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MICRO Flashcards

1
Q

what is the single most important etiologic agent of severe diarrheal dz of infants & children world wide?

A

rotavirus

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2
Q

what kind of genome does the rotavirus have?

A

nonenveloped, segmented dsRNA

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3
Q

Which virus is the major cause of food-borne, epidemic acute gastroenteritis in older children & adults?

A

norovirus

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4
Q

What is rotateq?

A

vaccine for rotavirus with 5 bovine-human reassortant viruses

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5
Q

what is rotarix?

A

vaccine for rotavirus with single attenuated human virus

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6
Q

humans are the only known reservoir for what virus that is known to cause symptoms via direct virus-mediated cell damage and tissue necrosis?

A

enteroviruses

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7
Q

where do enteroviruses initialy replicate?

A

in lymphoid tissue of upper respiratory tract and the gut

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8
Q

which type of virus causes pleurodynia (epidemic mylagia)?

A

group B coxsackie viruses (aka devil’s grip)

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9
Q

what virus causes hand-foot-mouth dz?

A

coxsackie virus A16

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10
Q

which virus causes myocarditis?

A

group B coxsackie virus

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11
Q

which virus can cause acute hemorrhagic conjunctivitis that is highly contagious?

A

enterovirus 70 & coxsackie A24

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12
Q

what kind of genome do the noroviruses have?

A

non-enveloped, nonsegmented, +RNA virus w/ 5’VPG & 3’ Poly A tail

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13
Q

which type of virus typically can be traced back to a single source like shellfish, cake frosting or salads?

A

norovirus

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14
Q

which virus has a shorter incubation period norovirus or rotavirus?

A

norovirus (1 day, 6-10 hrs)

Rotavirus (1-4 days)

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15
Q

what kind of genome does picornaviridaee have?

A

nonsegmented, ss +RNA

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16
Q

an infection by what kind of microbe can cause Guillan-Barre syndrome?

A

campylobacter infection

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17
Q

Name the E. coli serotype O157:H7

A

enterohemorhagic E. coli (EHEC)

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18
Q

what is the most common cause of traveler’s diarrhea?

A

ETEC

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19
Q

which bacteria is the leading cause of infantile diarrhea in developing countries?

A

EPEC

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20
Q

what is the most common cause of hemorrhagic colitis in the US?

A

EHEC

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21
Q

which microbe makes currant jelly mucoid colonies?

A

klebsiella pneumoniae

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22
Q

which microbe is the MCC of shigellosis in US?

A

S. Sonnei

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23
Q

what kinds of pts get shigellosis from S. Sonnei?

A

mostly children

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24
Q

Shiegella enter what kind of cells in the gut?

A

microfold (M) cells

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25
Q

name the microbe: contaminate wounds, bacteremia + UTI in hospital pts, found in feces of healthy pts

A

enterobacter

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26
Q

name the microbe: brick red opportunistic colonies causing pneumonia; found in feces of healthy pts

A

serratia marcescens

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27
Q

what are the swarming bacteria?

A

proteus-providencia morganella (nosocomial agents causing UTIs and antibody related diarrhea)

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28
Q

how does the shiga toxin work?

A

phage encoded cytotoxin (AB) that cleaves 28S RNA of ribosome

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29
Q

name the 2 microbes that produce a high amount of shiga toxin

A

Shigella dysenteriae & Enterohemorrhagic E. Coli

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30
Q

which microbe causes typhoid fever?

A

Salmonella Typhi

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31
Q

which microbe is a gram negative coccobacilli that looks like a safety pin?

A

yersinia entercolitica

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32
Q

Salmonella can be acquired from what household pets?

A

pet turtles

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33
Q

what is the name of the Virulence factor made by uropathogenic E. coli that binds to galactose disaccharides on uroepithelium

A

P fimbria (Pyelonephritis assoc. pili-PAP, binds P blood group antigen)

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34
Q

All the enteric pathogens are motile except which 3?

A

Enteroinvasive E. coli
Shigella
Klebsiella

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35
Q

which type of E. Coli is non-motile, doesn’t decarboxylate lysine and doesn’t ferment lactose?

A

EIEC

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36
Q

the invasion phenotype of EIEC is encoded by what?

