Epidemiology of Clostridium difficile in infants in Oxfordshire, UK: Risk factors for colonization and carriage, and genetic overlap with regional C. difficile infection strains.

Nicole Stoesser,Heather Godwin,Catrin E Moore,Mark H Wilcox,Kate E Dingle,Jessica Martin,Sarah Oakley,Thomas V Riley,Emily Mbuvi,A Sarah Walker,David Griffiths,Melina Kachrimanidou,Derrick W Crook,Gemma Pill,Kazimierz Wanelik,Alison Vaughan,Jack W Finney ,Tim Peto ,Sherwood L Gorbach ,David W Eyre ,Warren N Fawley ,T Phuong Quan

doi:10.1371/journal.pone.0182307

Abstract

BackgroundApproximately 30–40% of children <1 year of age are Clostridium difficile colonized, and may represent a reservoir for adult C. difficile infections (CDI). Risk factors for colonization with toxigenic versus non-toxigenic C. difficile strains and longitudinal acquisition dynamics in infants remain incompletely characterized.MethodsPredominantly healthy infants (≤2 years) were recruited in Oxfordshire, UK, and provided ≥1 fecal samples. Independent risk factors for toxigenic/non-toxigenic C. difficile colonization and acquisition were identified using multivariable regression. Infant C. difficile isolates were whole-genome sequenced to assay genetic diversity and prevalence of toxin-associated genes, and compared with sequenced strains from Oxfordshire CDI cases.Results338/365 enrolled infants provided 1332 fecal samples, representing 158 C. difficile colonization or carriage episodes (107[68%] toxigenic). Initial colonization was associated with age, and reduced with breastfeeding but increased with pet dogs. Acquisition was associated with older age, Caesarean delivery, and diarrhea. Breastfeeding and pre-existing C. difficile colonization reduced acquisition risk. Overall 13% of CDI C. difficile strains were genetically related to infant strains. 29(18%) infant C. difficile sequences were consistent with recent direct/indirect transmission to/from Oxfordshire CDI cases (≤2 single nucleotide variants [SNVs]); 79(50%) shared a common origin with an Oxfordshire CDI case within the last ~5 years (0–10 SNVs). The hypervirulent, epidemic ST1/ribotype 027 remained notably absent in infants in this large study, as did other lineages such as STs 10/44 (ribotype 015); the most common strain in infants was ST2 (ribotype 020/014)(22%).ConclusionsIn predominantly healthy infants without significant healthcare exposure C. difficile colonization and acquisition reflect environmental exposures, with pet dogs identified as a novel risk factor. Genetic overlap between some infant strains and those isolated from CDI cases suggest common community reservoirs of these C. difficile lineages, contrasting with those lineages found only in CDI cases, and therefore more consistent with healthcare-associated spread.

Highlights

Clostridium difficile remains one of the commonest causes of nosocomial infective diarrhea in high-income countries[1], increasing costs and morbidity[2]
In predominantly healthy infants without significant healthcare exposure C. difficile colonization and acquisition reflect environmental exposures, with pet dogs identified as a novel risk factor
Genetic overlap between some infant strains and those isolated from Clostridium difficile infections (CDI) cases suggest common community reservoirs of these C. difficile lineages, contrasting with those lineages found only in CDI cases, and more consistent with healthcare-associated spread