140033970 Microbiology USMLE Step 1 High Yield Images

Microbiology Lab Final – TA Review The Helminths I. Nematoda a. Trichinella i. Eating uncooked meat ii. Eating wild game (polar bear) iii. Travel to Mexico + Asia iv. LAB 1. Muscle biopsy – encysts in muscle

v. TX

1. Albendazole b. Ascaris i. Children of tropical/developing countries ii. LAB 1. Stool for eggs

iii. TX Vanisha Patel

1. Albendazole Page 1

c. Strongyloidiasis i. LAB 1. Larvae in stool

ii. TX

1. Ivermectin d. Enterobiasis i. Pinworm ii. LAB 1. Scotch tape test 2. NIH swab

iii. TX 1. Albendazole Vanisha Patel

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II.

Cestoda a. Taenia saginata i. Beef tapeworm

ii. TX

1. Niclosamide 2. Praziquantel b. Taenia solium i. Pork tapeworm ii. Causes Cysticerosis – cysts in brain iii. LAB 1. Swiss cheese appearance – Giant brain lesion

iv. TX

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1. Niclosamide 2. Albendazole + Prednisolone

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III.

IV.

c. Diphyllobothrium latum i. Fish tapeworm ii. Competes w/host for Vit B12 iii. TX 1. Praziquantel d. Echinococcus granulosus i. Dog tapeworm ii. Contaminated w/canine feces iii. LAB 1. Hydatid cyst in tissues iv. TX 1. Albendazole Trematoda a. Schistosomiasis i. Blood flukes ii. Snail host iii. LAB 1. Eggs in stool/urine iv. TX 1. Praziquantel Entamoeba Histolytica a. Liver abscess, bloody diarrhea b. Flask shaped ulcers c. LAB i. Bloody stool – cysts w/4 nuclei

d. TX

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i. Metronidazole

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V.

Giardia Lamblia a. Hiker’s diarrhea b. Bloating flatulence, foul smelling diarrhea c. LAB i. Trophozoite/cyst

d. TX VI.

i. Metronidazole Trichomonas Vaginalis a. Sexually transmitted flagellate b. Pear shaped, 4 anterior flagella c. Corkscrew motility d. Foul smelling greenish, yellow frothy discharge e. TX i. Metronidazole

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Mycoses I. Superficial Mycoses a. ONLY cosmetic problem* b. Pityriasis Versicolor i. Caused by Malassezia Furfur ii. Dry, scaly, hyper/hypopigmented lesions on torso, arms, and abdomen iii. LAB 1. Spaghetti + meatball appearance – KOH prep

iv. TX

II.

1. Selenium Sulfide 2. Topical Miconazole Cutaneous Mycoses a. Dermatophytosis i. Trichophyton – hair, skin, nails

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ii. Microsporum – skin, hair

iii. Epidermophyton – skin, nails

iv. Diseases 1. Tinea capitis – caused by T. tonsurans 2. Tinea barbae – area of alopecia 3. Tinea pedis – caused by T. rubrum 4. Tinea cruris – caused by T. rubrum v. LAB 1. Digested with KOH  see septate hyphae & calcofluor white 2. Wood’s light (UV light) Vanisha Patel

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vi. TX

III.

1. Skin – Ketaconazole, Miconazole, Clotrimazole 2. Hair – Ketoconazole shampoo 3. Nail – Oral Terbinafine/Itraconazole Subcutaneous Mycoses a. Sporotrichosis i. Rose Gardner’s Disease 1. Caused by sporothrix schenkii 2. Dimorphic ii. LAB 1. Tissue biopsy: cigar shaped budding yeast 2. Room temperature: daisy shaped conidia

iii. TX

IV.

