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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3063_Библиотеки_им_академика_М_И_Перельмана
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Results of cultures will not be given at the beginning of your ID cases. Treatment is
empiric.
Assessment
Any active IV drug abuser presenting with fever may have acute endocarditis. This patient also
has a cough, hemoptysis, and pleuritic chest pain. IV drug users are also at risk for pneumonia.
However, this patient has a heart murmur, and the pulmonary symptoms combined with
multiple, bilateral nodular lesions on chest x-ray most likely represent septic emboli to the
lungs from the right side of the heart. The tricuspid valve is most commonly involved in drug
abusers (50% of the time), with aortic valve involved 25% and mitral valve 20%.
The conjunctival petechiae and splinter hemorrhages are also indicative of endocarditis in both
the acute and subacute forms. Roth spots (retinal lesions), Janeway lesions (flat, painless,
purplish lesions on the hands and feet), and Osler nodes (pea-sized, painful nodules that
usually occur on the pads of the fingers and toes and on the palms) are usually associated with
subacute endocarditis. Most of the embolic phenomena are quite rare, and their absence should
never dissuade you from suspecting endocarditis.
Further Management Plan/Results
Further Management
Echocardiogram: vegetation visible on tricuspid valve with tricuspid regurgitation
IV antibiotics (e.g., nafcillin or oxacillin) for 4–6 wks, with gentamicin for first week
If acute decompensation occurs, surgical replacement of valve; also consider surgery for
myocardial abscess, repeated emboli, very large vegetations, fungal endocarditis, or
prosthetic valve endocarditis
31
NOTE
Start empirical antibiotics for all presumed infections after cultures have been drawn.
Discussion
Any IV drug user presenting with unexplained fever should be placed on IV antibiotics upon
admission. The concern is for suspected endocarditis, because of the rapid decompensation
that can occur with acute endocarditis. This should be done even in the absence of a murmur.
Always take 3 sets of blood cultures before starting the antibiotics within 1 hr.
A transthoracic echocardiogram (TTE), with sensitivity of only 60%, should be done first.
Detection of a vegetation is a positive test. If it is negative, then perform a transesophageal
echocardiogram (TEE), with sensitivity of 95%.
Patients with abnormal findings on TTE who may require further evaluation by TEE include
those with significant valvular regurgitation to determine need for surgery, and those with ≥1
risk factors for perivalvular abscess including new conduction delay on ECG, aortic valve
endocarditis, and persistent bacteremia or fever despite appropriate antimicrobial therapy.
S. aureus accounts for 60–90% of endocarditis in IV drug abusers, and, depending on local
conditions, a large percentage of this may be methicillin-resistant. A large portion of S. aureus
endocarditis cases are attributed to healthcare-associated bacteremia. Vancomycin and
gentamicin is good empiric coverage until the results of blood cultures are known.
Native valve subacute endocarditis is caused by Streptococci 50–60% of the time. Viridans
streptococci, which are normal inhabitants of the mouth, account for 75% of these.
Streptococcus bovis accounts for 20% and is particularly associated with neoplastic diseases
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of the colon. Staphylococci account for about 30% of native valve subacute endocarditis, and
90% of this is S. aureus. Enterococci account for 5 to 10% of cases.
Culture-negative endocarditis is caused by the HACEK organisms. The name is formed from
their initials:
Prosthetic valve endocarditis is caused most often by Staphylococci in the early postoperative
period. Staphylococcus epidermidis is more common in the first 2 mos after the replacement.
Currently, CHF is the most common cause of death. As time goes on, Streptococcus viridans
becomes more common.
Other complications of endocarditis are embolic phenomena to the brain, causing abscess and
mycotic aneurysm; renal infarction and abscess; and splenomegaly. The most common
complication is CHF from valvular degeneration. In the pre-antibiotic era, glomerulonephritis
was far more common. Strokes and major systemic embolic events are present in about 25% of
patients within 1 week of therapy.
