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Western U Microbio Primer


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Enteropathogenic E Coli (EPEC)
- Lactose fermenter
- Forms pedestals with type III secretion system
- Uses bundle forming pili to bind to microvilli which causes defect in cells ability to absorb
- Fever, NVD (non bloody)
- Infantile dz
- Not common in US

Enterohemorrhagic E Coli (EHEC)
- Found in US (O157:H7)
- Produces Shiga (vero) AB toxin that activates 28s rRNA
- Low infectious dose
- Diarrhea to dysentery
- May cause HUS in children
- Abx contraindicated (may cause HUS)
- Sorbitol NON-fermenter

Enteroinvasive E Coli (EIEC)
- Invades mucosa
- Can cause watery diarrhea to dysentery (like Shigella)
- rare in US
- Transfers from one cell to another via actin polymerization
- Need large innoculum

Salmonella Typhi
- GNR, lactose NON-fermenter, motile
- MacConkey, then Salmonella-shigella or hecktoen agar (black-eyed colonies on Heck)
- Invade intestinal M-cells and macrophages to allow for spread
- H2S gas production
- fecal-oral, not common in US
- Rose spots, fever, headache, myalgia, Diarrhea
- Can stay in gallbladder during carrier state

Salmonella Enteriditis
- GNR, lactose NON-fermenter, motile
- MacConkey, then Salmonella-shigella or hecktoen agar (black-eyed colonies on Heck)
- Invade intestinal M-cells and macrophages to allow for spread
- H2S gas production
- Usually Self-limited diarrhea (mild to severe)
- Vaccine available
- Many animal reservoirs

- MacConkey, then Hektoen to diff from salmonella
- Fever, Bacillary dysentery, abdominal cramps
- 4 groups

Yersinia Enterolitica
- GN, pleomorphic rods
- Associated with animals
- Can mimic appendicitis
- Can grow at 4C, contaminant of milk

V. Cholerae and V. Parahemolyticus
- Facultative anaerobic curved rod, oxidase positive
- Classic toxin (AB; B binds to GM1 and A stimulates cAMP)
- Zonula occludens toxins - loosens tight jxns
- Accessory Cholera toxin (increases fluid secretion)
- Associated with shellfish
- High innoculum
- V. Cholera not invasive (rice water diarrhea)
- V. parahemolyticus associated with shellfish and explosive (POW!) watery diarrhea

- GPR, spores, obligate anaerobes
- C. Perfringens has toxin. Can cause enteric infx and gas gangrene. Toxin of type C can cause enteritis necrosis
- C difficile can cause Abx-associated colitis and pseudomembranous colitis
- C botulinum - food poisoning

S aureus food poisoning
Coag, oxidase positive, mannitol fermenter, grows in relatively high salt
- Contaminated meat/dairy
- Heat stable superantigen causing projectile (HaDOOOOken!) vomiting

B Cereus
- GPR, spore former
- Emetic (ST) enterotoxin like S aureus assoc with fly lice
- Diarrheal (LT)enterotoxin like E coli assoc with meat/veggies

Helicobacter pylori
- GNR, curved, motile
- Urease positive
- Test with urease breath test, endoscopy or stool test (immunoassay for Abs)
- Linked to stomach adenocarcinoma and gastric MALTomas

Secondary Peritonitis
- Usually polymicrobial - anaerobes like Bacteroides Fragili and aerobes like Ecoli, Klebs, and Prots
- Assoc with appendicitis and trauma
- Sepsis and Endotoxin-mediated pathology

Tertiary Peritonitis
- Assoc with peritoneal dialysis
- Fever, leucocytosis, bacteria, or fungi from effluent fluid
- Monomicrobial and often due to skin microbes (staph, pseudomonas, Candida)

Lemierre Syndrome
- Oropharyngeal infx spreading to jugular vein, lungs, or other locations
- Usually due to fusobacterium necrophorum or other anaerobes
- Usually in 16- 25 yo

- ds segmented RNA, naked (oh noes!), icosahedral, member of reoviridae
- In US, starts in SW in autumn reaches NE by early spring
- Diarrhea, vomiting, fever, destroys intestinal epithelial cells
- Vaccine available

