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Medical Microbiology > Gram Positive Pathogens > Flashcards

Gram Positive Pathogens Flashcards

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1
Q

T/F. Streptococcus pyogenes is catalase positive.

A

False. Catalase negative

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2
Q

T/F. Streptococcus pyogenes is facultative anaerobe.

A

False. Microaerophilic

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3
Q

T/F. Streptococcus pyogenes is beta hemolytic.

A

True.

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4
Q

What are the adherence factors associated with S. pyogenes?

A

M proteins and lipoteichoic acid

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5
Q

What are the virulence factors associated with S. pyogenes?

A

Streptokinase and hyaluronidase

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6
Q

T/F. S. pyogenes produce endotoxin.

A

False. Exotoxin

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7
Q

What are the exotoxin associated with S. pyogenes?

A

Erythrogenic toxin and pyrogenic toxin.

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8
Q

Provide a representative organism of Group A Streptococcus.

A

S. pyogenes

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9
Q

S. pyogenes produces this toxin which damages cell membrane of capillary epithelium giving rise to scarlet fever.

A

Erythrogenic toxin or pyrogenic toxin

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10
Q

S. pyogenes produces this toxin which activates the host sepsis mediators (interleukin 1) leading to toxic shock syndrome.

A

Pyrogenic toxin or erythrogenic toxin

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11
Q

Which microorganism produces erythrogenic or pyrogenic toxin which damages cell membrane of capillary epithelium giving rise to scarlet fever?

A

S. pyogenes

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12
Q

What are the clinical findings associated with S. pyogenes?

A

Skin infections
Pharyngitis
Scarlet fever
Toxic shock syndrome
Necrotizing fasciitis

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13
Q

What are the three presentations of skin infection by S. pyogenes?

A

Pyoderma
Impetigo
Erysipelas

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14
Q

Treatment for S. pyogenes

A

high-dose penicillin with clindamycin and erythromycin

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15
Q

Diagnostic procedure for S. pyogenes

A

Gram stain, culture, and throat swab

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16
Q

B hemolysis by S. progenes is caused by what virulence factors?

A

Streptolysin O and S

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17
Q

T/F. Lipoteichoic acid serves as virulence factor for S. pyogenes.

A

False. Adherence factor

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18
Q

What properties does M protein provide for S. pyogenes?

A

adherence factor, anti-phagocytic, antigenic

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19
Q

T/F. Streptococcus agalactiae is a catalase negative organism.

A

True.

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20
Q

T/F. Streptococcus agalactiae is a aerophilic organism.

A

False. Facultative anaerobe

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21
Q

T/F. Streptococcus agalactiae is capable of alpha hemolysis.

A

False. beta hemolysis

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22
Q

Streptococcus agalactiae can be acquired by babies during deliver and cause what diseases?

A

Neonatal pneumonia
Neonatal meningitis
Neonatal sepsis

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23
Q

Give a representative organism for Group B Streptococcus.

A

S. agalactiae

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24
Q

What are the clinical findings associated with S. agalactiae?

A

Neonatal meningitis
Neonatal pneumonia
Neonatal sepsis

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25
Q

Treatment for S. agalactiae

A

Penicillin

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26
Q

Diagnostics of S. agalactiae

A

Gram stain of CSF or urine
Culture of CSF, urine, or blood

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27
Q

Provide the representative organisms of the Viridans Group.

A

Streptococcus mitis, S. mutans, S. salivarius, , S. intermedius and S. anginosus

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28
Q

T/F. Viridans infection usually start as dental infection but organism may travel the blood stream through cuts in the oral cavity and cause subacute endocarditis.

A

True.

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29
Q

T/F. The endocarditis produced by viridans is acute similar to the endocarditis produced by Staphylococcus aureus.

A

False. Subacute

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30
Q

Viridans group is catalase positive.

A

False. Catalase negative

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31
Q

T/F. Viridans are facultative anaerobe but may be microaerophilic.

A

True.

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32
Q

What are the clinical presentations associated with the viridans group?

