Resident Version
Infective Endocarditis Module
Created by Dr. Wendy Gerstein
Updated 5/09
1. Identify 4 risk factors and organisms associated with endocarditis.
2. Be able to use Duke Criteria to diagnose endocarditis.
3. Be able to choose initial empiric therapy for suspected endocarditis.
4. Recognize 3 common complications of endocarditis and institute appropriate
1. Mandell, Douglas, and Bennets Principles and Practices of Infectious Diseases,
sixth edition, Volume I; Cardiovascular Infections.
2. “infective endocarditis” and “prosthetic valve infections”
3. Reese and Betts ’ a Practical Approach to Infectious Diseases, Fifth Edition,
chapter 12 “Infective Endocarditis.”
Patient is a 79 yo male with past medical history notable for diabetes, hypertension, and
aortic prosthetic valve replacement who presents with abrupt onset of dizziness, fever to
103 F, weakness, and associated cough with sputum (unknown color). Patient denied
chest pain or tightness, denied sob, no GI or GU symptoms. He had no sick contacts, no
recent travel or procedures. No rashes and no recent breaks in skin except small wound
on left shin from bumping into metal chair, occurred one week ago, wife and patient did
not notice any signs of infection.
Past medical history:
AVR with mechanical valve 18 years ago
Percocet prn
Asa 81 mg daily
Finasteride 5 mg daily
Irbesartan 150 mg daily
Lovastatin 40 mg daily
Methocarbamol 500 mg tid
Warfarin 5 mg daily
Allergies: PCN – does not recollect reaction
Social history:
Lives with wife, retired military, quit tobacco and alcohol 40 years ago
T = 101.0 F, P 92-98, BP 101/40, RR 22 O2 Sat 93% RA
Gen: alert and oriented x 3, appears comfortable
Skin: no rashes, lesions, or evidence of embolic events; has one small dime size wound
on left shin, no surrounding erythema, scab in place.
Heent: PERRLA, EOMI, conjunctiva non-injected; mouth with pink, moist membranes,
no petechiae; neck without adenopathy, supple; teeth in good repair.
Lungs: few crackles at bases bilaterally, L>R; no wheezing, no egophony/dullness noted.
CV: Regular, s1, prominent s2, 2-3/6 SEM LUSB, and 2-3/6 SEM heard over apex. Apex
non-displaced. Normal pulses present.
Abd: soft, nt/nd, + bs, no masses, liver normal size.
Ext: no edema, warm, well-perfused.
Neuro exam – CN 2-12 intact/symmetric, strength normal, sensation intact.
Initial labs/studies:
UA completely negative except trace blood and 3 rbc/hpf
BUN/creatinine 48/1.8 (baseline 1.0)
Sodium 129, K 4.4, Cl 97, CO2 22
Transaminases and lfts wnl
Wbc 12.7, 94.9% neutrophils
Hct 43, platelets 151
INR 1.8
CXR: read by your resident:? patchy opacity LLL (small) – could be atelectasis vs small
EKG: no acute ST changes, normal intervals, no conduction abnormalities.
1. What is your initial differential diagnosis and management plan for this patient
based on the above information?
2. What is your working diagnosis now and how should management change?
TEE results: negative for vegetation, and shows a functioning AVR, and thickened
mitral valve leaflets with calcification.
3. Has endocarditis been ruled out, and can you safely stop the antibiotics?
Review Questions:
1. Predictors of mortality in prosthetic valve endocarditis (PVE) include which of
the following?
A) Late prosthetic valve infection
B) S. viridans infection
C) Severe heart failure
D) Persistent fever after 48 hours of antibiotics
2. Which organism is most frequently isolated in early (<60 days after
implantation) PVE?
A) S. viridans
B) S. aureus
C) E. faecalis
D) S. epidermidis
E) No organism identified
3. True or False questions
A) The Duke criteria for diagnosing endocarditis include echocardiography.
B) The TEE has 100% negative predictive value for endocarditis.
