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92 Microbiology II p186-p193


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p. 186
Gram-negative cocci
Polysacharide capsule
Neonatal conjunctivitis
Vaccine available
Meningitis w/ septicemia
Waterhouse - Friederichsen syndrome
Septic arthritis
Maltose fermentation
Primary and Secondary TB (figure)
p. 187
What is primary TB?
Reponse to TB infection by a non-immune host, consists of hilar node involvement and Ghon focus
What are possible outcomes of primary TB?
Healing by fibrosis (characterized by hypersensitivity w/ PPD+), progressive lung disease (ass. W/ HIV, malnutrition), severe bacteremia (leading to miliary TB and death), preallergic lymphatic or hematogenous dissemination (leads to dormant tubercle bacilli in several organs and reactivation in adult life)
What is secondary TB?
Response to reinfection by a partially immune hypersensitized host (usu adult) OR reactivation of dormant tubercle bacilli from primary infection -- consists of fibrocaseous cavitary lesion
What organs are commonly effected by extrapulmonary TB?
CNS (parenchymal tuberculoma or meningitis), vertebral body (Pott's disease), lymphadenitis, renal, GI
p. 187
What are common symptoms of TB?
Fever, night sweats, weight loss, hemoptysis
T/F: All mycobacteria are acid-fast
T/F: M. Tuberculosis and M. avium-intracellulare can be resistant to multiple drugs
T/F: M. kansasii is asymptomatic
False: causes pulmonary TB-like symptoms
T/F: M. scrofulaceum commonly causes cervical lymphadenitis in the elderly
False: usually causes cervical lymphadenitis in kids
Leprosy (Hansen's disease)
p. 187
What organism causes leprosy?
Mycobacterium leprae
T/F: M. leprae is an acid-fast bacterium that grows well in vitro
False - M. leprae does not grow in vitro
M. leprae likes ___ temperatures and infects ___ and ___ (tissues)
cool, skin, superficial nerves
What are the two forms of Hansen's disease? Which form is worse?
Lepromatous and tuberculoid, tuberculoid is self-limited, lepromatous is worse (failed cell-mediated immunity) "LEpromatous = LEthal"
What is wrong with armadillos?
Resevoir of leprosy in U.S.
What is treatmet for leprosy and associated toxicities?
Long-term oral dapsone, toxicity = hemolysis and methemoglobinemia. Alternate treatments include rifampin and combination of clofazimine and dapsone.
What is the classic triad of Rickettsial infection?
headache, fever, rash
True/False: Ricketsia are facultative intracellular parasites
False, they are obligate parasites and need CoA and NAD
Most Ricketsia are transmitted by what?
arthropod vector
Why is Coxiella an atypical ricketsia?
It is transmitted by aerosol and causes pneumonia and no rash. Has negative Weil-Felix test.
What is the treatment of choice for rickettsial infection?
Rickettsial diseases and vectors
What bug causes Rocky Mountain spotted fever? What is the vector?
Rickettsia rickettsii, tick vector
What bug causes Endemic typhus? What is the vector?
Rickettsia typhi, flea vector
What bug causes Epidemic typhus? What is the vector?
Rickettsia prowazeckii, human body louse
What bug causes Q fever? What is the vector?
Coxiella burnetii, only rickettsial disease without a vector
Rocky Mountain spotted fever
What three diseases have characteristic palm and sole rash?
Rocky Mountain spotted fever, syphilis, and coxsackievirus A16 (hand, foot, and mouth disease)
How does the rash of Rocky Mountain spotted fever progress?
centripetally, starting on palms and soles, migrating to wrists/ankles, then trunk
What are the symptoms of Rocky Mountain spotted fever? What is the causative agent?
Classic triad of rickettsial disease-headache, fever, rash. Rickettsia rickettsii
Where is Rocky Mountain spotted fever common?
Endemic to EAST coast
Weil-Felix reaction
What does the Weil-Felix reaction assay for?
antirickettsial antibodies using cross reactivity with Proteus antigen.
