WASHINGTON, Oct. 2 (Xinhua) -- A new type of antibiotic can effectively treat an antibiotic-resistant infection by disarming instead of killing the bacteria that cause it, according to a study published Tuesday in mBio, the online open-access journal of the American Society for Microbiology.
"Traditionally, people have tried to find antibiotics that rapidly kill bacteria. But we found a new class of antibiotics which has no ability to kill Acinetobacter that can still protect, not by killing the bug, but by completely preventing it from turning on host inflammation," says Brad Spellberg of the University of California, Los Angeles, a researcher on the study.
New drugs are badly needed for treating infections with the bacterium Acinetobacter baumannii, a pathogen that most often strikes hospital patients and immune-compromised individuals through open wounds, breathing tubes, or catheters. The bacterium can cause potentially lethal bloodstream infections. Strains of A. baumannii have acquired resistance to a wide range of antibiotics, and some are resistant to every FDA-approved antibiotic, making them untreatable.
Spelling and his colleagues found that in laboratory mice it was possible to mitigate the potentially lethal effects of the bacterium by blocking one of its toxic products rather than killing it.
They found that strains that caused the rapidly lethal infections shed endotoxin while growing. The more endotoxin shed, the more virulent the strain was. Blocking the synthesis of the endotoxin with a small molecule called LpxC-1 prevented infected mice from getting sick. Unlike traditional antibiotics, Spellberg says, LpxC-1 doesn't kill the bacteria, it just shuts down the manufacture of the endotoxin and stops the body from mounting the inflammatory immune response to it that is the actual cause of death in seriously ill patients.
Spellberg says this is a direction few researchers have taken when exploring ways to treat infections but that it could make the difference in finding an effective drug.