The U.S. Food and Drug Administration approved expanded use of Merck & Co Inc's antibiotic to treat hospital-acquired pneumonia in patients 18 years and older, Reuters reported.

The approval is based on the treatment’s late-stage trial results, which showed that Merck’s drug, Zerbaxa, was as effective as another antibacterial drug.

Hospital-acquired pneumonia occurs in patients at least two to three days after being admitted or in those who are on mechanical breathing machines and have life-threatening lung infections with high mortality rates.

These infections are typically treated using antibiotics, but the growing problem of antibiotic resistance has rendered some of the most commonly prescribed treatments ineffective.

Zerbaxa, which was previously approved for treating complicated urinary tract infections and intra-abdominal infections, was added to Merck's drug portfolio through its buyout here of antibiotics maker Cubist Pharmaceuticals.