Centers for Disease Control Director Tom Frieden explains how hospitals can prevent the spread of MRSA infections among patients. (Courtesy Centers for Disease Control)

Using germ-killing soap to wash the sickest patients every day and applying antibacterial ointment inside their noses turns out to be the most effective way to reduce deadly hospital bloodstream infections, according to a study published Wednesday that has broad implications for practical use.

The findings suggest the simple strategy could save lives, researchers said. Hospital Corporation of America, the country’s largest hospital chain, announced Wednesday that it is planning to adopt this protocol at about 450 adult intensive-care units at its 162 hospitals, a spokesman said. The chain took part in the research.

The study, published in the New England Journal of Medicine, found that daily application of mupirocin ointment inside the nose and daily washing with a cloth soaked in chlorhexidine soap reduced bloodstream infections by up to 44 percent and significantly reduced the presence of drug-resistant bacterium known as MRSA, or methicillin-resistant Staphylococcus aureus.

MRSA is resistant to first-line antibiotic treatments and is an important cause of illness and sometimes death, especially among patients who have had medical care. Three-fourths of Staphylococcus aureus infections in hospital ICUs are considered methicillin-resistant.

The research answers one of the biggest debates in medicine for decades, said Susan Huang, an infectious disease specialist at the University of California at Irvine and the lead author of the study: Do you target the superbug by screening people and treating those who have it? Or do you take a more proactive approach, treating a broad category of people who are at highest risk?

“This study is the first to answer the question — it’s the high-risk patient,” she said. “Stop screening. Treat them all.”

Chlorhexidine is a common antibiotic soap; mupirocin, an antibiotic ointment, is also widely used in hospitals.

Previous studies have shown similar results, but on a much smaller scale. The new study involved more than 74,000 patients at 43 community hospitals in 16 states. Researchers evaluated the effectiveness of three MRSA prevention practices. The hospitals were randomized and assigned one of three approaches.

One group of hospitals screened ICU patients for MRSA and isolated those found to be carriers, a typical practice at most hospitals. The second group did the same but added the special washing and ointment for carriers. The third group eliminated all screening. Instead, the hospitals gave every ICU patient a daily bath with chlorhexidine soap and applied mupirocin ointment in the nose for five days.

Nurses used a cloth soaked in chlorhexidine, which works against a range of pathogens, to wash the patient’s entire body and keep the pathogens off the skin for 24 hours. The ointment in the nose targets the normal home of the bacterium Staphylococcus aureus.

The proportion of ICU patients harboring MRSA fell by about 35 percent in the third group, compared with no significant drop in either of the other two groups, researchers said.

In addition to being effective at stopping the spread of MRSA in intensive-care units, the study found that the use of the germ-killing soap and ointment on all ICU patients was also effective for preventing infections caused by germs other than MRSA.

The study was carried out by researchers from the University of California at Irvine, Harvard Pilgrim Health Care Institute, HCA and the U.S. Centers for Disease Control and Prevention.

CDC Director Tom Frieden said the agency is weighing the findings for possible inclusion in CDC’s infection prevention recommendations.

In the study, researchers relied on the infection-control and quality-control systems already in place at the hospitals conducting the trial. That’s important, Huang said, because many studies often add extra investigators, resulting in better research findings.

“Here, everything we did was rolled out by the hospitals’ own systems,” she said. They put it into practice, she said, suggesting that it would be relatively straightforward for other hospitals to use as well.

In many hospitals, nurses already wash patients using cloths containing mild soap.