Micro 2 USMLE Flashcards by Mani Yavi

dermatophyte has a reservoir in pets

microsporum

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this obligate anaerobic bacilli is gram positive, spore forming

clostridia

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this clostridium species produces an exotoxin

clostridium tetani

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C tetani exotoxin works by blocking ________ release [inhibitory neurotransmitter] from Renshaw cells in the spinal cord

glycine

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this clostridia bacilli forms a preformed, heat-labile toxin that inhibits ACh release

C. botulinum

mneu: BOTulinum is from bad BOTtles of food (causes a flacid parralysis)

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this clostridia bacilli produces an alpha toxin (lethinasse) that causes myonecrosis, gas gangrene, or hemolysis.

C. Perfringes

mneu: PERFringes PERForates a gangrenous leg

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this clostridia bacilli produces a cytotoxin, an exotoxin that kills enterocytes, causing psudomembranous colitis. It is often secondary to antibiotic use, especially clindamycin or ampicillin.

C. difficile

mneu: DIfficile causes DIarrhea.

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how do you tx C. difficile

metronidazole.

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Diptheria is caused by _________ via exotoxin encoded by a Beta-prophage.

Corynebacterium diptheriaee

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the potent diptheria exotoxin works by inhibiting what via ADP ribosylation of EF-2

Protein synthesis

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coryne=______

club shaped

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Symptoms of infection with this bug include pseudomembranous pharyngitis (grayish-white membrane) with lymphadenopathy)

C. diptheriae.

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C diptheriae identified in the lab as a Gram ___, _____ with metachromatic ranules.

G+, rod

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C diptheriae grows on a ______ agar

tellurite

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What are the ABCDEG of diptheria and its exotoxin

ADP ribosylation
Beta-prophage
Corynebacterium
Diphtheriae
Elongation Factor 2
Granules

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pt presents with painless black skin lesions (vesicular papules covered by black eschar). He developes sepsis and dies. What G+ sporeforming rod that produces a toxin do you suspect

Bacillus anthracis

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Inhalation of anthrax spores from contaminated wool can lead to flulike symptoms that rapidly progress to fever, pulmonary hemorrhage, and shock. what is the name of this dz.

woolsorters dz.

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these two bugs are both gram + rods forming long branching filaments resembling fungi

actinomyces v. nocardia.

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this bug forms yellow “sulfur granules’ in sinus tracts

A. israelii

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this bug is a G+ ANAEROBE, that causes oral/facial abscesses with “sulfur granules” that may drain through sinus tracts in the skin. It is part of the normal oral flora.

Actinomyces israelii

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this bug is a gram + and weakly acid fast aerobe in the soil taht causes pulmonary infection in immunocompromized pts

Nocardia asteroides

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How do you tx nocardia? actinomyces?

mneu:  SNAP
Sulfa for 
Nocardia;
Actinomyces use
Penicillin

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Gram negative outer membrane layer inhibits entry of these 2 AB. Therefore G - bugs are resistant to these 2 drugs

Penicillin G

Vancomycin

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T or F. G- bugs are resistant to all derivitives of penicillin such as ampicillin

F–just resistant to PCN & Vanco.

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Neisseria is a gram ___, ____

neg, cocci

Neisseria Gonococci or Meningococci? | Polysaccharide capsule

Meningococci

Neisseria Gonococci or Meningococci? | No Polysaccharide capsule

Gonococci

Neisseria Gonococci or Meningococci? | No maltose fermintation

Gonococci

Neisseria Gonococci or Meningococci? | maltose fermintation

Meningococci

Neisseria Gonococci or Meningococci? | No Vaccine

Gonococci

Neisseria Gonococci or Meningococci? | Vaccine

Meningococci

Neisseria Gonococci or Meningococci? | causes gonorrhea, septic arthritis, neonatal conjunctivitis, PID

Gonococci

Neisseria Gonococci or Meningococci? | causes meningococcemia and meningitis, Waterhouse-Friderichsen syndrome

Meningococci

this bug is a small gram negative (coccobacillary) rod spread via aerosol transmission.

