WASHINGTON - Staffing agencies that find jobs for health care professionals should be required to obtain a license and hospitals must do more to prevent drug abuse and theft by workers, the Maryland state health department said Wednesday. The recommendations were included in a report issued in response to the case of a traveling health worker accused of exposing patients in Maryland and other states to hepatitis C. Described by prosecutors as a "serial infector," David Kwiatkowski is charged in New Hampshire with stealing syringes of a powerful painkiller for his own use and replacing them with saline-filled syringes tainted with his blood.