Honors Theses
Date of Award
2012
Document Type
Undergraduate Thesis
Department
Biology
First Advisor
Colin Jackson
Relational Format
Dissertation/Thesis
Abstract
Bacterial isolates obtained from samples of five varieties of leafy green vegetables were tested for resistance to four different antibiotics: ampicillin. erythromycin, streptomycin, and tetracycline. Isolates were separated based on media type (TSA vs. R2A media), sterilization techniques (surface sterilized vs. unsterilized). cultivation methods (conventional vs. organic), and specific lettuce type origins. Resistances were tested using a microscale broth culture technique, which allowed for growth of isolates in the presence of different concentrations of antibiotic. Antibiotic resistance was observed in all groups of isolates, although levels of resistance varied depending on the particular isolate and the antibiotic tested. Isolates were generally the most resistant to ampicillin, with some isolates showing resistance to 5000 pg/mL, 60 times the amount of ampicillin which would be used to treat human infections. Isolates generally showed the least amount of resistance to tetracycline, although many isolates grew at tetracycline concentrations exceeding a typical human dose. Over two thirds of the isolates were resistant to multiple antibiotics, with four isolates showing high levels of resistance to all four antibiotics tested. These four isolates were all obtained from green leaf lettuce and all four are potential human pathogens. Overall, bacterial isolates from green leaf lettuce samples collectively were the most antibiotic resistant of any of the five lettuce types. These results show that leafy green vegetables contain bacteria which are antibiotic resistant and could serve as a mechanism for an increased transmission of antibiotic resistance to bacteria within the human body.
Recommended Citation
Reynolds, Brooke Elizabeth, "Antibiotic Resistance of Bacteria Isolated from Leafy Green Salad Vegetables" (2012). Honors Theses. 2249.
https://egrove.olemiss.edu/hon_thesis/2249
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