1. Oral potassium iodide 2. Systemic – Itraconzaole/Amphotericin B Systemic Mycoses a. Coccidiomycoses i. Cali, Arizona, New Mexico ii. Inhalation of arthroconidia iii. LAB 1. Tissue biopsy: spherules w/endospores 2. Room temperature: branched hyphae w/arthrospores

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iv. TX

1. Fluconazole 2. Amphotericin B 3. Itraconazole b. Histoplasmosis i. Ohio, Mississippi ii. Bat feces, soil contaminated with bird droppings iii. LAB 1. Giemsa/Wright stain 2. Tissue biopsy: Yeast w/in macrophage

3. Room temperature: tuberculated macronida on hyphae

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iv. TX

1. Self limiting 2. Itraconazole/Amphotericin B c. Blastomycosis i. North, Central, Southeast USA ii. Decaying vegetation, soil contaminated w/beaver exreta iii. LAB 1. Tissue biopsy: Broad based budding yeast in KOH

iv. TX

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2. Room temperature: branched hyphae 1. Itraconazole 2. Amphotericin B

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d. Paracoccidiomycosis i. Central + South America ii. LAB 1. Pilot/captain wheel

2. Yeast w/multiple buds

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Opportunistic Mycoses I. Candidiasis a. Caused by C. albicans b. Diseases i. Oral thrush ii. Diaper rash iii. Vaginitis c. LAB i. Culture: smooth, creamy, pasty colonies ii. Gomorri silver methanamine

iii. ELISA iv. Stain: yeast like budding cells w/pseudohyphae

d. TX

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i. ii. iii. iv. v. vi.

Fluconazole Itraconazole Voricanazole Nystatin (oral) Amphotericin B Caspofungin Page 12

II.

Cryptococcosis a. Caused by C. neoformans b. Capsule = halo  ONLY opportunistic fungi w/capsule c. Pigeon droppings d. LAB i. India Ink ii. Budding cells w/halo and prominent capsule

e. TX

III.

i. Amphotericin B ii. Flucytosin iii. Oral fluconazole Aspergillosis a. Diseases i. Invasive aspergillosis ii. Farmer’s lung iii. Bronchopulmonary aspergillosis b. LAB i. Tissue biopsy: dichotomous branching hyphae w/45° septate

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c. TX

IV.

i. Itraconazole ii. Amphotericin B iii. Caspofungin Zygomycosis a. Found in soil, strawberries, moist bread b. Diseases i. Rhinocerebral zygomycosis c. LAB i. KOH w/calcofluor white stain ii. Broad, ribbon like, nonseptate hyphae @ 90°

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d. TX V.

i. Amphotericin B Pneumocystis a. Diseases i. Pneumocystis pneumonia – ground glass appearance b. LAB i. H&E: Alveoli w/foamy honeycomb appearance

ii. iii. iv. v.

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Lung biopsy: cysts-dark oval bodies on silver stain Toluidine blue-Ostain Giemsa stain Calcofluor white

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c. TX

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i. TMP-SMX i. Pentamidine

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Virology I. DNA Viruses a. Breakdown i. Enveloped 1. Double stranded a. Herpes b. Hepadno c. Pox* ii. Naked 1. Double stranded a. Papova b. Adeno 2. Single stranded* a. Parvo* b. Herpes i. Enveloped, Icosahedral ii. Alpha 1. HSV-1 a. Latent in DRG b. Syncitium formation c. Giant cell formation d. Cowdry bodies 2. HSV-2 a. Latent in lumbosacral region b. Diseases i. Herpes Whitlow ii. Herpes Encephalitis iii. Herpes Genitalis iv. Neonatal Herpes c. LAB i. Cowdry Type A inclusion bodies ii. PCR = gold standard method d. TX i. Acyclovir 3. VZV a. Latent in sensory nerve ganglion b. Diseases i. Chicken pox  dew drop rose petal vesicular lesions ii. Herpes Zoster c. LAB i. Tzanck smear – intranuclear inclusion bodies d. TX i. Acyclovir ii. Foscarnet iii. Beta 1. CMV (HHV-5) a. Latent in monocytes, macrophages, lymphocytes* b. Diseases i. Mononucleosis like syndrome – Heterophil Ab NEGATIVE Vanisha Patel

