Infective Endocarditis question

[Peeshee]

OK, I have a question regarding infective endocarditis.
My understanding was that Staph.aureus is the most common cause of infective endocarditis, but Goljan says that Strep. viridans is the most common cause. I know that Staph.aureus is the MCC in IV drug abuse. I thought that Strep. viridans affected already abnormal/damaged valves but then Goljan says that Staph.aureus can affect both normal and damaged valves.
Can anyone clear this up for me?
thanks!!

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[dukeblue01]

Sounds like most of what you said is right on. There are some arguments in the literature about whether S. aureus or Strep. viridans is the most common cause, but on a test I would go with Strep. Strep. typically affects abnormal or damaged valves which is where the majority of endocarditis comes from. Staph affects normal and abnormal valves and is typically more acute. And you are absolutely right, it is the number one cause in IV drug users, on the right side of the heart (another test tidbit). I think Staph has over taken Strep by now, but it will take years for textbooks to catch up to the most current literature which is not completely congruent.

 

[HiddenTruth]

don' forget abt enterococcous, which also causes infective endocard in previously damaged heart valves, albeit not the most common cause. I would also stick with stre viridens as the most common cause, (per kaplan).

 

[bigfrank]

The Step I isn't going to ask you "what is the most common cause of 'infective endocarditis'" -- therefore, purely epidemiological types of questions are unimportant (but commonly stressed by reviewers) on the Step I.

Rather, focus on the clinical presentation of the theoretical scenario. If a subacute picture is described, you could safely go with S. viridans. If an acute picture is given, however, and perhaps IVDU is mentioned, then you can safely go with S. aureus. Good luck.

 

[Idiopathic]

agreed, and the history helps, oftentimes: drug abuser (or visible track marks) versus recent dental surgery in a px with mitral valve prolapse.

Also remember which valves are affected. Staph from IVDA ALWAYS gets the tricuspid valve, and someone with new onset clinically important TR is most likely a drug abuser with endocarditis. Viridans usually gets mitral valve, since that one is the one most likely to have an inherent abnormality.

 

[phdmed07]

Hope this helps:
Acute: severe fulminant infection, no history of CHD, Very pathogenic organisms infecting valve, Left Valves – 65%, S. Aureas most common

Subacute: Wasting illness w/wt loss and low grade Fever, history of valve disease, organism low pathogenicity, Left Valves – 85%, Viradans most common

Streptococci – 60-80%: Viradans-30-40%, Enterococci-5-20%, Other-15-25%
Staphycocci – 20-35%: S. Aureas-25% (#1 in IV drug users), Coag Neg-5%

Special types of endocarditis – 1)Rt sided- bc IV drugs 50% - S. Aureas, P. Aeruginosa, candida 2)Prosthetic valve type-95% left sided, Staphycocci 3) Culture negative type- prior drugs, hard to isolate, or HACEK group

 

[Chandler]

Hope this helps:
Acute: severe fulminant infection, no history of CHD, Very pathogenic organisms infecting valve, Left Valves – 65%, S. Aureas most common

Subacute: Wasting illness w/wt loss and low grade Fever, history of valve disease, organism low pathogenicity, Left Valves – 85%, Viradans most common

Streptococci – 60-80%: Viradans-30-40%, Enterococci-5-20%, Other-15-25%
Staphycocci – 20-35%: S. Aureas-25% (#1 in IV drug users), Coag Neg-5%

Special types of endocarditis – 1)Rt sided- bc IV drugs 50% - S. Aureas, P. Aeruginosa, candida 2)Prosthetic valve type-95% left sided, Staphycocci 3) Culture negative type- prior drugs, hard to isolate, or HACEK group

Don't forget about Candida as a possible choice in an AIDS patient with VERY THICK vegetations in the mitral valve. Also, pseduomonas aerginosa if all 4 valves have vegetations in a cystic fibrosis patient. I AGREE WITH BIG FRANK 100%. The key is Acute vs Subacute coupled with clues about tricuspid vs mitral. The last thing is the immunecompromised state. Of course on an exam they are not going to say mitral valve or tricupid valve. That's where you have to remember, increase in murmur during inspiration is tricupsid, and an increase in murmur during expiration is mitral.

 

[Snuka]

OK, I have a question regarding infective endocarditis.
My understanding was that Staph.aureus is the most common cause of infective endocarditis, but Goljan says that Strep. viridans is the most common cause. I know that Staph.aureus is the MCC in IV drug abuse. I thought that Strep. viridans affected already abnormal/damaged valves but then Goljan says that Staph.aureus can affect both normal and damaged valves.
Can anyone clear this up for me?
thanks!!

I don't know if this will help but our notes say that Staph. aureus is the most common cause of acute infective endocarditis and Strep. viridians is the most common cause of subacute infective endocarditis. THe main difference being in the time frame for symptom on-set.

 

[applemas]

How large vegetation (for infective endocarditis) is indication for surgery?

Which antibiotic is best for treatment of infective endocarditis?

 

[Kishmish]

I am taking my NBDE part 1 on Monday and I was searching the web to find out the most common cause of infective endocarditis? and it says staph everywhere but I thought it was strep. Now I have a feeling I am totally gonna have this question... I guess I am gonna go with Strep. Viridans....