Washington State University
Office of the Campus Veterinarian
Standard Operating Procedures for Processing
Samples Submitted for Sanitation Monitoring
RODAC Plates
RODAC (Replicate Organism Detection and Counting) agar plates are used for
surface sampling. The media is trypticase soy agar with lecithin and polysorbate
80. The lecithin and polysorbate 80 are neutralizers to inactivate residual
disinfectants. The agar plates are domed shaped to allow the entire surface of
the media to be pressed against flat surfaces. The plate has a 10 mm grid to
facilitate the counting of bacterial colonies. RODAC plates are to be incubated at
35˚ C. The plates are checked for growth at 48 and 72 hours. The number of
colony forming units (CFU) are counted and recorded.
Culturette Swabs
The culturette swabs are streaked out on RODAC agar plates and incubated 4872 hours at 35˚C. After the incubation period, the number of colony forming units
(CFU) is counted and recorded.
The following scale is used to evaluate the sanitation process:
Colony Counts:
0-5 CFU
6-15 CFU
16-30 CFU
31-50 CFU
51 + CFU
None or very slight
Slight
Moderate
Significant
Heavy
Excellent
Good
Border line Acceptable
Poor
Unacceptable
Reporting of Results:
Results of Poor and Unacceptable will be rechecked. The results will be
provided to the Animal Facility Supervisor. A copy of the results and a written
report is to be kept on file at the Office of the Campus Veterinarian.
LME January 2008