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Questioning The Conventional Wisdom On Antibiotics And Prophylaxis

In my last blog (see ), I asked the readers for their opinions on antibiotic prophylaxis. Just as a recap, here are the clinical scenarios/questions that I posed.

1. You placed a prosthetic joint into a patient’s foot. Let us even expand it out since there are not as many joints being placed anymore. You placed some hardware into a patient’s foot while doing surgery on that foot. Let’s say the surgery was 18 months ago. The patient calls you because she is going to the dentist for some dental hygiene and to have a crown placed on a tooth. Do you or don’t you recommend antibiotic prophylaxis for this patient before the dental work?

2. A patient comes to see you for the chief complaint of a bunion. You discuss surgical correction. After the patient agrees to have the surgery scheduled, she informs you that she had a prosthetic knee implanted 18 months ago. Do you place the patient on prophylactic antibiotics to prevent a prosthetic joint infection following your foot surgery?

Here are some of the comments I received. The reader responses 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 American Diabetes Association (ADA) and American Academy of Orthopaedic Surgeons (AAOS) as well as follow-up decisions by both organizations. My take is that one has no choice but to recommend antibiotic prophylaxis 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 give prophylaxis to patients for dental work even if they have a prosthetic joint unless the patient was undergoing a “high risk” dental procedure.1 As recently as November 2009, they changed their position to recommend prophylaxis 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 me an idealist) to 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: A 30-year-old female presents with mitral valve prolapse. Does she need antibiotic prophylaxis for foot or ankle surgery with or without implants?

Absolutely none. The American Heart Association guidelines for prophylaxis against endocarditis are clear on this point.2 In 2007, they backed off many recommendations for prophylaxis 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 mitral valve prolapse. Clean elective surgery through surgically prepared skin has not required prophylaxis since the 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 antibiotics every time they brush their teeth. I think in the case of bunion surgery on a patient with a known knee prosthesis that preoperative cefazolin (Ancef, GlaxoSmithKline) is enough.

Great point. The issue is the development of bacteremia. This occurs every time someone brushes his teeth, flosses or eats hard food. You do not prophylax with each of these activities so there is no reason to do it for surgery. Only when an infection is being manipulated should one consider it.

In the first scenario, if the patient is immunocompromised in any way, I would advise a cephalosporin.

Good suggestion. It is interesting that “immunocompromise” of the patient does not seem to come up in any guideline. I do not know why.

In the second scenario, since the joint implant is less than two years old, I would recommended prophylactic antibiotics.

Excellent point. The two-year rule has been around for a while. It is presumed that if the implant is in place less than two 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 an infection and are doing your bunion surgery through surgically prepared skin, there should be no bacteremia and no reason to give prophylaxis, 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.

A Closer Look At The Emerging Literature

Now here is why I brought the aforementioned clinical scenarios up in the first place. In the January 1, 2010 issue of Clinical Infectious Diseases, there is a study by Berbari and colleagues out of the Mayo Clinic entitled “Dental Procedures as Risk Factors for Prosthetic Hip or Knee Infection: A Hospital-Based Prospective Case-Control Study” ( ).3 This elegantly done study looked at 339 patients admitted with prosthetic joint infections (PJI) versus 339 admissions of patients with non-infected prosthetic joints.

The authors 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.1 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 this is something we forget when making decisions on our individual patients. We do things 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 tens 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.


1. Antibiotic prophylaxis for bacteremia in patients with joint replacement.

2. Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditic: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007;116(15):1736-54.

3. Berbari EF, Osmon DR, Carr A, et al. Dental procedures as risk factors for prosthetic hip or knee infection: a hospital-based prospective case-control study. Clin Infect Dis. 2010; 50(1):8-16.

Editor’s note: This blog was originally published at and has been adapted with permission from Warren Joseph, DPM, FIDSA, and Data Trace Publishing Company. For more information about the Handbook of Lower Extremity Infections, visit .

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