“My basic premise,” Wetherbee said, “is that you take a capable microörganism like Klebsiella and you put it through the gruelling test of being exposed to a broad spectrum of antibiotics and it will eventually defeat your efforts, as this one did.” Although Tisch Hospital has not had another outbreak, the bacteria appeared soon after at several hospitals in Brooklyn and one in Queens. When I spoke to infectious-disease experts this spring, I was told that the resistant Klebsiella had also appeared at Mt. Sinai Medical Center, in Manhattan, and in hospitals in New Jersey, Pennsylvania, Cleveland, and St. Louis.
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Unlike resistant forms of Klebsiella and other gram-negative bacteria, however, MRSA can be treated. “There are about a dozen new antibiotics coming on the market in the next couple of years,” Moellering noted. “But there are no good drugs coming along for these gram-negatives.” Klebsiella and similarly classified bacteria, including Acinetobacter, Enterobacter, and Pseudomonas, have an extra cellular envelope that MRSA lacks, and that hampers the entry of large molecules like antibiotic drugs. “The Klebsiella that caused particular trouble in New York are spreading out,” Moellering told me. “They have very high mortality rates. They are sort of the doomsday-scenario bugs.”