A

high molecular weight plasmid (can be detected by PCR)

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37
Q

persistent diarrhea >10-14 days is likely from what?

A

parasite

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38
Q

what microbe is the #1 cause of UTIs?

A

E. coli

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39
Q

which type of e. coli can’t use sorbitol?

A

EHEC O157:H7 (grows white on sorbitol macConkey agar, while other e. coli are red/pink)

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40
Q

antibiotics are contraindicated for which type of E. coli?

A

EHEC (risk of HUS)

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41
Q

name the only species of salmonella

A

Salmonella enterica

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42
Q

describe the presentation of salmonellosis?

A

symptoms begin 20-72 hrs post consumption of improperly cooked food
-N/V, followed by abd. cramps & diarrhea lasting 3-4 days

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43
Q

what type of capsule antigen inhibits neutrophil uptake in typhoid fever?

A

Vi

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44
Q

describe the presentation of typhoid fever

A

insidious, rising fever, w/ headache, abd. pain

  • slow pulse, mental confusion
  • diarrhea late if at all
  • death possible by ruptured spleen or intestine
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45
Q

name the microbe that doesn’t cause gastroenteritis but does likely cause a disseminated infection via the fecal-oral route

A

Salmonella Typhi

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46
Q

Name the microbe:
Gram neg., non-motile rod
Lac neg., glu+, no gas, no H2S
leukocytes prominent in stool samples

A

shigella

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47
Q

which microbe causes pseudoappendicitis?

A

yersinia enterocolitica (abd. pains that can mimic appendicitis)

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48
Q

which microbe can characteristically cause aspiration pneumonia in alcoholics?

A

Klebsiella pneumoniae

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49
Q

name the microbe: slender, curved Gram neg. rods that are motile with polar flagella, microaerophilic, make VacA, use Type III Secretion system, and Cag protein

A

H. pylori

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50
Q

what does VacA do in H. pylori?

A

vacuolating cytotoxin (punches holes in organelles of cells)

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51
Q

what does Cag in H. Pylori infections do?

A

rearanges cytoskeleton (modifies proteins–>cell death)

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52
Q

what is the most common bacterial GI infection in developed nations?

A

campylobacter jejuni

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53
Q

what are some of the most common sources of campylobacter jejuni infections?

A

undercooked poultry & unpasteurized milk, contaminated water

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54
Q

name the microbe: thin, spiral shaped Gram neg. rod with gull-winged appearance & is also microaerophilic

A

campylobacter jejuni

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55
Q

which kind of GI infection is the most common antecedent to guillain-barre syndrome?

A

campylobacter jejuni infection

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56
Q

describe the clinical syndrome of campylobacter jejuni infection

A

incubation of 1 wk, fever, appendicitis-like lower abd. pain

-watery diarrhea that progresses to dysentery with blood & pus

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57
Q

which microbe is commonly associated with poor sanitation and related to spread by contaminated water and food. Has 2-3 day incubation period, abrupt onset of vomiting & high volume watery diarrhea

A

V. cholerae

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58
Q

which microbe causes rice-water stools?

A

v. cholerae

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59
Q

what is the TCP virulence factor of V. Cholerae?

A

PAI-encoded pilus that allows for attachment

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60
Q

how does the cholera toxin work?

A

ADP-ribosylation of GTP-binding protein, activation of adenyl cyclase leading to Cl- secretion and high volume watery diarrhea

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61
Q

if you wanted to do a stool culture for v. cholerae what kinds of medium would you use?

A

Thiosulfate citrate Bile salts sucrose (TCBS), or MacConkey

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62
Q

what is the most common food borne illness in japan?

A

vibrio parahaemolyticus (seafood associated food poisoning)

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63
Q

how could you get vibrio vulnificus?

A

consumption of raw oysters or wound infection (cellulitis)

64
Q

anaerobes lack what 2 enzymes that take care of ROS?

