Testing started on Friday on the patients of a New Hampshire hospital who may have been infected with the hepatitis C virus by a former worker, even as the hospital released a response to a new report critical of its former procedures.

David Matthew Kwiatkowski, a former lab technician at Exeter Hospital who has carried the virus since at least June 2010, was charged with federal drug crimes in July.

The Department of Justice said Kwiatkowski stole syringes filled with the painkiller Fentanyl, injected himself, then refilled the needles with saline to hide his actions and left them for re-use on patients.

Thirty former patients and one hospital employee had been infected with the same strain of hepatitis C as Kwiatkowski, including one new diagnosis made this week, said the New Hampshire Department.

Hepatitis C is caused by a virus that attacks the liver and is considered among the most serious hepatitis viruses. It is passed through contact with contaminated blood, often through shared needles.

Authorities, when they charged Kwiatkowski, called him a "serial infector."

Exeter Hospital responded on Thursday to a stinging assessment of its practices by the federal Center for Medicare and Medicaid, some of which showed how Kwiatkowski may have been able to commit his alleged crimes.

The Center slammed the hospital for failing to meet many safety measures, including securing narcotics such as the ones Kwiatkowski used on himself.

The 18-page report, based on an assessment made in June, noted that hospital staff routinely left certain medications unsecured.

Other violations included not cleaning equipment between patient uses, employees with potentially infectious or draining wounds working in patient care and lack of precautionary gear against infection worn by employees when entering patients' rooms.

The document said one employee was asked to leave work areas several times because his wounds were bleeding, or seeping fluid. Kwiatkowski was not named in the report.

Exeter Hospital said on Friday that it was making policy changes in response to the report.

"The hospital has thoroughly addressed each finding," officials said in a statement. Under new procedures, for example, "once filled, syringes are locked up by a nurse until the moment they are needed and only then are they unlocked."

Most changes had already been made in the past two months. The final one was to be put in place by August 26.

To ensure the changes are enacted, state health officials will make spot checks of the hospital in the coming months, said New Hampshire Bureau of Licensing manager John Martin.

Over the next few weeks clinics in southern New Hampshire will test over 3,000 patients treated at certain units of Exeter Hospital between April 2011 and May 2012.

Before coming to New Hampshire, Kwiatkowski, 32, a native of Michigan, worked as a radiology technician and in cardiac labs in over a dozen hospitals in seven states from 2007 to 2011.

A class action lawsuit and separate negligence complaint were filed in late July against Triage Staffing, the healthcare agency that hired and placed Kwiatkowski at Exeter Hospital.

Domenic Paolini, a Boston attorney, filed the lawsuits against Triage and said the critical HHS report could open Exeter Hospital up to litigation as well.

"This is going to open up many, many more lawsuits against Exeter Hospital," even cases not related to the hepatitis C outbreak, Paolini added.