Thursday, April 7, 2011

Antibiotic Resistance Takes a New Turn

A strain of bacterium called Klebsiella pneumoniae that causes blood infections and pneumonia has now developed resistance to the one remaining group of antibiotics that used to be effective against it, called carbapenems.

Especially worrisome is that K. pneumoniae is the first gram-negative bacterium of any significance to develop antibiotic resistance. Gram-negative bacteria exchange DNA with other bacteria more readily than do gram-positive bacteria such as methycillin-resistant Staphylococcus aureus (MRSA). (Gram-negative and gram-positive refer to whether the bacterium takes up a particular stain, and that is determined by differences in cell wall structure). The danger is that an antibiotic-resistant strain of K. pneumoniae might transfer the gene for antibiotic resistance to other gram-negative bacteria such as the much more common E. coli. And that would mean that antibiotic resistance would spread from one strain of gram-negative bacterium to another even though the bacteria were never exposed to the antibiotic at all.

It’s been just over 80 years since penicillin was first introduced, and despite the development of many new antibiotics over the years, the bacteria seem to be winning the battle. In recent years the development of new antibiotics has slowed to a trickle, to the point that there are no new types of antibiotics even in the drug-development pipeline. Pharmaceutical companies have lost interest in developing new antibiotics, in part because they know that antibiotic resistance is likely to render any new antibiotic less useful with the passage of time.

What to do? Can we research ourselves out of this dilemma, or are we doomed to remain one step behind in the perennial battle against bacteria?

Reference: McKenna, Maryn. The Enemy Within. Scientific American April 2011, pp. 46-53.

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