Medical Research: What are the main findings of the study?
Dr. Bowen: The Skin Sore Trial found that short courses (3 days of twice daily dosing or 5 days of once daily dosing) of oral co-trimoxazole worked just as well for treating impetigo in remote Indigenous Australian children as the standard treatment with an intramuscular injection of penicillin (BPG). Despite many randomised controlled trials (RCTs) on this common infection of childhood, few have been conducted where impetigo is severe and endemic and with over 100 million children affected at any one time, ongoing research is needed. This is only the second RCT to study impetigo in children where the problem is endemic and often severe. In our study, 70% of children had severe impetigo with a median of 3 body regions affected. BPG injections are painful and we knew from previous studies that not many children were receiving them. Our study confirmed that 30% of children had injection site pain 48 hours after receipt of the injection and 5 children ran away when they found out that they were randomised to the injection arm of the study.
Medical Research: Were any of the findings unexpected?
Dr. Bowen: We were able to show that co-trimoxazole works just as well at clearing group A Streptococcus (GAS) from skin sores as penicillin. This provided in vivo evidence that supported our in vitro work to conclude that co-trimoxazole does work well against GAS.
Clearance of GAS was the only predictor of sore healing, even in the context of 75% co-infection with Staphylococcus aureus and 13% methicillin resistant S. aureus (MRSA) rates. This confirmed an observation made over 40 years ago that impetigo is driven by GAS.
Medical Research: What should clinicians and patients take away from your report?
Dr. Bowen: Oral co-trimoxazole in very short courses is effective for the treatment of impetigo. It is cheap, palatable, had very few side effects and is also effective against MRSA. When systemic antibiotics are needed for impetigo (severe infection, multiple people affected), the current IDSA recommendation is treatment for at least 7 days. We found that much shorter courses work well which is more likely to result in full adherence and reduce transmission.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Bowen: Co-trimoxazole resistance to GAS and S. aureus were 0.5% and 1% respectively in our study. We need to continue to evaluate co-trimoxazole resistance as this antibiotic is used more widely. Even shorter courses of oral antibiotics might be an option for treatment of impetigo in the future. In a region of very high rates of post-streptococcal glomerulonephritis and acute rheumatic fever, we need to continue to evaluate the impact better treatment of impetigo has on these post-infectious sequelae.
Short-course oral co-trimoxazole versus intramuscular benzathine benzylpenicillin for impetigo in a highly endemic region: an open-label, randomised, controlled, non-inferiority trial
Dr Asha C Bowen FRACP,Steven Y C Tong PhD,Prof Ross M Andrews PhD,Irene M O’Meara RN,Malcolm I McDonald PhD,Mark D Chatfield MSc,Prof Bart J Currie FRACP,Prof Jonathan R Carapetis PhD
The Lancet – 27 August 2014