DENVER -- An "infection control breach" at a Denver hospital may have put some surgery patients at risk for surgical site infections or hepatitis B, hepatitis C or HIV, according to officials. Porter Adventist Hospital is notifying people who had spine or orthopedic surgery there between July 21, 2016, and Feb. 20 of this year, the Colorado Department of Public Health and Environment says in a statement.

"The process for cleaning surgical instruments following orthopedic and spine surgeries was found to be inadequate, which may have compromised the sterilization of the instruments," said the statement Wednesday from Larry Wolk, chief medical officer and executive director of the Colorado Department of Public Health and Environment.

The department said it is unaware of any infections among patients in relation to the breach, and that the risk of surgical site infection related to it is "unknown."

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It said the risk of getting HIV, hepatitis C or hepatitis B due to this issue "is considered very low."

When asked how widespread the health breach is, a health department spokesperson said it was "significant," CBS Denver reports. No specific numbers of patients at risk were provided.

Porter Adventist Hospital, which is operated by Centura Health, mailed letters on April 4 to patients who may have been put at risk. Anyone who had spine or orthopedic surgery there between the dates in questions -- July 21, 2016, and Feb. 20, 2018 -- can contact the hospital, the health department says.

"A disease control investigation is ongoing," Wolk's statement said. "The department last visited the hospital March 28, confirming that current infection-control practices meet standards."

Representatives for Porter Adventist and Centura did not immediately reply to requests for comment.