The FDA has approved a new antibiotic, Avycaz, to treat resistant infections. Above, a laboratory worker looks for strains of E.coli bacteria in vegetable cells placed in a petri dish, in La Mojonera near Almeria in southeastern Spain, June 2, 2011. Reuters/Francisco Bonilla

The U.S. Food and Drug Administration has approved Avycaz, a new antibiotic designated to treat complicated infections with few or no other options for treatment. Those infections include complicated intra-abdominal infections -- which would be treated in combination with another antibiotic, metronidazole -- as well as complicated urinary tract infections. The drug was approved Wednesday for use in adults with these infections.

“It is important that the use of Avycaz be reserved to situations when there are limited or no alternative antibacterial drugs for treating a patient’s infection,” Dr. Edward Cox, director of the office of antimicrobial products at the FDA's Center for Drug Evaluation and Research, said in an FDA statement announcing the drug's approval. His warning underscored the growing issue of antibiotic resistance, which has received increased attention from the government and the media in the past year, especially after outbreaks of highly resistant bacteria at hospitals in California and North Carolina this month led to at least four deaths. In 2014, the White House launched a strategy to combat antibiotic resistance, and in September 2014, President Barack Obama signed an executive order asking federal agencies to do the same.

Avycaz contains ceftazidime, which is another type of antibiotic, and avibactam, which is supposed to help prevent the development of resistance to the drug by inhibiting the production of enzymes in bacteria that can render certain antibiotics ineffective. Because it combines these two active ingredients in a single dose, it is known as a fixed-combination drug.

The FDA has approved a limited number of drugs -- Avycaz is the fifth -- under the label of Qualified Infectious Diseases Products, which is bestowed on antibiotics meant to treat life-threatening infections. The label is part of the FDA's Generating Antibiotic Incentives Now Act, which tries to give companies incentives to develop antibiotics. They are seen as being less profitable than other drugs by extending the period in which these antibiotics can be sold exclusively, without competition from generic versions. Drugs that qualify are given priority, so that applications for their approval are expedited by the FDA.

Common side effects of taking Avycaz, the FDA said, included vomiting, nausea, constipation and anxiety. Avycaz was developed by Forest Pharmaceuticals Inc., a company based in Cincinnati that was bought by Actavis, a pharmaceutical company headquartered in Dublin, in 2014 for $25 billion.