Randomized, Double-Blind Trial of Clindamycin, Trimethoprim-Sulfamethoxazole, or Placebo for Uncomplicated Skin and Soft Tissue Infections Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus (also known as “Staph”) is the most common cause of skin and soft tissue infections. In the past decade, our community has experienced an increase in the number of Staph infections that occur in otherwise healthy individuals. These Staph infections are increasingly resistant to the antibiotics usually used to treat these infections, and are referred to as community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). After draining a skin and soft tissue infection, it is not known which antibiotic is most useful to heal the area and prevent recurrent infections, or if antibiotics are even necessary at all.

The goal of this study is to determine the optimal management strategy for uncomplicated skin and soft tissue infections in children and adults in regions like ours where CA-MRSA is prevalent. The primary objective is to compare different treatment option after abscess drainage, including clindamycin, trimethoprim-sulfamethoxazole, or no antibiotics at all (placebo). If you decide to participate, the study will include 5 scheduled visits occurring over approximately 6 weeks.

Who is eligible to be enrolled in the study?

  • Subjects age 6 months to 85 years who are:
    • Willing and able to complete the study protocol, study-related activities, and visits
    • Diagnosed with uncomplicated skin abscess ≤ 5cm in diameter
    • Able to take oral antibiotic therapy, either in pill or suspension form
    • Not hospitalized for infection

Who is not eligible?

  • History of allergic reaction to clindamycin or trimethoprim-sulfamethoxazole
  • Hospitalization for current infection or within the prior 14 days
  • Disseminated or severe S. aureus infection, such as bacteremia or osteomyelitis
  • Infection at surgical or catheter sites, or at anatomical skin site requiring specialized management (for example, perirectal abscess or mastitis)
  • Abnormal blood pressure, heart rate, or oral temperatures
  • Systemic antibacterial therapy within the prior 14 days
  • Superficial skin infection only, including impetigo, ecthyma, folliculitis, etc.
  • Prior participation in this trial or in another clinical trial in the previous 30 days
  • Third trimester pregnancy or currently breastfeeding
  • Gastrointestinal symptoms that would preclude consumption of oral antibiotics
  • Severe or morbid obesity (BMI >40 kg/m2)
  • Residence in long-term skilled nursing facility
  • Immunocompromised host (for example diabetes or HIV)
  • Taking warfarin, phenytoin, methotrexate
  • Unstable psychiatric condition
  • Drug or alcohol dependence

What is involved in participation?

After informed consent is obtained and you are deemed eligible to participate in the study, you can expect to complete five study visits over six weeks:

  • Enrollment (Day 1)
    • Baseline medical history and physical examination will be performed
    • Skin and soft tissue infection assessment and culture
    • Study medication will be dispensed
  • Wound check (Day 3)
    • Assessment of wound
    • Questionnaire
  • End of treatment (Day 12)
    • Assessment of wound
    • Questionnaire
    • You will return any unused study medication and receive $30 for your time and travel
  • Test of cure (Day 17-20)
    • Evaluation of skin infection for clinical cure or failure
    • Questionnaire
    • You will receive $40 for your time and travel
  • One-month follow-up (Day 40)
    • Assessment of wound if necessary
    • Questionnaire assessing infection recurrences and occurrence of infections in household members and close contacts
    • You will receive $60 for your time and travel
  • We will also perform unplanned study visits as needed

Participants may be withdrawn from the study for the following reasons:

  • Any clinical adverse event, intercurrent illness, or other medical condition or situation that occurs such that continued participation in the study would not be in the best interest of the subject
  • Development while on study of any exclusion criteria that may be cause for discontinuation of study drug
  • Subjects are free to withdraw from participating in the study at any time upon request
  • Investigators may also withdraw a subject at any time for safety, behavioral, or administrative reasons

The information we learn from this study will help us determine the best treatments for skin and soft tissue infections.


We hope you will consider this exciting opportunity to work together to help learn about treating Staph infections. If you have any questions about the study or are interested in participation, please contact us:
Voice: 314-286-1207
Email: abscesstrial@kids.wustl.edu.