According to CDC guidelines, how frequently should biological spore testing be performed on dental office autoclave sterilizers?

The Centers for Disease Control and Prevention (CDC) Guidelines for Infection Control in Dental Health-Care Settings recommend that biological indicators (spore tests) be used at least weekly to monitor autoclave sterilizer performance. Some guidelines recommend testing with each load if the sterilizer is used infrequently. Biological monitoring using Geobacillus stearothermophilus (for steam sterilizers) or Bacillus atrophaeus (for dry heat or ethylene oxide sterilizers) is the most reliable method to verify sterilizer function. A positive spore test (bacterial growth after sterilization) indicates a sterilizer malfunction requiring immediate removal from service, notification of the infection control coordinator, investigation of the cause, and reprocessing of potentially non-sterile instruments.