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Three Part Question

In [all patients with cutaneous abscesses treated with incision and drainage in the emergency department] [does the use of antibiotics] improve [wound healing 3 to 7 days post-procedure or abscess recurrence] in the future?

Clinical Scenario

You treat a cutaneous abscess in young adult male in the emergency department with incision and drainage. You dress the wound and discharge him however wonder whether you should prescribe a course of antibiotics.

Search Strategy

Medline (1946 to May 2014) and Embase (1980 to 2014 week 23) and The Cochrane Library were searched with the following string: [exp Abscess/ OR abscess.mp OR absces$.mp OR exp Furunculosis/ OR exp Carbuncle/OR exp Soft Tissue Infections/] AND [exp Anti-Bacterial Agents/]

This gave a very high yield thus the searches were limited with the terms “English Language’, “Human” and “Therapy (Maximises specificity)”

A further search of the Cochrane Library of Systematic Reviews was also performed with the use of keywords as the [exp] search term is not valid for this particular database.

Search Outcome

This gave a yield of 1089 papers. 32 of these were relevant to the question and had full evaluation. From these there were 4 RCT’s , all of which were included in 1 meta-analysis. There was 1 other RCT but this was not included due to study design. 1 prospective study was also identified. Review of all references, including those of the 4 literature reviews identified highlighted 1 further prospective study (Moran et al. 2006) which was also included.

Overall this gave 1 meta-analysis and 2 prospective reviews to be included in the BET.

Additionally there were 2 ongoing randomised clinical trials located on the National Institute for Health website: www.clinicaltrials.gov. Trial numbers: NCT00729937 and NCT00730028 which may provide additional future evidence.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Singer & Thode 2013 New York, USA	"589 total. 428 adults & 161 children with simple non-complicated abscesses treated in the ED or outpatient clinics. These patients were randomised to 3 different antibiotics: cephridine (27), cephalexin (82) or trimethoprim sulfamethoxazole (161) or placebo (285). (34 lost to follow up)	Systematic Review	Clinical cure at 7-10 days after presentation. "	88.1% for antibiotic group. 86% for placebo.	"Small number of patients for systematic review (<600) from only 4 RCT’s therefore underpowered to detect small differences in treatment groups. Long-term follow-up only performed in 2 studies Differences between RCT’s not explained. Weaknesses of included RCT’s not taken into account - for example one study used cephalexin which is inactive against MRSA, 75% of abscesses were MRSA positive!
			Abscess recurrence after 30-90 days.	"Antibiotic group - 81.5% no recurrence Placebo group - 71.6% no recurrence
Moran et al. 2006 Georgia, USA	422 adult patients with a purulent skin and soft tissue infection of <1 week duration, 81% had an abscess, 11% an infected wound and 8% had cellulitis with purulent exudate. 66% (267) treated with I&D and antibiotics, 19% (79) with incision and drainage alone and 10% (39) with antibiotics alone.	Prospective Multi-centre Prevalence Study	Outcome of infection 2-3 weeks after initial presentation	No difference between treatment groups - 96% resolution of all infections. Additionally no difference between patients with MRSA positive wounds treated with effective antibiotics versus ineffective.	"None of the analyses were abscess specific, despite it being a major proportion. Results therefore may not be applicable. Results were also not stratified to treatment groups. Large number of patients lost of follow-up. No control group.
Lee et al. 2004 Texas, USA	"69 children with skin and soft tissue abscess with culture proven MRSA during study period. All patients received I&D of their abscess and then had various antibiotics prescribed before culture results were known. Children receiving effective antibiotics were compared to those receiving ineffective antibiotics. Following 1st follow-up appointment, 21 children (out of 58) were changed onto effective antibiotics.	Prospective Observational Study	Outcome of 1st follow-up appointment (1-6 days after presentation) - improvement or admittance to hospital.	"Effective antibiotics - 100% (5 children) improved, 0% (0 children) admitted. Ineffective antibiotic - 94% (58 children) improved, 6% (4 children) admitted. "	"Small number of patients with differing numbers in each group. Children received different antibiotics, with some receiving IV antibiotics as top up. No control group. Only children whose cultures grew MRSA were included so may not be relevant for negative -MRSA abscesses. "
			Outcome of 2nd (6-10 days after presentation) follow-up appointment — improvement, worse or DNA	"Effective antibiotic - 95% (21) improved, 5% (1) DNA Ineffective antibiotic — 84% improved, 3% (1) worse, 13% (5) DNA"

Comment(s)

Despite the weaknesses in the systematic review and lack of hard evidence in the prospective studies it does appear that antibiotics following incision and drainage of abscesses makes no difference to healing rates. The prospective studies highlight that, even when given the wrong antibiotic, lesions heal just as quickly. The prospective studies above only contained MRSA infections which are more prevalent in the United States than the UK (Lessa et al. 2010), however the results are still applicable here. Avoidance of antibiotic use after I&D of abscesses is also prudent given rising antibiotic resistance rates (Meropol & Metlay, 2013).

Clinical Bottom Line

If you treat an abscess with incision and drainage in the emergency department there is no need to prescribe a course of antibiotics.

Level of Evidence

Level 2 - Studies considered were neither 1 or 3.

References

1. Singer, Adam J., and Henry C. Thode Systemic antibiotics after incision and drainage of simple abscesses: a meta-analysis Emergency Medicine Journal 2013
2. Moran, Gregory J., et al. Methicillin-resistant S. aureus infections among patients in the emergency department. New England Journal of Medicine 2006; 355.7: 666-674
3. Lee, Michael C., et al. Management and outcome of children with skin and soft tissue abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus The Pediatric infectious disease journal 2004: 23.2: 123-127