A

Subacute endocarditis
Dental carries
Liver or brain abscesses

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33
Q

T/F. Viridans are beta hemolytic but may also be gamma hemolytic.

A

False. alpha hemolytic but may also be gamma hemolytic

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34
Q

This adherence factor allow viridans to adhere to heart valves.

A

extracellular dextran

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35
Q

What member of the viridans group produces dental caries?

A

S. mutans

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36
Q

What member of the viridans group produces brain or liver abcesses?

A

S. intermedius

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37
Q

Treatment for viridans group

A

penicillin

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38
Q

Diagnostic for viridans group

A

gram stain and culture

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39
Q

What are representatives of enterococcus Group D Streptococcus?

A

Enterococcus faecium and E. faecalis

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40
Q

What are representatives of non enterococcus Group D Streptococcus?

A

Streptococcus bovis, and S. equinis

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41
Q

T/F. Group D Streptococci are catalase positive organisms.

A

False. Catalase negative

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42
Q

T/F. Group D Streptococci are usually gamma hemolytic but maybe beta hemolytic.

A

False. Usually alpha but may be gamma

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43
Q

This adherence factors allows Group D Streptococcus to adhere to heart valves.

A

Extracellular dextran

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44
Q

What are the clinical findings associated with group D enterococcus?

A

Subacute endocarditis
Biliary tract infections
UTI

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45
Q

Treatment for group D Streptococcus

A

Ampicillin + aminoglycoside

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46
Q

Diagnostics for Group D Streptoccus

A

gram stain
Culture: enterococci at 40% bile and 6.5% NaCl; non enterococci in bile only

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47
Q

T/F. Culturing Group D non enterococci require bile and salt while culturing Group D enterococci require bile only.

A

False. non entero - bile only; entero - bile and salt

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48
Q

This organism is the primary cause of bacterial pneumonia and meningitis in adults, and otitis media in children.

A

Streptococcus pneumoniae

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49
Q

T/F. S. pneumoniae cells are arranged in chains.

A

False. Paired spheres (diplococci)

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50
Q

What are the virulence factors associated with S. pneumoniae?

A

capsules and pneumolysin

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51
Q

This virulence factor associated with S. pneumoniae binds to cholesterol in host-cell membranes.

A

Pneumolysin

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52
Q

Clinical findings associated wit S. pneumoniae

A

pneumonia
meningitis
sepsis
otitis media in children

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53
Q

Treatment for S. pneumoniae

A

Penicillin
Erythromycin
Ceftriaxone
Vaccine

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54
Q

Diagnostic for S. pnemoniae

A

gram stain, culture (does not grow in optochin and bile), positive Quellung reaction

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55
Q

How is S. pneumoniae differentiated from S. mitis?

A

susceptibility to optochin

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56
Q

T/F. Staphylococcus aureus is a catalase negative microorganism.

A

False. Calatase positive

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57
Q

T/F. S. aureus appear as chains of spheres.

A

False. grape-like clusters of spheres

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58
Q

T/F. S. aureus is alpha hemolytic.

A

False. S. aureus is beta hemolytic

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59
Q

T/F. All Staphylococcus species are coagulase positive.

A

False. Only S. aureus. S. epidermidis and S. saprophyticus are coagulase negative

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60
Q

This virulence factor of S. aureus binds IgG and prevents phagocytosis.

A

Protein A

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61
Q

This virulence factor of S. aureus induces clots as protection from phagocytes.

A

Coagulase

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62
Q

This virulence factor of S. aureus destroys RBC, neutrophiles, macrophages, and platelets.

A

Hemolysin

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63
Q

This virulence factor of S. aureus destroys WBC.

A

leukocidins

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64
Q

This virulence factor of S. aureus inactivates penicillin.

A

Penicillinase

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65
Q

This virulence factor of S. aureus breaks down hyaluronic acid.

A

Hyluronidase

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66
Q

This virulence factor of S. aureus lyses formed fibrin clots.

A

Staphylokinase

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67
Q

This virulence factor of S. aureus degrades fats and oils on skin

A

Lipase

68
Q

This toxin produced S. aureus causes scalded skin syndrome.

