A 77 year old woman presents 6 months after elective coronary artery bypass grafting and aortic valve replacement feeling unwell over a few days with fever and rigors. You suspect infective endocarditis. The results of a septic screen are awaited.

a. List 5 clinical findings you may encounter when you examine her

b.  List 3 organisms that are commonly implicated

c.   What antibiotic would you choose in this patient?              

Over the next few days she develops progressive worsening of renal function. Her serum creatinine is twice baseline

d.  Outline the causes for his worsening renal function

e. What are the indications for valve replacement in prosthetic valve endocarditis?

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College Answer

a. List 5 clinical findings you may encounter when you examine her
i.    New murmur
ii.  Skin rash
iii. Osler’s nodes – Tender nodules on pulps of fingers and toes
iv. Janeway lesions – non-tender haemorrhagic macules in the peripheries

v.  Roth spots – Retinal haemorrhages with a pale centre
vi. Splenomegaly
vii. New neurological signs

viii.Tender and swollen joints

b.  List 3 organisms that are commonly implicated
i.    Coagulase negative Staphylococcal sp. (CONS) / S. Epidermidis
ii.  S. Aureus (MSSA/MRSA)
iii. Streptococci (Viridans)
iv. HACEK organisms
Haemophilus aphrophilus, Haemophilus parainfluenzae and Haemophilus paraphrophilus
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis Eikenella corrodens Kingella kingae

c.   What antibiotic would you choose in this patient?               )
AB guidlelines suggest Vanc + gent only. Additional cephalosporin +/- quinolone,
acceptable
Further therapy governed by MIC/cultures\

Over the next few days she develops progressive worsening of renal function. Her serum creatinine is twice baseline

d.  Outline the causes for his worsening renal function

Dehydration

Cardiac failure

Nephrotoxic agents

Sepsis
Immune mediated Glomerulonephritis

e.      What are the indications for valve replacement in prosthetic valve endocarditis?

Hemodynamic instability
Recurrent emboli
Root abscess

Discussion

a)

Clinical manifestations of infective endocarditis include the following:

  • Osler's nodes
  • Janeway lesions
  • Splinter haemorrhages
  • Roth spots
  • Focal neurological signs suggestive of embolic phenomena
  • A new murmur or a worsening of an old murmur
  • Splenomegaly
  • Glomerulonephritis
  • Arthralgia and arthritis
  • Elevated ESR, CRP or rheumatoid factor
  • Haematuria

A 2009 article has a table (Table 3) which lists these manifestations according to their prevalence among a large patient cohort.

Typical valve-eating organisms may include the following:

  • S.epidermidis and other coagulase-negative staphylococci
  • Streptococcus viridans
  • S.aureus
  • Enterococcus
  • Coxiella burnetii (Q fever)

HACEK organisms are mentioned, even though they are responsible for only about 3% of native valve endocarditis.

  • Haemophilus species: H.aphrophilusH.parainfluenzae and H.paraphrophilus
  • Actinobacillus and Aggregatobacter species
  • Cardiobacterium hominis
  • Eikenella corrodens
  • Kingella kingae

The abovementioned large scale cohort review also lists microbial aetiology of IE in their patient group (their Table 5).

c)

There are a few different recipes around for the empirical management of IE, which makes perfect sense as these recommendations would differ according to the prevailing microbiome:

  • The Sanford guide (Hong Kong) recommends vancomycin and gentamicin or vancomycin and ceftriaxone as empiric therapy for native valve endocarditis, or vancomycin, gentamicin and rifampicin "triple therapy" for prosthetic valves. This is one of the few cases when one might give 1mg/kg of gentamicin every 8 hours.
  • The eTG (Australia) recommend benzylpenicillin, flucloxacillin and gentamicin, substituting vancomycin for the beta-lactams wherever MRSA is suspected or where the patient has sepsis or septic shock. For prosthetic valves, vancomycin flucloxacillin and gentamicin are recommended.

Historically, the CICM examiners seem to use eTG for their antibiotic choices. In this question they only said "AB guidlelines suggest Vanc + gent" without specifying which "AB guidelines" they meant. The patient in that specific question was recovering from AVR, and was "unwell over a few days with fever and rigors", which warrants vancomycin according to the eTG. Since 2008, eTG have also added flucloxacillin to vancomycin, as there is thought to be some sort of synergistic effect (Tong et al, 2016)

Immediate valve replacement for IE has been practiced for decades.

Even then, the following criteria for urgent surgery were followed:

  • Haemodynamic instability
  • Aortic root abscess
  • Ongoing embolic phenomena

A 1994 article reports that " surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%)". However, IE recurrence was observed in 30% of patients after 30 days, and 69% of patients after 60 days.

References

Murdoch, David R., et al. "Clinical presentation, etiology, and outcome of infective endocarditis in the 21st century: the International Collaboration on Endocarditis–Prospective Cohort Study." Archives of internal medicine 169.5 (2009): 463-473.

 

Richardson, JAMES V., et al. "Treatment of infective endocarditis: a 10-year comparative analysis." Circulation 58.4 (1978): 589-597.

 

Windsor, HARRY M., and MARK X. Shanahan. "Emergency valve replacement in bacterial endocarditis." Thorax 22.1 (1967): 25-33.

 

Yu, Victor L., et al. "Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only." The Annals of thoracic surgery 58.4 (1994): 1073-1077.