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30 Cards in this Set
- Front
- Back
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122. Gram positive Cocci- Catalase negative- Partial hemolysis (α-haemolytic- green) and Optochin sensitive, bile soluble, with a capsule (+Quellung)?!?
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a. Strep. pneumoniae.
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123. Gram positive Cocci- Catalase negative- Partial hemolysis (α-haemolytic- green) and Optochin resistant, not bile soluble, No capsule?
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a. Viridans strep (e.g. S. mutants).
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124. Gram positive Cocci- Catalase positive (clusters) and Coagulase positive?!?
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a. S. aureus.
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125. Gram positive Cocci- Catalase positive (clusters) and Coagulase negative and Novobiocin sensitive vs. resistant?
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a. Novobiocin sensitive- Staph. epidermidis
b. Novobiocin resistant- Staph. Saprophyticus. |
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126. Resistant to Novobiocin?
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a. Staph Saprophyticus.
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127. Sensitive to Novobiocin?
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a. Epidermidis
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128. Resistant to Optochin?
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a. Strep Viridans.
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129. Sensitive to Optochin?
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a. Strep Pneumoniae.
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130. Resistant to Bacitracin?
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a. Group B Strep.
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131. Sensitive to Bacitracin?
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a. Group A Strep
b. B-BRAS. = B Bacitracin resistant. A Sensitive. |
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132. α-Haemolytic bacteria on blood agar?
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a. Form Green ring around colonies on blood agar.
b. Include: 1. Strep pneumoniae (catalase negative and optochin sensitive) 2. Strep Viridans (Catalase negative and optochin resistant). |
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133. β-haemolytic bacteria on blood agar?
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a. Form clear area of haemolysis on blood agar.
b. Include (4): 1. Staph aureus (catalase and coagulase positive) 2. Strep pyogenes -group A strep (Catalase negative and bacitracin sensitive) 3. Strep agalactiae- group B strep (Catalase negative and bacitracin resistant. 4. Listeria Monocytogenes (tumbling motility, meningitis in newborns, Unpasteurized milk. |
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134. Catalase?!?
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a. Catalase degrades H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase.
b. Staph make catalase, whereas strep do not! c. “Staph make catalase bec they have more staff”. |
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135. Catalase-producing microbes in people w/chronic granulomatous disease?
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a. Easily degrade what little H202 is present in people w/chronic granulomatous disease (NADPH oxidase deficiency), thereby causing recurrent infections.
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136. What makes coagulase?
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a. S. aureus only.
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137. Protein A?
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a. A Staph aureus virulence factor.
b. Protein A binds Fc-IgG, inhibiting complement fixation and phagocytosis. |
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138. Staph aureus causes?
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1. inflammatory disease- skin infections, organ abscesses, pneumonia.
2. Toxin-mediated disease- Toxic Shock Syndrome (TSST-1 toxin), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (enterotoxins). 3. MRSA infection. |
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139. Why is MRSA resistant to β-lactams?
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a. Altered penicillin-binding protein.
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140. What is S. aureus food poisoning due to?
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a. Ingestion of preformed toxin.
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141. Toxic shock syndrome cause?
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a. TSST-1 toxin is a superantigen that binds to MHC III and TRR, resulting in polyclonal T-cell activation.
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142. Staph epidermidis causes?
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a. Infects prosthetic devices and IV catheters by producing adherent biofilms.
b. Component of normal skin flora; contaminates cultures. |
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143. What is Strep pneumoniae the most common cause of? (MOPS)
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1. Meningitis
2. Otitis Media (in children) 3. Pneumonia 4. Sinusitis b. Lancet shaped. Encapsulated. IgA protease. c. Most Optochin Sensitive (MOPS). |
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144. Viridans group strep cause what type of hemolysis?
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a. α-haemolytic.
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145. Where are Viridans strep normal flora?
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a. Oropharynx.
b. Cause dental caries (s. mutans) and subacute bacterial endocarditis (S. sanguis). |
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146. What differentiates Viridans from pneumoniae?
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a. Viridans are resistant to optochin, differentiating them from S. pneumoniae which are also α-haemolytic but are optochin sensitive.
b. “Viridans live in the mouth because they are not afraid of of-the-chin (op-to-chin resistant). |
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147. Step pyogenes (group A strep) causes?
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1. Pyogenic- pharyngitis, cellulitis, impetigo.
2. Toxigenic- scarlet fever, toxic shock-like syndrome. 3. Immunologic- rheumatic fever, acute glomerulonephritis. b. “Pharyngitis can result in rheumatic PHever and glomerulonephritis” c. “no Rheum for SPECCulation: Subacute plaques, Polyarthritis, Erythema marginatum, Chorea, Carditis” |
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148. How do S. pyogenes respond to bacitracin?
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a. Sensitive to it.
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149. What enhances host defense to S. pyogenes while at the same time giving rise to rheumatic fever?
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a. Antibodies to M protein.
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150. What detects recent S. pyogenes infection?
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a. ASO titre.
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151. How does Strep agalactiae (group B strep) respond to bacitracin?
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a. Resistant to it.
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