C) You can diagnose endocarditis with five minor criteria in the Duke Classification
D) Osler nodes and Roth spots are both immunologic phenomena.
E) Streptococcus species cause 60-80% of all native valve endocarditis.
Outline for discussion:
1. Definition of infective endocarditis (IE):
Infection of the endocardial surface of the heart; can include heart valves, septal defects,
mural endocardium. In addition arteriovenous, arterioarterial shunts (PDA), and
infections associated with coarctation of the aorta are clinically similar.
2. Epidemiology
A) Accounts for one case per 1000 hospital admissions
B) Annual incidence in the US is 10-20,000 new cases a year
C) Median age 58, men affected more commonly
D) Risk factors: most structural heart disease predisposes to IE (particularly if
creates disturbance in blood flow).
- Rheumatic heart disease major risk factor in the past in the US, but now
most predisposing cardiac condition only in developing countries.
- Congenital heart disease
- Marfan syndrome
- Degenerative cardiac lesions
- Mitral valve prolapse with thickened leaflets/redundancy
- Hemodialysis shunts/fistulas/nosocomial bacteremia
- Intracardiac prothesis (prosthetic valves), pacemaker wires, defibrillators
- HIV infection
3. Pathophysiology (simplified version)
A) Alteration of valve surface appears to be a prerequisite for subsequent bacterial
colonization. Initial alteration or trauma of the valve causes sterile fibrin-platelet
deposits to form, with associated interstitial edema and cellular distortion (called
nonbacterial thrombotic endocarditis – NTBE).
B) Areas of turbulent blood flow create conditions that subsequently lead to
bacterial colonization of NTBE lesion during transient bacteremia.
C) Transient bacteremia occurs whenever a mucosal surface heavily colonized
with bacteria is traumatized (dental extractions, GI/GU procedures). Low grade
bacteremia, usually lasts < 15-30 minutes.
D) These organisms can then adhere to the NBTE lesion on the valve, multiply,
causing IE.
E) Certain organisms are much more likely than others to adhere to the NBTE
4. Signs and Symptoms (severity related to causative agent)
A) Subacute Bacterial Endocarditis (SBE): insidious onset, weakness, fatigue,
night sweats, myalgias, fevers, can be for weeks to months. On exam there is
evidence of chronic illness, fever, and new murmur. Stigmata of endocarditis may
be present.
B) Acute Bacterial Endocarditis (ABE): abrupt onset of symptoms with high
fevers, chills, back pain, myalgias, usually ongoing for only a few days. On exam
patient is usually clinically ill with high fever, new murmur. Stigmata of
endocarditis may be present.
C) Other signs to look for include evidence of CHF, heart block or arrhythmias,
pericarditis (rare), and neurological symptoms.
5. Pathogens
A) Streptococci species are responsible for 60-80% of native valve IE. This
includes alpha-hemolytic strep species, Group D strep, S. pneumoniae, Group B
strep, Group G strep, Group A strep (in order of frequency). Reminder: S. bovis
is associated with colonic carcinoma – all patients with this organism need a
B) Staphylococci (coagulase positive > >> negative) are seen in 20-30% of cases.
In 1/3rd of cases of S. aureus acute IE, bacteria attack “normal” valves. S. aureus
IE is very acute/fulminant, 40% mortality.
C) Enterococci species: 5-18% of cases, usually subacute process, high mortality
due to intrinsic resistance of organisms.
D) Gram negative bacilli: 1-5% of cases. Persistent bacteremia common, CHF
common, mortality high (40-50%). Salmonella, E. coli, Klebsiella, Pseudomonas,
Serratia (IVDU).
E) Fungi: associated with IVDU, health care associated infection, cardiovascular
surgery. 2-4% of cases.
F) Rare: Neisseria species, HACEK organisms (Haemophilus, Actinobacillus,
Cardiobacterium, Eikenella, Kingella), anaerobic bacteria.
