Diebel Week 1 Flashcards
What are the normal biota of the cardiovascular system?
none
What are the natural defenses found in the cardiovascular system?
complement, white blood cells and antibodies
Define infectious endocarditis
inflammation of the inner lining of the heart (endocardium) typically caused by infection; usually mitral or aortic valve
What is the usual cause of acute endocarditis?
results of an overwhelming bloodstream challenge with bacteria with ability to colonize normal heart valves
Define vegetations
growth on the valves composed of fibrin, WBC, biofilm and bacteria; hampers cardiac function
What is the usual cause of subacute endocarditis?
develops slowly, less pronounced sx, preceded by prior damage to heart valves
Symptoms of subacute endocarditis
fever, anemia, abnormal heartbeat and sometimes abdominal or side pain; may look very ill and may have petechiae, septic emboli, Roth’s spots, splinter hemorrhages under the fingernails
What type of endocarditis may cause a large spleen?
subacute endocarditis; dt chronically fighting bacteria in the blood
Note the temporal evolution of acute endocarditis?
hectically febrile to rapidly damages cardiac structures to seeds infection in distal sites through sepsis to death
What are largely the causes of acute endocarditis?
Staphylococcus aureus and Streptococcus pyogenes
What are largely the causes of subacute endocarditis?
Streptococcal viridans and enterococcal species
What is the temporal evolution of subacute endocarditis?
indolent course of infection to causes structural cardiac damage slowly to rarely seed infection at distal sites to gradually progressive
What hemolysis is viridans?
alpha hemolytic on blood agar plates
What are the portals of entry for endocarditis?
oral cavity, skin and upper respiratory tract are the primary infection sites
Where is the local infection for endocarditis in the heart?
mitral valve, tricuspid valve (injection drug use) and prosthetic valves
What two things can give you a presumptive dx for endocarditis?
fever and valvular abnormalities (known injection drug use is also helpful)
What is the range for fever in subacute infectious endocarditis?
usually less than 103F
What is the temperature seen in acute infectious endocarditis?
103 to 104F
What is a positive Duke Criteria for infectious endocarditis?
2 major criteria met, 1 major and 3 minor criteria met or 5 minor criteria met
Can the Duke Criteria dx be overridden
Yes-if alternative dx is established, sx resolve and do not recur with less than 5 days of abx therapy or lack of histological evidence of endocarditis
What criteria denotes possible endocarditis?
1 major and 1 minor or 3 minor criteria
What are the 2 Duke Major Criteria?
- Positive Blood Culture
2. Evidence of endocardial involvement
What bacteria are included in a positive blood culture for Duke Major Criteria?
viridans streptococci or Streptococcus bovis or HACEK group microorganisms or Staph aureus or enterococci
How many positive cultures of blood samples drawn how many hours apart for a positive blood culture?
2+, more than 12 hours apart or all of 3+ or majority of 4 separate cultures drawn within an hour
What if detected in a single blood culture plus a positive IgG antibody titer is a positive blood culture for Duke Major Criteria?
Coxiella bruentii (Q fever)
What 3 things are evidences of endocardial involvement for a Duke Major Criteria?
- oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets or on implanted material 2. abscess 3. new partial dehiscence of prosthetic valve or new valvular regugitation
What are the 5 Duke Minor Criteria?
- predisposition (heart condition of injection drug use) 2. fever above 100.4F 3. vascular phenomena 4. immunological phenomena 5. microbiological evidence
Name vascular phenomena in endocarditis that are a Duke Minor Criteria?
arterial emboli, Roth’s spots
Name immunological phenomena in endocarditis that are a Duke Minor Criteria
Osler’s nodes, rheumatoid factor, glomerulonephritis, Janeway lesions
Name microbiological evidence that meet the Duke Minor Criteria for endocarditis
positive blood culture but not meeting major criterion
Name the organisms that make up HACEK
Haemophilus, Aggregatibacter (Actinobacillus), Cardiobacterium, Eikenella, Kingella
Describe the group that the HACEK organisms belong to
group of fastidious gram negative bacteria (won’t grow on regular plate–need chocolate agar)
Are HACEK a more or less common cause of endocarditis?
less common cause
What can cause endocarditis but are a normal part of the human microbiome within the oral-pharyngeal region?
