The microbiology of impetigo in indigenous children: associations between Streptococcus pyogenes, Staphylococcus aureus, scabies, and nasal carriage.

BACKGROUND: Impetigo is caused by both Streptococcus pyogenes and Staphylococcus aureus; the relative contributions of each have been reported to fluctuate with time and region. While S. aureus is reportedly on the increase in most industrialised settings, S. pyogenes is still thought to drive impetigo in endemic, tropical regions. However, few studies have utilised high quality microbiological culture methods to confirm this assumption. We report the prevalence and antimicrobial resistance of impetigo pathogens recovered in a randomised, controlled trial of impetigo treatment conducted in remote Indigenous communities of northern Australia. METHODS: Each child had one or two sores, and the anterior nares, swabbed. All swabs were transported in skim milk tryptone glucose glycogen broth and frozen at -70°C, until plated on horse blood agar. S. aureus and S. pyogenes were confirmed with latex agglutination. RESULTS: From 508 children, we collected 872 swabs of sores and 504 swabs from the anterior nares prior to commencement of antibiotic therapy. S. pyogenes and S. aureus were identified together in 503/872 (58%) of sores; with an additional 207/872 (24%) sores having S. pyogenes and 81/872 (9%) S. aureus, in isolation. Skin sore swabs taken during episodes with a concurrent diagnosis of scabies were more likely to culture S. pyogenes (OR 2.2, 95% CI 1.1 - 4.4, p = 0.03). Eighteen percent of children had nasal carriage of skin pathogens. There was no association between the presence of S. aureus in the nose and skin. Methicillin-resistance was detected in 15% of children who cultured S. aureus from either a sore or their nose. There was no association found between the severity of impetigo and the detection of a skin pathogen. CONCLUSIONS: S. pyogenes remains the principal pathogen in tropical impetigo; the relatively high contribution of S. aureus as a co-pathogen has also been confirmed. Children with scabies were more likely to have S. pyogenes detected. While clearance of S. pyogenes is the key determinant of treatment efficacy, co-infection with S. aureus warrants consideration of treatment options that are effective against both pathogens where impetigo is severe and prevalent. TRIAL REGISTRATION: This trial is registered; ACTRN12609000858291 .

Skin disease in the first two years of life in Aboriginal children in East Arnhem Land.

BACKGROUND: The most common skin infections affecting children in remote Aboriginal communities are scabies and impetigo. Group A streptococcal skin infections are linked to the high rates of heart and renal disease occurring in Aboriginal Australians. METHODS: A retrospective review of medical records was conducted in a primary health care centre in the East Arnhem region of the Northern Territory. Data was collected from all presentations to the clinic in the first 2 years of life for 99 children born between 2001 and 2005 as a component of the East Arnhem Regional Healthy Skin Project. RESULTS: The median number of presentations to the clinic in the first 2 years of life was 32. Skin disease was recorded in 22% of all presentations. By 1 year of age 82% of children had presented to the clinic with their first episode of impetigo and 68% with their first episode of scabies. Antibiotics were administered to 49% of children with impetigo. CONCLUSION: Skin infections are a major reason for presentation to primary health clinics and contribute to the high disease burden experienced by children in the first 2 years of life. This high frequency of presentation provides multiple opportunities for intervention and monitoring.

Group A streptococcal pharyngeal carriage, pharyngitis, and impetigo in two northern Canadian native communities.

The prevalence of pharyngeal carriage of group A streptococci, streptococcal pharyngitis, and impetigo was determined in schoolchildren in two northern communities, one Inuit (mean number of schoolchildren surveyed, 233) and one native Indian (mean number of schoolchildren surveyed, 349). At three surveys from November 1984 to May 1985, pharyngeal group A streptococcal carriage was 5.3%, 22%, and 34% in the Inuit community and 5.3%, 5.1% and 10% in the native Indian, with impetigo prevalence 1.6%, 3.8% and 1.0%, and 2.4%, 4.2% and 0.6%, respectively. Increased pharyngeal carriage correlated with the increasing number of household residents and the lower school grade. In 12 months of observation the incidence of group A streptococcal pharyngitis was 49/100 schoolchildren for the Inuit and 9.4/100 for the native Indian community, with impetigo 13/100 and 11/100 respectively. The maximal incidence of pharyngitis was late winter in the Inuit community and midsummer in the native Indian. The incidence of impetigo peaked in January for both communities. M and T typing showed consecutive outbreaks of different serotypes in the Inuit community, but a persistent low level of endemic infection in the Indian community. These observations suggest a seasonal prevalence of group A streptococcal pharyngeal carriage consistent with other North American populations, but marked inter-community variation in pharyngeal carriage and disease. The midwinter peak of impetigo appears unique to these populations.