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Questions and Answers
Which Staphylococcus species is most clinically important?
Which Staphylococcus species is most clinically important?
What can high concentrations of PVL cause in relation to PMNs?
What can high concentrations of PVL cause in relation to PMNs?
What is an effect of low concentrations of PVL on PMNs?
What is an effect of low concentrations of PVL on PMNs?
What is the role of coagulase in Staphylococcus aureus?
What is the role of coagulase in Staphylococcus aureus?
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What is an anti-phagocytic characteristic of Staphylococcus aureus derived from?
What is an anti-phagocytic characteristic of Staphylococcus aureus derived from?
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Which illness is commonly associated with Staphylococcus aureus?
Which illness is commonly associated with Staphylococcus aureus?
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Which characteristic is synonymous with the invasive pathogenic potential of Staphylococcus aureus?
Which characteristic is synonymous with the invasive pathogenic potential of Staphylococcus aureus?
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What can result from the release of granule contents from lysed PMNs?
What can result from the release of granule contents from lysed PMNs?
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What is the primary mode through which herbivores acquire anthrax?
What is the primary mode through which herbivores acquire anthrax?
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Which genetic material encodes the genes responsible for the protective agent in anthrax?
Which genetic material encodes the genes responsible for the protective agent in anthrax?
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What combination produces the edema toxin in anthrax?
What combination produces the edema toxin in anthrax?
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Which of the following is NOT a way humans can acquire anthrax?
Which of the following is NOT a way humans can acquire anthrax?
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What is the major virulence factor of anthrax?
What is the major virulence factor of anthrax?
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What effect does the edema toxin have on tissues?
What effect does the edema toxin have on tissues?
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Which statement about the anthrax cycle is true?
Which statement about the anthrax cycle is true?
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What is the function of the edema factor in anthrax virulence?
What is the function of the edema factor in anthrax virulence?
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Which combination leads to the formation of lethal toxin in anthrax?
Which combination leads to the formation of lethal toxin in anthrax?
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What is considered a rare mode of transmission for anthrax?
What is considered a rare mode of transmission for anthrax?
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What is the primary action of pyrogenic exotoxins produced by Group A β-hemolytic Streptococci?
What is the primary action of pyrogenic exotoxins produced by Group A β-hemolytic Streptococci?
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Which condition is most directly associated with pyrogenic exotoxins?
Which condition is most directly associated with pyrogenic exotoxins?
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What type of culture is specifically used to identify nasal carriers of Staphylococcus aureus?
What type of culture is specifically used to identify nasal carriers of Staphylococcus aureus?
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What result indicates that catalase is present in a specimen during the catalase test?
What result indicates that catalase is present in a specimen during the catalase test?
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What is the role of pyrogenic exotoxins as superantigens?
What is the role of pyrogenic exotoxins as superantigens?
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What is the primary method used by commercially-available rapid test kits for detecting bacterial antigens?
What is the primary method used by commercially-available rapid test kits for detecting bacterial antigens?
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Which organism is classified as catalase-negative?
Which organism is classified as catalase-negative?
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Which of the following statements about SpeA is correct?
Which of the following statements about SpeA is correct?
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How sensitive are the antigen detection tests compared to culture methods?
How sensitive are the antigen detection tests compared to culture methods?
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What kind of specimens are typically used with Mannitol Salt Agar?
What kind of specimens are typically used with Mannitol Salt Agar?
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What is the specificity range of antigen detection tests in comparison to culture methods?
What is the specificity range of antigen detection tests in comparison to culture methods?
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How long should Blood Agar Plates be incubated to see colonies of Staphylococcus species?
How long should Blood Agar Plates be incubated to see colonies of Staphylococcus species?
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Which of the following best describes the extraction method used by rapid test kits?
Which of the following best describes the extraction method used by rapid test kits?
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Which substance acts as a fibrinolysin in streptococcal infections?
Which substance acts as a fibrinolysin in streptococcal infections?
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What is the role of hydrogen peroxide in the catalase test?
What is the role of hydrogen peroxide in the catalase test?
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What could be a limitation of rapid antigen detection tests?
What could be a limitation of rapid antigen detection tests?
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What is the effect of pyrogenic exotoxins on blood clots?
What is the effect of pyrogenic exotoxins on blood clots?
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What is the primary mechanism through which pyrogenic exotoxins interfere with the immune response?
What is the primary mechanism through which pyrogenic exotoxins interfere with the immune response?
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Which of the following is NOT a characteristic of streptococcal toxic shock syndrome?
Which of the following is NOT a characteristic of streptococcal toxic shock syndrome?
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Which type of agar is used to recover Staphylococcus aureus from respiratory specimens?
Which type of agar is used to recover Staphylococcus aureus from respiratory specimens?
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What is the main function of the catalase test in differentiating bacterial species?
What is the main function of the catalase test in differentiating bacterial species?
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Study Notes
Bacterial Culture Techniques
- Catalase Test: Identifies Staphylococcus species by detecting cytochrome oxidase enzymes; a drop of hydrogen peroxide on the specimen results in bubble formation if catalase is present.
- Blood Agar Plates: Used to culture Staphylococcus species; colonies appear after 18 hours at 37°C; can indicate hemolysis and pigment production.
- Mannitol Salt Agar: Screens for nasal carriers of Staphylococcus aureus; effective for contaminated specimens with mixed microbiota.
Anthrax Cycle
- Transmission to Herbivores: Acquired by ingestion of soil bacteria; humans can get infected via contaminated skin, inhalation, or consumption of infected meat.
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Exotoxins: Compounds released by anthrax bacteria lead to tissue edema and death; encoded by pXO1 plasmid.
- Protective Agent (PA): Binds to receptors for entry of Edema Factor (EF) and Lethal Factor (LF).
- Edema Factor (EF): Forms edema toxin with PA, causing cell and tissue edema.
- Lethal Factor (LF): Combines with PA to produce lethal toxin, the major virulence factor causing death.
Staphylococcus aureus Characteristics
- Most clinically significant staphylococcal species, often causing superficial infections (e.g., impetigo) or systemic illnesses (e.g., septicemia).
- Coagulase-positive, associated with toxigenic illnesses such as Toxic Shock Syndrome (TSS) and food poisoning.
- Common causative agent of infective endocarditis.
Pyrogenic Exotoxins
- Function: Transforms plasminogen to plasmin, allowing bacteria to evade blood clots; interferes with serum inhibitors.
- Produced by Group A, β-hemolytic Streptococci; similar to exfoliative toxins.
- Linked to serious conditions like streptococcal toxic shock syndrome and scarlet fever; acts as superantigens, provoking cytokine release, shock, and tissue injury.
Antigen Detection Tests
- Rapid test kits utilize enzymatic or chemical methods to extract antigen from swabs; enzyme immunoassay or agglutination tests demonstrate the presence of antigens.
- High sensitivity (60-90%) and specificity (98-99%) compared to traditional culture methods.
Medically Important Staphylococci
- Staphylococcus aureus: Key pathogen with coagulase production.
- Staphylococcus epidermidis: Linked to nosocomial infections.
- Staphylococcus saprophyticus: Known for urinary tract infections.
- Staphylococcus lugdunensis: Associated with more severe infections compared to other coagulase-negative staphylococci.
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Description
This quiz explores the process of bacterial culture and diagnostic techniques for identifying Staphylococcus species. It includes details on the catalase test and the hydrolyzation of peroxide. Test your knowledge of microbiology and bacterial identification methods.
