Study: Dogs Are a Pediatric C. difficile Risk Factor

Pet dogs are a novel risk factor for Clostridium difficile (C. difficile) infection for otherwise predominantly healthy infants without any significant healthcare exposure, according to a new report.

Researchers from Oxford University in the United Kingdom enrolled 338 children under the age of 2 in their study in order to determine risk factors for C. difficile. The infants provided a total of 1,332 fecal samples which were later analyzed by the investigative team. In total, the samples represented 158 C. difficile colonizations or carriage episodes. Additionally, their parents completed questionnaires.

The researchers wrote that previously identified risk factors for pediatric C. difficile colonization or carriage included mode of delivery, age, breastfeeding and/or nutrition, previous antibiotic use, and the environment in which the child is residing, such as the hospital or outpatient. However, the researchers added that these were discovered in smaller studies.

Only 7 infants had hospital-onset diarrhea (2%), and all others had community-acquired C. difficile infection, the researchers reported. There were 58 infants who were colonized with C. difficile at study enrollment. For those patients, age, breastfeeding, and pet dogs were independently associated. Colonization prevalence increased to about 11 months of age and then decreased as breastfeeding declined with age. Infants in households with dogs had higher colonization rates, too, the investigators found.

The risk of infection independently increased with previous use of antibiotics, the researchers found, but that was only in toxigenic strains of C. difficile. Having a child-minder (non-institutional childcare) increased the colonization risk with non-toxigenic strains of C. difficile.

After a follow-up period of 8 months, 127 infants remained as part of the study. There were 77 infants from that group who acquired a new strain of C. difficile and 25 acquired 2 or more new strains. Older age at study initiation, Caesarean delivery method, and diarrhea since the previous samples were given were all independently associated with increased risk of acquiring the new strains, the researchers learned. However, they also found that current use of mixed formula and breastfeeding or exclusive breastfeeding and pre-existing C. difficile colonization independently reduced acquisition risk.

“This study confirms factors associated with infant C. difficile colonization identified in previous studies, and identifies pet dogs as a novel risk factor,” the researchers wrote. “In addition, systemic antibiotics represent a specific risk for colonization with toxigenic C. difficile.”

Finally, the researchers said that although about a third of patients with community-acquired C. difficile infection do not have typical risk factors, like antibiotic use or hospitalization, their data showed links between some strains of C. difficile and predominantly healthy, non-hospitalized infants. The common community reservoirs of C. difficile should be investigated via a large and targeted study, they recommended.

The paper, titled “Epidemiology of Clostridium difficile in infants in Oxfordshire, UK: Risk factors for colonization and carriage, and genetic overlap with regional C. difficile infection strains,” was published in the journal PLOS One.

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