Which rickettsia test positive with Weil-Felix? Which test negative?
typhus (R. typhi and R. prowazekii) and Rockey Mountain spotted fever (R. rickettsii) are usually positive. Q fever (C. burnetii, the weird one) is usually negative.
Mycoplasma pneumonia
Mycoplasma pneumonia causes what type of infection? Describe the symptoms. Which age group is it most common in?
Classic cause of atypical "walking" pneumonia. Insidious onset, headache, nonproductive cough, diffuse interstitial infiltrate. More common in patients under 30.
How does an X-ray appear in a Mycoplasma infection?
Streaky, much worse than the patient appears.
What is special about the mycoplasma cell wall?
Only bacterial membrane containing cholesteral
What can you test for in the blood of patient with Mycoplasma?
They have high titers of cold agglutinins (IgM)
Why can't you treat Mycoplasma infection with penecillin? What can you use?
Mycoplasma has no cell wall. Use tetracycline or erythromycin
What agar is Mycoplasma grown on?
True/False: Chlamydia is an obligate intracellular parasite.
Chlamydiae infects which type of surface?
How many forms does Chlamydia have? Describe them.
Two: Elementary body, small/dense (Enters cell) and Initial/Reticulate body (Replicates by fusion)
What is unusual about Chlamydia's cell wall?
The peptidoglycan wall lacks muramic acid.
What 4 things does Chlamydia cause?
arthritis, conjunctivitis, pneumonia, and nongonococcal urethritis
How do you diagnose a chlamydial infection? How do you treat it?
cytoplasmic inclusions seen on Giemsa or fluorescent antibody-stained smear. Use erythromycin or tetracyclin
Why is Chlamydia psittaci notable?
Has an avian reservoir
What species of animals do Chlamydia trachomatis and Chlamydia pneumonia infect? What do they cause?
They only infect humans. C. trachomatis causes arthritis. C. pneumonia causes atypical pneumonia; transmitted by aerosol.
Chlamydia trachomatis serotypes
p. 189
What are the serotypes of chlamydia?
A - K, L1 - 3
What do types A, B, C cause?
chronic infection; blindness in Africa (Africa/Blindness/Chronic infection
What do L1 - L3 cause?
L = Lymphogranuloma venereum (acute lymphadenitis - positive Frei test)
What do type D - K cause?
everything else!! --> urethritis/PID, ectopic pregnancy, neonatal pneumonia, or neonatal conjunctivitis
How is neonatal chlamydia aquired?
passage through infected birth canal
How is neonatal chlamydia treated?
erythromycin eye drops
p. 189
Describe the shape of a spirochete.
Spiral shaped bacteria with axial filaments
Name the three major spirochetes.
Borrelia (big size), Leptospira, Treponema (BLT. B is Big)
Which can be identified by light microscopy using aniline dyes (Wright or Giemsa)?
Borrelia (big size)
How is Treponema visualized?
dark-field microscopy
Lyme disease
p. 190
What is the classic symptom of Lyme dz and how is it characterized?
erythema chronicum migricans (an expanding "bull's eye" red rash with central clearing.
What else does Lyme dz affect?
joints, CNS, heart
What are the Sx of Stage 1 Lyme dz?
erythema chronicum migricans, flu-like sx
What are the Sx of Stage 2 Lyme dz?
neurologic and cardiac manifestations
What are the Sx of Stage 3 Lyme dz?
autoimmune migratory polyarthritis
What causes Lyme disease and how is it transmitted?
Borrelia burgdorferi, by the Ixodes tick.
What are important reservoirs?
What animal is required for the life cycle?
How do you treat Lyme disease?
Where in the US is Lyme disease common?
northeast (named after Lyme, Connecticut)
During what time of year is transmission most common?
summer months
Treponemal disease
p. 190
Treponemes are what type of organism?
What causes syphillis?
Treponema pallidum
What causes yaws?
Treponema pertenue
What is yaws?
a tropical infection that is not an STD (although, VDRL test is positive)
What causes syphilis?
Treponema pallidum, a spirochete
What is characteristic of primary syphilis?
A painless chancre (localized disease)
What is characteristic of secondary syphilis?
