One of the nearly 14,000 patients given potentially tainted injections of pain medicine sued the maker of the treatment in what may be the first of a wave of lawsuits over a deadly U.S. meningitis outbreak that shows no signs of abating.

The lawsuit was filed in a Minnesota federal court on Thursday by a woman who said she was given a steroid injection for back pain and has experienced symptoms consistent with meningitis. She is awaiting the results of tests.

Federal and state health authorities have confirmed 14 meningitis deaths nationwide since people who received the injections began coming to emergency rooms last month in Tennessee, the state with the most cases.

The number of people who contracted meningitis has risen rapidly in a week, and reached 169 on Thursday, an increase of 32 from the previous day.

The outbreak has turned into a major national health scandal with multiple investigations launched and a leading lawmaker, Senator Richard Blumenthal of Connecticut, calling for a criminal probe of the company at the center of the storm, New England Compounding Center of Massachusetts.

The Massachusetts health regulator accused the company on Thursday of flouting state laws for pharmacies. The compounding company has recalled the suspect product, surrendered its operating license and has said it is cooperating with the investigations.

Federal and state regulators also have come under scrutiny for allowing an obscure pharmaceuticals sector known as compounding to grow rapidly without much federal oversight. Compounders take drug ingredients and make specialized treatments for patients. The industry has grown so large that some of the companies operate more like drug manufacturers than pharmacies, critics say.

The U.S. Centers for Disease Control and Prevention said on Thursday it was working furiously to contain the meningitis outbreak from medications shipped to 23 states. Eleven of those states have reported cases of meningitis and there have been deaths in six states.

Of the 14,000 people at risk of infection, medical practitioners were still trying to reach about 2,000 patients to warn them to be tested immediately.

"We are not out of the woods yet," said Dr. Todd Weber, manager of the CDC response to the meningitis outbreak, during a briefing on Thursday.

While most of the patients at risk received epidural injections to alleviate back pain, the CDC spoke of a new concern on Thursday about patients who received injections in joints such as a knee or ankle.

They disclosed that a Michigan patient who had received an injection in an ankle, developed an infection. Tests have not yet been completed to determine if it is a fungal infection.

The CDC said all people who might have received the injections in joints from the suspect product also should seek medical attention.

Meningitis is an infection of the membranes covering the brain and spinal cord. Symptoms include headache, fever and nausea and it must be treated quickly to improve chances of survival. Fungal meningitis is a rare form and is not contagious.

Most people infected so far have displayed symptoms within two weeks of receiving the medication and as long as 42 days afterward. They cautioned that patients should be vigilant for several months if they received one of the injections.

Health authorities said more than 50 vials of the steroid, out of more than 17,000, had so far been confirmed as contaminated with more tests underway.

The lawsuit is Barbe Puro v. New England Compounding Pharmacy Inc, U.S. District Court, District of Minnesota, No. 12-2605.