ST. LOUIS -- Sen. Claire McCaskill said Thursday she's confident the Department of Veterans Affairs is doing all it can to correct sterilization problems at its St. Louis hospital, where patients may have been exposed to hepatitis and other diseases, but she said the hospital must improve its customer service.

The VA announced earlier this summer that 1,812 veterans were potentially exposed to hepatitis B, hepatitis C and HIV because of improperly sterilized dental equipment at its John Cochran Medical Center in St. Louis.

McCaskill, a Missouri Democrat, met with VA officials at the hospital Thursday for an update and learned that all but three of those veterans have either been tested or turned down the opportunity to be tested.

Three veterans treated at the dental clinic have tested positive for hepatitis, but officials don't know how they were infected. A fourth also tested positive for hepatitis, but the VA says that person's infection came from another source.

"I'm satisfied that all of the issues of sterilization are being taken care of," McCaskill said at a news conference. She also lauded the VA for the way it dealt with the problem.

"They've been very transparent about this process," she said.

Spokeswoman Marcena Gunter said the VA "remains steadfast in its resolve to provide safe, high quality care for our nation's veterans. VA's high standards for quality and patient safety mandate transparency and accountability in its handling of mistakes or failures."

McCaskill wasn't nearly as pleased with the way veterans are being served at the hospital, which she said has among the lowest customer service satisfaction ratings in the Veterans Affairs system.

In a separate meeting Thursday, she met with veterans and their advocates who generally gave high marks for medical care, but who told her numerous stories about VA employees being rude or unwilling to help.

McCaskill recalled the story of one veteran who called to set up a doctor's appointment.

"They just hung up on him," she said. "Well, that's just unacceptable."

McCaskill said she will work with veterans' organizations to begin monitoring the St. Louis hospital more closely to ensure veterans are treated with respect and provided with more help. She plans to launch a "secret shopper" program that will ask veterans to evaluate the service and care they receive.