One of this blog’s readers, Dr. McLeod, asked the following:

My question is: Does one need to prescribe antibiotics after I+Ding an abscess? I use to work at a county hospital in Oakland, California  where there was a high MRSA rate. At that time (2005), we were being taught not it is unneccessary to prescribe antibiotics after I+Ding an abscess, other than to practice defensive medicine. But, is it necessary to prescribe antibiotic in your opinion after an abscess I+D? I am talking about a classic abscess, not a cellulitis of any form.

This is an excellent question that allows me to go off in two directions.  First, to directly answer Dr. McLeod’s question, NO, the evidence is fairly strong that I&D of an abscess of <5cm in diameter without concomitant antibiotic therapy is considered adequate and appropriate therapy for an MRSA abscess.  For one of the first studies that really showed this, and the one that was probably quoted by the folks with whom you worked in 2005, I direct you to the 2004 paper by Lee et.al in the Pediatric Infectious Disease Journal (PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/14872177)

The 2^nd direction or “tangent” I want to explore with this entry has more to do with the follow up of this type of patient, or for that matter any infection patient.  The question is “How long do you need to continue antibiotic therapy?”

A few years ago I was sitting in on a lecture at the annual meeting of the Infectious Diseases Society of America.  Unfortunately, I can’t remember the speaker in order to give appropriate credit but what has stuck with me ever since is the concept he proposed: Why do we continue to routinely give 10-14 day prescriptions of antibiotics when the infection may be clinically cured in 2-3 days? Rather we should consider the concept of giving the patient antibiotics until clinically better and then for only another 2-3 days an idea that can be called “Better Plus 2”. 

Think about this…you automatically give someone a 7, 10, 14 day Rx for an antibiotic.  What do you tell them as you hand them the script?  “Make sure you take it until it is all finished”.  Heck, it even says it right on the bottle the patient receives from the pharmacy!  WHY?  Because we have been taught that is the way to prevent resistance development. Now, let’s look at the patient proposed by Dr. McLeod above.  You I&D that abscess AND give antibiotics for 10 days solely because this is what you have been taught or you want to practice defensive medicine, or whatever reason.  You see the patient back on Day 3 and the wound looks great.  The abscess and any surrounding cellulitis are gone BUT the patient still has 7 days of antibiotic to go; an antibiotic that is not medically necessary because the patient is clinically cured.  Think about it; how do we develop antibiotic resistance?  By giving an antibiotic when it isn’t necessary!  Is this a greater risk than stopping the antibiotic too early, I would venture an opinion that, yes, it is.

As you know from reading my posts, I am a believer in backing up what I write about with literature/science. Before writing this entry I tried to find some substantiation for this concept in the literature.  On my cursory PubMed search nothing came up. It may or may not be out there and I just could not find it.  If anyone is familiar with support for this concept please let me know. It is just one of those ideas that make perfect sense to me.  There is nothing of which I am aware supporting the routine use of 10-14 days of antibiotics, at least in skin and skin structure infections, so why should Better Plus 2 be any less valid or legitimate? I wanted to throw this out for you to ponder the next time you write that rote duration on your antibiotic Rx.

Well, the comments have come in and this is what I received – my comments, if any, are in italics:

- Interesting question as I just received a memo from the dental school at the University asking my preferences regarding antibiotic prophylaxis with implant (hardware) patients and dental surgery. The letter outlined the 2003 decision with the ADA and AAOS as well as followup decisions by both organizations. My take is that one has no choice but to recomend AP due to the medical-legal questions. There is little evidence suggesting it is required but one has to take this time honored procedure into consideration.  This is an interesting point.  Originally, the ADA and AAOS actually came out in a joint statement and concluded that it was NOT routinely needed to prophylax a patient for dental work even if they have a prosthetic joint unless the patient was undergoing a “high risk” dental procedure. As recently as Nov 2009 they changed their position to recommend prophy in these patients prior to any dental procedure!  As you will see below, this is not supported by science. As to the medico-legal issue, there is no question that this does come into play, unfortunately, when making medical decisions.  I think it is time (call be an idealist) we should practice medicine based on science and not fear of repercussions.

- No to both unless prior infection. Actually, this is the “correct” answer based on the paper I will share with you below.

