Why HIV exposure at hospital may have happened

A lapse in protocol for cleaning dental tools is linked to possible HIV and hepatitis exposure at a Missouri veterans hospital.
At issue, reportedly, is that the instruments were hand-washed before being put in a sterilizing machine. But how is that bad?
Proper procedure would have been to send them to be both sanitized and sterilized by machine, according to CNN affiliate KSDK.
An object with residual biological material on it cannot be sterilized, said Steve Streed, member of the Association for Professionals in Infection Control and Epidemiology's board of directors.
Normally, dental instruments at the hospital would be put in a washing device to dissolve biological debris; simply washing with soap and water won't get it off, he said.
The sterilization process itself cleans microbes; it does not remove debris, he said. Thus, washing the tools with soap and water could have contributed to people becoming exposed to virus.
This is the second recent case of a hospital alerting patients about potential infection. This month, Palomar Hospital in San Diego, California, sent letters to 3,400 patients who underwent colonoscopy and other similar procedures. Items used and reused in the procedures could have resulted in potential infection, the letters said.