Infective Endocarditis (M/A)

Infective Endocarditis (MA65)

Definition:

-microbial infection of endocardium

-prev called acute vs subacute, but no longer use this much

-Low-virulence bugs- a-hemolytic strep, enterococci, coag neg staph --> prolonged subacute illness

-Highly virulent bugs- staph a, other pyogenic bacteria (Strep neumo, b-hemolytic strep)--> acute illness

Epi:

-increasing incidence as pts w CHD survive

Bugs:

-S Viridans very adherent to valves

-gram neg bugs adhere poorly (in in vitro tests) and are rarely an etiology

-Gram+cocci are in 90% of adult cases - mostly a-hemolytic strep in all age groups, w Staph a and coag neg staph next

-most kids get it fr an infected intravascular device

-enterococcus much less common in kids vs adults

-Gram neg buts <10% of cases in kids, but in imm'comp pt and drug users, there's incr risk for gram neg

-HACEK group of fastidious GNBs:

-H parainflu, H aphrophilus, H paraphrophilus, H influenza, Actinobacillus actinomycet., Cardiobacterium hominis, Eikenella, Kingella Kingae, Kingella dentrificans

-Rare: N gon (but can destroy valves...)

-In IVDA pts, see isolated S aureus and GNBs, espec pseudomonas, also candida/other fungi

-Prosthetic valve endocarditis

-if <2-3mo postop- S aureus, coag neg staph (but the latter can wait a year to present)

-Anaerobes rare in kids

-Fungal- frequent complications- embolization espec

-Candida #1, also Aspergillus, and others

-high mortality

-5-10% pts w endocarditis have negative BCx

-Cx neg Endocarditis Dx made clinically/by echo - usually a HACEK (grows poorly in vitro)

Path:

-pre-existing congenital or acquired lesions of heart/vessels (e.g. catheter, IVDA etc)

-damage to endothelium, form a nonbacterial thrombotic endocarditis at surface, then transient bacteremia and bacterial adherence to the site, then prolif bacteria at the vegetation site

-Nearly all vegetations occur in areas where there's a P gradient that --> turbulent Q that --> trauma to endothelial surface fr high velocity jet.

-e.g. AV vlvs (atrial side) and semilunar valves (ventric side)

-the fibrin deposit around the bacterial site makes it hard for abx and for WBCs to attack

-emboli fr the site--> xx, in part bc of immune response

-RF+ for 6 weeks or more in 1/2 pts, usually w the low virulent (subacute) IE, fr hyperimmune syst...

-Circulating Immune complexes, may deposit in renal system

-Kidney may get micro/macroscopic emboli, usually sterile but abscess have formed fr septic emboli to kidney

-Pt may get glomerulonephritis- focal or diffuse

-dental procedure can dislodge bacteria at mucosa..., or can be spontaneous bacteremia...

Sx/Si:

-fever, systemic toxicity fr bacteremia

-L Heart IE--> periph embolization--> ischemia, infarct, mycotic aneurysm

-R Heart IE--> emboli missed bc of lung filter, but a large PE might complicate TV endocarditis

-Fever- low grade (max 39C) w alpha streph, but high w staph a...

-Subacute--> NonSp Sx- myalgia, arthralgia, HA, malaise, decr PO

-Acute--> toxic, high fever

-Murmur- increase in intenity of diastolic murmur of AR--> c/s progressive Ao vlvr deterioration which can worsen LV dysfx/HF, etc; or if a decr in the continuous murmur in a cyanotic kid w a syst to PA shunt, might mean shunt involvement...

-Extracardiac: splenomegaly (after weeks/months)

-Neuro: (20% kids)- abscess, infarct, aseptic meningitis

-Renal: proteinuria, hematuria, leukocyturia, if emboli or immune complex deposits

-Osler Nodes- small, tender, raised lesions at finger/toe pads

-Janeway lesions- small, nontender, flat, red lesions at palms/soles

-Roth spots- retinal hemorrhages w central white spots

-Splinter hemorrhages

-Neonates- can have few Sx, or shock/sepsis etc

Dx:

-BCx is key to Dx

-3 Separate BCx fr 3 diff puncture sites over 24 hours

-c/s waiting on abx until after BCx drawn

-the bacteremia is continuous, so you don't have to wait for a fever to get the BCx

-Get appropriate bld volume for each Cx- 20-30mL fr an adult, and 1-3mL in infant/toddler, 5-7mL in older kid

-no need for aerobes as it is a rare cause of IE

-ESR may be only minimally elevated initially, then increase, so trend it

-RF+ in 1/2 pts

-Anemia common

-WBC elevation is not consistent but more common w acute IE

Echo

-TTE >80% Sn for IE, but thus not Sn to be confident.

