An ongoing dialogue on HIV/AIDS, infectious diseases,
October 29th, 2016
Are Antibiotics Useful for Small Skin Abscesses? Now There’s an Answer
Let’s start with the clinical controversy, one that’s been bouncing around Emergency Rooms, outpatient practices, postgraduate courses, and medical journals for years. Specifically, are antibiotics helpful for skin abscesses that are adequately drained?
It’s still debated since of course most patients with this annoying problem will get better on their own provided the drainage is adequate. What do the antibiotics add, if anything?
Now, thanks to a superb clinical trial presented this past week in New Orleans at the annual IDWeek Meeting, we have some answers.
And though the study is important, there’s a good chance you don’t know about it, even if you attended IDWeek. First, just like the last time this group presented results of a different trial on at a national meeting, the abstract presentation took place in front of a only a handful of meeting participants.
Second, even if you wanted to come see the presentation, you might have been stymied by the vast travel distances inside the New Orleans Convention Center, which must be one of the longest indoor spaces on the planet. Safe to say that no one who attended this meeting finished a day with fewer than 10,000 steps, unless they brought along their hoverboards or Segways. Sometimes it felt like I was walking half the way to Baton Rouge.
(For the record, that first study ended up being a major paper in the esteemed New England Journal of Medicine. Justice!)
Anyway, here are some of the details of this new study:
- Adults and children with small skin abscesses were eligible provided they weren’t immunocompromised, diabetic, or systemically ill.
- They all underwent abscess drainage and cultures.
- Participants were randomized 1:1:1 to receive TMP/SMX, or clindamycin, or placebo for ten days. (Glad they followed the Golden Rule.)
- 786 subjects enrolled (505 adults and 281 children) at several sites around the country.
- 67% had positive cultures for Staph aureus; 74% of these isolates were MRSA.
- At a 10-day post-therapy visit, cure of infection was seen in 83.1% and 81.7% of clindamycin and TMP/SMX treated patients respectively — both significantly better than placebo (68.9%).
- TMP/SMX was better tolerated than clindamycin, with adverse event rates of 11% (TMP/SMX) and 22% (clindamycin). Placebo was 12.5% (guess that’s the “nocebo” effect). There were no cases of C diff or severe rashes.
- Clindamycin-treated patients had fewer relapses than those receiving TMP/SMX.
The droll presenter, Dr. Robert Daum, and the senior author, Dr. Chip Chambers, made a couple of other interesting observations. First, if the culture grew a Staph aureus resistant to clindamycin, responses were reduced. The good news is that this resistance was observed in only around 5% of isolates, a much lower percentage than typically seen in Staph aureus from hospitalized patients.
Second, if cultures were negative for staph, response rates were similar between all three treatment arms — meaning you could potentially stop antibiotics in select patients based on culture results (though important caveat, this strategy wasn’t tested).
The results of this study add to a growing body of evidence that antibiotics do in fact improve outcomes even for drained skin abscesses, swinging the pendulum further back in the direction of using them for this indication. Whether you and your patient think that this net 10-15% increase chance of cure is worth the risks of antibiotics will probably depend on the case — but at least now we have the data to make an informed decision.
And boy, do my feet hurt.