HACEK organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
What do you use to tx subacute endocarditis?
gear tx towards a strep infection: AMPICILLIN/SUBLACTAM + GENTAMICIN or TOBRAMYCIN; or VANCOMYCIN + CEFTRIAXONE
What abx are good for Staph aureus but NOT MRSA?
nafcillin or oxacillin +/-gentamicin or tobramycin (think naf for staph)
What abx is good for gram (+) multidrug-resistant bacteria only including MRSA, S.epidermidis, Enterococcus species, Clostridium difficile
Vancomycin
What abx is good for severe gram (-) rod infections and works synergistically with beta-lactam antibiotics?
gentamicin (an aminoglycoside); also works on HACEK organisms
penicillinase-sensitive penicillin; extended spectrum penicillin
Ampicillin
What is used against S. pneumoniae, S.pyogenes, Actinomyces, N. meningitidis, T. pallidum?
Penicillin (G or V)
a beta-lactamase inhibitor; often added to penicillin antibiotics to protect the penicillin from destruction
sublactam
3rd generation cephalosporin; used for serious gram (-) infections including N. gonorrheae, N. meningitidis and disseminate Lyme disease
Ceftriaxone
If pt. has a penicillin allergy what do you use to treat endocarditis?
cephalosporins (3rd to 5th generation) or carbapenems or vacomycin
what is the most common cause overall of endocarditis?
Staphylococcus aureus
gram positive facultative anaerobe
Staphylococcus aureus
What are the virulence factors of Staphylococcus aureus?
biofilm formation, capsule, adhesins, secreted enzymes and hemolysins, and pathogenicity islands for methicillin resistance
bacteria, gram +, cocci, catalase +, cogaulase +
Staph aureus
most common infectious agent of the skin; superficial infections like boils or abscesses, can produce several toxins that lead to serious toxin-mediated diseases
Staphylococcus aureus
Describe the clinical presentation of Staphylococcus aureus
localized skin/subq infection (impetigo, cellutlitis, folliculitis, furuncles, carbuncles; common infectious agent of surgical wounds
What does Staph aureus use to colonize the skin?
protein A (binds Fc portion of IgG), coagulase (forms fibrin coat around the organisms), hemolysins and leukocidins (destroy RBCs and WBCs)
How does an infection reach the blood stream?
neutrophils localize to the infection site and purulent abscesses form, then skin/subq infections may more deeply invade and reach blood stream
What are the virulence factors for deep tissue invasion of Staphylococcus aureus?
hyaluronidase (breaks down connective tissue), staphylokinase (lyses formed clots), lipase (breaks down fat)
What is the 2nd major cause overall of endocarditis?
Streptococcal species (viridians); several oral Streptococcal species possible
What species usually involves underlying mitral valve damage (rheumatic fever, etc) which provides the site for bacterial colonization?
Streptococcal species (viridans); often S. mutans
What can viridans species of Streptococcus produce to assist in colonization?
dextran for glycocalyx formation and surface adhesion proteins
What is the 3rd major overall cause of endocarditis?
Enterococcus species
What cause of endocarditis is most frequently found following genitourinary procedures in older men and obstetric procedures in younger women?
enterococcus species (preceded by bacteremia)
Name the virulence factors of enterococcus species?
pili, surface proteins, extracellular enzymes like proteases and hyaluronidases
What causes endocarditis but is usually resistant to penicillin and carbepenems?
Enterococcus species
Describe the clinical presentation of Streptococcus pyogenes
- localized skin/subcutaneous infection=impetigo, erysipelas, cellulitis 2. toxin-mediated=toxic shock syndrome, necrotizing fasciitis
What bacteria can colonize the skin (following trauma) leading to colonization to inflammation to pustular lesions and honeycomb-like crusts (impetigo)?