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c. LAB i. Owl’s eye basophilic inclusion bodies d. TX i. Gancyclovir ii. Foscarnet iii. Cidofavir 2. HHV 6 + 7 (Roseola) a. Biphasic iv. Gamma 1. EBV a. Latent in B cells b. Downey cells (atypical T cells) c. LAB i. Monospot test – Heterophile Ab POSITIVE d. Diseases i. Infectious Mononucleosis ii. Burkitt’s lymphoma iii. Hairy oral leukoplakia 2. HHV-8 a. Kaposki sarcoma b. AIDS c. Hepadna i. Enveloped ii. Dane particle* iii. Ground glass appearance* iv. Serology 1. 3 antigens a. HbsAg – ACUTE b. HbcAg – Viral multiplication c. HbeAg – BEWARE (HIGH infectivity) 2. 4 antibodies a. Anti HBs/HbsAb – immunized b. Anti HbcAg-IgM – active infection c. Anti hbcAg-IgG – chronic/post infection d. Anti Hbe – low infectivity d. Pox i. Replicates in cytoplasm* ii. Bullet shaped iii. Enveloped iv. Diseases 1. Smallpox – cytoplasmic inclusion bodies 2. Molluscum contagiosum – pearly freshly colored benign nodule v. TX 1. Prednisone, Methotrexate e. Papova i. Polyoma 1. Naked, circular 2. Latent in kidney 3. Diseases a. BK b. JC  PML Vanisha Patel

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II.

ii. Papilloma 1. HPV 6,11; 16,18; 1,4 2. Diseases a. Plantar/palmar warts – HPV 1,4 b. Condyloma acuminate – HPV 6, 11 c. Cervical intraepithelial neoplasia – HPV 16, 18 i. Koilocytes in PAP smear 3. TX a. Cidofavir f. Adeno i. Naked ii. Spikes iii. Diseases 1. Acute febrile pharyngitis 2. Acute respiratory diseases – military 3. Pharyngocojunctival fever 4. 2nd MCC of infantile diarrhea iv. Intranuclear inclusion bodies g. Parvo i. ssDNA, naked ii. Smallest iii. Erythroid progenitor cell of BM = target iv. Diseases 1. Erythema infectiosum 2. Aplastic anemia 3. Hydrops fetalis RNA Viruses a. Breakdown i. Single stranded 1. (-) stranded a. Enveloped i. Filo ii. Orthomyxo/influenza iii. Bunya iv. Rhabdo v. Arena vi. Paramyxo 2. (+) stranded a. enveloped i. Toga ii. Flavi iii. Corona iv. Retro b. Naked i. Picorna ii. Calici ii. Double stranded 1. Naked a. Reo

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Antimicrobial Susceptibility Testing I. Disc Diffusion susceptibility test – Kirby- Bauer Test a. Compares susceptibility of antibiotics

II. III.

MIC – Minimum Inhibitory Concentration a. Tells minimum concentration of drug that kills bacteria MBC – Minimum Bacteriocidal Concentration a. Tells minimum concentration of drug that inhibits bacteria

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IV.

E Test a. Arrow  MIC i. Where inhibition of growth starts

Serological Diagnosis I. Immunological tests a. Agglutination b. Flocculation c. Immunofluorescense i. Chlamydia ii. HSV iii. Legionella iv. Mycoplasma v. Toxoplasma d. ELISA i. Antigens (direct) – HBV antigen ii. Antibodies (indirect) – HIV iii. Sensitive test, used for screening iv. e. Complement fixation f. Western blot i. Detection of protein ii. Confirmation of HIV infection iii. Specific test

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II.

III.

HIV diagnosis a. ELISA – used as a sensitive test b. Western blot – used to confirm dx c. PCR – viral load d. EXCEPTION IN NEW BORNS i. p24 antigen test NO staining used in: a. Rickettisa b. Chlamydia c. Mycoplasma d. Mycobacterium e. Spirochetes

Random Must Knows I. NO Cell wall a. Mycobacterium i. Tuberculosis 1. TX a. Isoniazid b. Rifampin c. Ethambutol d. Pyrazindamide ii. Leprae 1. TX a. Dapsone b. Rifampin b. Mycoplasma i. COLD agglutinin ii. Fried egg appearance II. Spirochete a. Borrelia burgdorferi – Lyme disease i. Bulls-eye rash ii. LAB 1. Wright Giema stain iii. TX 1. Doxycycline b. Treponema pallidum - Syphilis i. LAB 1. Dark field microscopy – primary syphilis 2. VDRL, FTA tests ii. TX 1. Penicillin G c. Leptospira i. Question mark III. Campylobacter a. Sea gull wing appearance b. Microaerophilic @ 42° IV. Yersinia a. Safety pin appearance

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