Questions and Answers
What characteristic makes this organism capable of surviving on surfaces for extended periods?
What is the function of the coagulase produced by this organism?
Which of the following groups is most likely to have higher numbers of this organism on their skin?
What role does Protein A play in the virulence of this organism?
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Which method is most likely responsible for the spread of this organism?
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What medical condition is most commonly associated with Staphylococcus aureus?
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Which feature is characteristic of Staphylococcus aureus?
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What toxin does Staphylococcus aureus produce that is associated with Toxic Shock Syndrome?
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Which of the following is a common source of infection for Staphylococcus aureus?
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What is a characteristic feature of Staphylococcus saprophyticus?
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Which species is associated with suppurative lesions and skin infections?
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What is NOT a potential complication associated with Staphylococcus aureus?
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Which feature helps in differentiating Staphylococcus saprophyticus from other species?
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What is the primary mechanism of action for penicillin?
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Which of the following antibiotics is primarily associated with nephrotoxicity?
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What adverse effect is most commonly associated with linezolid?
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Which antibiotic is typically not used as monotherapy due to its drug interactions?
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What is the mechanism of action of fluoroquinolones?
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Which adverse effect is associated with daptomycin?
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Which antibiotic is known for causing discoloration of secretions?
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What effect does vancomycin demonstrate aside from nephrotoxicity?
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Which class of antibiotics primarily targets gram-negative bacteria when used alone?
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Which antibiotic should typically be used in combination with a cell wall active agent to treat gram-positive infections effectively?
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What is the primary cause of rheumatic heart disease?
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Which virus is commonly associated with myocarditis?
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Which of the following statements is true regarding infective endocarditis?
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What is a typical laboratory finding indicative of infective endocarditis?
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Which microorganism is NOT commonly associated with infective endocarditis?
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Which procedure is known to potentially introduce bacteria leading to infective endocarditis?
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How many separate blood cultures are needed to diagnose infective endocarditis based on the Duke criteria?
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Inflammation of the heart endothelium, often involving the valves, is known as what?
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What is the primary management strategy to prevent tick bites?
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What causes the relapses in Relapsing Fever?
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Which form of relapsing fever is transmitted by soft ticks?
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What laboratory test is NOT appropriate for diagnosing Lyme Disease?
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What is a potential consequence of treating Lyme disease too early?
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During which season are most cases of Tick-Borne Relapsing Fever (TBRF) reported?
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How many episodes of fever might one experience before a Tick-Borne Relapsing Fever resolves?
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What is a significant risk related to Louse-Borne Relapsing Fever outbreaks?
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Study Notes
Rheumatic Heart Disease and Related Conditions
- Rheumatic heart disease results from immune damage due to untreated Streptococcus pyogenes pharyngitis.
- Myocarditis can be caused by Coxsackie B virus and circulating diphtheria toxin.
- Acute benign pericarditis is often viral, while bacterial pericarditis presents a greater risk.
- Vascular inflammation from infections contributes to plaque formation and is significant in atherosclerosis.
Infective Endocarditis (IE)
- Endocarditis is inflammation of the heart endothelium, often affecting heart valves.
- It can be infectious or autoimmune. Fever occurs in 90% of patients; ~85% exhibit heart murmurs.
- Diagnosis follows Duke Criteria, which involve identifying microbes through blood cultures.
Key Microorganisms for Blood Cultures in IE
- Typical microorganisms include:
- Viridans streptococci
- Streptococcus bovis
- HACEK group
- Staphylococcus aureus
- Persistent positives are defined as:
- At least two positive cultures drawn 12 hours apart.
- Majority of four cultures positive, with the first and last drawn at least one hour apart.
Source of Causative Agents
- Causative agents are mostly normal flora but can also be pathogens or contaminants.
- Key risk factors include oral healthcare procedures, dental work, and poor hygiene.
- Staphylococcus aureus, a coagulase-positive organism, is often linked to infections.
Virulence of Staphylococcus aureus
- Clumping factor aids attachment to fibrinogen on endothelial surfaces.
- Coagulase converts fibrinogen to fibrin, shielding bacteria from phagocytosis.
- Alpha toxin creates pores in cell membranes, causing cell leakage and contributing to infection.
- Produces various enzymes and toxins, enhancing virulence and tissue injury.
Medically Important Staphylococci
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Staphylococcus aureus:
- Coagulase-positive and beta-hemolytic.
- Associated with conditions like abscesses, endocarditis, toxic shock syndrome, and osteomyelitis.
Antibiotic Classes and Their Mechanisms
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Penicillins (e.g., Ampicillin, Nafcillin):
- Mechanism: Cell wall synthesis inhibition.
- Side effects: Hypersensitivity reactions.
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Cephalosporins:
- Mechanism: Similar to penicillin with enhanced efficacy against Staph.
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Vancomycin:
- Mechanism: Cell wall elongation inhibition.
- Side effects: Nephrotoxicity, ototoxicity.
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Daptomycin:
- Mechanism: Depolarizes cell membranes.
- Side effects: Muscle aches.
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Aminoglycosides:
- Mechanism: 30S ribosomal inhibition for protein synthesis.
- Side effects: Nephrotoxicity, ototoxicity.
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Rifampin:
- Mechanism: RNA polymerase inhibition.
- Side effects: Hepatotoxicity.
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Fluoroquinolones:
- Mechanism: Topoisomerase inhibition.
- Side effects: Tendon-related issues.
Lyme Disease Management
- Infection prevention involves proper clothing, repellents, and regular tick inspections.
- Early Lyme disease is treated with oral doxycycline; severe cases require systemic treatment.
- Reinfection is possible if treatment occurs before immunity develops.
Relapsing Fever
- Characterized by recurring febrile episodes, often with headaches and muscle aches.
- Antigenic variation leads to relapses.
Types of Relapsing Fever
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Tick-borne Relapsing Fever (TBRF):
- Caused by Borrelia species transmitted via infected ticks.
- More prevalent in summer; ~25 cases reported annually in the U.S.
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Louse-borne Relapsing Fever (LBRF):
- Caused by Borrelia recurrentis, transmitted human-to-human via body lice.
- Associated with high mortality rates in outbreaks, especially in Africa.
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Typical TBRF experience involves 1-4 fever episodes before resolution.
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Description
This quiz covers various cardiovascular diseases including Rheumatic heart disease, Myocarditis, and Pericarditis, highlighting their causes and implications. It also touches on Infective Endocarditis and its effects on the heart. Test your understanding of these critical conditions and their infectious origins.