A strain of MRSA（耐甲氧西林金黄色葡萄球菌） that causes bloodstream infections is five times more lethal¹ than other strains and has shown to have some resistance to the potent² antibiotic³ drug vancomycin（万古霉素） used to treat MRSA, according to a Henry Ford⁴ Hospital study. The study found that 50 percent of the patients infected with the strain died within 30 days compared to 11 percent of patients infected with other MRSA strains.

The average 30-day mortality rate（死亡率） for MRSA bloodstream infections ranges from 10 percent to 30 percent.

Researchers say the strain USA600 contains unique characteristics that may be linked to the high mortality rate. But they say it is unclear whether other factors like the patients' older age, diseases or the spread of infection contributed to the poor outcomes collectively or with other factors. The average age of patients with the USA600 strain was 64; the average age of patients with other MRSA strains was 52.

The study is being presented at the 47th annual meeting of the Infectious Diseases Society of America Oct. 29-Nov.1 in Philadelphia.

"While many MRSA strains are associated with poor outcomes, the USA600 strain has shown to be more lethal and cause high mortality rates," says Carol Moore, PharmD., a research investigator⁵ in Henry Ford's Division of Infectious Diseases and lead author of the study.

"In light of（考虑到） the potential for the spread of this virulent⁶（有毒的，恶意的） and resistant⁷ strain and its associated mortality, it is essential that more effort be directed to better understanding this strain to develop measures for managing it."

MRSA, or Methicillin-resistant Staphylococcus aureus（金币）, is a bacterium⁸ that is resistant to common antibiotics⁹ like penicillin¹⁰（青霉素）. It can cause skin, bloodstream and surgical¹¹ wound（外科伤口） infections and pneumonia¹²（肺炎）. The majority of infections occur among patients in hospitals or other health care settings, though a growing number of infections are being acquired by otherwise healthy people outside those settings.

MRSA strains can be resistant to many drugs, though they are typically susceptible¹³ to（对……敏感） the antibiotic vancomycin. MRSA infections are often treated with vancomycin administered intravenously（静脉注射地）. The USA600 strain in this study was shown to be more resistant to vancomycin.