A

SOD, catalase

65
Q

name the microbe: gram negative coccobacillus w/ antiphagocytic capsule, major component of the human GI tract, opportunistic pathogen, MC anaerobic infection

A

bacteroides fragilis

66
Q

name the microbe: gram neg. coccobacillus, antiphagocytic capsule, found in GI tract, nasopharyngeal & vaginal flora. MIcrobe is an opportunistic pathogen forming abscesses in pulmonary & periodontal areas

A

Prevotella Melaninogenia

67
Q

name the microbe: gram-positive spore forming rods that are the only anaerobic endospore-forming bacteria

A

clostridium

68
Q

name the microbe: large, boxcar gram+ rods, causing gas gangrene & cellulitis, also food poisoning

A

c. perfringens

69
Q

most humans get infections of c. perfringes from what?

A

from spores in soil or food

70
Q

how long does it take you to get sick from c. perfringens food poisoning, and when will you get better?

A

sick 8-24 hrs post consumption (nausea, abd. pain, diarrhea, no fever), full recovery within 24 hrs

71
Q

what is the name of the toxin that C. tetani makes that enters the NMJ and is transported by motor neurons to ganglia?

A

tetanospasmin (AB neurotoxin)

72
Q

how does tetanospasmin work?

A

cuts v-snare

  • vesicle with NT can’t fuse w/ neuron membrane
  • prevents release of inhibitory NTs (glycine & GABA), blocking postsynaptic inhibiton of spinal motor reflexes
73
Q

how do you treat tetanus?

A

HTIG (to soak up excess toxin)
keep the pt calm
sedation (wait for generation of new axon terminals)

74
Q

which toxin is probably the most toxic bacterial exotoxin, (works by cleaving V and/or T-snare)?

A

AB toxins made by c. botulinum, 1g of toxin could kill 1 million people, prevents the release of ACh

75
Q

what is the cause of floppy baby syndrome?

A

infant botulism (probably from ingesting spores from carpets)

76
Q

which microbe can cause acute, symmetric descending flaccid paralysis?

A 
classic botulism (food poisoning)
-symptoms begin 12-36 hrs post ingestio
77
Q

how can you get classic botulism?

A

consumption of toxin contaminated food
-spores are resistant to heat, germinate after cooking
release toxin: subsequent heating will inactivate the toxin

78
Q

how do you treat classic botulism?

A

mechanical ventilation

horse anti-toxin

79
Q

how long after eating contaminated food could you get botulism and what would it look like?

A

12-36 hrs after eating food

  • nausea, dry mouth, diarrhea, blurred vision
  • paralysis descends to resp. muscles, trunk & extremities
  • possible death by resp. failure
80
Q

what is the most common nosocomial infection, most common diarrhea disease associated with antibiotic use?

A

C. difficile

81
Q

describe the toxin that C. diff uses?

A

A: enterotoxin&raquo_space;> diarrhea
B: cytotoxin&raquo_space;>inflammation

82
Q

how can you diagnose C. difficile?

A

detection of Tox B activity from stool on tissue culture cells
RADT detection of Tox A or B in stools

83
Q

what is the major reservoir of EHEC?

A

cattle

84
Q

Name the Virulence factor that ETEC makes that is similar to cholera toxin, has A subunit w/ 5 B subunits, binds to the same receptors as cholera and has identical enzymatic activity to cholera toxin

A

heat-labile enterotoxin (LT)

85
Q

name the virulence factor made by ETEC that leads increase in cGMP (has same effects as increase in cAMP). This toxin binds to guanylate cyclase located on apical membranes of host cells activating it and leading to secretion of fluid & electrolytes resulting in diarrhea.

A

heat stable toxin (ST)

86
Q

the heat labile toxin (LT) made by ETEC binds to what type of gangliosides on cell surfaces?

A

GM1

87
Q

name the toxin made by ETEC that activates adenylate cyclase leading to chloride efflux

A

heat labile toxin (LT)

88
Q

heat stable toxin made by ETEC causes increases cGMP, then cGMP activates PKA which regulates the activity of ______________-

A

CFTR

89
Q

which type of E. coli is non-motile?

A

EIEC

90
Q

the invasion phenotype of EIEC is endoded by what and can be detected by PCR and probes for specific invasion genes?

A

high molecular weight plasmid

91
Q

EPEC has a plasmid-encoded protein called _______________ that enables localized adherence of bacteria to intestinal cells

A

EPEC Adherence factor (EAF)

92
Q

what is the name of the non fimbrial adhesin that is an outer membrane protein that mediates the final stages of EPEC adherence

A

Intimin

93
Q

adherence of EPEC is mediated by _____________ and produces change in ultrastructure of cells resulting in rearrangements of actin (attachment and effacement of cells)

A

LEE (locus of enterocyte effacement)

94
Q

which type of pathogenic E. coli has a very low infectious dose?