This patient has methicillin-sensitive S. aureus, and nafcillin (or oxacillin or cefazolin) should
be used for 4 wks; they are usually used with gentamicin or another aminoglycoside for the first
5 days (optional).
These are bacteriocidal and must be used over vancomycin if the organism is methacillin-
sensitive.
Haemophilus (Haemophilus parainfluenzae), (Haemophilus aprophilus), (Haemophilus
paraprophilus)
Actinobacillus
Cardiobacterium hominis
Eikenella corrodens
Kingella (Kingella kingae)
33
This patient will likely need 6 wks of antibiotics because of the vegetation and evidence of
septic emboli in the lungs.
For patients with native valve subacute endocarditis from a sensitive S. viridans, penicillin G
or ceftriaxone for 4 wks alone is often sufficient. Alternatively, use gentamicin plus either
aqueous crystalline penicillin G or ceftriaxone for 2 wks, in the absence of renal insufficiency.
Enterococcus is best treated with a beta-lactam antibiotic such as penicillin or ampicillin, in
combination with an aminoglycoside (gentamicin or streptomycin) for the entire 4 to 6 wks.
HACEK organisms are treated with ceftriaxone, ampicillin-sulbactam, or ciprofloxacin for 4
wks.
If the patient has urticarial rash to vancomycin or MIC for vancomycin is >2, use daptomycin to
treat right-sided MRSA endocarditis. Daptomycin is used for MRSA skin and soft tissue
infection, right-sided endocarditis, and bacteremia, usually due to line sepsis. Do not use
daptomycin for pneumonia, as it is inactivated by surfactants.
CLINICAL PEARL
Oxacillin, nafcillin, and cefazolin are the best antibiotics for MSSA.
Daptomycin inserts into the cell membrane, where it then aggregates. The aggregation of
daptomycin creates holes that leak ions. This causes rapid depolarization, resulting in a loss of
membrane potential leading to inhibition of protein, DNA and RNA synthesis, which results in
bacterial cell death.
Indications for surgery are the following:
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Infective endocarditis prophylaxis is recommended for patients with the following (high-
yield):
Other rules to follow:
Evidence of uncontrolled infection can mean persistence of positive blood cultures while
already on therapy, recurrent emboli formation of myocardial or valvular ring abscesses, or
spread of the infection to involve the conduction system of the heart
Acute heart failure indicates degeneration of the valves, papillary muscles, or chordae
tendinea sufficient to cause evidence of CHF
Valvular regurgitation
Recurrent embolic event because of a large vegetation
Prosthetic cardiac valve
Previous episode of infective endocarditis
Congenital heart disease characterized by unrepaired cyanotic congenital heart disease,
including palliative shunts and conduits; a completely repaired congenital heart defect with
prosthetic material or device during the first 6 months after the procedure; and repaired
congenital heart disease with residual defects
Cardiac transplantation recipients in whom cardiac valvulopathy develops
Antibiotic prophylaxis is recommended for all dental procedures which involve
manipulation of gingival tissue or periapical region of the teeth or perforation of oral
mucosa; limit to patients with the cardiac conditions mentioned above.
Antibiotic prophylaxis is no longer recommended for any GI or GU procedure.
Antibiotic prophylaxis is reasonable for procedures on the respiratory tract which involve
incision or biopsy (e.g., tonsillectomy, bronchoscopic biopsy), and on infected skin, skin
structures and musculoskeletal tissue; limit to patients with the cardiac conditions mentioned
above.
For those who need prophylactic antibiotics, give amoxicillin 30–60 minutes before the
35
Final Diagnosis
Acute bacterial endocarditis
Basic Science Correlate
CLINICAL PEARL
Libman-Sacks endocarditis is due to sterile vegetations which arise in association with
SLE. Vegetations are present on and under the surface of the mitral valve, and result in
mitral regurgitation. (Think of this in a young female with rash, joint pain and MR
without fever!)
procedure.
In cases of penicillin-allergy, give clindamycin, cephalexin, or a macrolide.
