Occurrence and Quantification of Antibiotic Resistant Bacteria and Genes in Animal Impacted Environment and Retail Meats

Siqin Liu, Tennessee State University


Antimicrobial resistance (AR) is a major challenge with severe implications for public health. AR bacteria disseminate to humans through foods of animal origin, spraying and irrigating food crops with contaminated groundwater, and use of animal waste in agriculture. Since the mainstream of emerging infectious diseases is of zoonotic origin, it is essential to determine the occurrence of AR bacteria and genes in foods of animal origin and agroecosystems. This study characterized microbial communities, AR profiles, and virulence factors in retail meats and selected poultry and cattle farms in Tennessee. A total of 160 edible offal and 188 muscle meats were purchased from retail stores in Nashville, Tennessee. Salmonella enterica serovar (4.4% and 4.3%), Campylobacter (1.9% and 1.1%), E. coli (79.4% and 89.4%), and Enterococci (88.1% and 95.7%) were detected in offal and muscle meats, respectively. However, no significant differences in the occurrence of the pathogens compared with indicator bacteria. The multidrug resistance profiles (n=41) were identified and erythromycin (98.3-99.1%), tetracycline (94.0-98.3%), and vancomycin (88.8-92.2%) significantly (P < 0.05) displayed the highest resistance compared to ceftriaxone resistance both in edible offal and muscle meats. Metagenonic analysis showed that the most abundant species were Proteobacteria (34.91%), Cyanobacteria (15.67%), and Actinobacteria (14.95%). The pathogenic bacteria, including Salmonella Typhimurium, Salmonella Infantis, E. coli O121:H7, Clostridium perfringens, Klebsiella oxytoca, Klebsiella pneumonia, Morgnelle Morganii, Pseudomonas aeruginosa, Staphylococcus aureus, and Yersinia pestis were isolated from animal farms. Among 31 AR genes, the most abundant genes were for tetracycline (33.41%), beta-lactam (30.30%), and macrolide (9.32%). Among 147 virulence factors (eg. Burkholderia pseudomallei GENE opr and Klebsiella pneumoniae GENE orf6) in 20 different classes of bacteria, the top abundance virulence genes were displayed for Burkholderia pseudomallei (28.50%), Bacteroides fragilis (22.15%), Proteus mirabilis (16.66%), and Klebsiella pneumoniae (10.73%). The results suggest that edible offal and muscle meats of poultry and cattle origin are a source of antibiotic-resistant bacteria; AR, VR genes undergo complex interactions between animals, pathogenic bacteria, and their environments such as soil, water, and application of antibiotics in poultry and cattle farms. The occurrence and distribution of AR bacteria and genes data obtained in this study can be applied to mitigate antimicrobial resistance in poultry and cattle farms and retail meats.

Subject Area

Microbiology|Food Science

Recommended Citation

Siqin Liu, "Occurrence and Quantification of Antibiotic Resistant Bacteria and Genes in Animal Impacted Environment and Retail Meats" (2021). ETD Collection for Tennessee State University. Paper AAI28410751.