A drugmaker that has its U.S. base in King of Prussia received federal approval Monday for a new drug to treat a common form of pneumonia.

Nabriva Therapeutics said its drug is the first of its products to be approved by the U.S. Food and Drug Administration, signaling that the drug can now be sold in the United States. It also represents the first of a new class of antibiotics to be introduced in the U.S. in nearly two decades to treat community-acquired bacterial pneumonia (CABP), which afflicts about five million people a year and is one of the leading causes of infection-related death in the nation, the company said.

Nabriva’s drug - branded as Xenleta and also called lefamulin - is expected to be available at hospitals by mid-September.

Current antibiotics are less effective against drug-resistant bacteria, the company said. Lefamulin is part of a class of drugs called pleuromutilins that works differently from older antibiotics and is the first of this group to be approved by the FDA for intravenous and oral treatment of bacterial pnemonia in adults, Nabriva said.

The oral antibiotic option will allow hospitals to discharge patients sooner and save the health system money, the company maintained.

The most common side effects found in 2 percent of patients include nausea, diarrhea, insomnia, and headache, company officials said during a conference call with analysts.

The drug therapy is supposed to last five to seven days. Xenleta will have a wholesale price of $205 per IV treatment per day and $275 per oral treatment day. Some observers point out that there are cheaper generic drugs available, which may limit the drug’s use.

"Today’s approval of Xenleta is a significant breakthrough in the collective fight against the growing threat of antimicrobial resistance and provides a desperately needed IV and oral empiric monotherapy treatment option for adults with CABP,” Ted Schroeder, chief executive of Nabriva, said in a statement. He said the drug was discovered in the company’s labs more than a decade ago.

Nabriva’s corporate headquarters are in Dublin but its U.S. base is in King of Prussia. The company has 45 employees in King of Prussia and 74 total in the U.S.

Nabriva plans to hire 60 sales representatives in the U.S. following the FDA approval, the company said.

The stock closed Monday at $2.21, down $.07. But the FDA approval came after the market closed at 4 p.m. And after hours, the stock rose to $2.73, up 52 cents or 23.53 percent.

The company has incurred $435.9 million in losses since its inception, according to its filings with the Securities and Exchange Commission. Its 2018 loss came to $114.8 million.

Nabriva also is seeking FDA approval of another drug branded as Contepo, which the firm says could treat multi-drug resistant strains of urinary tract infections that threaten hospitalized patients.