| Popis: |
Antibiotic resistant (AR) and pathogenic enteric bacteria are of human health concern. Antibiotic use in high density animal agriculture (CAFOs) is a potential source of human exposure to these bacteria. This pilot study was intended to assess impacts of CAFOs on human pathogens (Salmonella) and AR enteric bacteria (E. coli and Enterococcus) on environmental waters and people living near or working on these facilities. Eleven swine CAFOs were compared with six row crop farms for occurrence and frequency of AR bacteria in ground and surface water. Fecal samples were collected from 87 people associated with both farm types, to assess risk of AR enteric bacteria carriage. High concentrations and frequencies of AR E. coli, Enterococcus, and Salmonella were found in swine wastes; they were also found in surface waters but at lower concentrations. E. coli or Enterococcus concentrations were not significantly different when comparing upstream and downstream samples within farm types. However, Salmonella concentrations were significantly higher in surface water downstream of CAFOs than upstream. Bacteria concentrations of downstream surface waters were not significantly different between CAFOs and row crop farms. Risk of AR carriage was higher in people associated with CAFOs (RR= 1.42 [95% CI =1.17 1.72]) but the proportion of human isolates with multiple AR was higher among those people associated with row crop farms. As concentrations of bacteria in waters of both farms types were not statistically different and phenotypic links between the bacteria found in animal wastes, water and people could not be established, the AR bacteria in human stool samples could not be attributed to the farms. This study found high frequencies of AR bacteria on CAFOs and that people associated with CAFOs had higher risk of carriage of AR bacteria than people associated with row crop farms. However, those associated with row crop farms had bacteria with more resistance traits. Further analysis on multiple CAFOs is necessary to increase statistical power and to establish links, if any, between AR bacteria found on farms and in people to conclusively assess impacts of swine agriculture on human health effects associated with AR and pathogenic enteric bacteria. |
