A small piece of DNA that helps bacteria commonly found in US meat and poultry resist several antibiotics has also been found in the plague bacillus Yersinia pestis, gene sequence researchers report.
The ability to resist many of the antibiotics used against plague has been found so far in only a single case of the disease in Madagascar. But because the same ability is present in other kinds of bacteria from a broad range of livestock, antibiotic resistance could potentially spread to other Y. pestis and also other bacterial pathogens. In a paper published March 21 in the new journal PLoS ONE, the authors say this possibility "represents a significant public health concern."
Genetic ability to disable antibiotics, including multidrug resistance (MDR) sequences, is carried on plasmids, small circles of DNA that are passed easily between bacteria. In this study, the same MDR plasmids found in the Y. pestis from Madagascar were also present in bacteria such as Salmonella and Escherichia coli found in retail samples of beef, pork, chicken, and turkey from several US states.
"What we've done is revealed a mechanism for the acquisition of multidrug resistance in Y. pestis. Obviously, this is an event that might have serious human health consequences. But the sequencing work we've done has given us a way to monitor this plasmid in future," says senior author Jacques Ravel of The Institute for Genomic Research (TIGR) in Rockville, MD.
"The fact that we found a plasmid usually found in Salmonella in Y. pestis is a big problem. It also raises a question about how this happened, how it went from one to the other. But that's a question we cannot answer in this paper," Ravel notes. He urges a new monitoring program to track MDR in Y. pestis.
MDR Salmonella and E. coli have been found in droppings from wild geese, raising the possibility that wild animals might be able to spread MDR far beyond the livestock where it originate
Contact: Jacques Ravel
Public Library of Science