This findings attains significance as VAP can strike up to 15 per cent of people who are intubated to aid breathing, and can cause death in an estimated 20 percent to 40 percent of those stricken.
"VAP is a relatively common infection and increasingly one caused by antibiotic-resistant bacteria," says the study's lead author, Dr. Marin H. Kollef, a Washington University pulmonary specialist at Barnes-Jewish Hospital.
"There have been many attempts to prevent VAP, most of which have revolved around modifying hospital practices. The silver-coated endotracheal tube has an advantage in that it doesn't require any additional effort by nurses, therapists and doctors, who may already be over burdened," the researcher adds.
According to the researchers the silver-coated endotracheal tube's adoption will not require any change in standard hospital procedures, as it is structurally identical to a typical tube.
For their study, the researchers observed 1,509 patients in 54 centres who were intubated for 24 hours or more, and found that 7.5 per cent of those with uncoated tubes developed VAP, compared to 4.8 per cent of those with silver-coated tubes.
The researchers reckoned that it was a 36 per cent reduction.
Kollef says that about 80 percent of patients are intubated for less than 10 days, and that looking at that period of intubation, the silver-coated tubes were associated with a 48 percent reduction in VAP.
The researchers also observed that when VAP occurred in patients with silver-coated tubes, it occurred later on average than in those with uncoated tubes.
Silver kills bacteria and yeast by sticking to the organisms' enzymes, genetic material and other molecular components, preventing basic functions and interfering with reproduction. These organisms very rarely develop resistance to silver, and the metal has no known side effects in humans.
The new endotracheal tubes are coated with a silver-containing polymer that releases silver ions to the surface of the tubes, where silver exerts a broad-spectrum antimicrobial effect, reduces adhesion of bacteria to the tube, and blocks the formation of biofilms - communities of microorganisms that build up special protective structures on surfaces.
Kollef says that the number of antibiotic-resistant organisms is on the rise, making it ever more vital to prevent VAP and related infections.
Even when an infection can be treated with antibiotics, it takes a physical toll on a patient, he adds.
Though the silver-coated tubes are likely to be more expensive than uncoated tubes, Kollef says that the cost is easily recovered if the silver-coated tubes can reduce the number of VAP cases.
"I think this is just the beginning for this kind of technology. The silver-polymer coating will most likely be applied also to tracheostomy tubes and also become available for use in pediatric medicine. In the future, we could see other types of coatings with other functions placed on devices that come into contact with the body," Kollef says.
The study has been published in the Journal of the American Medical Association.