at preventing disease

An A-B Toxin: Vibrio Cholerae.

B-subunit binds to epithelial lining of small intestine, A-subunit activates adenylate cylase-cAMP produced from ATP

1. Normal movement, Na from lumen to blood, no net Cl movement

2.Colonization and toxin production, activation of epithelial adenly cylclase cholera toxin

3.Na movement blocked, net Cl movement to lumen

4.Massive water movement to the lumen

Gram -, LPS is called the endotoxin.

causes host cells to release endogenous pyrogens--cause fever, decrease in lymphocyte, leukocyte, and platelet number, cause hemorrhagic shock and tissue necrosis. Lipid A portion toxic, polysaccharide portion makes it water soluable and immunogenic, both nec. to cause toxic effects in vivo. Very small amts of LPS will cause rxn in pple

causes strep throat, can cause ear stuff, swollen mammary glands and impetigo, scarlet fever (cause by strain containing a lysogenic phage that codes for pyrogenic toxins)

Other strep syndrome: Nectrotizing Faciitis, Rheumatic Fever, Glomerulonephritis

caused by Cornybacterium diphtheriae

disease: resp. tract, form pseudomembranes of mucous that interfere with breathing and can lead to suffocation.

Pathology: mediated by secreted exotoxin which interferes with protein synthesis

causes Diphtheria

gram + rod or club shape

lysogenized by bacteriophage b, which encodes the toxin

cells lodge in throat, produce toxin that leads to pseudomemrane formation

causes whooping cough

gram - bacillus

adheres to cells of resp. tract

produces exotoxin which induces cAMP production

caused by Mycobacterium tuberculosis

spread easy, acquired by inhalation

leading cause of death from an infectious agent

90 percent of those infected mount effective CD4+ T cell mediated response in the lung containing the bacteria in a granulomatous tubercle

TB GRANULA FORMATION- chronic activation of CD4 T cells---accumulation of macrophages, formation of a granuloma, tissue necrosis, tubercles seens as rings of marcophages with caseous in middle

causes leprosy, cannot be grown in culture so experimented on armadillos. Transm. by direct contact and resp. routes, incubation time weeks to decades, grows within macrophages

less serious: tuberculoid

most serious: lepromatous

gram -

transmitted to host through air, attaches to cells in nose cause upper resp. tract. infection

can lead to bacterial meningitis--inflammation of meninges (lining around brain and spinal cord)

highly cont. virus

resp. transmission, with viral replication in nasopharynx and lymph nodes

highly cont. viral illness, spread by droplets of saliva or mucous from the mouth, nose, or throat of an infected person

swelling of salivatory glands, inflammation of testes, ovaries, breasts, deafness

LIVE ATTENUATED VIRUS introduced in 1967

virus caused by rubella virus

spread by airborne droplets derived from upper resp. tract of an active case, fever and rash, major complication is congential rubella syndrome (moms have it and affects uterus)

live attenuated vaccine introduced in 1969

enveloped single stranded RNA virus

orthomyxoviridae family

negative sense segmented genome codes for 11 proteins

Subtype of type A:

-Hemagglutinin (H)

-Neuraminidae (N)

gram + cocci

resistent to drying

disperse in dust and surfaces

common pathogens of humans esp wounds

contact with asymptomatic carrier

causes variety of disease

SUPPURATIVE infection---produce PUS

Coaulase- causes fibrin to accumulate around bacterial cells making it difficult for immune system to get to them

many strains are antibiotic resistant

gram -

pathogen associated with gastritis, ulcers, and gastric cancer

colonizes the non-acid secreting mucous of stomach and upper gi

80 percent of ulcer patients have this bacterial infection

Rickettsia- small bacteria, intracellular parasites in vertebate

assoc. with blood sucking arthropods-fleas, lice, tiks

closely related to mitochondria

3 groups: typhus hroup, spotted fever group, ehrlichiosis group

typhus- human to human by common louse

infection occurs when puncture from louse bite contaminated with louse feces

fever, headache, weakness, rash, damage to CNS, lungs, kidney, heart.

mortality rate of 6-30 percent

Borrelia Burgdorferi---spirochete spread by bite of deer tick

headache, backache, fever, chills

75 percent of cases develop erythema migrans at site of tick bite

bulls eye rash

untreated can progress to chromic stage

arthritis, neuro involvement

diagnosis difficult

member of flavivirus group

-symmetrical, enveloped icosahedral capsid

-positive, ssRNA genome

spread by mossy, primarily disease of birds

caused by Yersinia Pestis

gram -

aerobic rod

rodents

fleas

lymph nodes--causes swollen areas called buboes--bubonic plague

capsule prevents phagocytosis

eventually enter bloodstream causing septicemia

multiple hemorrages under skin---black splotches===black death in 3-5 days

Pneumonic plague occurs when cells are inhaled directly into lungs--2 days then dead, highly contagious

Septicemic plaque when bacteria rapidly spread through bloodstream, death occurs quickly

rare disease

caused by rabies virus, member of Rhabdovirus family

Negative-sense ssRNA

virus infects CNS, present in saliva of infected animal

enters body by bite wound

proliferates in brain

death by respiratory paralysis

member of bunyaviridae family

enveloped negative-sense ssRNA virus

fever and pulmonary capillary leakage

reduced exposure by elimanating rodents

Survives in stomach

Attaches to human gastric epithelium (extracellular)

Produces Urease: breaks down urea to ammonia, protecting bacteria from highly acidic enviornment (adaptation to life in GI tract)

VacA--> vacuolating cytotoxin causes vacuoles and pore formation-->apoptosis

Cag---> cytotoxin associated gene, codes for protein that is secreted into host cell, messes with host proteins

Bab/Sab--->?

