Investigating Pedestrian Traffic as a Possible Contributor to Tetracycline Resistance in Public Land Soil Microbiomes

Abstract

Since the development of the first antibiotic in the early 20th century, antibiotic resistance has become one of the greatest challenges faced by clinicians and public health experts in modern history. Previous research has demonstrated an exchange of antibiotic resistance between livestock and environmental microbiomes, as well as human and livestock microbiomes. The goals of this study were to investigate a similar relationship between human and environmental microbiomes using antibiotic growth media and polymerase chain reaction assays. Soil samples were collected from the Sangre de Cristo Mountains in north New Mexico. Tetracycline resistance assays were used to quantify the percentage of colony-forming units (CFUs) in each sample that demonstrated resistance to tetracycline to determine if collection sites with higher amounts of human foot traffic showed higher levels of resistance. PCR and gel electrophoresis were applied to test for the presence of four common tetracycline resistance genes (tet(A), tet(B), tet(D), and tet(E)) in the high-traffic samples. Samples taken from the high and moderate-traffic sites showed statistically significant levels of resistance, while the low-traffic site did not. Additionally, the high-traffic site demonstrated levels of tetracycline resistance that were greater than both moderate and low-traffic sites. Five samples tested positive for tet(A), and five tested positive for tet(E). No samples tested positive for either tet(B) or tet(D). These results indicate a correlation between human foot traffic and tetracycline resistance in soil samples.

Keywords: Bacteria, tetracycline, antibiotic resistance, soil microbiome

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