Diebel: Intro to CV Infectious Disease Flashcards
What are the normal biota of the CVS?
NONE
Blood is one of the 3 areas of the body that should never have microorganisms (other two are CNS and lymphatics)
What are the natural host defenses found in the CVS?
THOUSANDS of leukocytes, Abs and complement
Blood stream infections are referred to as systemic infections. What is a defense against blood stream infections?
Leukocytes!
Thousands/mL
Describe the pathway to infection in the CVS.
Exposure to pathogen adherence to skin invasion of epithelium colonization and growth production of VFs Toxicity Tissue damage and release
Where does damage (which leads to disease) come from?
Growth of organism: direct cell lysis, apoptosis, autophagy d/t viral/bacterial infection
Toxins produced by microorganism (bacteria)
Immune system collateral damage
What is infectious endocarditis?
A BACTERIAL disease associated with SEPSIS and typically an underlying HEART DEFECT, that leads to INFLAMMATION of the inner lining of the heart (endocardium).
How does bacterial disease cause endocarditis?
Bacteria cells travel through the bloodstream and lodge on abnormal heart valves (native- mitral, tricuspid or prosthetic) or damaged heart tissue. At these sites bacteria grow and produce vegetations, blocking the valves normal fxn and blood flow. Vegetations encapsulate the bacteria and protect them from the immune response making them hard to treat!
What is a vegetation?
Collection of bacterial cells, platelets, fibrin and inflammatory cells
What subgroup of the population are particularly susceptible infectious endocarditis?
IV Drug users
Particularly targets the tricuspid valve (80% strep aureus)
What are the portals of entry for pathogens into the bloodstream?
Oral cavity
skin
upper respiratory tract
What is indicative of infectious endocarditis in a pt?
positive blood cultures–> indicate presence of bacteria in the blood
What are the two types of endocarditis and how do they differ?
Acute (103-104) and Subacute (<103)
They have similar sxs, but subacute progresses more slowly and is less pronounced. It is often accompanied by splenomegaly.
What are sxs commonly associated with endocarditis?
LOOK ILL
FEVER, CHILLS/SWEATS, HEART MURMUR
low grade fever night sewats chills fatigue malaise generalized weakness anorexia low back pain
What are physical findings associated with endocarditis?
cardiac murmur conjuntival petechiae Unexplained arterial emboli: (splinter hemorhages in the nails, Roth's spots) osler nodes Janeway lesions
What are common laboratory findings associated with infectious endocarditis?
Anemia elevated ESR elevated CRP Presence of RF Circulating Immune complexes
What bacteria are commonly responsible for acute endocarditis?
Staph Aureus (Mainly) Strep pyogenes (sometimes)
Describe the temporal progression of Staph aureus in acute endocarditis?
Hectically febrile
Rapidly damages cardiac structures
Seeds infection in distal sites through sepsis
If untreated leads to death in weeks
What bacteria commonly cause subacute endocarditis?
Streptococcal species (viridans)
Enterococcal species
Describe the temporal progression of Strep Viridans in Subactue endocarditis?
Indolent course of infection
Causes structural damage slowly
rarely seed infection at distal sites
progresses gradually
What does viridis mean in latin? And how does this relate to bacteria?
Green
Viridans just refers to “green-growers” on the blood agar plate not a specific species. (alpha hemolytic)
What is the difference between gamma, alpha and beta on a blood agar plate?
Gamma- no hemolysis
Alpha- partial deconstruction of blood cells in media–> greenish color
Beta- completely destroys RBCs in the agar so it looks yellow (color of hte agar plate)
How do strep mutans/viridans differ from strep pyogenes on an agar plate?
Mutans/viridans are alpha hemolytic.
Pyogenes is beta hemolytic.
What is indicative of a Positive result for endocarditis according to Duke’s Criteris?
2 major criteria OR
1 major and 3 minor criteria OR
5 minior
What are the 2 major criteria for endocarditis?
- Positive blood culture (same organisms, 2 positive cultures separated by time)
- Evidence of endocardial involvement (valve issues) –> apparent with echocardiogram
What are the 4 minor criteria for endocarditis?
- Predisposition (heart condition/drug use)
- Fever above 100.3
- Vascular phenomena (arterial emboli, janeway lesions)
- Immunological phenomena (osler’s nodes, roth’s spots, rheumatoid factor)
- Microbiological evidence (positive blood culture, but doesn’t meet criteria)
What is a Janeway lesion?
Non-tender, small hemorrhagic lesion on the palms/soles