Endoscopic methods: histology, rapid urease test, culture

Non-invasive methods: stool test, urea breath test, serology

Urease breath test: radioactive isotope found in exhaled breath if broken down by urease, indicates H pylori in stomach

H pylori infection makes stomach cancer 2-10 times more likely

Stomach cancer occurs as a result of inflammation, cell death, p27 decrease

-reactive oxygen species, cytokines, DNA damage

Hpylori-->apoptosis--->compensatory cell proliferation--->cancer

p27 is tumor suppressor (acts by inhibiting cell cyle progression), h pylori decreases p27, cell cycle less regulated--> cancer

How do host factors influence whether H pylori cause disease?

Host factors determine pathology (cancer vs ulcers, or no symptoms)

-every immune system responds diff. to infect.

-certain genes predispose host toward certain symptoms

-different strains of h pylori can cause different pathology

mostly asymptomatic, can cause superficila gastritis, atrophic gastritis (carcinoma), peptic ulcers, and lymphoma

H pylori is a class I carcinogen, directly implicated in 70 percent of stomach cancer cases

1. Nematodes: Roundworms

2. Cestodes: Tapeworms

3. Trematodes: Flukes

both 2 and 3 are flatworms

The pork tapeworm (cestode)

adult worms aquired from eating undercooked pork containing cysticeri (larvael form), adult attaches to intestinal mucosa using scolex (four suckers and hooks)

worm may grow 6 meters and contain many proglottids

hundreds of thousands of eggs released from proglottids and excreted in feces where they contaminate enviornment and may be ingested by pig and pple

adult worms cause few symptoms, but serious disease results from ingestion of eggs

larval form called cysticeri get deposited in brain, muscle, form little holes

causes schistosomiasis-->liver and bladder disease

aquired by contact with contaminated water

snail is intermediate host, cercaria form penetrates skin (while host is in water), migrates throughout body

prefered route: intestine to feces

washback route: like to elave through feces but sometimes get washed back to liver, causes pathology

liver inflammation and worms clogging liver blood vessels cause gigantic swollen vessels; granulomas form around eggs

intestinal nematodes: anemia, malnutrition, enteritis, colitis, intestinal obstruction

intestinal/tissue: inflammation muscle, intestine, tissue migration may damage heart, muscle, cns, eye

tissue: lymphedema, disfigurement, loss of mobility, blindness, skin disease

larvae infect human, grows into adult, lay eggs, eggs leave through feces, grow into larvae in enviornment, can infect next person

adult hookworms attach to small int. villi, suck up blood cells and tissue

cause anemia, intestinal malabsorption, growth delay, cognitive deficits

migrating dog and cat larvae cannot grow into adults in humans, instead they migrate around skin causing "creeping eruption" known as lara migrans

Food poisoning: caused by eating foods with preformed toxins

Food infection: caused by eating food with pathogen

indicators of fecal contamination of water

live in intestinal tract

presence of coliforms indicates fecal contamination of water and suggests water is unsafe for human consumption

protozoan cryptosporidium parvum

small, coccidia invade and grow intracellularly in mucosal epithelium of stomach and intestine

produces thickwalled oocysts--resistant to chlorine. water must be filtered

consumption of fecally contaminated water.

responsible for largest waterborne outbreak in us

caused by Legionella Pneumophila

found in large number of cooling towers and evaporative condensers of large air conditioning systems

found in hot water tanks and spas

resistant to heating and chlorination

infection occurs by breathing airborne droplets

intracellular parasite--invades and grows in alveolar marcophages and monocytes

can be asymptomatic or cause mild cough

Salmonella typhi

humans are only hosts

infection via ingestion of contaminated food or water

contaminated with feces from asymptomatic carrier

bacteria in blood phagocytized, not killed by marcophages

Entamoeba hystolytica

contaminated water

anaerobic amoeba-lack mitrocondria

produces cysts

S. Aureus common cause food poisoning.

produces several heat stable toxins

causes nausua, vomiting, diarrhea with 1-6 hours of ingestion

foods kept at rm temp

toxin is heat stable- reheating foods does not inactivate it

can be serve

clears up within 48 hrs

antibiotics don't help--caused be preformed toxin

Clostridium perfringens and clostridium botulinum

both gram + spore formers

canning and cooking won't destroy the spores

under anaerobic conditions the spores will germinate

Clostridium perfringens: found in soil and gi tract, sewage

most common cause of food poisoning in us

found in cooekd and uncooked animal meatonce ingested, organism sporulates in intestine and triggers enterotoxin production which alters permeability of intestinal epithelium

begins 7-15 hours after eating, resolves within 24 hrs

Clostridium botulinum: severe, often fatal, consuming botulinum toxin, inhabits soil or water, spores may contaiminate raw foods before harvest or slaughter

causes flaccid paralysis, destroyed by high heat

rare

food infection caused by salmonella

inhabits animal gi tract

ALL SALMONELLA SPECIES ARE PATHOGENIC TO HUMANS

8-48 hr after infection

if enters blood, causes typhoid fever

200 known pathogenic e coli strains--can cause fatal diarrheal disease and UTI

EHEC: causes hemorrhagic diahea and kidney failure

E Coli 0157:H7 causes 60,000 infections and 50 deaths per year

Irradiation of ground beef was approved specifically to prevent infection by this strain

Pathogenic e coli form pedestals

pedestal formation assoc. with attaching and effacing (AE) lesions in epithelial cells

1. Quick deaths, outbreaks self contained

2. Efficient killing, limits its effectiveness

3. Sign that humans are not the natural host

Pathlogical route of Schistosomiasis

3 types

S mansoni, S japonicum: Those cause liver pathology

Hematobium--bladder. UTI kind of thing