G) IVDUs: S. aureus (MRSA), Pseudomonas, Serratia, strep species,
polymicrobial, fungal.
H) Culture negative: Coxiella burnetii, Bartonella species, presence of antibiotics.
6. Diagnosis
A) Duke Criteria: uses both clinical and pathological criteria to classify cases as
definite. Definite cases of endocarditis require one of the following:
- Direct evidence of IE based on histology
- Gram’s stain results or cultures of specimens obtained from surgery or
- Two major criteria (see table below)
- One major and any three minor criteria
- Five minor criteria
Table 1. Modified Duke criteria for the diagnosis of infective endocarditis (IE)
Major criteria:
1) Positive Blood cultures for IE
A) Typical microorganisms consistent with IE from 2 separate blood cultures:
- viridans streptococci
- Streptococcus bovis, HACEK group,
- Staphylococcus aureus;
- Community-acquired enterococci, in the absence of a primary focus;
B) Persistently positive blood cultures, defined as recovery of microorganisms
consistent with IE from:
-At least 2 positive cultures of blood samples drawn 12 h apart
- All of 3 or a majority of >4 separate cultures of blood (with first and last
sample drawn at least 1 h apart)
C) Single positive blood culture for Coxiella burnetii or antiphase I IgG antibody
titer >1:800.
2) Evidence of endocardial involvement
A) Echocardiogram positive for IE (TEE recommended in: patients with
prosthetic valves, rated at least “possible IE” by clinical criteria, or complicated
IE [paravalvular abscess]; TTE as first test in other patients):
-Oscillating intracardiac mass on valve or supporting structures, in the
path of regurgitant jets, or on implanted material in the absence of an
alternative anatomic explanation.
-New partial dehiscence of prosthetic valve
B) New valvular regurgitation (worsening or changing of pre-existing murmur not
Minor criteria
1) Predisposition: predisposing heart condition or injection drug use.
2) Fever, temperature 38.0C.
3) Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic
aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway’s lesions.
4) Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth’s spots, and
rheumatoid factor.
5) Microbiological evidence: positive blood culture but does not meet a major criterion as
noted above or serological evidence of active infection with organism consistent with IE.
7. Treatment – will discuss empiric coverage only – need ID consult and specific
recommendations when organism isolated.
A) Native valve, no h/o IVDU: obtain 3 sets of blood cultures over 24 hours;
vancomycin plus synergistic gentamicin dosing (1 mg/kg q 8 hours); other option
is ampicillin (for enterococcus) + nafcillin + synergistic gentamicin.
B) IVDU or R-sided endocarditis: vancomycin
C) Prosthetic valve: vancomycin, gentamicin (1mg/kg q 8 h), plus rifampin 300
mg po q 8 hours.
D) Obtain CT surgery consult for the following: prosthetic valve, any S. aureus
IE, evidence of heart failure, valvular dysfunction, persistent fever for 10 days
while on appropriate antibiotics, new EKG conduction abnormalities, fungal IE,
recurrent embolic events, abscess, highly resistant organism, persistent bacteremia
on appropriate antibiotics (rule out metastatic infection), relapse after completion
of therapy.
E) Duration of antibiotics dependent on organism/resistance profile – average is 6
8. Complications/associated clinical syndromes
A) Mycotic aneurysms (cerebral vessels, abdominal aorta, splenic, coronary,
pulmonary vessels).
B) Cerebral emboli: seen in 20% of cases, MCA most common
C) Splenic infarctions
D) Glomerulonephritis (seen in 40-80% of cases) and renal abscesses
E) Skin lesions – Osler nodes, janeway lesions, petechiae, splinter hemorrhages
F) Pulmonary septic emboli in right sided lesions
G) Septic emboli can involve virtually every organ system
Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to
Dr. Wendy Gerstein, Department of Medicine, VAMC (111).
1) Topic of module:__________________________
2) On a scale of 1-5, how effective was this module for learning this topic? _________
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient
curriculum in general:
6) Please circle one:
Resident (R2/R3)
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