A

EHEC (~100 microbes)

95
Q

UPEC make a hemolysin called _______________ which is cytotoxic due to formation of transmembranous pores in host cell membranes and represents a strategy for obtaining iron and other nutrients

A

EC hemolysin

96
Q

UPEC has resistance to the complement system by making a polysaccharide capsule that is made of what?

A

K antigen

97
Q

what is the name of the major determinant of virulence among strains of E. coli that cause neonatal meningitis?

A

K1 antigen (inhibits phagocytosis, complement, and host immune response)

98
Q

what are the names of the 2 most frequent serotypes of Salmonella that cause dz in the US?

A

S. Enteritidis & S. Typhimurium

99
Q

which bug more commonly causes a disseminated infection, Salmonella or shigella?

A

salmonella

100
Q

Sickle cell children are particularly vulnerable to what bacterial infection?

A

Salmonella (makes sense, they typically don’t have a spleen and so can’t get rid of capsulated bacteria)

101
Q

what is the name of salmonella typhi’s special capsule that protects it from being phagocytosed by PMNs?

A

Vi antigen (virulent)

102
Q

which type of Shigella produces 1000x more shiga toxin than the other shigellae?

A

S. dysenteriae

103
Q

what is the 2nd most common shigella in the US, MC in gay men, MC in many other countries?

A

S. Flexneri

104
Q

which type of shigella causes 70% of all shigellosis in US, mainly dysentery in children?

A

S. Sonnei

105
Q

Name the 2 bacterial microbes that produce high amounts of Shiga cytotoxin?

A

S. dysenteriae

EHEC

106
Q

EHEC can cause diarrhea that becomes bloody in about how much time?

A

24 hours (non-inflammatory, no fecal leukocytes)

107
Q

what is the name of the virulence factor used by EHEC; encoded on PAI, type III secretion system, delivers E. coli receptor to host cell, pedestal formation for attachment & is responsible for diarrhea

A

Locus of enterocyte effacement

108
Q

name the virulence factors used by ETEC for attachment?

A

CFA I or II

109
Q

which type of E. coli has pedestal formation via LEE, but no Stx, ST or LT?

A

EPEC has pedestal formation via Lee (not EIEC), doesn’t have Stx (not EHEC), doesn’t have ST or LT (not ETEC)

110
Q

What is the name of a frank bacterial pathogen that is a significant source of gastroenteritis from food poisoning?

A

Salmonella

can’t be shigella b/c shigella is rarely transmitted by food

111
Q

what are the at risk groups for disseminated salmonellosis?

A

AIDS, hodgkin’s pts (bacteremia)
Sickle cell (osteomyelitis)
Elderly, and infants

112
Q

which frank pathogen is exclusively in humans, spread by fecal oral route, in developing nations, invades M cells, survives in macrophages and also has the Vi capsule antigen?

A

S. Typhi

113
Q

If S. typhi spreads to blood it can cause sepsis, and what major complication can lead to severe hemorrhage?

A

perforations in GI tract at necrotic Peyers patches can lead to severe hemorrhage

114
Q

which microbe can sometimes cause chronic infection of the gallbladder?

A

S. typhi

115
Q

Name the microbe:

Gram neg, Lac. neg., Glu+, w/ H2 gas , & H2S

A

Salmonella

remember S. Typhi doesn’t make H2 gas

116
Q

name the microbe: gram neg. coccobacilli w/ bipolar staining

A

yersinia enterocolitica

117
Q

why is a campylobacter infection self limiting while helicobacter infections can last for decades?

A

there is a mechanical clearance of campylobacter infection

118
Q

name the microbe: curved gram neg. rods that are motile with polar flagellum, oxidase positive, commonly found in saltwater and cause disease in warm months

A

vibrio

119
Q

how is vibrio cholera spread?

A

spread by contaminated water & food (assoc. w/ poor sanitation)

120
Q

what are the name of the 2 serogroups of v. cholerae that are responsible for epidemic and pandemic cholera?

