Maryn McKenna—my favorite “Scary Disease Girl” and author of Superbug—will be taking questions during a live chat today at Scientific American’s Facebook page. The chat starts at 2:00 Eastern and lasts for a half-hour.The chat is connected to a new article that Maryn wrote for Scientific American, which centers around some disturbing new trends in antibiotic resistance. You may have heard about the recently announced discovery of a pneumonia-causing bacteria, called Klebsiella pneumoniae, that had developed a resistance to a class of antibiotics called carbapenems. This is more than just another bacteria resistant to another antibiotic.
Carbapenems are the antibiotics of last resort. The end of the line before we literally run out of ways to treat bacterial disease. The fact that bacteria are growing resistant even to them would, alone, be concerning. But the type of bacteria involved also matters. A lot. Klebsiella pneumoniae is a gram-negative bacteria.
That designation, which borrows the name of a Danish 19th-century scientist, superficially indicates the response to a stain that illuminates the cell membrane. What it connotes is much more complex. Gram-negative bacteria are promiscuous: they easily exchange bits of DNA, so that a resistance gene that arises in Klebsiella, for example, quickly migrates to E. coli, Acinetobacter and other gram-negative species. (In contrast, resistance genes in gram-positives are more likely to cluster within species.)
Gram-negative germs are also harder to kill with antibiotics because they have a double-layered membrane that even powerful drugs struggle to penetrate and possess certain internal cellular defenses as well. In addition, fewer options exist for treating them. Pharmaceutical firms are making few new antibiotics of any type these days. Against the protean, stubborn gram-negatives, they have no new compounds in the pipeline at all. All told, this unlucky confluence of elements could easily export disaster from medical centers to the wider community.
Scientific American: The Enemy Within