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USMLE Step 1 Random Facts > Micro > Flashcards

Flashcards in Micro Deck (237):
1

characteristic tumbling motility

Listeria monocytogenes

2

transmitted via respiratory droplets

N.meningitidis, RSV, H.influenzae, M.tuberculosis

3

arthropod bites

leishmaniasis (sandfly)
malaria (Anopheles mosquito)
Chagas (reduviid bug)
Lyme dz (Ixodes tick bite)

4

needle stick transmission

HBV, HCV, HIV

5

H.influenzae

small, gram neg coccobacilliary rod
epiglottis, meningitis, otitis media, pneumonia
"haEMOPhilus"

6

causes a palm & sole rash?

2ndary syphilis
Rocky mountain spotted fever
coxsackievirus A
Kawasaki dz

"you drive KAWASAKI CARS w/ your HANDS AND FEET"
(CA = cox A, R = RMSF, S = syphilis)

7

can cross placenta and allow infection from mother to fetus?

TORCHES:
TOxoplasma gondii
Rubella
Cytomegalovirus
HErpes, HIV (HSV-2 transmitted VIA DELIVERY)
Syphilis

8

2 obligate intracellular parasites (require host ATP for energy)

Chlamydia
Ricketssiae

9

common causes of atypical pneumonia (class types)

Mycoplasma
Legionella
Chlamydia
Viruses

10

5 pediatric diseases w/ rash

Measles
Rubella
Scarlet fever (S.pyogenes)
Roseola (HHV-6)
Erythema infectiosum (parvovirus B19) - "slapped cheeks"

11

5 causes of common cold

rhinovirus
coronavirus
adenovirus
influenze C virus
coxsackievirus

12

3 common causes of conjunctivitis

H.influenzae
Adenovirus
S.pneumoniae

13

most common viral cause of mental retardation in US

CMV

14

cancers caused by EBV

Burkitt's lymphoma
nasopharyngeal carcinoma (in East Asians)

15

HBV, HCV, HDV 4 characteristics:

Blood transmission
Chronic carrier state
Cirrhosis
HCC

16

smallpox eradicated bc of?

1) only ONE serotype existed
2) NO CARRIER state
3) NO ANIMAL RESERVOIRS

17

enveloped viruses?

susceptible to anything capable of destroying lipids (ex. bile acids)

18

use host cell TRANSLATION machinery

ssDNA viruses

19

use host cell TRANSCRIPTION machinery

dsDNA viruses

20

Parvovirus B19 =

ssDNA linear, nonenveloped

21

HPV =

nonenveloped, dsDNA circular

22

HPV uses what 2 factors to grow?

E6 (blocks p53), E7 (blocks Rb)

23

JC virus =

dsDNA circular, nonenveloped

24

adenoviruses =

dsDNA linear, nonenveloped

25

adenoviruses can cause?

resp tract infection
conjunctivitis
hemorrhagic cystitis
gastroenteritis

26

adenoviruses remain latent where?

tonsillar adenoids following infection

27

adenoviruses contain what factor?

hemagglutinin fibers in each of 12 vertices of capsid

28

HSV-1, HSV-2, VZV =

enveloped, dsDNA linear

29

HSV, CMV, EBV envelope?

only virus that obtains envelope by budding from nuclear membrane

30

HSV-1 can cause?

gingivostomatitis
keratoconjunctivitis (recurrence of --> common cause of blindness in U.S)
cold sores
**temporal lobe encephalitis (focal necrosis)

31

HSV-1 dormant in?

trigeminal ganglion

32

HSV-2 dormant in?

lumbosacral ganglion

33

HSV-2 passed from mother to fetus can cause?

congenital defects
abortion
neonatal encephalitis

34

most common cause of encephalitis in U.S

HSV-1 = adults
HSV-2 = neonates

35

"dew on a rose petal"

VZV

36

VZV dormant in?

DRG

37

CMV =

dsDNA linear, enveloped

38

CMV causes?

cytomegalic inclusion dz [deafness, hepatosplenomegaly, microcephaly in newborns)
heterophil-NEGATIVE mononucleosis
retinitis (esp in AIDS pt)
pneumonia (esp in transplant pts)
esophagitis

39

cancers ass w/ EBV?

