Are abx always necessary? Soft Tissue Abscess Are abx always necessary?

Pathophysiology & Epidemiology Abscess refers to infection of the deeper dermis with inflammatory debri however overlying epidermis is normal. By contrast, erysipelas is infection of the upper dermis and cellulitis involves infection/inflammation of the loose connective tissue. Incidence > 200,000 ED visits annually & about 2% of all ED visits. Incidence of pediatric abscesses has risen considerably in the past 20 years; Lopez et al found that hospitalizations secondary to SSTIs doubled from 1997-2009.

9 y/o male presents with “mosquito bite” on the right lower extremity for the past 3 days. How do you treat him? I&D + Cephalexin + TMP-SMX I&D Cephalexin alone I&D alone I&D and council for IVDU

I&D + Cephalexin + TMP-SMX I&D Cephalexin alone I&D alone I&D and council for IVDU Well….it depends

Abx may not be needed for simple abscess I&D alone has been shown in several studies to have similar results to I&D with antibiotics However, abx (TMP-SMX) confer some benefit compared to placebo in clinical cure rate after incision and drainage in other studies. So when should we use abx?

When to use abx vs I&D alone Antibiotics should be used in severe disease, rapid progression, surrounding cellulitis, signs of systemic illness such as fever or tachycardia, associated comorbidities or immunosuppression, or recurrent abscesses with prior treatment failure.

Abx choice MSSA and MRSA most commonly isolated organisms Among pts w/uncomplicated cellulitis, use of cephalexin plus trimethoprim- sulfamethoxazole compared to cephalexin alone did not result in higher rates of clinical resolution of cellulitis….however “further research may be needed” Basically it remains debatable and choice should be based on local antibiogram

What about packing the abscess? Multiple studies have compared packing to no wound packing following incision and drainage of superficial skin abscesses including the pediatric ED and found no major difference. However irrigation and packing of drained abscesses is still common practice.

Use of bedside ultrasound Ultrasound is your friend! Look for hypoechoic or anechoic area of fluid collection or “swirl sign” Can help prior to I&D to identify the best place for incision to ensure that the entire abscess will be drained. Can help after procedure to identify remaining loculations or fluid collections

References Duong M, Markwell S, Peter J, et al. Randomized, controlled trial of antibiotics in the management of community-acquired skin abscesses in the pediatric patient. Ann Emerg Med 2010;55:401-407. Hankin A, Everett WW. Are antibiotics necessary after incision and drainage of a cutaneous abscess? Ann Emerg Med 2007;50:49- 51. Llera JL, Levy RC. Treatment of cutaneous abscess: A double-blind clinical study. Ann Emerg Med 1985;14:15-19. Rajendran PM, Young D, Maurer T, et al. Randomized, double-blind, placebo-controlled trial of cephalexin for treatment of uncomplicated skin abscesses in a population at risk for community-acquired methicillin-resistant Staphylococcus aureus infection. Antimicrob Agents Chemother 2007;51:4044-4048. Talan DA et al. Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess. NEJM 2016; 374 (9): 823 – 32. O’Malley GF, Dominici P, Giraldo P, et al. Routine packing of simple cutaneous abscesses is painful and probably unnecessary. Acad Emerg Med 2009;16:470-473. Kessler DO, Krantz A, Mojica M. Randomized trial comparing wound packing to no wound packing following incision and drainage of superficial skin abscesses in the pediatric emergency department. Pediatr Emerg Care 2012;28:514-517. Moran GJ, Krishnadasan A, Mower WR, et al. Effect of Cephalexin Plus Trimethoprim-Sulfamethoxazole vs Cephalexin Alone on Clinical Cure of Uncomplicated Cellulitis: A Randomized Clinical Trial. JAMA. 2017;317(20):2088-2096.