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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #378497

Research Project: Intestinal Microbial Ecology and Metagenomic Strategies to Reduce Antibiotic Resistance and Foodborne Pathogens

Location: Food Safety and Enteric Pathogens Research

Title: Differential impact of OTC regimen on growth and gut microbiota of pigs co-infected with respiratory pathogens

item MOU, KATH - Orise Fellow
item RICKER, NICOLE - University Of Guelph
item Trachsel, Julian
item Brockmeier, Susan
item Allen, Heather

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Objective: Along with judicious antibiotic use, there is great interest in how the dose regimen of an antibiotic affects the animal gut microbiota. We examined the effectiveness of two dosing regimens of oxytetracycline (OTC) against respiratory pathogen challenge in pigs and what impact this had on the pig gut microbiota. Methods: Eighty 3-week-old pigs were divided into 4 groups. One group was not challenged and given non-medicated feed (NONINFnm). The other three groups were infected with Bordetella bronchiseptica and Pasteurella multocida seven days and three days prior to OTC treatment (day 0), respectively, and divided by OTC dosing regimen: no OTC treatment/non-medicated feed (INFnm), OTC injection/non-medicated feed (INFinject), and non-injected/OTC feed (INFfeed) until necropsy (days 4 or 7). Animal weights were recorded to assess average daily gain. OTC levels in nasal wash, plasma, and lung were measured using LC-MS. Lungs were examined and scored for lung lesion severity. B. bronchiseptica and P. multocida colonization in nasal cavity, lung, trachea, and tonsil were assessed. Fecal microbial population shifts were characterized by 16S rRNA gene sequence analysis. Results: OTC administration had minimal effect on B. bronchiseptica and P. multocida colonization. No significant impact on lung lesion development was detected among all four groups. Average daily gain was higher for INFinject and NONINFnm compared to INFnm on days 4 and 7. OTC was detected in plasma, nasal cavity, and lungs at varying concentrations depending on the dosing regimen. The gut microbial shifts of INFnm, INFinject, and INFfeed were driven by time and OTC treatment, especially on day 7. Relative abundances of microbial populations were detected among the three groups at the order level. Conclusion: While OTC was detected in animals after administration, there was minimal impact on colonization of B. bronchiseptica and P. multocida and disease pathology. Interestingly, injected OTC limited negative impacts of infection on weight gain. OTC impacted gut microbiota.