140033970 microbiology usmle step 1 high yield images

7/27/2019 140033970 Microbiology USMLE Step 1 High Yield Images

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Vanisha Patel Page 1

Microbiology Lab Final TA Review

The HelminthsI. Nematoda

a. Trichinellai. Eating uncooked meatii. Eating wild game (polar bear)iii. Travel to Mexico + Asiaiv. LAB

1. Muscle biopsy encysts in muscle

v. TX1. Albendazole

b. Ascarisi. Children of tropical/developing countries

ii. LAB1. Stool for eggs

iii. TX1. Albendazole


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c. Strongyloidiasisi. LAB

1. Larvae in stool

ii. TX1. Ivermectin

d. Enterobiasisi. Pinworm

ii. LAB1. Scotch tape test2. NIH swab

iii. TX1. Albendazole


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II. Cestodaa. Taenia saginata

i. Beef tapeworm

ii. TX1. Niclosamide2. Praziquantel

b. Taenia soliumi. Pork tapewormii. Causes Cysticerosis cysts in brain

iii. LAB1. Swiss cheese appearance Giant brain lesion

iv. TX1. Niclosamide2. Albendazole + Prednisolone


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c. Diphyllobothrium latumi. Fish tapewormii. Competes w/host for Vit B12iii. TX

1. Praziquanteld. Echinococcus granulosus

i. Dog tapewormii. Contaminated w/canine feces

iii. LAB1. Hydatid cyst in tissues

iv. TX1. Albendazole

III. Trematodaa. Schistosomiasis

i. Blood flukesii. Snail host

iii. LAB1. Eggs in stool/urine

iv. TX1. Praziquantel

IV. Entamoeba Histolyticaa. Liver abscess, bloody diarrheab. Flask shaped ulcersc. LAB

i. Bloody stool cysts w/4 nuclei

d. TXi. Metronidazole


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V. Giardia Lambliaa. Hikers diarrheab. Bloating flatulence, foul smelling diarrheac. LAB

i. Trophozoite/cyst

d. TXi. Metronidazole

VI. Trichomonas Vaginalisa. Sexually transmitted flagellateb. Pear shaped, 4 anterior flagellac. Corkscrew motilityd. Foul smelling greenish, yellow frothy dischargee. TX

i. Metronidazole


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MycosesI. Superficial Mycoses

a. ONLY cosmetic problem*b. Pityriasis Versicolor

i. Caused by Malassezia Furfurii. Dry, scaly, hyper/hypopigmented lesions on torso, arms, and abdomen

iii. LAB1. Spaghetti + meatball appearance KOH prep

iv. TX1. Selenium Sulfide2. Topical Miconazole

II. Cutaneous Mycosesa. Dermatophytosis

i. Trichophyton hair, skin, nails


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ii. Microsporum skin, hair

iii. Epidermophyton skin, nails

iv. Diseases1. Tinea capitiscaused by T. tonsurans2. Tinea barbae area of alopecia3. Tinea pedis caused by T. rubrum4. Tinea cruris caused by T. rubrum

v. LAB1. Digested with KOH see septate hyphae & calcofluor

white2. Woods light (UV light)


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vi. TX1. Skin Ketaconazole, Miconazole, Clotrimazole2. Hair Ketoconazole shampoo3. Nail Oral Terbinafine/Itraconazole

III. Subcutaneous Mycosesa. Sporotrichosis

i. Rose Gardners Disease1. Caused by sporothrix schenkii2. Dimorphic

ii. LAB1. Tissue biopsy: cigar shaped budding yeast2. Room temperature: daisy shaped conidia

iii. TX1. Oral potassium iodide2. Systemic Itraconzaole/Amphotericin B

IV. Systemic Mycosesa. Coccidiomycoses

i. Cali, Arizona, New Mexicoii. Inhalation of arthroconidia

iii. LAB1. Tissue biopsy: spherules w/endospores2. Room temperature: branched hyphae w/arthrospores


