Molecular Epidemiology of Colonization in Families With Infants.

BACKGROUND

Community-associated infection is a major public health hazard to adults and older children. Infants frequently excrete toxigenic asymptomatically in their stool, but their importance as a community reservoir of is uncertain.

METHODS

Families of healthy infants were recruited at the baby's 4-month well child visit and were followed longitudinally until the baby was approximately 9 months old. Babies and mothers submitted stool or rectal swabs every 2 weeks that were cultivated for ; fathers' participation was encouraged but not required. isolates were strain-typed by fluorescent polymerase chain reaction ribotyping and by core genome multilocus sequence typing, and the number of families in whom the same strain was cultivated from >1 family member ("strain sharing") was assessed.

RESULTS

Thirty families were enrolled, including 33 infants (3 sets of twins) and 30 mothers; 19 fathers also participated. was identified in 28 of these 30 families over the course of the study, and strain sharing was identified in 17 of these 28. In 3 families, 2 separate strains were shared. The infant was involved in 17 of 20 instances of strain sharing, and in 13 of these, the baby was identified first, with or without a concomitantly excreting adult. Excretion of shared strains usually was persistent.

CONCLUSIONS

strain sharing was frequent in healthy families caring for an infant, increasing the likelihood that asymptomatically excreting babies and their families represent a reservoir of the organism in the community.