BACKGROUND: Carriage rates of Staphylococcus aureus on affected skin in atopic dermatitis (AD) are approximately 70%. Increasing disease severity during flares and overall disease severity correlate with increased burden of S. aureus. Treatment in AD therefore often targets S. aureus with topical and systemic antimicrobials.
OBJECTIVES: To determine whether antimicrobial sensitivities and genetic determinants of resistance differed in S. aureus isolates from the skin of children with AD and healthy child nasal carriers.
METHODS: In this case-control study, we compared S. aureus isolates from children with AD (n = 50) attending a hospital dermatology department against nasal carriage isolates from children without skin disease (n = 49) attending a hospital emergency department for noninfective conditions. Using whole genome sequencing we generated a phylogenetic framework for the isolates based on variation in the core genome, then compared antimicrobial resistance phenotypes and genotypes between disease groups.
RESULTS: Staphylococcus aureus from cases and controls had on average similar numbers of phenotypic resistances per isolate. Case isolates differed in their resistance patterns, with fusidic acid resistance (FusR ) being significantly more frequent in AD (P = 0·009). The genetic basis of FusR also differentiated the populations, with chromosomal mutations in fusA predominating in AD (P = 0·049). Analysis revealed that FusR evolved multiple times and via multiple mechanism in the population. Carriage of plasmid-derived qac genes, which have been associated with reduced susceptibility to antiseptics, was eight times more frequent in AD (P = 0·016).
CONCLUSIONS: The results suggest that strong selective pressure drives the emergence and maintenance of specific resistances in AD.
Bibliographical note© 2018 The Authors. British Journal of Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.
- Administration, Cutaneous
- Anti-Infective Agents, Local/administration & dosage
- Carrier State/diagnosis
- Case-Control Studies
- Child, Preschool
- Dermatitis, Atopic/diagnosis
- Drug Resistance, Bacterial/drug effects
- Healthy Volunteers
- Infant, Newborn
- Microbial Sensitivity Tests
- Nasal Mucosa/microbiology
- Peptide Elongation Factor G/genetics
- Severity of Illness Index
- Staphylococcal Skin Infections/diagnosis
- Staphylococcus aureus/isolation & purification