Constitutional symptoms, maculopapular rash, and condylomata lata.
What is characteristic of end state syphilis?
Gummas, aortitis, neurosyphilis (tabes dorsalis), Argyll Robertson pupil.
What do you treat syphilis with?
Penicillin G
What do VDRL and FTA-ABS test for? Which is better and why?
treponemes (syphilis), FTA-ABS is more specific, turns positive earlier and stays positive longer.
VDRL false posititves
What does VDRL detect? What disease is it used for?
Nonspecific antibody that reacts with beef cardiolipin. Used for diagnosis of syphilis.
What false positives are detected with VDRL?
viral infection (mononucleosis, hepatitis), some drugs, rheumatic fever, rheumatoid arthritis, SLE, and leprosy.
Spores: fungal
p. 191
Most fungal spores are sexual or asexual?
How are coccidioidomycosis and histoplasmosis transmitted?
inhalation of asexual spores
What are asexual spores called?
conidia (e.g. blastoconidia, arthroconidia)
Candida albicans
p. 191
Is c. albicans infection local, systemic, or both?
What is the morphology of c. albicans in culture at 20 deg C?
budding yeast with pseudohyphae
What is the morphology of c. albicans in culture at 37 deg C?
germ tubes
What does "alba" mean?
What disease does c. albicans cause in immunocompromised patients?
thrush in throat (neonates, steroids, diabetes, AIDS)
What disease does c. albicans cause in IV drug users?
What disease does c. albicans cause s/p antibiotic tx?
What disease does c. albicans cause in people who wear diapers (i.e. babies)?
diaper rash
What is the treatment for superficial c. albicans infection?
What is the treatment for serious systemic c. albicans infection?
amphotericin B
Systemic Mycoses
p. 191
Name 4 types of systemic mycoses.
Coccidioidomycosis, Histoplasmosis, Paracoccidioidomycosis, Blastomycosis
Name the Endemic location of Coccidioidomycosis.
Southwestern United States, California.
Why is the disease caused by Coccidioidomycosis called “valley fever?”
Common in the San Joaquin Valley or desert (desert bumps) "valley fever"
Name the Endemic location of Histoplasmosis.
Mississippi and Ohio river valleys.
What is a common form of transmission of Histoplasmosis.?
Bird or bat droppings
Is Histoplasmosis found intracellularly or extracellularly?
Intracellular (frequently seen inside macrophages)
Name the Endemic location of Paracoccidioidomycosis.
Rural Latin America.
What is special about ParacoccidioidomycosisÂ’ appearance?
"Captain's wheel" appearance.
Name the Endemic location of Blastomycosis.
States east of Mississippi River and Central America.
How does Blastomycosis reproduce?
Big, Broad-Based Budding.
What is a dimorphic fungus?
Mold in soil (at lower temperature) and yeast in tissue (at higher/body temperature: 37°C) Cold=Mold; Heat=Yeast
Which of the following are dimorphic: Coccidioidomycosis, Histoplasmosis, Paracoccidioidomycosis, Blastomycosis ?
All except coccidioidomycosis, which is a spherule in tissue.
What is the appropriate treatment for local infection with the systemic mycoses?
Treat with fluconazole or ketoconazole for local infection
What is the appropriate treatment for systemic infection with the systemic mycoses?
Treat with amphotericin B for systemic infection.
What acid fast bacterial disease can the systemic mycoses mimic?
TB (granuloma formation)
What is the appropriate agar to use for culturing of systemic mycoses?
Culture on Sabouraud's agar.
Cutaneous Mycoses
p. 191
What organism causes Tinea versicolor?
Malassezia furfur. Causes hypopigmented skin lesions.
What organism causes Tinea nigra?
Cladosporium werneckii
How do you treat Tinea versicolor?
miconazole, selenium sulfide
What part of the skin is infected by tinea nigra and how does it present?
Infection of keratinized layers of skin. Appears as brownish spots
How do you treat tinea nigra?
sialicylic acid
Concerning Tinea pedis, cruris, corporis, capitis, what does the lesion look like?