Haemophilus influenzae

HaEMOPhilus Influenzae causes (4)

Epiglottis, Meningitis, Otitis media & Pneumonia.

Most invasive form of H. influenzae is caused by capsular type ___

H. influenzae produces ____ protease.

IgA.

how do you culture H. influenzae

chocolate agar w/ factors V (NAD) & X (hematin) for growht mneu: when child has "flu" mom goes to five(V) & dime (X) to buy some chocolate.

H. flu vaccine contains type B capsular polysaccharide conjugated to diptheria toxoid or other protien. It is given between ____ and _____ mo of age.

2 and 18

this group is a diverse family including E. coli, salmonella, shigella, klebsiella, enterobacter, serratia, porteus

enterobacteriaceae.

all enterobacteriaceae have somatic (__) Ag (polysaccharide of endotoxin. The capsular (__)Ag related to virulence of the bug. The flagellar (__) Ag is found in motile species

O K H

enterobacteriaceae ferment ____ and are oxidase ____

glucose | negative

with enterobacteriaceae think COFFEe.

``` Capsular O Ag Flagellar Ag Ferment glucose Enterobacteriaceae ```

these bacteria grow pink colonies on MacConkey's agar. Examples include Klebsiella, E. coli, Enterobacter, and Citrobacter

Lactose fermenters | Lactose is KEE

These 2 organisms are similar in that both are non-lactose fermenters. Both invade intestinal mucosa and can cause bloody diarrhea

Salmonella v. Shigella

Salmonella v. Shigella: Only _______ is motile and can invade further and disseminate hematogenously. Symptoms may be prolonged with AB treatments, and there is typically a monocyte response.

Salmonella mneu: Salmon swim (motile and disseminate

_____ has an animal reservoir

salmonella.

Shigella is transmitted via the 4 Fs

Food, fingers, feces, & fliies

usually transmitted from pet feces (e.g., puppies), contaminated milk, or pork. Outbreaks are common in day-care centers. Can mimic Crohn's or appendicitis, can disseminate to produce lymphadenitis.

Yersinia enterocolitica.

Bugs causing food poisoning: | contaminated seafood

Vibrio parahaemolyticus & V. vulnificus

Bugs causing food poisoning: | reheated rice

Bacillus cereus

Bugs causing food poisoning: meats, mayonaise, custard s/s starts quickly and ends quickly

S. aureus

Bugs causing food poisoning: reheated meat dishes

clostridium perfringes

Bugs causing food poisoning: undercooked meat

E. Coli O157:H7

Bugs causing food poisoning: poultry, meat, & eggs

Salmonella

Pt presents with bloody diarrhea. culture shows comma or S- shaped, oxidase positive organisms that grow at 42*C. What is the species

Campylobacteria

Pt presents with bloody diarrhea. culture shows motile organisms What is the species

Salmonella

Pt presents with bloody diarrhea & dysentery. Culture shows nonmotile species with very low ID50. What is the species

Shigella.

What is more virulent Shigella or Salmonella

Shigella (only 100 organisms causes dz)

Pt presents with bloody diarrhea which progresses to HUS. culture shows shiga-like toxin. What is the species

Enterohemorrhagic E. coli

Pt presents with bloody diarrhea. culture shows O157:H7 which has invaded the colonic mucosa What is the species

Enteroinvasive E. coli

child at day care center presents with bloody diarrhea and pain that mimicks appendicitis. What is the bug?

Yersinia enterocolitica

Pt presents with bloody diarrhea & pseudomembranous colitis. What is the species

C. dificile

Pt presents with bloody diarrhea. culture shows protozoa. What is the species

entamoeba histolytica

Pt presents with watery diarrhea. Hx of traveling out of the country. No preformed toxin. What is the species

Enterotoxigenic E. coli (ETEC)

Pt presents with rice watery diarrhea . culture shows comma shaped organisms. What is the species

V. cholerae

Pt presents with watery diarrhea and gas gangrene. What is the species

C. perfringes

Immunocompromized pt presents with watery diarrhea. what do you suspect.

protazoa (e.g., giardia, cryptosporidium)

Pt presents with watery diarrhea . What viruses could cause this

Rotavirus, adenovirus, Norwalk virus

This toxin acts via ADP ribosylation that perminantly activates adenyl cyclase (increase cAMP). It perminantly activates G(s)causing rice-water diarrhea.

Vibrio cholerae toxin Cholera turns the "on" on