A

Exfoliatin

69
Q

What are the toxins produced by S. aureus

A

Enterotoxin
Toxic shock syndrome toxin (TSST-1)
Exfoliatin

70
Q

What are clinical findings associated with the exotoxins produced by S. aureus.

A

Gastroenteritis
TSS
Scalded skin syndrome

71
Q

What are clinical findings associated with direct invasion by S. aureus.

A

Pneumonia
Meningitis
Acute bacterial endocarditis
UTI
etc.

72
Q

Treatment for S. aureus

A

Penicillinase- resistant penicillins
1st gen cephalosporins
Clindamycin

73
Q

Diagnosis for S. aureus

A

Gram stain
Culture (B-hemolytic, golden yellow pigment)
catalase (+)
coagulase (+)

74
Q

Culturing S. aureus in blood agar produces what characteristic morphology?

A

B hemolysis
Golden yellow pigment

75
Q

What are characteristic culture morphology of Bacillus species.

A

Aerobic
Hemolysis in B. cereus
Gelatin liquefaction
Inverted tree morphology in galatin stabs

76
Q

What are representative of aerobic, spore forming rods?

A

Bacillus anthracis
B. cereus

77
Q

T/F. As opposed to Clostridium species, Bacillus species are anaerobic.

A

False. Bacillus species are aerobic.

78
Q

T/F. Bacillus species as opposed to Clostridium always have a terminal spores.

A

False. Always have spores located centrally.

79
Q

T/F. B. anthracis primarily affects herbivores.

A

True.

80
Q

T/F. Humans are directly infected by B. anthracis.

A

False. humans are infected via contact with diseased animals

81
Q

B. anthracis in humans are primarily through inhalation of spores.

A

False. 95 cutaneous, 5% inhalation, GI anthrax is rare

82
Q

In animal hosts, B. anthracis portal of entry is through?

A

Mouth

83
Q

The capsule of B. anthracis is encoded in what plasmid?

A

pXO2

84
Q

The capsule of B. anthracis is composed of what chemical?

A

poly-D-glutamic acid

85
Q

The capsule of B. anthracis confers what effector?

A

Prevention of phagocytosis

86
Q

T/F. B. anthracis is a spore former.

A

True.

87
Q

The exotoxins of B. anthracis is encoded in what plasmid?

A

pXO1

88
Q

This exotoxin produced by B. anthracis, similar to B subunit of an AB toxin, promotes entry of the edema factor into host cells.

A

Protective antigen

89
Q

This exotoxin produced by B. anthracis, similar to an A subunit of a AB toxin, performs the toxic function by impairing neutrophil thereby causing massive edema.

A

Edema factor

90
Q

This exotoxin produced by B. anthracis stimulates release of tumor necrosis factor.

A

Lethal factor

91
Q

This clinical finding associated with B. anthracis is characterized by painless, black vesicles.

A

Cutaneous anthrax

92
Q

This clinical finding associated with B. anthracis is characterized by abdominal pain, vomiting, and bloody diarrhea.

A

GI anthrax

93
Q

Clinical findings associated with B. anthracis

A

Cutaneous, pulmonary, and GI anthrax,

94
Q

Treatment for B. anthracis

A

Ciprofloxacin
Doxycycline
Raxibacumab (pulmonary)
Vaccines

95
Q

Diagnostic for B. anthracis

A

Gram stain
Culture
Serology
PCR of nasal swab

96
Q

T/F. Bacillus cereus is motile and capsulated.

A

False. motile but non-encapsulated

97
Q

This microorganism causes food poisoning when spores are ingested.

A

B. cereus

98
Q

T/F. B. cereus produces endospores.

A

True.

99
Q

What are the two types of enterotoxin produced by B. cereus.

A

heat-labile toxin
heat-stable toxin

100
Q

This enterotoxin produced by B. cereus causes nausea, abdominal pain, and diarrhea.

A

heat-labile toxin

101
Q

This enterotoxin produced by B. cereus causes nausea and vomiting but limited diarrhea.

