A strain of bacteria causing the plague that is resistant to antibiotics normally used to treat the disease occurred in Madagascar. Although researchers have isolated it say they know of no other instances of resistant bacteria, they note that genes that confer drug resistance can easily spread to other plague strains, which pose a threat new pandemics of disease.
Transmitted primarily by flea bites, the last bubonic plague broke out as a pandemic, there are more than 100 years in Hong Kong before spreading around the world. Today, although the disease is always fatal if not treated in time, antibiotics have reduced mortality in patients with fever of about 10%.
But tomorrow New England Journal of Medicine , a team of researchers from the Institut Pasteur in Paris and Antananarivo, Madagascar, reports having isolated a drug-resistant strain of Yersinia pestis , the bacterium responsible for plague, a patient in Madagascar. The patient has not responded to conventional therapy of the disease, a cocktail of antibiotics chloramphenicol, streptomycin and tetracycline. Y. pestis isolated patient also failed to respond to another antibiotic mixture containing sulfonamides and tetracycline, which is often given to people who may have been exposed to plague. The patient survived, however, thanks to another antibiotic, trimethoprim, which the virus strain was not resistant.
Just how the bacterium manages to outsmart the drugs are not yet clear. But researchers report the isolation of the new strain of a small circular DNA strand, known as a plasmid. Similar plasmids carry the genes for resistance to an antibiotic with other resistant bacteria such as Enterobacteriaceae and E. coli inhabiting the intestines of humans and other animals. The team showed that in the test tube plasmid could be transferred to the resistant Y. pestis both a laboratory strain of the bacterium E. coli . "The transfer [of plasmids] occurs at a high frequency," said team member Elisabeth Carniel of the Institut Pasteur in Paris, suggesting that antibiotic resistance could easily spread.
David Dennis of the Centers for Disease Control and prevention in Fort Collins, Colorado, cautions that this discovery could have international implications, "it is an isolated case, but it seems a warning that we must be alert to the possibility that it could spread to other strains, "he said. "If it does, it would be a significant public health problem."
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