Burkitt's lymphoma, nasopharyngeal carcinoma (East Asians)

40

EBV dormant in?

B cells

bind and infect B cells via C3d complement receptor

41

atypical lymphocytes charact of?

EBV infection

cytotoxic T-lymphocytes react against infected B cells

42

HBV =

enveloped, dsDNA circular

43

HBV and weak immune response =

chronic state

44

HBV tx?

alpha-IFN or pegylated alpha-IFN
lamivudine

45

smallpox =

enveloped, dsDNA linear

46

smallpox presentation?

start as macules --> evolve to pus-filled vesicles --> crust over in 2-3 wks --> infectious particles released

47

molluscum contagiosum =

enveloped, dsDNA linear

48

unlike HSV or VZV, molluscum contagiosum is?

limited to epidermis
NO latent state

49

Molluscum contagiosum presentation?

flesh-colored pearly nodules/papules w/ central crater

"dome-like"

50

features of acid-fast bacilli?

cell wall w/ mycolic acid (a lipid) --> makes wall hydroPHOBIC
after stained, retains stain!

51

spirochetes shape/motility?

corkscrew bc flexible/thin cell walls
periplasmic flagella (b/w outer membrane and cell wall) --> corkscrew motility

52

mycoplasma distinguishing feature?

no cell wall

53

chlamydia/rickettsiae species are?

obligate intracellular bacteria

54

mycolic acid cell wall protects from?

phagocytosis, germicides, dryness

55

M.tuberculosis cell wall contains?

sulfatides - inhib phagosome from fusing lysosome

56

M.tuberculosis =

thin RODS, non-motile obligate aerobes
linear growth

57

acid-fast staining bacteria?

mycobacteria, nocardia

58

live-attenuated vaccines for bacteria?

BCG and F.tulerensis vaccines

59

Mycobacterium avium complex consists of?

M.avium, M.intracellulare
major opportunistic inf in AIDS pts

60

M.bovis seen w/?

GI tuberculosis; unpasteurized milk

61

M.leprae =

same as M.tuberculosis but also grows at low temps, phenolase positive

62

M.leprae infect?

cells of nerve sheaths

63

tuberculoid leprosy =

strong immune response
granulomas formed
thickened palpable nerves and 1-2 anesthethized lesions that are hypopigmented and hairless

64

lepromatous leprosy =

weak immune response
inflamm damage --> sensory loss at face, extremities
loss of eyebrows, saddle-nose deformity (thick nose), leonine facies (thick cheeks), infertility

65

tx of leprosy SE?

type 1 = DTH response --> intensified tuberculoid-like sympt; tx w/ prednisone
type 2 = immune-complex dep --> erythema nodosum leprosum; tx w/ thalidomide

66

T.pallidum =

spirochete
microaerophilic
sensitive to high temps

67

T.pallidum contains?

endoflagellum (b/w cell wall and outer membrane)

68

Giemsa stain

Chlamydia
Borrelia
Ricketssiae
Trypanosomes
Plasmodium

"Certain Bugs Really Try My Patience"

69

PAS stain

stains GLYCOGEN, mucopolysaccharides
dx Whipple's Dz (Tropheryma whipplei)

70

Ziehl-Neelson stain (carbolfuchsin)

acid-fast organisms (Nocardia, Mycobacteria)

71

India Ink

C.neoformans (stains CLEAR)

72

mucicarmine stain

C.neoformans (stains capsule RED)

73

Silver stain

Fungi (Pneumocystis)
Legionella
H.pylori

74

chocolate agar w/ factors V (_____), X (________) media for?

H.influenzae
NAD+;hematin

ENRICHMENT MEDIA

75

Thayer-Martin media contains?

Vancomycin (inhib Gram + org)
Polymyxin (inhib Gram - org except Neisseria)
Nystatin (inhib fungi)

SELECTIVE MEDIA!

76

Thayer-Martin media for?

N.gonorrheae/meningitidis

77

Bordet-Gengou (_______) agar for?

B.pertussis
potato!

78

cystine-tellurite plate

C.diphtheriae --> forms black colonies

79

Loffler's media

C.diphtheriae

80

Lowenstein-Jensen agar for?

