Lecture 19: Bacteremia and Endocarditis

Question 1

Infection of Endocardium-Endocarditis

Answer 1

1) Injury to the endocardial surface (pre-existing valve abnormality is common)
2) transient bacteremia
3) adherence of bacteria to valve surface, colonization of valve-staph and strep have surface proteins that make them more likely to attach to host proteins, G- rods less likely to attach which explains the microbiology of infective endocarditis

4) persistence and multiplication of bacteria on valve
- local tissue damage and/or vegetation
- hematogenous dissemination to other organs
- continous bacteremia

Question 2

What are the risk factors for infective endocarditis?

Answer 2

1) IV drug use
2) underlying structural heart disease
3) prior infectious endocarditis
4) catheter related bacteremia
5) prosthetic valve

Question 3

T/F negative echo rules out endocarditis

Answer 3

False

negative echo does NOT rule out endocarditis

Question 4

What organisms are suspicious for endocarditis?

Answer 4

1) Staph. aureus 60-70%
2) Viridans Streptococci and enterococci 15-20%
* find continuous bacteremia due to them, suspect endocarditis

Question 5

When do you do surgery?

Answer 5

1) heart failure
2) persistent infection
3) emboli
4) difficult organisms

Question 6

What is associated with a source infection at a particular site (Ex. pyelonephritis, pneumonia)?

Answer 6

Intermittent bacteremia

Question 7

What am I describing?

1) Multiple blood cultures are all positive, typically endovascular (ex. infective endocarditis).
2) Can ALSO have met sites of infection concurrently.
3) bacteria is present in the blood for long periods of time reflecting a persistent endovascular infection. Ex. endocarditis, infection of a vascular graft
4) Treatment goal: treat the focus-infection is within blood stream

Answer 7

Continuous bacteremia

Question 8

If you find staph aureus in the blood, what is the patient at risk for?

Answer 8

1) endocarditis

2) metastatic infection

Question 9

Gram + lancet shaped diplococci

Answer 9

Strep. pneumo

Question 10

Which type of bacteremia occurs:
1) after a procedure (dental procedure or abscess drainage)

2) in the setting of a bacterial infection (pneumonia, pyelonephritis, skin and soft tissue infections)

Answer 10

Intermittent (transient) bacteremia

Question 11

How do you minimize false positives in blood cultures?

Answer 11

1) proper technique and use of skin antiseptic prior to draw
2) avoiding the drawing of cultures through intravascular catheters (at least 1 set drawn from direct venipuncture site)
3) avoiding use of just 1 blood culture set

Question 12

How do you minimize false negatives in blood culture?

Answer 12

obtaining cultures prior to starting antibiotics

Question 13

How many blood cultures should you do for bacteremia diagnosis?

Answer 13

3 is happy number, beyond 3 is not helpful

Question 14

When should additional sets of blood cultures be ordered?

Answer 14

1) If the patient continues to have fevers despite adequate therapy
2) to document clearance of bacteremia with Staphylococcus aureus-make sure bacteremia stops–> keep doing even if afebrile after 24 hours to make sure clear
3) when endocarditis is suspected

Question 15

Staph aureus

Answer 15

1) IV drug users

2) when you see staph-think endocarditis

Question 16

What am I describing?

1) constant antigenic stimulation of the immune system, immune complex formation and deposition (skin, kidneys)
2) seeding of any organ to form abscesses (ex. liver, spleen, kidney, brain)

Answer 16

Continuous Bacteremia

Question 17

Infective endocarditis

Answer 17

1) early (within 2 months) or late
2) similar rates of infection for mitral and aortic, similar for mechanical or bioprosthesis

3) pathogenesis
- intra-operative contamination esp. for elderly
- bacteremia from lines or wound infection
- bacteremia from other sources and similar to native valve

Question 18

How does endocarditis manifest?

Answer 18

1) Local tissue destruction-valvular regurg, perivalvular abscess, conduction abnormalities, heart failure
2) Continuous bacteremia- immune complex deposition, seeding other organs with abscess formation
3) Embolic Lesions-due to breaking of vegetations

Question 19

What does this patient have?

General manifestations:
– fever, myalgias, anorexia, night sweats, weight loss

Cutaneous:
–  rash
–  splinter hemorrhages (nail beds) –  Osler’s nodes 
(painful)
–  Janeway lesions (painless, flat)

Ocular:
– endophthalmitis, conjunctival hemorrhages


Answer 19

Infective endocarditis

Question 20

What are the cardiac manifestations of endocarditis?

