Date of Award

8-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Comparative and Experimental Medicine

Major Professor

Jiangang Chen

Committee Members

Robert Donnell, David Bemis, Kelli Fecteau

Abstract

Triclocarban (3,4,4'-trichlorocarbanilide; TCC) is a non-prescription antimicrobial compound found in bar soaps. Once applied to the skin, TCC is absorbed and can be detected systemically. Evidence of endocrine disruption has been documented both in vitro and in vivo in adult and immature rats. To date, little research attention has been paid to early life TCC exposure. Here, we demonstrated reduced survival among neonates born to rats provided 0.2 percent w/w or 0.5 percent w/w TCC supplemented chow during lactation. TCC was detected in the breastmilk and suckling neonates developed distended abdomens with liquid mustard colored diarrhea indicating a disturbance of the gut microbiota. When the concentration of TCC provided to dams through the chow was lowered to 0.1 percent w/w TCC, all neonates survived. However, sequencing of the V4 region of 16S rRNA on the MISeq platform revealed that TCC exposure modified the composition of the gut microbiota of suckling neonates. In addition, exposure to post-weaned rats at concentrations of 0.2 percent and 0.5 percent w/w TCC through the diet modified the gut microbial composition of older animals. Though, when exposure was removed from post-weaned rats, the compositional profile of microbial communities eventually rebounded and became more similar to samples collected from animals never exposed to TCC at subsequent collection dates. To better understand the exposure pathway of TCC to the gut microbiota, a method was developed to analyze the concentration of TCC in the rat fecal matrix. This dissertation collectively adds to the growing body of concern related to TCC exposure and provides information to both the general public and regulatory agencies on the safety of nonprescription antimicrobial use during early life.

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