Thursday, January 17, 2013

The [Non] Help?: Oral Antibiotics Post I & D of Uncomplicated Skin Abscesses

Let's say you have a male patient who presents to the emergency department with an abscess in the right axilla. The patient appears to be a relatively healthy gentleman with no significant past medical history (other than the heartburn that develops when he socially drinks on the weekends every now and then). He has not been hospitalized for any previous infection or recent surgery within the past year, and he denies the use of IV drugs. The abscess, he states, "just came out of nowhere about four days ago and has a grown a little bit every day." Upon examination of the axilla, you find that there is indeed an angry-looking, erythematous and indurated abscess that is about 3 cm in diameter and 4 cm deep. You deem it to be an uncomplicated skin abscess that requires the simple intervention of incision and drainage (I & D). I & D occurs successfully without any complications, and the site is sufficiently irrigated and packed with wound dressing. The wound culture obtained from the I & D is sent to the microbiology lab to determine the organism and the sensitivity pattern. The question now becomes what oral antibiotic(s) will need to be prescribed to the patient upon discharge and the duration of therapy.

Or is it?
We may not have to necessarily ask this question. An effective I & D that is properly performed is the ultimate treatment of such uncomplicated skin and soft tissue infections. Even the experts of the IDSA agree: the recommendation for the management of simple abscesses and boils is I & D alone, and the role of antibiotics following I & D needs to be further defined through additional studies.

An article published in 2007 thoroughly reviewed several studies to determine if oral antibiotic therapy is necessary following I & D of cutaneous abscesses. The authors of the study came to the conclusion that patients who received I & D alone had similar rates of resolution of the infection compared to patients who received oral antibiotic therapy following I & D. In addition, both groups of patients demonstrated full resolution of the infection without complications. The review also demonstrated a clinical resolution rate of at least 90% or more without the presence of any complications in patients who received I & D, regardless of whether oral antibiotic therapy was administered.

Here is a brief summary of two additional studies by Duong and colleagues and Schmitz and colleagues that evaluated the clinical outcomes of patients who have been prescribed antibiotics in the setting of uncomplicated skin and soft tissue infections following I & D:



I do want to point out that these studies are relatively small in sample size and that clinical significance here may be difficult to apply to real world scenarios when an estimated 90% of the nearly 2 million MRSA infections that occur in the United States on an annual basis are skin and soft tissue infections. The other nuance when interpreting these studies is that patients were only included if they were otherwise healthy, and those with any sort of significant comorbidities (including immunocompromise) and previous infections were excluded. We need to consider patients with increased risk factors for serious MRSA infections that may warrant treatment antimicrobials such as household contacts with documented MRSA infections, recent antibiotic use (within 1 month of infection), and IV drug abusers. In fact, in the same recommendations provided above, the IDSA does provide some guidance regarding specific populations of patients who should receive antimicrobial therapy:
  • Elderly or very young
  • Significant comorbidities or immunocompromised states
  • Severe or extensive disease (multiple sites of infection)
  • Clinical signs and symptoms of systemic illness
  • Areas in which the abscess may be difficult to drain
  • Rapid progression of the abscess with overlying cellulitis
  • Lack of response to previous I & D alone
It all boils down (no pun intended) to the individual patient. For the case of our gentleman above, I would be comfortable forgoing antibiotic therapy provided that the patient verbalizes understanding of appropriate wound care and agrees to return to the emergency department for follow up and monitoring if the infectious abscess fails to resolve or appears to become worse.

Larger, multicenter, randomized, and placebo-controlled trials do need to be conducted in order to provide more clarification the role of antimicrobial therapy for these types of uncomplicated skin infections post I & D. We will have to see the results of this trial as well as this trial to make an informed decision.

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