This toxin acts via ADP ribosylation that perminantly activates adenyl cyclase (increase cAMP). It perminantly disables G(i)causing whooping cough. It also promotes lymphocytosis by inhibiting chemokine receptors

Pertussis toxin Pertussis turns the "off" off

This bug is a gram neg. rod that gram stains poorly. It is spread via aerosol transmission from enviornmental water source hapitat. It is not spread person to person.

Legionella pneumophelia

How do you cx & stain Legionella pneumophelia

grow on charcoal yeast extract culture with iron and cysteine stain with silver stain. mneu: Think of French legionnaire (ssoldier) with his silver hlmet, sitting around a campfire (charcoal) with is iron dagger--he is no sissy (cysteine)

How do you tx Legionnaires' dz

erythromycin

this bug is associated with wound and burn infections. It is an aerobic gram negative rod. It is non lactose fermenting, oxidase positive. it produces pyocyanin which is a blue green pigment and is usually associated with a water source.

Pseudomonas aeruginosa. mneu: AERuginosa--AERobic. think water connnection & blue green pigment.

Pseudomonas aeruginosa causes pneumonia in these patients

Pseudomonas aeruginosa causes black lesions on the skin when this happens

sepsis

When pseudomonas aeruginosa causes external otitis, it is also known as

swimmers ear

Pseudomonas aeruginosa produces an endotoxin which causes (2)

fever & shock

Pseudomonas aeruginosa produces an exotoxin (A) which does this to EF-2

inactivates it

how do you tx Pseudomonas aeruginosa

aminoglycoside plus extended-spectrum penicillin (e.g., Piperacillin, ticarcillin.

this gram - rod causes gastritis and up to 90% of duodenal ulcers.

Helicobacter pylori

Is H. pylori urease + or -

+ think the urease breath test.

what other bug is urease +

Proteus | cleaves urea to amonia

H. pylori is a risk factor for (2)

peptic ulcer and gastric carcinoma

H. pylori creates this kind of envirnment (acid or alkaline)

alkaline

tx H. pylori w/ triple therapy-what is it

1) bismuth (pepto-bismol) 2) metronidazole 3) tetracycline or amoxycillin or (more expensive) 1) metronidazole 2) omeprazole 3) clarithromycin

this zoonotic bacteria causes lyme dz and is transmitted by the bite of the Ixodes tick that live on deer and mice

Borrelia Burgdorferi

this zoonotic bacteria causes Undulant fever and is transmitted by dairy products and contact with animals

Brucella species

this zoonotic bacteria causes Tularemia and is transmitted by ticks that live on rabbits & deer

Francisella tularensis

this zoonotic bacteria causes plague and is spread via flease that live on rodents, especially prarie dogs

Yersinia pestis

this zoonotic bacteria causes cellulitis and is spread via bites from cats and dogs

pasteurella multocida

On pelvic exam you note a greenish vaginal discharge with a fishy smell. Pt reports no pain. Smear shows clue cells and cx grows out a pleomorphic, gram variable rod. What is the dx and the bug.

Bacterial Vaginosis | Gardnerella vaginalis

What anaerobe is also involved with B.V

Mobiluncus.

How do you tx B.V.

metronidazole

what are clue cells

vaginal epithelial cells covered with bacteria, visable under microscope

TB granulomas with lobar and perihilar lymph node involvement. Reflects primary infection or exposure

Ghon complex

pt presents with fever, night sweats, weight loss & hemoptysis. What mycobacterium do you suspect

mycobacterium tuberculosis

pt presents with TB like symptoms but it is not mycobacterium tuberculosis, what other mycobacterium could it be

M. kansasii

child presents with cervical lymphadenitis. What mycobacterium?

M. scrofullaceum

AIDS pt presents with disseminated dz. Bug is resistant to multilple drugs. What mycobacteria

M. avium-intracellulare

all mycobacteria should be stained this way

acid fast

what dz involves loss of eyebrows, nasal collapse, lumpy earlobe, and "leonine facies"

Leprosy (Hansen's dz)

This bug is an acid fast bacillus that likes cool temperatures (infects skin and superficial nerves) and cannot be grown in vitro.

Mycobacterium leprae

What is the reservoir in US for M. leprae

armadillos.

TB granulomas with lobar and perihilar lymph node involvement. Reflects primary infection or exposure

Ghon complex

pt presents with fever, night sweats, weight loss & hemoptysis. What mycobacterium do you suspect

mycobacterium tuberculosis

