Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (88 page)

•
Adjust abx regimen & duration
based on valve (NVE vs. PVE); if possible, de-escalate abx to organism-directed Rx guided by
in vitro
sensi's or local patterns of Rx-resist. Add rifampin for PVE due to staph spp. (usually after BCx
to ↓ risk resistance develops).

• Repeat BCx qd until Pt defervesces and BCx
; usually 2–3 d • Fever may persist even >1 wk after appropriate abx or due to metastatic sites • Systemic anticoagulation relatively
contraindicated
given risk of hemorrhage in cerebral embolic strokes; w/o stroke, can continue short-acting anticoag for pre-existing indication • Monitor for complications of endocarditis (CHF, conduction block, new emboli, etc., which can occur even on abx) and of abx Rx (interstitial nephritis, ARF, neutropenia, etc.) • Duration of Rx: usually
4–6 wk
. With NVE & sx <3 mo → 4 wk of abx; sx >3 mo → ≥6 wk. Uncomplicated right-sided NVE or PCN-S strep spp → 2 wk may be comparable.

• Posthospitalization outPt IV abx monitoring; future endocarditis Ppx
Indications for surgery
(
EHJ
2009;30:2369;
Circ
2010;121:1005 & 1141)

• Several days of abx (if possible) to ↓ recurrence of infection and improve structural integrity of tissue to receive prosthesis •
Severe valvular dysfunction
→
refractory CHF
:
emergent
if refractory cardiogenic shock (ie, despite ICU-level Rx);
urgent
(w/in days) if persistent refractory heart failure;
elective
(w/in wks) if asx severe AI or MR

•
Uncontrolled infxn
(urgent surgery w/in days): periannular abscess (10–40% NVE, 60– 100% PVE), fistula, worsening conduction, PVE w/ dehiscence, ↑ veg. size or persistent sepsis (eg,
BCx [? or fever] after ~1 wk of appropriate IV abx and no drainable metastatic focus or other identifiable cause) •
Organism
: consider surgery for
S. aureus
, fungal or multiRx resistant organisms •
Systemic embolism
(20–50%): risk 4.8/1000 Pt days in 1st wk, 1.7/1000 thereafter

urgent surgery if L-sided w/ >10 mm veg & severe AI/MR (
NEJM
2012;366:2466) or if recurrent emboli, embolism & >10 mm veg, or >15 mm veg despite approp. abx

cerebral emboli
no longer considered contraindic to surgery unless hemorrhage (then ideally wait 1 mo) or severe stroke (
Stroke
2006;37:2094)

•
PVE
: esp. w/ valve dysfxn
or
dehiscence
or S. aureus
or GNR infection. Seek ID eval.

Prognosis

• NVE: non-IVDU
S. aureus
→ 30–45% mortality; IVDU
S. aureus
(typically right-sided) → 10–15% mortality; SBE → 10–15% mortality • PVE → 23% mortality • Aortic valve worse prognosis than mitral valve

BACTEREMIA

Etiologies

• 1° infxn due to direct inoculation of the blood, frequently assoc w/ intravascular catheters. Catheter-related bloodstream infection = same org from peripheral cx
and
cath tip cx
or
cx drawn from catheter (
CID
2009;49:1).

• 2° infxn due to infection in another site (eg, UTI, lung, biliary tree, skin) spreading to blood
Microbiology

• 1° infxn/indwelling catheters (
ICHE
2008;29:996): coag-neg staph (incl
S. epi
and others) 34%,
S. aureus
10%, enterococci 16%,
Candida
spp. 12%,
Klebsiella
spp. 5%

• 2° infxn: dependent on source
Risk factors for true bacteremia
(
JAMA
2012;308:502)

•
Pt
: fever, shaking chills, IVDU, comorbidities, immunosupp, indwelling catheter, SIRS

•
Organism

more likely pathogenic:
S. aureus
, b-hemolytic strep, enterococci, GNR,
S. pneumo, Neisseria
less likely pathogenic: coag-neg staph (~10%), diphtheroids,
Propionibacterium
(~0%)

•
Time to growth
: <24 h → higher risk, >72 h → lower risk (except for slow-growing organisms such as HACEK group) •
Factors increasing the likelihood of endocarditis
: high-grade bacteremia w/o source, persisting after line removal or drainage of focal source, in hosts at risk for endocarditis or w/ organisms known to cause IE (Duke criteria); emboli
Diagnosis

•
Blood Cx
: prior to 1st abx dose if possible; 10 cc in each Cx bottle; add’l Cx if high risk
Treatment

•
1
°
infxn
: antibiotics based on Gram stain/culture results; tailor abx to sensitivities empiric therapy for GPC: vanco to cover coag-neg staph and MRSA while awaiting sensi

•
2
°
infxn
: assess for primary source of infection and treat. Source control essential for cure and to prevent recurrence.

•
Persistently
BCx
: d/c indwelling catheters, consider metastatic infxn, infected thrombosis or infected prosthetic material (joint, abscess, vascular graft, pacemaker, etc.)

TUBERCULOSIS

Epidemiology

• U.S.: 10–15 million infected (10× ↑ risk if foreign-born or minority); worldwide: ~2 billion • After resurgence in U.S. 1984–1992, rates declined, though slower than CDC goals • Multidrug resistant (
MDR
)
TB:
resistant to isoniazid (INH) and rifampin (RIF). Can occur as new (not previously treated) infxn if exposed in former Soviet Republics, Russia, China • Extensively drug resistant
(XDR) TB
resistant to INH, RIF, FQ and injectables •
Pts more likely to develop TB disease
(
NEJM
2011;364:1441)

High-prevalence populations
(more likely to be exposed to & infected): immigrant from high-prevalence area, homeless, IDU or medically underserved, resident or worker in jail or long-term facility, HCW at facility w/ TB, close contact to Pt w/ active TB

High-risk populations
(infected & likely to progress to active disease): HIV
, immunosupp. incl. biologics, uncontrolled DM & smoking, close contact w/ active TB Pt, underweight, CKD, organ Tx, IVU, EtOH, malnourished, cancer, gastrectomy