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A gram positive, spore forming, obligate anaerobic bacilli has 4 subtypes. What are their mechanisms of action.
- Cloustridium
- 1. C. tetani- tetanospasmin blocks glycine and GABA from Renshaw cells in the spinal cord.
2. C. botulinum- preformed heat labile toxin that inhibits release of Ach at neurotransmitters.
3. C. perfringens - alpha toxin(lectihinase) that causes myonecrosis and hemolysis
4. C. difficile- Toxin A(enterotoxin) binds brush border and toxin B(cytotoxin) destroys cytoskeletal structure of enterocytes -> pseudomembranous colitis.
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What is the difference between primary and secondary tuberculosis caused by mycobacterium tuberculosis?
- PRIMARY:
- occurs in nonimmune host like a child
- forms Ghon complex at base of the lung
- SECONDARY (reactivation):
- occurs in partially immune hypersensitized host like an adult.
- Forms fibrocaseous cavity lesions in upper lobe usually
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What bacterias are rods that form white colonies on MacConkay and are oxidase(-)?
- These are lactose nonfermentors gram negative rods:
- Shigella
- Salmonella
- Proteus
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What is the difference between the subtypes of the gram-negative cocci that ferments glucose and produces IgA protesases?
Neisseria
- 1. Gonococci:
- No polysaccharide capsule
- No maltose fermentation
- no vaccine
- Sexually transmitted
- -> gonorrhea, septic arthritis, neonatal conjunctivitis, PID and Fitz-Hugh-Curtis syndrome.
- 2. Meningococci:
- Via respiratory and oral secretions
- -> meningococcemia and meningitis, Waterhouse-Friderichsen sydrome.
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What is the similarity between the bacteria that produces shiga-like toxin and Hemolytic-uremic syndrome and the bacteria that causes lobar pneumonia in alocholics and diabetics?
- EHEC and Klebsiella
- Both are gram negative rods that ferment lacotse on MacConkay fast.
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What gram negative rod produces weil's disease.
Leptospira interogans (found in water contaminated with rodent urine)
Weil's = severe form with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage and anemia.
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What causes the following and how do you treat it?
Stage 1: erythema chronicum migrans(bull's sys red rash) and flulike symptoms.
Stage 2: Bells palsy and AV nodal block
Stage 3: Chronic monoarthritis and migratory polyarthritis, also
Lyme Disease: Borrelia burgdorferi transmitted by Ixodes tick.
Treatment = Doxycycline(early) and ceftriaxone (late)
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What is the organism that can cause bacillary angiomatosis in immunocompromised patient's?
Bartonella = cat scratch fever
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What disease is caused by the organism that is negative for producing antibodies that cross react to Proteus O antigens and agglutinates?
- This reaction is the Weil-Felix reaction of Rickettsial infections.
- Coxciella burnetti is the rickettsial that tests negative.
- C. burnetti leads to Q fever. (No rash no vector)
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What is special about the bacteria that causes atypical pneumonia, is grown on Eaton's agar, and produces high titer of cold agglutinins; which can agglutinate or lyse RBC's?
- This is mycoplasma pneumoniae
- No cell wall
- cholesterol containing membrane
TX: tetracycline or erythromycin
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What is important about the dimorphicity of the fungi that causes pneumonia and meningitis: and disseminates to bone and skin. It is found in California.
This is coccidioidomycosis which is a spherule in tissue.
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What organism is this?
mold with irregular nonseptate hyphae branching at wide angles. Proliferates in blood vessels , penetrate cribiform plate, -> frontal lobe abscesses, headache, facial pain, and black necrotic eschar on face.
Mucor and Rhizopus spp.
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What is the treatment for the dimorphic fungi that lives on vegetation and causes ascending lymphangitis?
- This is sporothrichosis.
- Treatment = itraconazole or potassium iodide.
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An neonate presents with chorioretinitis, hydrocephalus, and intracranial calcifications. What should the mother have been treated with.
- This is toxoplasmosis- the cat crap disease
- Treatment: sulfadiazine & pyrimethamine
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What is the treatment for the protozoa that causes hemolytic anemia and fever? It is transmitted by Ixodes tick
DX: blood smear- no RBC pigment and appear as Maltese cross.
- This is Babesia
- TX: Quinine, clindamycin
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Helminth that contamintes eggs -> granulomas (retinal blindness) and visceral larva migrans. TX: Diethylcarbamazine
Toxocara canis
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Undercooked fish -> causes inflammation of the biliary tract -> pigmented gallstones. Also associated with cholangicarcinoma.
What other Trematodes are treated with the same drug?
This is Clonorchis sinensis and it is treated with Praiquantel.
- Other trematodes are Schistosoma
- and Paragonimus westermani
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What are the live attenuated vaccines and which one can be given to HIV(+) patients?
Smallpox, yellow fever, chickenpox(VZV), Sabin's polio virus(orally), and MMR
MMR is the only live attenuated vaccine that can be given to HIV patients
No booster needed.
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Organism is transmitted by parental, sexual, and maternal-fetal routes. Predisposes individual to chronic hepatitis, cirrhosis, or hepatocellular carcinoma. What is this organism?
HBV or DNA hepadnavirus (enveloped dsDNA partial circular virus)
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A patient's serum contains the following:
HBsAg (-)
Anti-HBsAb (+)
HBeAg (-)
Anti-HBeAb (+)
Anti-HBcAb (IgG)
What is this patient's status?
This patient has an HBV infection but is now in recovery.
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Mutation to what receptor makes a person immune to HIV infection?
CCR5 (macrophages)
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What infections is a patient with HIV at risk for with a CD4 count of <200?
Reactivation of HSV, cryptosporidiosis, Isospora, disseminated coccidioidomycosis, and pneumocystis pnemuonia.
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What is the normal flora dominant in the oropharnyx?
viridans group streptococci
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What are the most common causes of pneumonia in children from 4wks -18 yoa?
- RSV
- Mycoplasma
- Chlamydia pneumoniae
- Strep pneumo
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