M.tuberculosis

81

pink colonies on MacConkey's agar?

lactose-fermenting enterics!
fermentation prod acid --> turns colony pink

DIFFERENTIAL MEDIA

82

eosin-methylene blue agar?

E.Coli (colonies w/ green metallic sheen)

83

charcoal yeast extract agar buffered w/ _________ and used for?

cysteine and iron

Legionella!

84

Sabouraud's agar

Fungi

"Sab's a FUN Guy"

85

obligate aerobes

Nocardia
Pseudomonas aeruginosa
M.tuberculosis
Bacillus (some are facultative anaerobes)

"Nagging Pests Must Breathe"

86

obligate anaerobes

Clostridium
Bacteroides
Actinomyces

"anaerobes Can't Breathe Air"

foul smelling, difficult to culture, produce gas in tissue

87

what drug class is ineffective against anaerobes?

Aminoglycosides (req O2 to enter)

88

obligate intracellular

Rickettsiae
Chlamydia

can't make own ATP

89

facultative intracellular

Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia pestis

"Some Nasty Bugs May Live FacultativeLY"

90

catalase + organisms

Pseudomonas
Listeria
Aspergillus
Candida
E.Coli
S.aureus
Serratia

"you need PLACESS for your CATS"

91

urease + bugs

Cryptococcus
H.pylori
Proteus
Ureaplasma
Nocardia
Klebsiella
S.epidermidis
S.saprophyticus

92

yellow "sulfur" granules prod by?

Actinomyces israelii
composed of filaments of bacteria

93

yellow pigment

S.aureus

94

blue-green pigment

Pseudomonas aeruginosa

95

red pigment

Serratia marcescens

96

Protein A virulence factor?

S.aureus
binds Fc region of Ig --> prevents opsonization/phagocytosis

97

IgA protease virulence factor?

S.pneumo, H.flu B, Neisseria ("SHiN")
cleaves IgA --> colonize respiratory mucosa

98

M protein virulence factor?

group A strep
prevent phagocytosis and activation of complement!

99

features of exotoxin

genes located for in plasmid or bacteriophage;
made of polypeptide;
induces high-titer Ab (antitoxins)
ONLY staph enterotoxin not destroyed at 60 degrees C

100

features of endotoxin

located in outer cell membrane of Gram -;
made of LPS;
causes fever, shock by release of TNF, IL-1

101

superantigen cause what?

overwhelming release of IFN-gamma and IL-2

102

3 effects of endotoxin

activates macrophages (TNF, IL-1, NO)
activates complement (C3a, C5a)
activates tissue factor (coag cascade --> DIC)

103

transformation?

take up naked DNA from environement (form recomb organism)
SHiN organisms!!

104

what inhibits transformation from occurring?

adding deoxyribonuclease (degrades naked DNA)

105

what contains genes for sex pilus and conjugation?

F+ plasmid

106

transposition?

segment of DNA that can jump (excision, reintegration) from one location to another

can carry AB resistance or virulence factors

107

transduction uses?

phages!

108

5 bacterial toxins encoded in lysogenic phage?

shigA-like toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin of Strep pyogenes

"ABCDE"

109

beta-hemolytic bacteria

S.aureus
S.pyogenes
S.agalctiae
Listeria monocytogenes

"forms clear area"

110

classic drugs used to tx anaerobic infections

metronidazole
clindamycin

111

branching, filamentous Gram (+) rods w/ sulfur granules

Actinomyces israelii

112

spore forming bacteria

B.cereus
B.anthracis
Clostridrium botulinum/tetani/perfringens

113

see "picnics" and egg salad or chicken salad, think?

S.aureus - immed (1-6 hrs) vomiting/diarrhea
Salmonella - occurs 1-3 days later

114

transmission from turtle

Salmonella

115

traveller's diarrhea

ETEC

116

staghorn calculi are what stones?

ammonium-magnesium-phosphate stones (struvite stones)

117

what bug causes staghorn calculi?

