GlaxoSmithKline and Johnson & Johnson are the best of the big pharmaceutical companies at tackling the growing “superbug” threat, according to an index released Tuesday at the World Economic Forum in Davos, Switzerland.

The index, which rates companies on their contributions to preventing the spread of bacteria that are resistant to antibiotics, found Mylan to be the best of the generic drug makers and rated a little-known company, Entasis, as top among biotechnology companies.

The World Health Organization considers antibiotic resistance “a global health emergency that will seriously jeopardize progress in modern medicine,” said its director-general, Tedros Adhanom Ghebreyesus.

Growing numbers of people are dying from “flesh-eating” microbes; from infections picked up in hospital and nursing homes; and from strains of pneumonia, tuberculosis, gonorrhea and other diseases that are impervious to most drugs. Such infections kill about 23,000 Americans a year, the Centers for Disease Control and Prevention estimates.