Streptococcus viridans is the most common overall organism to cause endocarditis.
It is a low-virulence organism that infects previously damaged valves (MVP or
chronic rheumatic heart disease because of valve scarring). Subacute endocarditis is
typically associated with small vegetations that do not destroy the valve.
Staphylococcus aureus is a high virulence organism associated with IV drug use. It
results in large vegetations which rapidly destroy the valve.
Staphylococcus epidermidis is associated with endocarditis of prosthetic valves
within 2 months after surgery.
Streptococcus bovis is associated with colorectal cancer.
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CLINICAL PEARL
In chronic rheumatic heart disease, patients are often immigrants from developing
countries. The mitral valve is almost always involved and causes mitral stenosis with
“fish-mouth” appearance.
37
Case 2
Chief Complaint
Pain and swelling of left leg
History and Physical Examination
A 72-year-old white man with a history of prostatic cancer metastatic to bone and the
lymphatic system comes to the emergency department because of a several-day history of
increasing swelling and erythema of left leg from the knee down. He denies shortness of
breath or chest pain. The patient feels warm. His T is 38.4 C (101.1 F).
Physical examination reveals a left leg that is swollen and erythematous below the knee,
moderately tender and warm to touch; there is no palpable fluid collection or skin
breakdown.
Differential Diagnosis
Initial Management
Setting: outpatient or emergency department
Diagnostic/Therapeutic Plan
Cellulitis
1.
Deep venous thrombosis
2.
Lymphangitis
3.
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Test Results
Assessment
With a unilateral red, tender, warm, swollen leg without evidence of deep venous thrombosis,
cellulitis is the most likely possibility. No further diagnostic tests are required. The primary
means of diagnosing cellulitis is by clinical examination and history.
Venography is not the first test to exclude a thrombosis, even though it is slightly more
sensitive and specific than U/S. This is because of the risk of renal toxicity in the elderly or
allergic reaction from exposure to the required contrast agent. Venogram is done if the
suspicion for a clot is very high and U/S is negative.
Specific microbiologic diagnosis is not routinely indicated. This is sometimes done in
unresponsive cases by injecting a small amount of saline subcutaneously into the leading edge
of the infection. Then, aspirate and send the sample for culture.
CCS NOTE
A specific microbiologic diagnosis is almost never obtained at any point in the clinical
management of a skin infection. Treatment is both initiated and continued on an empiric
basis.
Treatment Plan
Duplex U/S scan of venous system of the leg
No evidence of thrombosis
39
Discussion
The most likely organisms in cellulitis are group A streptococci (S. pyogenes) and S. aureus.
The magnitude of CA-MRSA infections has reached epidemic proportions in the United States.
Certain risk factors have been described which put certain groups at higher risk:
IV antibiotics with oxacillin or nafcillin
1.
Elevation of leg and warm soaks
2.
Oral dicloxacillin (mild cases); if mild penicillin allergy such as rash, use oral
cephalexin; if life-threatening penicillin allergy such as anaphylaxis, use clindamycin,
macrolides, and new fluoroquinolones
3.
Mild infections can be treated in the outpatient setting with oral dicloxacillin or oral
cephalosporins.
For moderate cellulitis or cellulitis that does not resolve with oral treatment, a first-
generation IV cephalosporin such as cefazolin or cephalexin is appropriate.
In cases of severe penicillin allergy (e.g., anaphylaxis), vancomycin or clindamycin is used.
Rates of cross-reaction between penicillin and cephalosporins are <5%. For reactions that
were originally just a rash, cephalosporins are safe to use.
Antibiotics are continued until symptoms have resolved. Duration of treatment varies
depending on how long it takes to improve.
Vancomycin cannot be used orally to treat cellulitis because it is not absorbed.
Household contacts of patients with proven CA-MRSA infection
Children
Men who have sex with men (MSM)
Injection drug users
Athletes engaged in contact sports
Certain racial and ethnic groups such as Native Americans and Pacific Islanders
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