pt presents with TB like symptoms but it is not mycobacterium tuberculosis, what other mycobacterium could it be

M. kansasii

child presents with cervical lymphadenitis. What mycobacterium?

M. scrofullaceum

Hansen's dz (Leprosy) has 2 forms: lepromatous & tubberculoid. Which is worse?

Lepromatous is worse--it involves failed cell mediated immunity; tuberculoid is self limited mneu: LEpromatous=LEthal.

these are obligate intracellular parasites that cause mmucosal infections

Clamydiae

chlamys=_______

cloak (intracellular

Chlamydiae exists in 2 forms What are they?

1) Elementary body (small, dense) Enters cell via Endocytosis 2) Reticuliate body, which Replicates in cell by fission

This chlamydia species causes reactive arthritis, conjunctivitis, and nongonococcal urethritis

Chlamydia trachomatis

These 2 chlamydia species cause atypical pneumonia, and is transmitted via aerosol droplets

C. pneumoniae & C. psittaci

C. psittaci is notable in that it has an ____ reservior

avian

The clamydial peptidoglycan wall is unusual in that it lacks ______

muramic acid

Dx of clamydia is made by cytoplasmic incusions seen on _______ or fluorescent Ab stained smear

giemsa

how do you tx clamydia

erythromycin or tetracylcine

Clamydia trachomatis serotypes: | A,B,C

ABC=Africa/Blindness/Chronic infection

Clamydia trachomatis serotypes: | D-K

urethritis/PID, ectopic pregnancy, neonatal pneumonia, or neonatal conjunctivitis D-K=everything else

Clamydia trachomatis serotypes: | L1-L3

Lymphogranuloma venerium

Neonate develops conjunctivits via passage through infected birth canal. How do you tx his chlamydia

erythromycin eye drops

Name 3 spirochetes

Borrelia (Big-can be visualized under light microscopy using aniline dyes (Wright's or Giemsa stain)) Leptospira Treponema mneu: BLT

pt presents with erythema chronicum migrans, an expanding "bull's eye" red rash with central clearing. Dz may progress to affect joints CNS, & heart.

Lyme dz

Lyme dz caused by what spirochete and what vector

Borrelia burgdorferi, transmitted by the tick Ixodes

important reservoir for Lymme dz

mice

animal required for tick life cycle

deer.

lyme dz transmission is most common during this season

summer

3 stages of Lyme dz

1) erythema chronicum migrans, flulike symptoms 2) neurologic and cardiac manifestations 3) autoimmune migratory polyarthritis mneu: BAKE a Key LYME pe: Bells palsy, Arthritis, Kardiac block, Erythema chronicum migranes.

treponemes are ______

spirochetes

________ causes syphilis

Treponema pallidum

_______ causes yaws (a tropical infxn that is not an STD, although VDRL test is +.

T. pertenue

describe primary syphilis

localized dz-painless chancre

describe secondary syphilis

disseminated dz w/ constitutional symptoms, maculopapular rash (palms & soles) condylomata lata mneu: Secondary syphilis=Systemic

pt preents w/ broad-based ataxia positive Romberg, charcot joints, stroke without hypertension

tertiary syphilis

describe tertiarry syphilis

gummas, aortitis, neurosyphalis (tabes dorsalis), argyl Robertson pupil

child presents with deafness, saber shins, sadddle nose. what dx

congenital syphilis

describe primary siphilis

localized dz-painless chancre

describe secondary syphilis

disseminated dz w/ constitutional symptoms, maculopapular rash (palms & soles) condylomata lata mneu: Secondary syphilis=Systemic

pt preents w/ broad-based ataxia positive Romberg, charcot joints, stroke without hypertension

tertiary syphilis

describe tertiarry syphilis

gummas, aortitis, neurosyphalis (tabes dorsalis), argyl Robertson pupil

child presents with deafness, saber shins, sadddle nose. what dx

congenital syphilis

constricts with accomodation but is not reactive to light. Pathognomonic for tertiary syphilis

Argyll Robertson Pupil "prostitute's pupil" -- accommodates but does not react.

FTA-ABS is specific for these. It turns + earliest in dz & remains positive for longest

treponemes mneu: FTA-ABS=Find The Antibody-ABSolutely: 1) Most specific 2) earliest positive 3) remains positive the longest

VDRL or FTA interpretation: | Active infection

both

VDRL or FTA interpretation: | Probably false positive

VDRL

VDRL or FTA interpretation: positive after successful treatment

FTA

this test detects a nonspecific Ab that reacts with beef cardiolipin

VDRL

VDRL false positive

