Bacteremia & Endocarditis Flashcards
What is bacteremia?
Bacteremia is the presence of viable bacteria in the blood stream.
What are potential sources of bacteremia?
- focal infections
- indwelling devices
- medical procedures
Focal infection = a localized infection that has the potential to spread
What is infective endocarditis and how does it affect the heart?
Infective endocarditis is inflammation/infection of the endocardium, typically affecting the heart valves, that is caused by microorganisms entering the bloodstream.
What are the major criteria within the Modified Duke Criteria?
- Positive blood cultures from two or more sets
- positive lab tests for coxiella burnetii
- ECG showing vegetation, abscess, or fistula
- significant new valvular regurgitation
- evidence of IE documented by direct inspection during cardiac surgery
How is Modified Duke Criteria used to diagnose infective endocarditis?
Based on the number of major and minor criteria that are fulfilled, patients are categorized into three separate groups:
- definite infective endocarditis
- possible infective endocarditis
- rejected infective endocarditis
What risk factors are associated with bacteremia?
- advanced age
- IV drug use
- presence of indwelling prostheses like vascular catheters
These factors can compromise the immune system or provide entry points for bacteria
Which organisms are the common cause of infective endocarditis?
- staphylococcus aureus
- strep viridans
- enterococci
These organisms can readily adhere to damaged heart valves.
What is the role of echocardiography in the diagnosis of bacteremia and infective endocarditis?
ECG is used to visualize valvular vegetations and assess cardiac function.
In bacteremia, ECG helps rule out or confirm the presence of infective endocarditis – especially with S. aureus.
What is the significance of MRSA bacteremia and how does it impact treatment?
MRSA bacteremia is significant because penicillins are ineffective so the use of vancomycin or daptomycin is required. MRSA complicates treatment.
What are the consequences of vegetations?
Vegetations are colonies of bacteria on heart valves that are protected from antimicrobials and hosts defenses.
- valve damage
- embolization
- systemic complications
Why are follow-up blood cultures important in the management of bacteremia and infective endocarditis?
Follow-up blood cultures are important to assess the effectiveness of antimicrobial therapy and to confirm clearance of bacteremia. Persistent positive cultures may indicate antimicrobial resistance or an undrained focus of infection.
When and how is antimicrobial prophylaxis against infective endocarditis?
- Antimicrobial prophylaxis is used to prevent IE in high-risk individuals that cause bacteremia.
- Patients with prosthetic heart valves and/or history of IE are considered high-risk.
- Amoxicillin is the drug of choice for prophylaxis
What organism is the leading cause of community-acquired and hospital-acquired bacteremia?
staph aureus
When is day 0 of antibiotic therapy for staph aureus bacteremia?
Day 0 for SAB is the first day the blood cultures come back negative.
What diagnostic tests are completed for SAB?
staph aureus bacteremia
- blood cultures (2 sets) Q48-72H
- TTE is performed first, but TEE is better and preferred for MRSA bacteremia
TTE = transthoracic echocardiography
TEE = transesophageal echocardiography (more invasive)
How should catheters and prosthetic devices be viewed in patients with SAB?
staph aureus bacteremia
Consider all IV catheters and prosthetic devices to be infected in patients with SAB until infection is ruled out.
What are the empiric treatment options for staph aureus bacteremia?
- vancomycin IV
- daptomycin IV
Empiric treatment goal is to cover MSSA and MRSA.
What are the treatment options for MRSA bacteremia?
- vancomycin IV
- daptomycin IV
- AUC/MIC goal of 400-600 for vanc
What are the treatment options for MSSA bacteremia?
- Nafcillin IV
- Oxacillin IV
What is duration of treatment for SAB based upon?
uncomplicated vs complicated vs complicated w/ metastatic infection
What are the abx treatment durations for uncomplicated SAB, complicated SAB, and complicated SAB with metastatic infection?
- uncomplicated –> 14 days from first negative blood culture
- complicated –> 4 weeks
- complicated w/ metastatic infection –> 6-8 weeks
Day 0 of abx therapy is the first day the blood cultures come back negative
What are the criteria for uncomplicated SAB?
- exclusion of endocarditis (negative TTE, TEE)
- no indwelling or implantable devices or prostheses
- follow-up blood cultures drawn 2-4 days after initiation of IV therapy and removal of source of infection are negative
- patient is afebrile within 2-3 days after initiating IV therapy and removal of source of infection
- no evidence of metastatic infection
- Must meet all criteria to be uncomplicated
- Duration of therapy is 14 days of IV therapy from first negative blood culture
What route should be used for abx in the treatment of SAB?
staph aureus bacteremia
IV therapy for the full duration is gold standard for SAB.
Exam Q
What is the treatment duration for bacteremia due to streptococci?
What route?
14 days and you can transition from IV to PO in bacteremia due to strep
gram-positive cocci
What are the treatment options for bacteremia due to strep?
- penicillin
- ceftriaxone (s. pneumo)
Duration: 14 days
Transition from IV –> PO
What is the treatment duration for bacteremia due to enterococci?
gram-positive cocci
7 days
What are the treatment options for bacteremia due to enterococci?
- If e. faecalis –> ampicillin
- If e. faecium –> vancomycin
- if VRE –> dapto or linezolid
Duration: 7 days
What is the duration of treatment for uncomplicated gram-negative bacteremia?
7 days from the start of therapy
- 7 total days of therapy
- longer is not always better
How does treating staphylococci (MRSA or MSSA) IE differ between native valve and prosthetic valve?
- native –> use DOC
- prosthetic –> use DOC + rifampin + gentamicin
- duration of tx is 6 weeks in both cases
How does treating group strep IE differ between penicillin susceptible and penicillin resistant?
- pcn sus –> monotherapy or combo
- pep resist –> combo
- monotherapy: pcn or ceftriaxone
- combo: (HD pcn or ceftriaxone) + gentamicin
How do treatment durations differ for IE between native valve and prosthetic valve?
- native –> 4 weeks
- prosthetic –> 6 weeks
What are the treatment options for enterococcus IE?
- ampicillin + gentamicin
- penicillin + gentamicin
- ampicillin + ceftriaxone
- ampicillin + streptomycin
- penicillin + streptomycin
- vancomycin + gentamicin
- daptomycin
- linezolid
- TX BASED ON SUSCEPTIBILITY
- if the regimen is missing a pcn OR gentamicin, the duration is 6 weeks
- otherwise, 4-6 weeks duration
What are the treatment options for HACEK IE?
Haemophilus, Aggregatibacter, Cardibacterium, Eikenella, Kingella
- ceftriaxone
- ampicillin +/- sulbactam
- ciprofloxacin
Native –> 4 weeks
prosthetic –> 6 weeks
What are the treatment options for culture-negative native valve IE?
- acute onset –> vancomycin + cefepime
- subacute onset –> amp/sulbactam + vancomycin
What is the treatment option for early onset culture-negative PVE?
vancomycin + gentamicin + rifampin + cefepime
4 drug regimen
What is the treatment option for late onset culture-negative PVE?
vancomycin + ceftriaxone
What are the treatment options for culture-negative endocarditis with suspected bartonella?
ceftriaxone + gentamicin +/- doxy
What is the treatment option for culture-negative endocarditis with documented bartonella?
gentamicin + doxy
What is the drug of choice for IE prophylaxis?
amoxicillin
When is day 0 of abx therapy for any kind of endocarditis?
The first day of negative cultures