Answer 20

1) valvular regurgitation (murmur, new or changing)
2) heart failure-leading cause of death, leading surgical indication
3) conduction abnormalities

Question 21

What are the neuro manifestations of endocarditis?

Answer 21

1) emboli to the brain leading to infarcts/strokes
2) abscesses
3) mycotic aneurysms with bleeding
- all can manifest as focal deficits, mental status changes, seizures, encephalopathy, meningitis, or an epidural abscess

Question 22

What are the renal manifestations of endocarditis?

Answer 22

1) microscopic hematuria
2) elevated creatinine

Kidney Involved By:

1) immune complex deposition
2) embolic infarcts
3) decreased perfusion due to decreased cardiac output
4) medication/antibiotic toxicity

Question 23

CBC:
Diagnostic findings
–  Anemia (70-90%)
–  normal or high WBC
Metabolic panel:
–  may find elevated Cr, low albumin, High globulins
Urinalysis:
–  microscopic hematuria (30-60%) 
–  Proteinuria (50-60%)

Answer 23

Staph. aureus endocarditis findings

-lab testing can be normal or abnormal depending on organ systems involved

Question 24

What are diagnostic findings of Staph. aureus endocarditis?

Answer 24

1) Hypergammaglobulinemia
2) **Markedly elevated ESR and CRP (>90%)
3) May have positive ANA, RF, false positive VDRL
4) EKG: conduction abnormalities
5) Echocardiography: vegetations, valve lesions, regurgitation – can be negative

MULTIPLE POSITIVE BLOOD CULTURES

Question 25

How do you get culture negative endocarditis?

Answer 25

due to prior antibiotic administration

Question 26

How do you diagnose infective endocarditis?

Answer 26

History:

1) prior cardiac lesions
2) source of bacteremia – can help predict organism

Exam:
1) Regurgitant murmur, heart failure
2) signs of embolization - fundi, conjunctivae (Eye),
skin (Osler’s, splinters)
3) Neurologic findings
4) Musculoskeletal: arthritis

Question 27

What are the major duke criteria?

Answer 27

Microbiologic
– continuous bacteremia with organism typical of IE

Echocardiographic
– oscillating vegetation in the path of a regurgitant jet
– perivalvular abscess
– partial dehiscence of a prosthetic valve new regurgitant
murmur

Serologic
– positive Coxiella (Q fever) phase II serology

*need either 1 major and 1 minor or 3 minors!

Question 28

What are the minor duke criteria?

Answer 28

1) Predisposing heart condition
2) Intervenous Drug Use
3) Fever > 38 C
4) Vascular phenomena: emboli, aneurysm, Janeway lesions
5) Immunologic phenomena: Osler’s nodes, Roth spots
6) Culture results not meeting major criteria

*need other 1 major and 1 minor or 3 minors!

Question 29

What are the modified duke criteria?

Answer 29

One major and one minor or 3 minors

-how you diagnose infective endocarditis

Question 30

How do you treat infective endocarditis?

Answer 30

• Bactericidal antibiotic whenever possible (ex. Penicillin)
• Treatment is usually intravenous (need high levels)
• Duration is prolonged, usually several WEEKS, depending on the organism and location of valve involved (right or left sided), and presence of metastatic foci of infection

Question 31

Indications for surgery in endocarditis?

Answer 31

*if antibiotics don’t work, need surgery!

1) Heart Failure (NYHA classification 3 or 4)
– the most common indication for surgery
– mortality of IE with severe CHF is 75% when treated medically, and less than 25% when treated surgically
2) Fungal endocarditis
3) Perivalvular extension
4) Persistent bacteremia despite adequate antibiotics
5) Recurrent emboli

Question 32

What are the indications for surgery in prosthetic valve endocarditis?

Answer 32

1) Heart Failure (NYHA classification 3 or 4)
– the most common indication for surgery
– mortality of IE with severe CHF is 75% when treated medically, and less than 25% when treated surgically
2) Fungal endocarditis
3) Perivalvular extension
4) Persistent bacteremia despite adequate antibiotics
5) Recurrent emboli
*same as before

same as native valve but ADD:

6) early prosthetic valve endocarditis (first 2 months after surgery)
7) Valve obstruction
8) Unstable prosthesis

Question 33

Endovascular infections

Answer 33

1) Infection of Vascular grafts
2) Infection of central venous catheters
3) Suppurative thrombophlebitis (Vein)
4) Endarteritis (arteries)

*ALL have continuous bacteremia, and present with similar symptoms to those of endocarditis
*Local manifestations and microbiology may be different