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iv. TX1. Fluconazole2. Amphotericin B3. Itraconazole

b. Histoplasmosisi. Ohio, Mississippiii. Bat feces, soil contaminated with bird droppings

iii. LAB1. Giemsa/Wright stain2. Tissue biopsy: Yeast w/in macrophage

3. Room temperature: tuberculated macronida on hyphae


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iv. TX1. Self limiting2. Itraconazole/Amphotericin B

c. Blastomycosisi. North, Central, Southeast USAii. Decaying vegetation, soil contaminated w/beaver exreta

iii. LAB1. Tissue biopsy: Broad based budding yeast in KOH

2. Room temperature: branched hyphaeiv. TX

1. Itraconazole2. Amphotericin B


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d. Paracoccidiomycosisi. Central + South America

ii. LAB1. Pilot/captain wheel

2. Yeast w/multiple buds


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Opportunistic MycosesI. Candidiasis

a. Caused by C. albicansb. Diseases

i. Oral thrushii. Diaper rashiii. Vaginitis

c. LABi. Culture: smooth, creamy, pasty coloniesii. Gomorri silver methanamine

iii. ELISAiv. Stain: yeast like budding cells w/pseudohyphae

d. TXi. Fluconazoleii. Itraconazoleiii. Voricanazoleiv. Nystatin (oral)v. Amphotericin Bvi. Caspofungin


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II. Cryptococcosisa. Caused by C. neoformansb. Capsule = halo ONLY opportunistic fungi w/capsulec. Pigeon droppingsd. LAB

i. India Inkii. Budding cells w/halo and prominent capsule

e. TXi. Amphotericin Bii. Flucytosiniii. Oral fluconazole

III. Aspergillosisa. Diseases

i. Invasive aspergillosisii. Farmers lungiii. Bronchopulmonary aspergillosis

b. LABi. Tissue biopsy: dichotomous branching hyphae w/45 septate


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c. TXi.

Itraconazoleii. Amphotericin Biii. Caspofungin

IV. Zygomycosisa. Found in soil, strawberries, moist breadb. Diseases

i. Rhinocerebral zygomycosisc. LAB

i. KOH w/calcofluor white stainii. Broad, ribbon like, nonseptate hyphae @ 90


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d. TXi. Amphotericin B

V. Pneumocystisa. Diseases

i. Pneumocystis pneumonia ground glass appearanceb. LAB

i. H&E: Alveoli w/foamy honeycomb appearance

ii. Lung biopsy: cysts-dark oval bodies on silver stainiii. Toluidine blue-Ostainiv. Giemsa stainv. Calcofluor white


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c. TXi. TMP-SMXi. Pentamidine


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VirologyI. DNA Viruses

a. Breakdowni. Enveloped

1. Double strandeda. Herpesb. Hepadnoc. Pox*

ii. Naked1. Double stranded

a. Papovab. Adeno

2. Single stranded*a. Parvo*

b. Herpesi. Enveloped, Icosahedral

ii. Alpha1. HSV-1

a. Latent in DRGb. Syncitium formationc. Giant cell formationd. Cowdry bodies

2. HSV-2a. Latent in lumbosacral regionb. Diseases

i. Herpes Whitlowii. Herpes Encephalitisiii. Herpes Genitalisiv. Neonatal Herpes

c. LABi. Cowdry Type A inclusion bodiesii. PCR = gold standard method

d. TXi. Acyclovir

3. VZVa. Latent in sensory nerve ganglionb. Diseases

i. Chicken pox dew drop rose petal vesicularlesions

ii. Herpes Zosterc. LAB

i. Tzanck smear intranuclear inclusion bodiesd. TX

i. Acyclovirii. Foscarnetiii. Beta

1. CMV (HHV-5)a. Latent in monocytes, macrophages, lymphocytes*b. Diseases

i. Mononucleosis like syndrome Heterophil AbNEGATIVE


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c. LABi. Owls eye basophilic inclusion bodies

d. TXi. Gancyclovirii. Foscarnetiii. Cidofavir

2. HHV 6 + 7 (Roseola)a. Biphasic

iv. Gamma1. EBV

a. Latent in B cellsb. Downey cells (atypical T cells)c. LAB

i. Monospot test Heterophile Ab POSITIVEd. Diseases

i. Infectious Mononucleosisii. Burkitts lymphomaiii. Hairy oral leukoplakia

2. HHV-8a. Kaposki sarcomab. AIDSc. Hepadna

i. Envelopedii. Dane particle*iii. Ground glass appearance*iv. Serology

1. 3 antigensa. HbsAg ACUTEb. HbcAg Viral multiplicationc. HbeAg BEWARE (HIGH infectivity)