-TTE better for pt w structurally Nl heart or isolated valvar problem

-adult data shows TEE better than TTE, but no evidence in kids

-still TEE in kids lets you look for paravalvar leakage and xx like dehiscence of prosthetic vlv

Dx Criteria:

-see Modified Duke criteria:

Tx:

-the bacteria are in high [ ] within the fibrin vegetations, and have low rate of division--> less abx susceptible to Rx that affects fell wall (e.g. beta lactams)

-Better to use bactericidal (not bacteriostatic) Rx

-must ensure you clear the bacteremia w neg BCx, and w f/u BCx to ensure no relapse

-surgery to check infection site determined by clinical course- c/s if signif embolic events, persistent infection, progression to heart failure (espec Ao vlv or MV xx)

Strep Endocarditis

-very PCN Sn

-#1 bug in kids

-most are group D strep viridans, or gAS

-Tx w PCN-G, x4 weeks, or Ampicillin if PCN not available; or ceftriaxone x4 weeks

-in adults, some do 2 weeks of gent + PCN or CTX for uncomplicated pts w very Sn Strep D or S bovis

-not good if pt has had IE x >3mo, prosthetic valve, shock/decr perfusion mycotic aneurysm/cerebritis, renal failure, vestibular dysfx, or vegetations on echo.

-if PCN allergic, can do de-Sn'ion or vanc course +/- gent if resistance

Staph Endocarditis

-Nafcillin or Oxacillin x6 weeks +/- gent for first 3-5 days (gent doesn't incr cure rate but does more quickly --> neg BCx)

-Rifampin good against most staph, but --> resistance if used alone

-if oxacillin resistant, then use vanc

Gram-Negative Bacterial Endocarditis

-HACEK bugs...

-use 3rd/4th ceph or use amp/sulbactam, or cipro in adults if others not tolerated

-if E coli, pseudo aeruginosa, Serratia marcescens (mainly in IVDA pts), then tx by Sn (maybe ceftaz...)

-if N gon (rare), tx w high dose PCN, or 3rd gen ceph

Fungal Endocarditis

-poor Px, high M&M

-abx Tx nearly always not enough, need surgery

-ampho B, then surgery after 1-2 weeks

Cx-Negative Endocarditis

-less than 20% are Cx negative

-if pt had abx before BCx, rate of recovery decreases by 35-40%

-refer to AHA guidelines for Cx neg IE

Prosthetic Valve Endocarditis

-abx for at least 6 weeks

-if very Sn to PCN, Tx w PCN or CTX x6 weeks, else use same as nonproethetic valve, but continue gent for 2 weeks

-Vanc if PCN allergic...

-adult lit- early sugical replacement may reduce excessively high mortality, but timing must be individualized

-Operative indications: signif valvar obstruction, progressive HF 1y to vlv insuffic/dehisc, fungal endocarditis, persistent course of abx, recurrent major emboli

Prophylaxis

-Recent AHA guidelines on IE ppx:

-bacteremia fr daily activities is much more likely to cause IE than fr dental procedures, and only a very small number of IE cases might be prevented w abx ppx, even if it was 100% effective

-No longer rec ppx solely on incr lifetime risk of IE, but instead only for pts w underlying CV condition assoc w high risk of adverse outcomes of IE (see table)

-abx rec based on in vitro studies, with no good clinical trials to validate abx ppx efficacy

-rec against IE ppx for MVP

-SHOULD give ppx for dental procedures that involve manipulation of gingival tissue or periapical region of teeth or perforation of oral mucosa

-a TOF repaire w conduit would get ppx like a prosthetic vlv pt would, but pt w just an outflow tract VSD patch would not need Tx...

-ensure good dental hygiene/periodontal hygeine

-also give abx ppx for respiratory tract procedure, or infected skin procedure

-give the abx perioperatively (just before doing the procedure)

-use PCN, amp, amox- e.g. 50mg/kg up to 2gm

-ppx for open heart surgery w 1st gen ceph or vanc perioperatively