Longitudinal Shedding Patterns and Characterization of Antibiotic Resistant <i>E. coli</i> in Pastured Goats Using a Cohort Study

• Main Authors: Eunice Ndegwa, Hanin Almehmadi, Kim Chyer, Paul Kaseloo, Ankrah A. Ako
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Antibiotics
• Subjects: antibiotic resistance; goats; goat kids; resistant genes; virulence genes; phylogenetic grouping
• Online Access: https://www.mdpi.com/2079-6382/8/3/136

There is a scarcity of information on antibiotic resistance in goats. To understand shedding of resistant <i>Escherichia coli</i> in pastured goats, we collected fecal samples from a mixed age cohort over a one-year period. No antibiotic had been used on the study animals one year prior to and during the study period. Resistant isolates were detected in all age groups and prevalence in goat kids was significantly higher than adults; 43&#8722;48% vs. 8&#8722;25% respectively. The proportion of resistant isolates was higher when animals were congregated near handling facility than on pasture. Most isolates were resistant to tetracycline (51%) and streptomycin (30%), but also to antibiotics that had never been used on the farm; ampicillin (19%). <i>TetB, bla_-TEM</i>, (<i>aadA</i> and <i>strpA/strpB</i>) genes were detected in 70%, 43%, (44% and 24%) of tetracycline, ampicillin, and streptomycin resistant isolates respectively. Resistant isolates also harbored virulent genes and some belonged to D and B2 phylogenetic groups. Thus, pastured goats, despite minimal exposure to antibiotics, are reservoirs of resistant <i>E. coli</i> that may contaminate the environment and food chain and spread resistant genes to pathogenic bacteria and some that are potential animal and human pathogens. Environmental sources may play a role in acquisition of resistant bacteria in pastured goats.