Proteus

118

hemolysis color for alpha-hemolytic

green

119

hemolysis color for beta-hemolytic

clear

120

water contaminated w/ rodent urine =

hantavirus

121

Borrelia burgdorferi transmitted by, and, natural reservoir =

transmit by Ixodes tick (also holds Babesia)
reservoir = mouse

122

BILATERAL Bell's palsy ass w/?

stage 2 Lyme dz

123

stage 2 Lyme dz manifestations?

bilateral bell's palsy (w involved forehead);
AV nodal block

124

3 biggies in atypical (interstital) pneumonia

Legionella pneumophila
Chlamydophila pneumoniae
Mycoplasma pneumoniae

125

MRSA resistant to beta-lactams by?

altering penicillin-binding protein

126

S.pneumo is _______ sensitive or resistant and causes?

optochin sensitive

Meningitis
Otitis media (in children)
Pneumonia
Sinusitis

MOPS

127

normal flora of oropharynx and causes dental caries

S.mutans

128

causes subacute bacterial endocarditis at damaged valves, and by doing what?

S.sanguis - sticks to damaged valves by making glycocalyx

129

most commonly precedes acute PSGN

impetigo > pharyngitis

130

S.viridans are ________ resistant or sensitive?

optochin resistant

131

S.pyogenes is __________ sensitive or resistant?

bacitracin sensitive

132

other S.pyogenes virulence factors

hyaluronate in capsule (antiphagocytic activity)
Streptolysin O
DNase (depolymerize viscous DNA in pus + disintegrate PML)
streptokinase (catalyze plasminogen --> plasmin)

133

S.agalactiae is _________ resistant or sensitive and prod what factor?

bacitracin resistant
CAMP factor (enlarge area of hemolysis formed by S.aureus)

134

S.agalactiae positive culture requires what prophylaxis?

penicillin

135

Enterococci (Group D strep) are resistant to what drug and grow in what?

resistant to penicillin G
grow in 6.5% NaCl and bile

136

S.bovis causes what?

subacute endocarditis in COLON CANCER PTS

137

C.diphtheriae acquires virulence via? has a toxin similar to? appearance in microscope?

bacteriophage-mediated infection w/ Tox gene --> codes for AB exotoxin;

P.aeruginosa

Gram positive rods w/ metachromatic (blue/red) granules resembling chinese letters

138

spores have what in their core?

dipicolinic acid

139

describe Clostridria species

Gram (+), spore-formers, obligate anaerobic bacilli
oxidase (-)

140

C.difficile toxins

Toxin A --> enterotoxin (binds to brush border of gut --> intestinal fluid secretion and inflamm)

Toxin B --> cytotoxin (destroys cytoskeletal structure of enterocytes = kills enterocytes)

141

DOC for C.difficile

metronidazole
2nd = oral vanco

142

drugs against C.diphtheriae

erythromycin, penicillin; vaccine

143

B.anthracis unique feature

polypeptide capsule containing D-glutamate

144

3 toxins of anthrax

edema factor
lethal factor
protective antigen

145

wool, goat's hair contain spores for?

Anthrax

146

widened mediastinum and pulm hemorrhage seen in?

Woolsorter's dz (B.anthracis)

147

reheated rice synd + cause/toxin

B.cereus --> cereulide (preformed toxin)

148

able to multiply at 4 degrees C

L.monocytogenes

149

L.monocytogenes is a ? and tx = ?

facultative intracellular microbe (taken up by monocytes) acquired by ingestion of unpasteurized milk/cheese and deli meats + passed on during vaginal birth
tx = ampicillin in infants/elderly/immunocomp

150

Actinomyces 4 defining features

Gram (+) anaerobe
Not acid-fast
oral/facial abscesses (usually of mandible) draining through sinus tracts [bc part of normal oral flora]
yellow "sulfur" granules

151

tx for actinomyces?

penicillin

152

Nocardia 4 defining features

Gram (+) aerobe
Acid-fast
in soil, dust, vegetation
pulmonary infections in immunocompromised; cutaneous infections after trauma in immunocompetent

153

Nocardia tx?

sulfonamides

154

congenital toxoplasmosis classic triad?

chorioretinitis
hydrocephalus
intracranial calcifications

155

cell types rich in smooth ER?

hepatocytes
steroid hormone-producing cells of adrenal cortex

156

formation of spiral septum?

truncoconical swellings fuse + turn 180 degrees
neural crest cell derivative!