2. 4 antibodiesa. Anti HBs/HbsAb immunizedb. Anti HbcAg-IgM active infectionc. Anti hbcAg-IgG chronic/post infectiond. Anti Hbe low infectivity

d. Poxi. Replicates in cytoplasm*ii. Bullet shapediii. Envelopediv. Diseases

1. Smallpox cytoplasmic inclusion bodies2. Molluscum contagiosum pearly freshly colored benign nodule

v. TX1. Prednisone, Methotrexatee. Papova

i. Polyoma1. Naked, circular2. Latent in kidney3. Diseases

a. BKb. JC PML


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ii. Papilloma1. HPV 6,11; 16,18; 1,42. Diseases

a. Plantar/palmar warts HPV 1,4b. Condyloma acuminate HPV 6, 11c. Cervical intraepithelial neoplasia HPV 16, 18

i. Koilocytes in PAP smear3. TX

a. Cidofavirf. Adeno

i. Nakedii. Spikesiii. Diseases

1. Acute febrile pharyngitis2. Acute respiratory diseases military3. Pharyngocojunctival fever4. 2nd MCC of infantile diarrhea

iv. Intranuclear inclusion bodiesg. Parvo

i. ssDNA, nakedii. Smallestiii. Erythroid progenitor cell of BM = targetiv. Diseases

1. Erythema infectiosum2. Aplastic anemia3. Hydrops fetalis

II. RNA Virusesa. Breakdown

i. Single stranded1. (-) stranded

a. Envelopedi. Filoii. Orthomyxo/influenzaiii. Bunyaiv. Rhabdov. Arenavi. Paramyxo

2. (+) strandeda. enveloped

i. Togaii. Flaviiii. Coronaiv. Retro

b. Nakedi. Picornaii. Calici

ii. Double stranded1. Naked

a. Reo


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Antimicrobial Susceptibility TestingI. Disc Diffusion susceptibility test Kirby- Bauer Test

a. Compares susceptibility of antibiotics

II. MIC Minimum Inhibitory Concentrationa. Tells minimum concentration of drug that kills bacteria

III. MBC Minimum Bacteriocidal Concentrationa. Tells minimum concentration of drug that inhibits bacteria


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IV. E Testa. Arrow MIC

i. Where inhibition of growth starts

Serological DiagnosisI. Immunological tests

a. Agglutinationb.

Flocculationc. Immunofluorescense

i. Chlamydiaii. HSViii. Legionellaiv. Mycoplasmav. Toxoplasma

d. ELISAi. Antigens (direct) HBV antigenii. Antibodies (indirect) HIViii. Sensitive test, used for screeningiv.

e. Complement fixationf. Western blot

i. Detection of proteinii. Confirmation of HIV infectioniii. Specific test


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II. HIV diagnosisa. ELISA used as a sensitive testb. Western blot used to confirm dxc. PCR viral loadd. EXCEPTION IN NEW BORNS

i. p24 antigen testIII. NO staining used in:

a. Rickettisab. Chlamydiac. Mycoplasmad. Mycobacteriume. Spirochetes

Random Must KnowsI. NO Cell wall

a. Mycobacteriumi. Tuberculosis

1. TXa. Isoniazidb. Rifampinc. Ethambutold. Pyrazindamide

ii. Leprae1. TX

a. Dapsoneb. Rifampin

b. Mycoplasmai. COLD agglutininii. Fried egg appearance

II. Spirochetea. Borrelia burgdorferi Lyme disease

i. Bulls-eye rashii. LAB

1. Wright Giema stainiii. TX

1. Doxycyclineb. Treponema pallidum - Syphilis

i. LAB1. Dark field microscopy primary syphilis2. VDRL, FTA tests

ii. TX1. Penicillin G

c. Leptospirai. Question markIII. Campylobacter

a. Sea gull wing appearanceb. Microaerophilic @ 42

IV. Yersiniaa. Safety pin appearance

140033970 microbiology usmle step 1 high yield images

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