A startup pharmaceutical company recently came under fire for increasing the price of a generic drug called Daraprim, which the company acquired in August, from $13.50 to $750, The New York Times reports.

Turing Pharmaceuticals bought Daraprim, a drug used to treat toxoplasmosis, from Impax Laboratories and immediately implemented a 5,500 percent price increase on the drug. Turing CEO Martin Shkreli said the move was necessary for the company to fund the development of better toxoplasmosis drugs.

The Infectious Diseases Society of America (IDSA) and the HIV Medicine Association (HIVMA) tackled the issue in a joint letter addressed to Turing earlier this month, urging the company "to immediately revise the pricing strategy for the recently acquired drug."

"Pyrimethamine (generic name of Daraprim) is particularly important for the treatment of toxoplasmosis, a parasitic infection that has severe consequences if not effectively treated in pregnant women, patients with HIV infection, cancers and other conditions that compromise the immune system," the letter said.

The letter also said the treatment cost for toxoplasmosis, which will climb up to $336,000 per year, because of the Daraprim price increase, is unjustifiable.

"This cost is unjustifiable for the medically vulnerable patient population in need of this medication and unsustainable for the health care system."

However, Shkreli maintained that raising the price of Daraprim was necessary. In a recent interview, he explained the drug was "underpriced relative to its peers." The new price, he said, would cover costs in production, distribution, FDA and others.

"Those costs have increased dramatically over the years," he told Bloomberg.

Daraprim is the only available treatment for toxoplosmosis, one of the leading causes of death from foodborne illnesses in the U.S. It is caused by a parasite called Toxoplasma. Pregnant women, newborns infected through their mothers, HIV patients, cancer patients and those with weakened immune systems face the greatest risk from toxoplasmosis, according to the U.S. Centers for Disease Control and Prevention.

Daraprim was approved by the U.S. Food and Drug Administration in 1953. Several years ago, it cost no more than a dollar, but its price increased when CorePharma bought it in 2010. CorePharma was acquired by Impax in 2014.

Democratic presidential frontrunner Hillary Clinton said in a tweet that the Daraprim price hike was "outrageous."

Dr. Judith Aberg, infectious diseases division chief at the Icahn School of Medicine at Mount Sinai, said the Daraprim price increase would cause hospitals to look for "alternative therapies that may not have the same efficacy," according to The New York Times.