First of all, the proper and effective treatment of a cutaneous abscess is ALWAYS incision and drainage. With that out of the way, let us address the more controversial question. Should a child be prescribed antibiotics after I&D? We’ll look at the evidence as it stands then address the main question in a scenario-based approach. Certainly MRSA is the main reason why this question is so important to address. In some locales nearly all cutaneous abscesses will be caused by the aforementioned gram positive bacterium – see Fridkin and Moran et al NEJM for more. Most of the following studies discuss treatment failure as an outcome. In gereral this means that one or more of the following occurred within a set time period after I&D:

Return of any of the following symptoms at the original site of the I&D:

  • Erythema
  • Warmth
  • Induration
  • Fluctuance
  • Tenderness

Worsening symptoms requiring:

  • Further surgical drainage
  • Change in medication
  • Hospital admission for intravenous antibiotics

 

Let’s take a look at the evidence shall we?

Rajendran et al Antimicrob Agents Chemother, 2006

A RCT of 166 adults randomized to 7 days of placebo versus cephalexin. The primary outcome was treatment failure at 7 days. 70% of the abscess cultures had staph isolates, and of these isolates 87% were methicillin resistant. Placebo cure rate was 90.5% (95% CI, 0.82 to 0.96) and 84.1% (95% CI, 0.74 to 0.91) in the cephalexin group P=0.0006 (95% confidence interval, -0.0461 to 0.0472; P = 0.25). Sure, they randomized to an antibiotic that MRSA laughs at, but both groups had high cure rates.

Paydar et al Arch Surgery 2006

This retrospective review of 376 patients with abscesses noted a high rate of MRSA isolates, but a low rate of provision of effective antibiotics (Only 25 of 284 MRSA cases). Only one patient failed treatment in this inappropriate group (osteomyelitis). This study used data from 2000 to 2001 and certainly is limited by its design.

Ruhe et al Clin Infect Dis 2007

A retrospective review of 492 adult patients with 531 abscesses, all MRSA positive. Most had an I&D performed. Treatment failure occurred in 8%. Therapy was successful for 95% (296/312) of patients who received an active antibiotic vs 87% (190/219) who didn’t (p=.001). On logistic regression analysis the authors noted that use of an inactive antimicrobial agent was an independent predictor of treatment failure adjusted odds ratio=2.80; (95% CI, 1.26-6.22; P=.01).

Duong et al Annals of Emerg Med 2010

A double-blind, placebo controlled RCT of 161 pediatric patients with cutaneous abscesses. Patients were randomized to receive 10 days of placebo or trimethoprim-sulfamethoxazole after I&D. The follow up was either a visit or phone call at 10-14 days and then a call 90 days. The primary outcome was treatment failure, with new lesions at 10 and 90 days serving as the secondary outcomes. The threshold for non-inferiority was set at <7%. Per the authors, the failure rates were 5.3% (n=4/76) and 4.1% (n=3/73) in the placebo and antibiotic groups, respectively, difference 1.2%, (95% CI -infinity to 6.8%). They saw new lesions at 10-days in 26.4% of placebo and 12.9% of the ™P-SMX group, difference 13.5%, (95% CI -infinity to 24.3%). At 90 days 28.8% of placebo and 28.3%of the antibiotic group had new lesions, difference 0.5%, (95% CI -infinity to 15.6%). They thus concluded that although a short term decrease in the formation of new lesions may be seen antibiotics were not required for resolution in most pediatric skin abscesses after I&D.

So, as you can see the evidence is not 100% convincing either way, but it seems that treatment failure rates are not appreciably different with or without antibiotics. This obviously doesn’t completely answer the question, and certainly there are some situations where antibiotics are more likely to be beneficial than others. Let’s therefore turn our attention to the 2010 Infectious Diseases Society of America’s (IDSA) practice guideline for skin and soft tissue infections and the IDSA’s 2014 Update. Here’s what the panel of experts recommended:

Incision and drainage is the primary treatment for cutaneous abscesses

Antibiotics are recommended for:

  • Severe or extensive disease (multiple sites of infection, size greater than 5 cm)
  • Rapid progression in presence of associated cellulitis
  • Signs and symptoms of systemic illness (fever, ill appearance)
  • Associated comorbidities or immunosuppression (diabetes, cancer, lupus – the list goes on and on, use your judgement)
  • Extremes of age (especially babies under 6 months of age, and probably 12 months)
  • Body location of abscess makes drainage difficult (face, hand, and genitalia)
  • Associated septic phlebitis
  • Lack of response to incision and drainage alone

Treat purulent cellulitis (cellulitis draining pus, but without a drainable abscess) with a MRSA appropriate antibiotic for 5-10 days

Empiric MRSA coverage should take local resistance patterns into account, and could include:

  • Clindamycin
  • Trimethoprim-sulfamethoxazole
  • Tetracyclines (doxycycline or minocycline)
  • Linezolid

Get a wound culture if:

  • The patient is already on, or you will place them on antibiotic therapy
  • There are signs of severe local infection
  • Signs of systemic illness
  • The patient has not responded adequately to initial treatment
  • There is a concern for a cluster or outbreak

Now let’s take a look at what you might do if you encountered a few common scenarios, including what I’d recommend you discuss with patients and families.

The patient is not yet on antibiotics, you just performed an I&D

Have a discussion with the family about whether or not the child truly needs antibiotics. Use your time wisely and explain what an abscess is and why a walled-off collection of pus is inaccessible to antibiotics. If the child has any of the following you should choose a MRSA active drug while simultaneously considering local resistance patterns:

  • The abscess itself is >5 cm
  • Multiple lesions
  • Extensive surrounding cellulitis
  • Associated comorbidities or immunosuppression
  • Systemic signs of infection (fever due to the skin infection alone)
  • Body location making I&D more challenging/risky (face, genitals, hands/fingers)

Already started on antibiotics by another provider, you just performed an I&D

It is quite possible that the TMP-SMX that they are on helped treat the initial cellulitis and that you are now left with an abscess. It is also possible that they didn’t need them in the first place. in the (common) scenario that the child has already been started on antibiotics, especially if it is more than 2-3 days, I would recommend continuing them barring signs of allergy or other reaction.

Not yet an abscess but probably will be in 2-3 days

Start antibiotics if the patient has cellulitis. Talk to the parents about what an abscess is and how and why they form. Spend time helping parents recognize the signs and symptoms of an abscess and arrange for optimal follow up. Give the primary doctor a call and let them know how likely you think it is that a drainable abscess may form. They can then appropriately manage, or send the patient back to the ED if needed. If the lesion is very small and spontaneously draining you can recommend warm compresses an conservative treatment alone.