The microorganism Staphylococcus epidermidis is harmless on human skin, but it is the leading cause of hospital-acquired infections and infections of indwelling medical devices. S. epidermidis is associated with an enormous number of infections in people with prosthetic joints, replacement heart valves, and intravenous catheters, and antibiotic resistance makes it tough to battle. Moreover, the mechanism through which the organism becomes so pathogenic once the protective barrier of the skin is removed remains unclear.
In their study appearing online on February 3 in advance of publication in the March 1 print edition of the Journal of Clinical Investigation, Michael Otto and colleagues from Rocky Mountain Laboratories demonstrate that S. epidermidis secretes an extracellular polymer called poly-gamma-glutamate (PGA) to facilitate growth and ensure survival of the bacteria inside the human host. PGA protects the pathogen from innate host defenses during infection. S. epidermidis is the only human pathogen known to produce PGA other than Bacillus anthracis, but several differences exist in how the two pathogens use PGA to their advantage. PGA is currently used as an antigen for vaccine production against Anthrax
This paper presents PGA as a promising target for drug development aimed at combating these hospital-acquired infections and other illnesses caused by related bacteria.
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