157

underlying cause of transposition of great vessels

180 degree spin didn't take place

158

underlying cause of persistent truncus arteriosus

failure of neural crest cell migration

159

congenital defects with present shunts

persistent truncus arteriosus - VSD
tricuspid atresia - REQ BOTH ASD + VSD
TAPVR - ASD + sometimes PDA
ToF - VSD
transposition of great vessels - REQ ASD, VSD, OR PFO

160

2 common causes of osteomyelitis in otherwise healthy children

#1 = S.aureus
#2 = S.pyogenes

161

osteomyelitis in sickle cell dz

Salmonella

162

E.Coli virulence factor for UTIs?

fimbriae

163

E.Coli virulence factor for pneumonia/neonatal meningitis?

K capsule

164

E.Coli virulence factor for shock?

LPS

165

organisms that use fimbriae/pili to attach to tissues/cause infection

N.meningitidis
UTI/diarrhea-causing E.coli
B.pertussis
V.cholera

166

common cause of Acute otitis externa

swimmer's ear!
P.aeruginosa
S.aureus

167

common cause of Acute otitis media

S.pneumo
nontypable H.influenzae
M.catarrhalis

168

difference seen b/w bacterial and fungal/TB meningitis?

bacterial - increased PMNs!
fungal/TB - increased lymphocytes!

169

parvoviridae

non enveloped, ssDNA

170

what do Cowdry type A bodies look like?

intranuclear eosinophilic droplets (seen in HSV, CMV)

171

conjugated vaccines are what?

polysaccharide antigen + protein

172

exotoxin not destroyed at 60 degrees C is made by

S.aureus

173

conjugation w/ F+ plasmid will

NOT transfer chromosomal genes

174

conjugation w/ high-freq recombination cell (Hfr) will

transfer plasmid AND chromosomal genes

175

toxins w/ genes encoded in a lysogenic phage

shigA-like toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin of S.pyogenes

"ABCDE"

176

alpha-hemolysis produces what area

green ring around colonies

177

DOC for C.perfringens

metronidazole
2 - oral vanco

178

DOC for GBS prophylaxis

intrapartum penicillin

179

cutaneous anthrax

black eschar (painless ulcer)
lethal factor and edema factor

180

pulmonary anthrax

pulm hemorrhage, mediastinitis (widened, hemorrhagic mediastinum), shock

181

B.cereus

diarrhea
cereulide (preformed toxin)
reheated rice

182

L.monocytogenes

tumbling motility (actin)
able to multiply @4 degrees C (cold)
ampicillin for empirical meningitis tx
listeriolysin - activated in acidified phagosomes in monocytes; can lyse vacuolar membrane

183

Actinomyces

oral/facial abscesses draining thru sinus tracts
tx = penicillin

184

Nocardia

pulm infections in immunosupp
cutaneous infections after trauma in immunocompetant
tx = sulfonamides

185

Mycobacterium 2 factors in virulent strains

cord factor - inhib macrophage maturation + induce release of TNF-alpha; "serpentine" looking

sulfatides (surface glycoproteins) - inhib phagolysosomal fusion

186

tx for leprosy

tuberculoid - dapsone + rifampin 6 mo.
lepromatous - dapsone, rifampin, clofazimine 2-5 yrs

187

Gram neg bacteria resistant to?

penicillin G and vancomycin

188

N.gonorrheaoe vs. N.meningitidis

N.Meng - has polysacch capsule; nasopharyngeal colonization (resp/oral transmission)

189

HiB vaccine unique in that

it contains pentose monosacch (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein

190

which bug shows up w/ hyponatremia on labs

L.pneumophila

191

otitis externa distinguishing feature

granulation tissue w/in ear canal

192

EHEC unique from other E.Coli in that it doesn't

ferment sorbitol

193

Salmonella vs Shigella

Sal:
flagella
dissem hematogenously
prod hydrogen sulfide
causes monocytic response
animal reservoir (turtles)

Shigella:
cell-to-cell trans (P2P, contaminated food/water)
AB shorten duration of fecal excretion
causes PMN response

194

can be transmitted from domestic animals to humans

C.jejuni

195

V.cholerae can benefit from what state

achlorhydia (from PPI use, ex)