- +ssRNA, naked, icosahedra, member of picornaviridae
- Initially in GI, then to lymphs, then to CNS
- Lifelong immunity after exposure
- Salk Vaccine

- +ssRNA, naked, icosahedral member of picornaviridae
- Non-specific febrile illness, assoc with septic meningitis
- dsDNA assoc with diarrhea
Hep A
- +ssRNA naked, hepadnavirus
- fecal-oral (large quants released in poo before symptoms)
- Immunity after infx
- Vaccine available
- IgM for acute, IgG during convalescence

Hep B
- partially dsDNA, enveloped, circular DNA
- Uses RT
- Envelope contains HBVsAg
- Incomplete virions also released. Used as decoy. Creates type III hypersensitivity rxn
- Spread via bodily fluids (including sex)
- About 90% resolve, 1% to fulminant hepatitis, and rest have chronic dz
- Predispose to HPCC
- IgM Ab to HBcAg means acute infx
- HBeAg and HBsAg without HBsAb means chronic infx
- Vaccine available
- Resists detergents even tho is enveloped

Hep C
- +ssRNA, enveloped memeber of Hapaci (Flavi) viridae
- Interrupts apoptotic signals in cell, so survives intracellularly
- Often becomes chronic and can lead to cirrhosis and HPCC
- PCR detection of RNA is best

Hep D
- -ssRNA
- Needs coinfection with HBV (uses HBsAg)
- 40% go to fulminant Hep

Hep E
- +ssRNA hepeviridae
- Fatality low except in preggers

Balandtidium Coli
- Ciliary movement
- Dysentery by no extra-intestinal travel
- Relatively large and has kidney-bean shaped nucleus

- Non-motile protozoan
- C Hominis for humans
- Mostly in immunosuppressed
- Water diarrhea
- Acid fast stain to detect
- Appear as blue spheres on mucosa

Isospora Belli
- Non-motile opportunistic protozoan
- Self limited diarrhea in normal peeps
- Severe runs in immunocompromised
- Maybe hemorrhagic colitis in AIDS
- Oocysts in stool to ID. Can also use UV autofluorescence microscopy

T Saginata and Solium
- Humans definitive host, Cattle, pigs are intermediate
- Humans poo out eggs, animals eat, eggs hatch and go into animal muscle, humans eat undercooked meat and cysticercus larvae develop into adults and lay eggs in GIT
- T Solium is bad if humans eat eggs, can develop in muscle, brain, or eye

Echinococcus Ganulosis
- Dog Tapeworm
- Humans can be intermediate host. Develop hydatid cyst in liver, CNS, lungs, etc
- Dogs are normal definitive host and sheep are normal intermediate host
- Treat with Albendazole

Fasciola Hepatic
- Liver fluke
- Adults in hepatic bile duct
- Humans poop eggs out, gets into water, snails eat, it gets out of the snail and onto a water plant, if humans eat THAT, larvae can develop into adults
- Serological test or operculated eggs in stool to ID

Clonorchis Sinensis
- Chinese liver fluke (nah nah nah nah naht naht naht naht nahhh)
- Get by raw/undercooked fish
- Mature in bile duct and release eggs
- Rxn to eggs can cause granuloma

Ascaris Lumbricoides
- Adults can be up to 1 foot long and live in intestine
- Infx through ingested egg (resistant to dessication)
- Once egg hatches in intestine, larva burrow into blood stream, can burrow into lungs, crawl up throat, then get swallowed to the GIT where they develop into adults
- If a lot of them get into lungs, secondary infx is possible (loffler syndrome?)
- If heavy infx, intestines can rupture as adults are quite large

Enterobius Vermicularis
- Mostly asymptomatic, but can cause anal itching (due to female laying eggs out there) and appendicitis
- Eggs are somewhat oval with one somewhat-flattened side

Trichurius Trichiura
- Can stimulate inflammation resulting in rectal prolapse
- Eggs are football shaped with plugs at each end
- Eggs ingested, dev into adults in GIT, eggs released in stool

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