Infections of the Heart

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Questions and Answers

What characteristic makes this organism capable of surviving on surfaces for extended periods?

Lives in anaerobic conditions

Requires moisture to thrive

Sturdiness (correct)

Forms spores

What is the function of the coagulase produced by this organism?

Enhances phagocytosis

Converts fibrinogen to fibrin (correct)

Promotes tissue repair

Inhibits cell membrane permeability

Which of the following groups is most likely to have higher numbers of this organism on their skin?

Hospital patients with respiratory issues

Individuals with diabetes requiring insulin (correct)

Children with allergies

Athletes

What role does Protein A play in the virulence of this organism?

Binds Fc portion of IgG to inhibit phagocytosis Signup and view all the answers

Which method is most likely responsible for the spread of this organism?

Sloppy health care practices Signup and view all the answers

What medical condition is most commonly associated with Staphylococcus aureus?

Osteomyelitis Signup and view all the answers

Which feature is characteristic of Staphylococcus aureus?

Coagulase positive Signup and view all the answers

What toxin does Staphylococcus aureus produce that is associated with Toxic Shock Syndrome?

Enterotoxins Signup and view all the answers

Which of the following is a common source of infection for Staphylococcus aureus?

Endogenous flora Signup and view all the answers

What is a characteristic feature of Staphylococcus saprophyticus?

NF in skin Signup and view all the answers

Which species is associated with suppurative lesions and skin infections?

Staphylococcus aureus Signup and view all the answers

What is NOT a potential complication associated with Staphylococcus aureus?

Neurological disorders Signup and view all the answers

Which feature helps in differentiating Staphylococcus saprophyticus from other species?

Susc to novobiocin Signup and view all the answers

What is the primary mechanism of action for penicillin?

Inhibit cell wall cross linking Signup and view all the answers

Which of the following antibiotics is primarily associated with nephrotoxicity?

Aminoglycosides Signup and view all the answers

What adverse effect is most commonly associated with linezolid?

Thrombocytopenia Signup and view all the answers

Which antibiotic is typically not used as monotherapy due to its drug interactions?

Rifampin Signup and view all the answers

What is the mechanism of action of fluoroquinolones?

Block topoisomerase II and IV Signup and view all the answers

Which adverse effect is associated with daptomycin?

Muscle aches Signup and view all the answers

Which antibiotic is known for causing discoloration of secretions?

Rifampin Signup and view all the answers

What effect does vancomycin demonstrate aside from nephrotoxicity?

Ototoxicity Signup and view all the answers

Which class of antibiotics primarily targets gram-negative bacteria when used alone?

Aminoglycosides Signup and view all the answers

Which antibiotic should typically be used in combination with a cell wall active agent to treat gram-positive infections effectively?

Aminoglycoside Signup and view all the answers

What is the primary cause of rheumatic heart disease?

Untreated Streptococcus pyogenes pharyngitis Signup and view all the answers

Which virus is commonly associated with myocarditis?

Coxsackie B virus Signup and view all the answers

Which of the following statements is true regarding infective endocarditis?

Heart murmurs are common in approximately 85% of patients. Signup and view all the answers

What is a typical laboratory finding indicative of infective endocarditis?

Positive blood culture for typical microorganisms Signup and view all the answers

Which microorganism is NOT commonly associated with infective endocarditis?

Escherichia coli Signup and view all the answers

Which procedure is known to potentially introduce bacteria leading to infective endocarditis?

Urinary tract manipulation Signup and view all the answers

How many separate blood cultures are needed to diagnose infective endocarditis based on the Duke criteria?

Two cultures drawn 12 hours apart Signup and view all the answers

Inflammation of the heart endothelium, often involving the valves, is known as what?

Endocarditis Signup and view all the answers

What is the primary management strategy to prevent tick bites?

Tuck pant legs into socks and use DEET repellent. Signup and view all the answers

What causes the relapses in Relapsing Fever?

Antigenic variation. Signup and view all the answers

Which form of relapsing fever is transmitted by soft ticks?

Tick-borne relapsing fever. Signup and view all the answers

What laboratory test is NOT appropriate for diagnosing Lyme Disease?

Urine antigen test. Signup and view all the answers

What is a potential consequence of treating Lyme disease too early?

Reinfection can occur before immunity develops. Signup and view all the answers

During which season are most cases of Tick-Borne Relapsing Fever (TBRF) reported?

Summer Signup and view all the answers

How many episodes of fever might one experience before a Tick-Borne Relapsing Fever resolves?

1-4 episodes Signup and view all the answers

What is a significant risk related to Louse-Borne Relapsing Fever outbreaks?

Mortality can reach 30 to 70% in outbreaks. Signup and view all the answers

Study Notes

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

Staphylococcus aureus:
- Coagulase-positive and beta-hemolytic.
- Associated with conditions like abscesses, endocarditis, toxic shock syndrome, and osteomyelitis.

Antibiotic Classes and Their Mechanisms

Penicillins (e.g., Ampicillin, Nafcillin):
- Mechanism: Cell wall synthesis inhibition.
- Side effects: Hypersensitivity reactions.
Cephalosporins:
- Mechanism: Similar to penicillin with enhanced efficacy against Staph.
Vancomycin:
- Mechanism: Cell wall elongation inhibition.
- Side effects: Nephrotoxicity, ototoxicity.
Daptomycin:
- Mechanism: Depolarizes cell membranes.
- Side effects: Muscle aches.
Aminoglycosides:
- Mechanism: 30S ribosomal inhibition for protein synthesis.
- Side effects: Nephrotoxicity, ototoxicity.
Rifampin:
- Mechanism: RNA polymerase inhibition.
- Side effects: Hepatotoxicity.
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

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.
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.
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.