- Related question: 30 yo F w/ Mitral Valve Prolapse. Need ABX prophy for foot or ankle surgery w/ or wo/ implants? Absolutely NONE!  The American Heart Association guidelines for prophylaxis against endocarditis are clear on this point (I think I see another blog post idea).  In 2007 they backed off many recommendations for prophy and now only recommend it when surgically manipulating an actual infection (abscess, cellulitis, etc) in a patient with a “high risk” for infective endocarditis.  These high risks are mostly prosthetic heart valves and other major cardiac conditions and do NOT include MVP. Clean elective surgery through surgically prepared skin has not required prophy since their 1997 Guidelines.

- No to both of these questions. If they had a tooth abscess then I may consider. As far as I know they don’t have people with foot/knee/hip implants take abx everytime they brush their teeth. I Think in the case of bunion surgery on a patient with a known knee prosthesis that preop Ancef is enough. Great point! The issue is the development of bacteremia.  This occurs every time someone brushes their teeth, flosses, eats hard food. You don’t prophy with each of these activities so there is no reason to do it for surgery.  Only when an infection is being manipulated should it be considered.

- In the first scenario, if the patient is immunocompromised in any way, I would advise a cephalosporin. Good suggestion.  Interesting “immunocompromise” of the patient does not seem to come up in any guideline.  I don’t know why.

- In the second scenario, since the joint implant is less than 2 years old, I would recommended prophylactic antibiotics.  Excellent point!  The 2 year rule has been around for a while.  It is presumed that if the implant is in place less than 2 years there is a higher risk of it getting infected.  I am not really certain where that comes from or the validity of it. My only issue would be that if you are not manipulating and infection and are doing your bunion surgery through surgically prepared skin, there should be no bacteremia and no reason to give prophy…just like if it was for endocarditis.

I want to thank those who took the time to respond.  I really enjoyed reading, and thinking about your comments. 

Now here is why I brought it up in the first place:  In the January 1, 2010 issue of Clinical Infectious Diseases there is a study by Berbari et.al. out of the Mayo Clinic entitled “Dental Procedures as Risk Factors for Prosthetic Hip or Knee Infection: A Hospital-Based Prospective Case-Control Study.  (PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19951109 ) .  This elegantly done study looked at 339 patients admitted with prosthetic joint infections (PJI) vs. 339 admissions of patients with non infected prosthetic joints.  They examined dozens of parameters including; the type of dental procedure, time from implant to the dental procedure, time from dental procedure to current admission, operative factors, diabetes, immunocompromise, organisms recovered and many others.  I think it is important for you to read verbatim what they stated in the Results and Conclusion parts of their Abstract:

RESULTS: A total of 339 case patients and 339 control subjects were enrolled in the study. There was no increased risk of prosthetic hip or knee infection for patients undergoing a high-risk or low-risk dental procedure who were not administered antibiotic prophylaxis (adjusted odds ratio [OR], 0.8; 95% confidence interval [CI], 0.4-1.6), compared with the risk for patients not undergoing a dental procedure (adjusted OR, 0.6; 95% CI, 0.4-1.1) respectively. Antibiotic prophylaxis in high-risk or low-risk dental procedures did not decrease the risk of subsequent total hip or knee infection (adjusted OR, 0.9 [95% CI, 0.5-1.6] and 1.2 [95% CI, 0.7-2.2], respectively).

CONCLUSIONS: Dental procedures were not risk factors for subsequent total hip or knee infection. The use of antibiotic prophylaxis prior to dental procedures did not decrease the risk of subsequent total hip or knee infection.

They go on to question the recent AAOS recommendations since they were seemingly not based on any science.  They recognize in the manuscript: “Although the adverse risk of antibiotic prophylaxis in the individual patient may seem remote and unlikely, the risk to the overall population with a joint arthroplasty and to society at large seems prohibitive”.  I believe that this is something we forget when making decisions on our individual patients.  We do thing, like give possibly unnecessary antibiotics to “cover ourselves” from medico-legal concerns and because, frankly, it probably will not hurt that one patient.  But when you multiply your actions times thousands of practitioners thinking the same thing, times the 10s of thousands of patients being treated we start to have an impact on the global microbiota. 

I urge my readers to seek out this article since there are lots of other interesting points that are made and I don’t have the space to go into with this post.