The "persister" is a
hypothetical cell state in which microorganisms are protected from
all types of
antimicrobial insults. This hypothesis has been developed to explain
"kill
versus time"
curves and "kill versus concentration" curves that exhibit tailing.
Even when
biofilms are
treated for prolonged periods of time or with elevated antimicrobial
concen-
trations, a
small fraction of the population persists. Persisters may
constitute one percent
or less of a
biofilm population.
Though small in
relative numbers, this protected subpopulation is sufficient to reseed
the
biofilm in the
event of catastrophic chemical or physical challenge.
-The Center
for Biofilm Engineering at Montana State University - Bozeman
| New study discovers why “persister” cells never say die |
NU biologist isolates
gene making infections drug-resistant
 Contact Genevieve Haas at 617 373 5470 (12-4-04) BOSTON, Mass. – Northeastern University today announced that biologist Kim Lewis has discovered the gene that prevents antibiotics from successfully destroying infections within biofilm. For years, scientists have struggled to understand why a certain type of infection – known as biofilms – are often resistant to antibiotics. Biofilms contain cells that are identical to the infecting cells, but are not corrupted and destroyed by antibiotics. Lewis discovered these “persister” cells, contain a gene (HipA) that generates a toxin (the ReIE toxin) which puts the cell into hibernation and because antibiotics must work on growing cells to destroy them, the hibernating cells can outlast the antibiotic and then repopulate the infection. The results of the study appears in the most recent issue of the Journal of Bacteriology, titled “Specialized Persister Cells and the Mechanism of Multidrug Tolerance in Escherichia coli.” Lewis, the lead author, worked with NU graduate students Iris Keren, Devang Shaw and Amy Spoering, as well as Niilo Kaldalu of Tartu University in Estonia. “ The implications for the discovery are significant; medical science is racing the clock against increasingly drug-tolerant infections. Biofilm infections are notoriously difficult to stamp out. Armed with the knowledge of the HipA gene that allows the infections to persist, sometime for years, biologists can look for ways to deactivate the gene and wipe out the infection,” says Lewis. Biofilm infections, which attach to a surface while encased in a membrane, typically attack surgically implanted medical devices, such as mechanical heart valves or artificial joints. They can also take the form of periodontal disease, ear infections or fatal lung infections. The infection can be nearly impossible to eradicate, requiring implants to be removed at great risk and cost. Deleting or deactivating the HipA gene could save thousands of lives and millions of dollars. About Northeastern Northeastern University, located in the heart of Boston, Massachusetts, is a world leader in practice-oriented education and recognized for its expert faculty and first-rate academic and research facilities. Northeastern integrates challenging liberal arts and professional studies with the nation’s largest cooperative education program. Through co-op, Northeastern undergraduates alternate semesters of full-time study with semesters of paid work in fields relevant to their professional interests and major, giving them nearly two years of professional experience upon graduation. The majority of Northeastern graduates receive a job offer from a co-op employer. Cited for excellence three years running by U.S. News & World Report, Northeastern has quickly moved up into the top half of the “Best National Universities” rankings—an impressive 30 spots in three years. In addition, Northeastern was named a top college in the northeast by the Princeton Review 2003/04. For more information, please visit http://www.northeastern.edu. |
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