Pruritic lesion wit central clearing resembling a ring.
What organisms cause Tinea pedis, cruris, corporis, & capitis?
Dermatophytes: Microsporum, Trichophyton, Epidermophyton
Concerning Tinea pedis, cruris, corporis, capitis, what do you see in a KOH prep?
Mold hyphae, not dimorphic
Concerning Microsporium, what is the reservoir for this organism
How is Microsporum infetction treated?
topical azoles
Opportunistic fungal infections
p. 192
What organism is the cause of thrush in immunocomprornised?
Candida albicans
Other than thrush and vulvovaginitis, what other diseases can Candida albicans cause?
Disseminated candidiasis (to any organ) & chronic mucocutaneous candidiasis
What is the morphology of Candida albicans?
Pseudohyphae + budding yeasts or Germ tubes at 37 degrees C
What pulmonary disease is caused by Aspergillus fumigatus?
lung cavity aspergilloina ("fungus ball"), invasive aspergillosis.
What is the morphology of Aspergillus fumigatus?
Mold with septate hyphae that branch at a V-shaped (45°) angle.
Is Aspergillus fumigatus dimorphic?
What diseases does the yeast Cryptocuccus neoformans cause?
Cryptococcal meningitis, cryptococcosis.
What is the morphology of Cryptocuccus neoformans?
Heavily encapsulated yeast.
Is Cryptocuccus neoformans dimorphic?
What type of budding pattern is seen in Cryptocuccus neoformans?
Narrow-based unequal budding
What natural environment is Cryptocuccus neoformans usually found?
Found in soil, pigeon droppings.
What do you culture Cryptocuccus neoformans on?
Culture on Sabouraud's agar.
What special stain is used for Cryptocuccus neoformans ?
Stains with India ink.
What special test does the capsule of Cryptocuccus neoformans allow you to do?
Latex agglutination test detects polysaccharide capsular antigen
What is the morphology of Mucor?
Mold with irregular nonseptate hyphae branching at wide angles (> 90°).
What immune modifying diseases (2) state is commonly associated with infection with Mucor?
Disease mostly in ketoacidotic diabetic and leukemic patients.
How does infection with Mucor lead to sympotms (pathogensis)?
Fungi proliferate in the walls of blood vessels and cause infarction of distal tissue.
Pneumocystis carinii
p. 192
What disease does Pneumocystis carinii cause?
Causes pneumonia (PCP).
What class of organism is Pneumocystis carinii?
Yeast (originally classified as protozoan)
How is Pneumocystis carinii transmitted to caused disease?
What predisposes to disease with Pneumocystis carinii?
Most infections asymptomatic. Immunosuppression (e.g., AIDS) predisposes to disease.
How do you stain for Pneumocystis carinii?
Silver stain of lung tissue.
How do you treat infection with Pneumocystis carinii?
Treat with TMP-SMX, pentamidine.
With regards to P. carinii, what should you do for an AIDS patient with CD4 below 200 cells/mL to prevent PCP?
Start prophylaxis when CD4 drops below 200 cells/mL in HIV patients.
Sporothrix schenckii
Where is Sporothrix schenckii normally found and how is it transmitted?
Found on vegetation and transmitted by trauma to the skin, typically by a thorn ("rose gardener's" disease)
What are the symptoms of Sporcitrichosis?
Local pustule or ulcer with nodules along draining lymphatics. Little systemic illness.
How do you treat Sporcitrichosis?
Treat with itraconazole or potassium iodide.
Medically important protozoa (from a table)
p. 193
Entamoeba histolytica
p. 193
What disease(s) does it cause?
Rapidly fatal meningoencephalitis
How is it transmitted?
Swimming in fresh water lakes
How is it diagnosed?
Amebas in spinal fluid
How it is treated?
Giardia lamblia
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What are the different species?
P. vivax, P. ovale, P. malariae, P. falciparum
Trichomonas vaginalis
p. 193
Trypanosoma cruzi
p. 193
Trypanosoma gambiense & rhodesiense
p. 193
Leishmania donovani
p. 193
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