Streptococcus pyogenes
What do deeper infections of Streptococcus pyogenes cause?
erysipelas and cellulits
Invasion from skin infections of Streptococcus pyogenes can lead to what? but NOT what?
can lead to glomerulonephritis but not Rheumatic fever
Name the important virulence factors for spread and inflammation of Streptococcus pyogenes?
Streptokinase (converts plasminogen to plamsin), M protein (resists phagocytosis), Hyaluronidase (breaks down connective tissue), DNase (digests DNA), Streptolysin O (destroys RBCs), Streptolysin S (destroys WBCs)
pathway to toxic shock syndrome from skin (Streptococcus pyogenes)
skin infection (cellulitis) to systemic release of pyrogenic exotoxins A (superantigen) to polyclonal activation of T cells to acute fever, shock, multi-organ failure
pathway to Necrotizing fasciitis (Streptococcus pyogenes)
trauma allows for deep seated infection to release of exotoxin B (protease) to rapid necrosis along fascial planes with no damage to muscles
cause of Rheumatic Heart Disease
Streptococcus pyogenes pharyngitis (genetically predisposed individuals)
What is a definitive clinical indicator of Streptococcus pyogenes?
mitral stenosis following pharyngitis with a rash is a definitive clinical indicator
What is the cause of the damage to the heart muscles valves in Rheumatic heart disease?
autoantibodies (antibodies to bacterial antigens cross-react with meromyosin in the heart); a type 2 hypersensitivity
Name the risk factors for rheumatic heart disease
strep throat infection (prolonged/untreated); prior case of rheumatic fever; age 5 to 15 years old
Symptoms of Rheumatic Heart Disease
usually appear 2 to 4 weeks after strep infection; pain swelling in large joints, fever, weakness, muscle aches, shortness of breath, chest pain, nausea and vomitting, hacking cough, circular rash, lumps under the skin
Inflammation of the myocardium (middle layer of the heart wall); usually cuased by a viral infection (coxsackievirus B and adenovirus in children)
Myocarditis
possible cause of chest pain, heart failure, and abnormal heart rhythms
Myocarditis
name a virus, ssRNA (+), Group IV, nonsegmented, icosahedral nucleocapsid, noneveloped, picornaviridae, enterovirus
Coxsackievirus B
Define pericarditis
inflammation of the pericardium (sac-like membrane surrounding the heart)
Is pericarditis typically acute or chronic?
acute
What is the usual cause of pericarditis
coxsackieviruses A and B, echoviruses and influenza virus; usually during summer months with increase in enterovirus infections
chest pain associated with the irritated layers of the pericardium rubbing against each other
pericarditis
Name three picornaviruses that cause carditis
coxsackie A virus, cosackie B virus, echovirus
What is the cause of Rocky Mountain Spotted Fever ?
bacterium Rickettsia rickettsii
What are the symptoms of Rocky Mountain Spotted Fever?
fever, headache, abdominal pain, vomiting, muscle pain, rash starting from extremeties
What is the classic triad that can be diagnostic of Rocky Mountain Spotted Fever?
fever, headache, rash and in an area with known ticks (can be later confirmed with lab tests)
What is the first line tx of Rocky Mountain Spotted Fever?
Doxycycline (effective is started before teh 5th day of sx)
Name two obligate intracellular parasites that need host ATP
chlamydiae and rickettsiae
Name three causes of palm and sole rash
RMSF, syphillus, coxsackievirus
Where does rickettsia ricettsii proliferate?
in endothelial cells
what is the vector for Rickettsia rickettsii?
Dermacentor wood or dog tick
What is the cause of the rash in rickettsia rickettsii?
inflammation of endothelial lining of small blood vessels to maculpapular rash from palms and soles spreading to the trunk to vasculitis to headache and CNS, renal damage to death