A

heat-stable toxin

102
Q

What are the clinical findings associated with B. cereus?

A

Food poisoning: nausea, vomiting, diarrhea
Bacteremia/endocarditis: rare

103
Q

Treatment for B. cereus

A

Vancomycin
Clindamycin
No treatment for food poisoning

104
Q

Diagnostic for B. cereus

A

Culture from contaminated food

105
Q

What is diagnostic procedure for C. botulinum

A

Gram stain and culture

106
Q

T/F. As opposed to Bacillus species, Clostridium have spores that is always centrally located.

A

False. Clostridium spores may be central, subterminal, or terminal

107
Q

T/F. Clostridium species are peritrichously-flagellated.

A

True

108
Q

T/F. Unlike Bacillus species, Clostridium species are generally anaerobes with few aerotolerant.

A

True.

109
Q

T/F. Clostridium species are generally alpha hemolytic and grows well in blood-enriched media.

A

False. Beta hemolytic

110
Q

Treatment for C. botulinum

A

Antitoxin for WB and FB
BIG IV for IB
Penicillin
Intubation and vent
Surgical debridement

111
Q

This Clostridium species are mainly found in soil, canned or bagged food products, smoked fish, and honey.

A

C. botulinum

112
Q

This microorganism causes flaccid paralysis.

A

C. botulinum

113
Q

What are the three presentations of botulism?

A

infant, adult (food-borne), and wound botulism

114
Q

In botulism, the toxin inhibits the release of what compound from peripheral nerves causing inability to contract muscles?

A

acetylcholine

115
Q

T/F. Toxins of C. botulinum is released while the organism is still alive.

A

False. released upon death of bacterium

116
Q

This presentation of botulism is characterized by GI symptoms, cranial nerve palsies, muscle weakness, and respiratory paralysis.

A

Food-borne botulism

117
Q

This presentation of botulism is characterized by the same symptoms as food-borne botulism but without the GI symptoms.

A

wound botulism

118
Q

T/F. C. tetani infection is usually caused by skin trauma by any spore- contaminated object.

A

True.

119
Q

Sustained contraction of skeletal muscles is called?

A

tetany

120
Q

This toxin produced by C. tetani causes sustained contraction of skeletal muscles.

A

Tetanospasmin

121
Q

Tetanospasmin inhibits the action of what type of neurons?

A

Renshaw cell interneuron

122
Q

Tetanospasmin inhibits the action of Renshaw cell interneuron preventing release of what inhibitory neurotransmitters, leading to high frequency impulses to the muscle?

A

GABA and glycine

123
Q

Clinical findings for C. tetani

A

Muscle spasms
Lockjaw
Risus sardonicus
Respiratory muscle paralysis

124
Q

This characteristic appearance of patients infected with C. tetani is produced by the locking of the jaws due to constant contraction of the jaw muscles.

A

risus sardonicus “grinning face”

125
Q

Treatment for C. tetani

A

Tetanus toxoid (part of DTaP vaccine)
Antitoxin (human tetanus immune globulin)
Clean the wound
Metronidazole or penicillin

126
Q

This Clostridium species causes gas gangrene, found in soil, and rampant as one of the primary causes of death in soldiers before penicillin.

A

C. perfringens

127
Q

The alpha toxin of C. perfringens is what kind of enzyme?

A

lecithinase

128
Q

This clinical finding associated with C. perfringens is characterized by exposed necrotic skin and crepitus which is the appearance of moist, spongy, crackling consistency in the wound due to pocket of gas.

A

Cellulitis/wound infection

129
Q

Primary presentation of C. perfringens.

A

Cellulitis/wound infection

130
Q

This characteristic appearance of C. perfringens wound infection produces moist, spongy, crackling consistency due to pockets of gas.

A

Crepitus

131
Q

This presentation of C. perfringens infection causes destruction of muscles.

A

myonecrosis

132
Q

This presentation of C. perfringens infection is caused by ingested contaminated food and characterized by watery diarrhea.