196

triple therapy for H.pylori

PPI, clarithromycin, amoxicillin/metronidazole

197

H.pylori mainly colonizes where

gastric antrum (duodenal bulb)

198

spirochetes disting factor

axial filaments (flagella located in diff location than others)

199

leptospira

jaundice
photophobia w/ conjunctivitis
"question-mark" shaped

200

DOC for stage 1/2 of Lyme dz

doxycycline
azithromycin (in children)

201

DOC for later stages of Lyme dz

ceftriaxone (for 28 days)

202

stage 3 lyme dz

chronic monoarthritis/migratory polyarthritis
encephalopathy/polyneuropathy

203

tertiary syphilis physical signs

broad-base ataxia
argyll-robertson pupil

204

early sign of cong syphilis

snuffles (blood tinged nasal secretions)

205

DOC for/cause of bacterial vaginosis

metronidazole
from overgrowth of certain bacteria in vagina

206

R.typhi, R.prowazekii cause

typhus; rash starts centrally + spreads out, sparing palms/soles

207

sign of Ehrlichiosis

granulocytes w/ berry-like inclusions in cytoplasm

208

DOC for LGV

doxycycline

209

chlamydial cell wall unique bc it

lacks muramic acid

210

unique sequelae of Mycoplasma pneumo

mild anemia due to high titer of COLD agglutinins (IgM)

211

histoplasmosis

mississippi and ohio river valleys
w/in macrophage - smaller than RBC

212

blastomycosis

east of Mississippi river and central america
granulomatous nodules
broad-based budding yeast - same size as RBC

213

coccidioidomycosis

southwestern US, California; San Joaquin valley fever
spherules - larger than RBC

214

Tinea versicolor caused by

M.furfur
degrad of lipids --> prod acids --> damage melanocytes --> hypo/hyperpigmented patches (not pruritic)

215

other tinea lesions usually show what histo

pruritic lesions w/ central clearing resembling ring

216

tx for vaginal/localized candidiasis

nystatin (topical med)

217

disseminated candidiasis predisposition =

decreased neutrophils

218

superficial/localized candidiasis predisposition =

decreased T-lymphocytes

219

Aspergillus can produce

aflatoxins (ass w/ HCC)
conidophore w/ radiating chains of spores

220

C.neoformans causes what sign in brain; also, found where?

soap-bubble lesions;
found in soil, pidgeon droppings

221

mucor/rhizopus features

HA, facial pain (periorbital pain)
black necrotic eschar on face (palate or nose usually)
have ketone reductase (therefore prolif in excess glucose/ketone)

222

DOC for PCP

TMP-SMX
pentamidine, dapsone (if sulfa allergy)

223

DOC for sporothrix schenckii

itraconazole or K iodide

224

DOC for Giardia lamblia

metronidazole
tinidazole

225

tx for asympt E.histolytica cyst passers

iodoquinol

226

sympt of E.histolytica

bloody, mucous-y diarrhea
liver abscess
RUQ pain
flask-shaped ulcer if colon ruptures

227

tx for Toxoplasmosis

sulfadiazine + pyrimethamine

228

features/tx for Trypanosoma brucei gambiense/rhodesiense

LAD, RECURRING FEVER (due to antigenic variation), coma (late)
suramin (if blood-borne dz)
melarsoprol (for CNS penetration)

229

Babesiosis features

fever
hemolytic anemia

230

loa loa features

worm in conjunctiva
tx = diethylcarbamazine

231

river blindness caused by

onchocerca volvulus;
hyperpigmented skin + blindness
tx = ivermectin

232

Elephantiasis caused by/tx

Wuchereria bancrofti;
blocks lymphatic vessels
tx = diethylcarbamazine

233

Taenia solium ingested from eggs causes

cysticercosis
neurocysticercosis ("swiss-cheese" appearance in brain) - tx w/ -bendazoles + dexamethasone

234

diphyllobothrum latum causes

vit B12 def

235

before removing E.granulosus cysts what do you do?

preinject w/ ethanol to kill cysts

236

S.hematobium ass w/?

SCC of bladder

237

C.sinenis ass w/?

pigmented gallstones (from biliary tract inflamm)
cholangiocarcinoma