JH IM Board Review - Infectious Disease VII Flashcards
Infective endocarditis (IE) - Types:
- Native valve endocarditis ==> Acute and subacute.
- Prosthetic valve endocarditis ==> Early and late.
- IVDU-related.
How is IE now classified?
BY ORGANISM (rather than the time course of infection).
==> Because the etiologic agent is what determines treatment.
IE - Predisposing factors:
- Age >60.
- Male sex.
- Abnormal cardiac anatomy (abnormal heart valve - MVP).
- Prosthetic valves.
- IVDA.
- Poor dentition.
- Presence of intravascular device, such as a catheter.
- Previous endocarditis.
- Hemodialysis.
- HIV.
IE - Absence of visible vegetation does NOT …?
Exclude Dx.
IE - Systemic emboli are seen in up to …?
45% of patients ==> May involve any organ.
IE - Large emboli are common in …?
FUNGAL IE.
IE - Immune complex disease:
More often in patients with subacute bacterial endocarditis.
- Glomerulonephritis.
- Roth spots (retinal hemorrhages).
- Osler nodes (tender nodules on finger or toe pads).
IE - Culture-negative IE - Etiology:
- HACEK are now readily cultured with contemporary blood culture systems. 3-5% of native valve infections.
- May need to hold blood cultures for 3weeks if organisms such as Bartonella, Brucella are suspected.
Unusual IE organisms:
- C.burnetii (Q fever) ==> Dx by serology, culture often negative.
- Fungi ==> Candida spp. most common, followed by Aspergillus spp.; susceptible hosts include those with history of injection drug use, prosthetic valve recipients, and immunocompromised hosts.
- Bartonella, Chlamydia, Legionella, Brucella, Mycoplasma spp. are rare causes of IE.
Prosthetic valves - Early and late IE:
EARLY ==> Within 2 months of valve insertion.
LATE ==> Within 12 months after valve insertion.
The risk of prosthetic valve endocarditis is highest in the …?
FIRST 6 MONTHS following valve placement.
==> Infections less than 2 months after surgery are often NOSOCOMIAL, although those that occur MORE THAN 2 MONTHS after surgery are more likely to be community-acquired.
MCCs of prosthetic valve IE:
- S.aureus.
- CN staph spp.
==> Viridans group strep spp ==> RARE CAUSE OF EARLY prosthetic IE, but relatively COMMON CAUSE OF LATE prosthetic IE.
Causes of bacterial IE - “Typical”:
- S.aureus (MC).
- Viridans.
- Enterococcus.
- CN staph.
- S.bovis biotype 1.
- Other strep spp.
Causes of bacterial IE - “HACEK” group - Other:
- Haemophilus aphrophilus.
- Haemophilus parainfluenza.
- Actinobacillus actinomycetemcomitans.
- Cardiobacterium hominis.
- Eikenella corrodens.
- Kingela kingii.
Causes of bacterial IE - Injection drug use:
- S.aureus (MCC).
- Viridans.
- Enterococcus.
- Pseudomonas.
- Candida.
- S.epi.
- Polymicrobial.
Causes of bacterial IE - Unusual causes:
NO DOMINANT ORGANISM:
- Candida.
- Aspergillus.
- Coxiella.
- Bartonella.
- Chlamydia.
- Mycoplasma.
- Legionella.
- Brucella.
Causes of bacterial IE - EARLY prosthetic valve:
- S.aureus and CN staph (s.epi) ==> MCC.
- Gram (-) bacilli.
- Enterococcus.
- Diphtherioids.
- Fungi.
Causes of bacterial IE - LATE prosthetic valve:
- Viridans group strep, S.aureus.
- CN staph.
- Gram(-) bacilli.
- Enterococcus.
IE - Dx - DEFINITE bacterial IE is a …?
PATHOLOGIC Dx MADE BY CULTURE CARDIAC TISSUE.
IE - Dx - Blood cultures:
3 SEPARATE SETS of cultures should be drawn, ideally from 3 different sites.
==> They should also be separated in time, ideally 6 HOURS APART.
IE - Dx - TTE:
1st step in patients with native valves, no congenital heart disease, and no previous endocarditis.
==> Se = 62%.
==> If intermediate-to-high risk probability of having endocarditis ==> Proceed to transesophageal echo (TEE).
IE - Dx - TEE:
Can consider as a 1st step in pts with prosthetic valves, congenitl heart disease, and previous endocarditis/valve abnormalities.
==> Sometimes a 1st step in pts with limited transthoracic windows, clear stigmata of endocarditis, and new murmurs.
==> Se = 90-100% in native valve IE. Lower in prosthetic valve IE.
==> A negative TEE does NOT r/o IE.
IE - Tx - Principles:
- Parenteral abx preferred to ensure consistent and therapeutic abx levels.
- Extended therapy indicated - Usually 4-6 weeks, depending on the etiologic agent (shorter courses associated with risk of relapse).
- Bactericidal abx are preferred to bacteriostatic abx.
==> Abx choice should be guided by culture and sensitivity results.
Synopsis of Tx of bacterial IE - Viridans group strep or strep bovis biotype I with PCN MIC <0.12:
4 weeks PCN G.
==> If non-severe penicillin allergy use ceftriaxone.