``` VDRL Viruses (mono, hepatitis) Drugs Rheumatic fever & arthritis Lupus & leprosy ```

coccidiomycosis and histoplasmosis are fungus transmitted by _______

inhalation of conidia (asexual fungal spores)

this fungus can cause a systemic of superficial fungal infection. It is dimorphic forming budding yeast with psudohyphae in cx at 20*C and germ tube formation at 37*C

Candida albicans

alba=_____

white

causes thrush esophagitis with immunocompromized pts (neonates, steroides, diabetes, AIDS), endocarditis in IV drug users, vaginitis (post-antibiotic), diaper rash

Candida albicans

Tx of candida for superfical infxn

nystatin

Tx of candida for systemic infxn

amphotercin B

this dz causes San Joaquin Valley or desert "valley fever." It is known as desert bumps and on cx you may see a spherule filled with endospores

Coccidiomycosis

this dz is spread by bird or bat droppings in Mississippi and Ohio river valleys. Characterized by tiny yeast inside macrophages

Histoplasmosis

This organism endemic in rural Latin America and is characterized by a "Captain's wheel" appreance.

PARACOCCIDIOMYCOSIS

This fungis is endemic to states east of Mississippi River & Central America, it is characterized by Big, Broad-Based Budding yeasts

Blastomycosis.

histo, paracoxie, and blastomycoisis are all caused by _______ fungi, which are mold in soil (low temp) adn yeast in tissue (higher temp)

dimorphic

coxie is the exception in that it is a ______ in tissue

spherule

tx coxie, histo, paracoxie, and blastomycoisis locally with

fluconazole or ketoconazole

tx coxie, histo, paracoxie, and blastomycoisis systemically

amphotericin

systemic mycosis can form granulomas and mimick this dz

this dz causes hypopigmented skin lesion and occurs in hot, humid weather.

tinea versicolor

tinea versicolor is caused by

malassezia furfur

tx tinea versicolor with topical

miconazole or selenium sulfide (Selsun)

this dz is an infxn of keratinized leyer of skin. It appears as a brownish spot.

tinea nigra

tinea nigra is caused by this fungus

Cladosporium wernecki.

tx tinea nigra with topical______

salycylic acid

pruritic lesions with central clearing resembling a ring

Tinea (pedis, cruris, corporis, capitis)

Tinea (pedis, cruris, corporis, capitis) caused by

dermatophytes (microsporum, trichophyton, and epidermophyton)