Master of Science (MS)


Environmental Sciences

Document Type



Wild birds carry diverse microbial communities, including antibiotic-resistant bacteria (ARB). With the ever-increasing use of antibiotics in agricultural and clinical settings, genes that code for antibiotic resistance in bacteria have been selected for. These bacteria persist in the environment in a culturable state, but little is understood about communities of antibiotic-resistant bacteria in the environment. Birds with predictable behaviors may serve as useful indicators of these communities, and provide insights into how bacterial communities spread and evolve in the environment. To understand the utility of birds as indicators of the presence of antibiotic-resistant bacteria in the environment, we collected bacterial samples from forest birds in a cypress-tupelo/bottomland hardwood forest fragment surrounded by urban Baton Rouge, Louisiana. Densities of total and antibiotic-resistant bacteria varied by bird sex, age group, and foraging guild. Specifically, female birds had a higher prevalence of antibiotic-resistant bacteria than males, juvenile birds carried higher densities of antibiotic-resistant bacteria than adult birds, and tree-foraging birds carried higher densities than did ground-foraging birds. These data suggest that specific behaviors from each group may be associated with higher colonization by antibiotic-resistant bacteria and that birds may be useful indicators of contamination by viable potential pathogens in the environment. In a separate analysis, we sequenced the 16S rRNA gene from almost 100 isolates and used BLASTn analysis to determine the lowest possible taxonomic level for each sequence. We found that there were four orders of bacteria present from all of our samples; Lactobacillales, Pseudomonadales, Bacillales, and Enterbacterales. The Louisiana birds sampled in this study yielded a diverse array of bacteria, and highlighted the importance of future studies of antibiotic-resistant bacteria in birds.



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Committee Chair

JOHNSON, Crystal