Synopsis of Tx of bacterial IE - Viridans group strep or strep bovis biotype I with PCN MIC <0.12 - Comments:
2 weeks PCN or ceftriaxone, combined with gentamicin reasonable alternative for select patients with select infections (incl. prosthetic valve infection).
==> Severe PCN allergy ==> Use vanco.
Synopsis of Tx of bacterial IE - Viridans group strep with PCN MIC >0.12 and <0.5:
4 weeks PCN G or ceftriaxone, combined with gentamicin for first 2 weeks.
Synopsis of Tx of bacterial IE - Viridans group strep with PCN MIC >0.12 and <0.5 - Comments:
Severe PCN allergy: use vanco.
==> If prosthetic valve infection, use combination therapy for 6 weeks.
Synopsis of Tx of bacterial IE - MSSA, native valve, left-sided:
4 weeks nafcillin or oxacillin for uncomplicated disease.
For complicated disease ==> 6 WEEKS.
Complicated = Perivalvular abscess, metastatic disease, uncontrolled diabetes.
==> Tx decisions should be individualized.
Synopsis of Tx of bacterial IE - MRSA, native valve:
4-6 WEEKS vancomycin targeting a trough of 15-20microgram/mL.
Synopsis of Tx of bacterial IE - MRSA, native valve - Comments:
Complicated infections require at least 6-week course + discussion with infectious diseases and cardiac surgery consultants.
Synopsis of Tx of bacterial IE - S.aureus, prosthetic valve:
6 weeks therapy with nafcillin or oxacillin or vanco (depending on pathogen and sensitivities) in combination with aminoglycoside for initial 2 weeks and rifampin for 6 weeks after blood cultures have cleared (for S.aureus).
==> EARLY SURGICAL CONSULTATION is advised.
Synopsis of Tx of bacterial IE - Enterococcus spp:
4-6 weeks ampicillin combined with gentamicin or streptomycin if susceptible.
Synopsis of Tx of bacterial IE - Enterococcus spp. - Comments:
- Must ensure isolate susceptible to both ampicillin and gentamicin.
- If PCN allergic, consider desensitization, but if anaphylaxis consider vancomycin.
- If aminoglycoside resistance demonstrated ==> pursue combination therapy with ampicillin + ceftriaxone; other antimicrobial resistance is common and should prompt infectious diseases consultation.
Synopsis of Tx of bacterial IE - Fungal:
Early surgery usually required.
Tx of IE - When to consider surgery:
- Failure of medical therapy (ie persistent bacteremia or fungemia).
- Infection with difficult to treat organisms (eg fungal, pseudomonas, brucella.
- Major embolic events.
- New CHF (+ moderate/severe AR/MR).
- Significant valve dysfunction, especially in prosthetic valves.
- Paravalvular extension; may be manifested by prolonged fever, aortic valve ring abscess, AV conduction defects, +/- fistulas and mycotic aneurysms.
- Prosthetic valve and organisms such as S.aureus, Pseudomonas spp, fungi, and resistant enterococci.
Prevention of endocarditis - Prophylaxis:
Recommendations were revised in 2007 because the risk of endocarditis from dental procedures is LESS than previously estimated.
==> Proph ONLY to patients with HIGH-RISK cardiac conditions who are undergoing procedures that are likely to cause bacteremia.
Procedures likely to cause bacteremia include:
- Dental procedures that involve manipulation of the gingiva or periapical region of the teeth, or perforation of the oral mucosa (not routine dental cleaning).
- Procedures of the respiratory tract that will lead to an incision or Bx of the respiratory mucosa.
- GI or GU procedures, only in patients with active GI/GU infections.
- Procedures involving infected skin or musculoskeletal tissue.
- Cardiac surgery involving placement of prosthetic material.
High-risk cardiac conditions include:
- Prosthetic cardiac valves, bioprosthetic and homograft.
- Presence of prosthetic material used for valve repair.
- Previous IE.
- Unrepaired CCHD, incl. palliative shunts and conduits.
- Completely repaired congenital heart defect with prosthetic material or device during the first 6 months after the procedure.
- Repaired congenital heart disease with residual defects at the site or next to prosthesis.
- Cardiac transplant recipients who develop cardiac valvulopathy.
Abx recommendations for IE prevention:
- Single-dose oral amoxicillin (2g) 30-60min before procedure (clindamycin, clarithromycin, or azithromycin if PCN allergic).
- Parenteral alternative: ampicillin 2g IV or IM (cefazolin or ceftriaxone 1g IM or IV are also acceptable).
- If patient has a severe PCN allergy and is unable to take oral medications, a single dose of clindamycin (600mg), azithromycin (500mg), or vancomycin (15mg/kg) can be used.
- If Bx through active infection, consider vanco if MRSA is a concern.
Low-risk patients for whom abx prophylaxis is NOT recommended:
- MVP.
- Bicuspid aortic valve.
- Acquired aortic or mitral valve disease.
- Pacemakers.
- Defibrillators.
Low-risk procedures for which endocarditis prophylaxis is NOT recommended:
- GI endoscopy (except sclerosis or dilatation/ ERCP).
- Restorative dentistry.
- Gynecologic procedures: vaginal hysterectomy, vaginal delivery, cesarean section.
- Cardiac procedures: cardiac catheterization, balloon angioplasty.