A

O1 and O139

121
Q

the O1 serogroup of v. cholerae are subdivided into which 2 types?

A

El Tor, classical

122
Q

name the microbe: incubation of 2-3 days, abrupt onset of vomiting and high volume watery diarrhea with rice water stools

A

vibrio cholerae

123
Q

name the toxin: AB toxin comprises 5B & 1 A subunit, ADP ribosylation of GTP binding protein & activates adenylyl cyclase

A

cholera toxin (encoded by phage)

124
Q

what is the name of the special stool culture you might use for v. cholerae?

A

TCBS or MacConkey agars

125
Q

most common foodborne illness in japan

A

v. parahaemolyticus

126
Q

name the microbe: free-living in sea water (gulf & pacific coasts), causes watery diarrhea often with abd. cramps N/V, low grade fever, 24 hrs after exposure

A

V. parahaemolyticus

127
Q

name the microbe: free living in sea water, consumption of raw oysters or wound infection (cellulitis)

A

V. vulnificus

128
Q

what is the most common anaerobic infection; causes intrabdominal infections, abscesses, PID, & pulmonary infections?

A

bacteroides fragilis

129
Q

rich meat dishes at low temperatures allows what kind of spores to germinate before consumption?

A

c. perfringens

130
Q

how might a person get a c. tetani infection?

A

spore contamination of wounds

131
Q

name the disease: consumption of toxin-contaminated food, acute, symmetric descending flaccid paralysis, possible death by respiratory failure?

A

classic botulism C. botulinum

132
Q

Name the microbe: causes symptoms 12-36 hours post ingestion; nausea, dry mouth, diarrhea, then blurred vision; paralysis descends to resp. muscles, trunk & extremiities

A

C. botulinum

133
Q

what causes floppy baby syndrome?

A

c. botulinum

134
Q

which virus has the dane particle?

A

HBV

135
Q

what kind of genome does HBV have?

A

enveloped partially ds DNA genome

136
Q

what kind of genome does HAV have?

A

family picornaviridae: nonenveloped ss RNA + genome

137
Q

HBeAg is a secreted form of what other viral marker?

A

HBcAg

138
Q

in a pt infected with HBV his blood is loaded with trillions of what that contain HBsAg & phospholipid but no genome?

A

20 nm particles and filaments

139
Q

HBV primarily replicates in what organ?

A

liver

140
Q

what kind of genome does HDV have?

A

defective circular ss RNA (requires HBV for transmission)

141
Q

what kind of genome does HCV have?

A

nonenveloped ss RNA +

142
Q

HCV has the highest incidence in what age group?

A

45-55 y/o

143
Q

how is HCV able to evade the immune system?

A

has hypervariable region (HVR1) found near the 5’ end of E2 glycoprotein gene

144
Q

how long will it take a chronic HCV pt to develop cirrhosis?

A

20 yrs

145
Q

how long will it take a chronic HCV pt to develop HCC?

A

30 yrs

146
Q

which virus can cause a 20% mortality rate in pregnant women?

A

HEV

147
Q

which family is HAV in?

A

picornaviridae

148
Q

which family is HEV in?

A

caliciviridae

149
Q

which family is HBV in?

A

hepadnaviridae

150
Q

which family is HCV in ?

A

flaviviridae

151
Q

name some groups that are at risk for HAV?

A

travelers to endemic areas (mexico)
native americans
diners
day care workers

152
Q

what are the 4 major proteins made by HBV?

A

DNA polymerase (reverse transcriptase)
HBsAg (surface antigen, attachment protein)
HBcAg (capsid protein)
X antigen (influences gene expression)

153
Q

what are the 3 stages of chronic HBV infection?

A

immune tolerance phase
immune clearance phase
residual phase

154
Q

if you get acute hepatitis B you have about a 90% chance of _____________

A

resolution

155
Q

if you get acute hepatitis B you have about a 1% chance of going into what?

A

fulminant hepatitis

156
Q

if you get acute hepatitis B you have about a 9% chance of the infection becoming what?

A

chronic (> 6 months)

157
Q

if you get chronic hepatitis C, 85% of the time what will happen next?

A

you’ll get a persistent infection 85% of the time

-15% of time you get recovery & clearance

GI (12 decks)

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