Mizzou Microbiology 3200 Exam 4

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What are general features of Mycobacteria?

Acid-fast rods, slow-growing, waxy mycolic acid cell wall, weakly Gram-positive.

What is the doubling time of M. tuberculosis?

About 24 hours.

What makes Mycobacteria acid-fast?

Mycolic acids in their cell envelope.

What is the reservoir for M. tuberculosis?

Humans.

How is TB transmitted?

Aerosol droplets.

What is a granuloma?

Immune structure that walls off M. tuberculosis.

What is latent TB?

Infection controlled in granulomas without symptoms.

What is primary tuberculosis?

Active disease occurring shortly after initial infection.

What is reactivation TB?

Disease occurring years later due to immune decline.

What is miliary TB?

Disseminated TB throughout body organs.

What tests diagnose TB exposure?

TST (PPD) and IGRA (QuantiFERON).

What stains are used for TB?

Acid-fast stains like Ziehl-Neelsen or Auramine-Rhodamine.

What is the treatment regimen for TB?

RIPE: Rifampin, Isoniazid, Pyrazinamide, Ethambutol.

What species causes leprosy?

Mycobacterium leprae.

What cells does M. leprae infect?

Schwann cells and macrophages.

Two forms of leprosy?

Tuberculoid (TH1, few lesions) and Lepromatous (TH2, many lesions).

How is leprosy transmitted?

Long-term respiratory contact.

U.S. reservoir for leprosy?

Armadillos.

What disease does M. ulcerans cause?

Buruli ulcer.

What toxin does M. ulcerans produce?

Mycolactone.

What are fungi dimorphic forms?

Yeast and mold forms.

Who is most at risk for cryptococcal meningitis?

AIDS patients.

What is Candida albicans' virulent form?

Hyphae at 37°C.

Where is Histoplasma endemic?

Ohio & Mississippi River valleys.

What does Histoplasma look like on biopsy?

Intracellular yeasts in macrophages.

What are protozoan cysts?

Infective, environmentally resistant forms.

What are protozoan trophozoites?

Active, metabolizing, replicating forms.

What is the definitive host?

Host where sexual reproduction occurs.

What is the intermediate host?

Host where asexual reproduction occurs.

What disease does Entamoeba histolytica cause?

Amebiasis.

How is E. histolytica transmitted?

Fecal-oral ingestion of cysts.

What lesion is characteristic of amebic colitis?

Flask-shaped ulcers.

What is an amebic liver abscess?

Abscess caused by trophozoites spreading through portal vein.

What organism causes giardiasis?

Giardia duodenalis.

Classic stool description in giardiasis?

Foul-smelling, greasy, floating stools.

What causes balantidiasis?

Balantidium coli.

Reservoir for B. coli?

Pigs.

What organisms are intestinal coccidia?

Cryptosporidium, Cyclospora, Cystoisospora.

Which coccidian is immediately infectious?

Cryptosporidium.

What symptoms do coccidian infections cause?

Watery diarrhea.

What genus causes malaria?

Plasmodium.

Most dangerous malaria species?

P. falciparum.

Vector for malaria?

Anopheles mosquito.

Cause of cyclic malaria fevers?

RBC lysis during erythrocytic cycle.

What causes babesiosis?

Babesia microti.

Vector for babesiosis?

Ixodes tick.

Diagnostic sign of babesiosis?

Maltese cross.

What causes cutaneous leishmaniasis?

Leishmania.

What causes visceral leishmaniasis (kala-azar)?

Leishmania donovani.

Symptoms of visceral leishmaniasis?

Fever, cachexia, hepatosplenomegaly, pancytopenia.

What organism causes RMSF?

Rickettsia rickettsii.

Vector for RMSF?

Dermacentor tick.

Pathogenesis of RMSF?

Endothelial infection → vasculitis.

Rash pattern in RMSF?

Starts on wrists/ankles → spreads to trunk.

Treatment for RMSF?

Doxycycline.

What causes Ehrlichiosis?

Ehrlichia chaffeensis.

Vector for Ehrlichia?

Lone Star tick.

Where does Ehrlichia replicate?

In leukocytes forming morulae.

Treatment for Ehrlichiosis?

Doxycycline.

What causes Cat Scratch Disease?

Bartonella henselae.

Transmission of Bartonella?

Cat scratches, bites, flea feces.

What causes Lyme disease?

Borrelia burgdorferi.

Vector for Lyme disease?

Ixodes tick.

Stage 1 Lyme sign?

Erythema migrans.

Stage 2 Lyme symptoms?

Facial palsy, carditis, migratory pain.

Stage 3 Lyme symptoms?

Chronic arthritis, neuro symptoms.

Diagnosis of Lyme?

ELISA then Western blot.

Treatment for Lyme?

Doxycycline.

What causes relapsing fever?

Borrelia hermsii (tick) or B. recurrentis (louse).

What causes syphilis?

Treponema pallidum.

Primary syphilis sign?

Painless chancre.

Secondary syphilis sign?

Widespread rash, palms/soles.

Tertiary syphilis sign?

Gummas, aortic aneurysm, neurosyphilis.

Diagnostic tests for syphilis?

RPR/VDRL + FTA-ABS.

Treatment for syphilis?

Penicillin.

What causes leptospirosis?

Leptospira interrogans.

Transmission of Leptospira?

Water contaminated with animal urine.

General features of Chlamydia?

Obligate intracellular, Gram-negative coccobacilli, EB/RB cycle.

What is an EB?

Infectious, dormant extracellular form.

What is an RB?

Replicating, metabolically active intracellular form.

How is Chlamydia cultivated?

In cell culture, eggs, or animals.

What diseases do serovars A-C cause?

Trachoma.

What diseases do serovars D-K cause?

NGU, cervicitis, inclusion conjunctivitis.

What diseases do L1-L3 cause?

Lymphogranuloma venereum.

What is trachoma?

Chronic conjunctivitis leading to blindness.

Transmission of trachoma?

Hand-eye contact, contaminated clothing, flies.

What causes inclusion conjunctivitis in newborns?

Chlamydia from infected birth canal.

Most common bacterial STD in the US?

Chlamydia trachomatis.

Complications of untreated chlamydia?

PID, infertility, ectopic pregnancy.

What is LGV?

Invasive chlamydia causing buboes and genital destruction.

What causes psittacosis?

Chlamydophila psittaci.

What causes atypical pneumonia similar to Mycoplasma?

Chlamydophila pneumoniae.

How is Chlamydia diagnosed?

NAAT/PCR.

Treatment for Chlamydia?

Doxycycline or azithromycin.

General features of Mycoplasma?

No cell wall, smallest free-living bacteria, pleomorphic.

Why don't Mycoplasma respond to penicillin?

They lack peptidoglycan.

What disease does Mycoplasma pneumoniae cause?

Walking pneumonia.

Symptoms of Mycoplasma pneumonia?

Persistent dry cough.

Treatment for Mycoplasma pneumonia?

Tetracycline or macrolides.

What is Ureaplasma urealyticum?

Urease-producing Mycoplasma causing NGU and PID.