A

diarrheal illness

133
Q

Treatment for C. perfringens infection

A

Surgery (may include amputation)
Penicillin
Hyperbaric oxygen

134
Q

This microorganism causes antibiotic- associated pseudomembranous colitis.

A

C. difficile

135
Q

This presentation of C. difficile infection is characterized by red, inflamed mucosa and areas of white exudate.

A

pseudomembranous colitis

136
Q

This toxin produced by C. difficile causes diarrhea

A

Toxin A

137
Q

This toxin produced by C. difficile is cytotoxic to the colonic cells.

A

Toxin B

138
Q

This newly discovered toxin produced by C. difficil produces 15 to 20 times more toxins

A

Clostridium difficile binary toxin (CDT)

139
Q

Treatment for C. difficile infection

A

Discontinue antibiotics
Fidaxomycin
Oral vancomycin
Metronidazole
Fecal transplantation

140
Q

T/F. As opposed to Clostridium and Bacillus species, Corynebacterium diphtheriae are non spore forming.

A

True.

141
Q

T/F. Corynebacterium diphtheriae are constantly rod shaped.

A

False. Coccobacillus/pleomorphic rods

142
Q

T/F. C. diphtheriae is aerobic organism.

A

False. Facultative anaerobic

143
Q

T/F. C. diphtheriae is catalase positive.

A

True

144
Q

T/F. C. diphtheriae is motile.

A

False. nonmotile

145
Q

As opposed to Listeria monocytogenes, C. diphtheriae is non-motile.

A

True. Motility test to differentiate Listeria monocytogenes from C. diphtheriae

146
Q

The toxin produced by C. diphtheriae is what kind of toxin?

A

AB toxin

147
Q

This toxin produced by C. diphtheriae blocks EF-2, inhibiting protein synthesis.

A

A subunit

148
Q

This toxin produced by C. diphtheriae provides entry into cardiac and neural tissues.

A

B subunit

149
Q

Clinical findings of C. diphtheriae.

A

diphtheria

150
Q

This disease caused by C. diphtheriae is characterized by mild sore throat, fever and pseudomembrane on pharynx.

A

diphtheria

151
Q

T/F. Similar to sore throat caused by S. pyogenes, C. diphtheriae causes the same symptoms but with darker coloration of exudates.

A

True.

152
Q

Treatment for C. diphtheriae infection.

A

Antitoxin
Penicilline or erythromycin
Vaccine: DTAP

153
Q

This microorganism appear as dark colonies in culture of potassium-tellurite
agar.

A

C. diphtheriae

154
Q

This microorganism appear as reddish granules after staining with methylene on Loeffler’s culture.

A

C. diphteriae

155
Q

Culture medium for C. diphtheriae

A

potassium-tellurite agar - dark black colonies
Loeffler’s medium - reddish granule after staining with methylene blue

156
Q

This microorganism is found in wide range of environments, survives at low temp (4oC), low pH, high salt, and is associated with dairy products or pre-packed raw produce.

A

Listeria monocytogenes

157
Q

T/F. L. monocytogenes appears as long rods.

A

False. Short rods.

158
Q

T/F. L. monocytogenes is microaerophilic.

A

False. Facultative anearobic

159
Q

T/F. L. monocytogenes is catalase-negative.

A

False. Catalase positive.

160
Q

T/F. L. monocytogenes is alpha hemolysis.

A

False. beta hemolysis

161
Q

Virulence factors associated with L. monocytogenes

A

Listeriolysin O and phospholipases

162
Q

What effector do its virulence factors provide to L. monocytogenes.

A

evasion of phagocytosis

163
Q

Other than Group B Strep, what other organism causes neonatal meningitis.

A

L. monocytogenes

164
Q

What is the clinical presentation of L. monocytogenes in pregnant women?

A

septicemia

165
Q

What is the clinical presentation of L. monocytogenes in immunosuppressed patient?

A

Meningitis

166
Q

Treatment for L. monocytogenes

A

Ampicillin
Trimethoprim/ sulfamethoxazole

167
Q

Diagnostic for L. monocytogenes

A

gram stain, culture

Medical Microbiology (9 decks)

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