July 16, 2018
2 min read

Adding azithromycin to ivermectin does not improve impetigo, scabies treatment

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The addition of azithromycin to an ivermectin mass drug administration, or MDA, had a similar effect as ivermectin alone for treating scabies and impetigo, according to published study results in Clinical Infectious Diseases.

“In low-income settings, scabies infestation is a major cause of secondary bacterial infection,” Michael Marks, PhD, MRCP, DTM&H, assistant professor and National Institute for Health Research clinical lecturer at the London School of Hygiene & Tropical Medicine, told Infectious Diseases in Children. “This study aimed to understand if providing antibiotics alongside treatment of scabies reduced the prevalence of bacterial skin infections more than simply treating the scabies.”

Marks and colleagues conducted an open-label study of six communities in Malaita province of the Solomon Islands, where the prevalence of scabies and impetigo is high. The communities were randomly assigned to receive treatment of ivermectin-based MDA or ivermectin-based MDA and azithromycin. Communities were isolated from each other to avoid cross-contamination between the two treatment cohorts.

There were 1,291 residents (90.8% of the population of the communities; median age, 25 years) who received treatment, and 1,083 of those residents were examined at a12-month follow-up visit.

The researchers collected lesion swabs from children aged 13 years and younger at baseline and at 3 months. The children were selected because that age group was expected to have the highest prevalence of impetigo. At 12 months, swabs were collected from all participants with active impetigo.

The ivermectin-only cohort had prevalences of scabies and impetigo of 11.8% and 10.1% at baseline, respectively, whereas the combined treatment cohort had prevalences of 9.2% and 12.1%, respectively. The prevalences for scabies and vitiligo at 1 year had fallen to 1% and 2.5% for the ivermectin-treated cohort and 0.7% and 3.3% for the combined treatment cohort.

There was very little change in impetigo lesions containing Staphylococcus aureus between baseline (80%) and at 12 months (86%), with no significant differences between the two cohorts. However, there was a significant drop in the proportion of impetigo lesions with pyogenic streptococci, from 63% at baseline to 23% at 12 months (P < .01).

Although eight of 15 S. aureus isolates were resistant to macrolides in the combined treatment cohort at 3 months, no resistant strains were found after 1 year.

“We found no additional benefit of adding an antibiotic alongside community treatment of scabies in terms of reducing the prevalence of secondary bacterial infections,” Marks concluded. by Bruce Thiel

Disclosures: Marks reports consultancy fees from WHO. Please see the study for all other authors’ relevant financial disclosures.