Skin microbe transmission in households of pediatric AD
patients
Besides lesional sites of AD, the anterior nares and inguinal creases
are common reservoirs of S. aureus . Clinical studies have shown
that S. aureus strains can be shared between the reservoirs and
distal skin sites, indicating that skin microbes are spread through
physical transfer or through the airborne route.51, 52The seeding of S. aureus between reservoirs and other body sites
may promote recolonization, disrupting optimal AD control.
There is also growing appreciation for the importance of other non-self
reservoirs and skin microbial transmission between individuals in close
contact in perpetuating AD. Studies utilizing 16S or whole genome
sequencing of skin microbiomes have further demonstrated a general
sharing of skin microbes apart from S. aureus between members of
the same household.52, 53 In a cross-sectional study
of 30 primary caregiver-child pairs (children aged 4- 10 years) in
households with pediatric AD and the same number of age matched control
pairs, Chia et al demonstrated significant microbiome similarities
between the skin of clinically healthy caregivers and the skin of their
children.52 A subset of caregivers in households with
pediatric AD also exhibited lower relative abundances of some skin
commensals like S. hominis and Dermacoccus
nishinomiyaensis . Furthermore, the ratio of S. aureus toS. hominis within skin microbiomes was a more sensitive and
specific marker for an individual’s (caregiver or child) affiliation to
a house with an AD patient than just S. aureus relative
abundances alone, underscoring the importance of additional shared
microbial influences within families. While cross-sectional cohorts have
shed light on possible microbiome sharing between family members,
further studies involving prospective cohorts are necessary to establish
stronger evidence for the role of intra-familial microbial transmission
in the onset, progression, and recurrence of pediatric AD. These studies
are important to establish if the risk of recurrent AD is associated
with the re-acquisition of microbes including S. aureus after
their eradication following initial treatment.
Taken together, the current literature supports further investigations
into whether clinically healthy household members should also undergo
decolonization to manage recurrent pediatric AD. A clinical trial has
shown that both S. aureus decolonization of all household members
of children below 18 years of age (median age 3.9 years, range,
1.1–17.1 years) with community-acquired methicillin-resistant S.
aureus (MRSA) skin and soft tissue infections (SSTI) or individualized
decolonization of only household members with history of SSTI had a
modest effect on the risk of study participants developing future
SSTI,54 but no trial has been conducted in the context
of recurrent pediatric AD to date. The ineffectiveness of these
household decolonization strategies could be due to the lack of
decontamination of household surfaces and fomites, which are significant
reservoirs of S. aureus , or due to potential complexities with
re-acquisition of S. aureus from sources outside the household.
More comprehensive decolonization regimes will need to be trialled to
evaluate the efficacy of expanding treatment beyond the index patient
for managing recurrent pediatric AD.