An evaluation of microbiologic contamination on a phosphor plate system: is weekly gas sterilization enough?

Objective. This study was performed to determine: 1) the rate and source of microbiologic contamination of photostimulable phosphor plates (PSP) in a predoctoral clinic; and 2) whether a combination of weekly gas sterilization and barrier protocols can prevent contamination of PSP plates. Methods: Fifty plates in clinical use and 25 gas-sterilized control plates were selected for examination. The PSP plates were pressed onto blood agar medium and incubated at 37 degrees C. The number, size, distribution, and variety of resulting colonies were noted. To test whether these bacteria could have come from oral sources, 17 colonies were selected for culture on Mitis-Salivarius (M-S) agar. Those colonies that grew on the M-S agar were Gram stained. Results. Twenty-eight test plates (56%) exhibited growth of bacterial colonies on blood agar. Seventeen of those bacterial colonies were selected for growth on M-S agar, and 13 (76.47%) showed growth, 69% of them gram positive. Conclusion. Our results indicate reinforcing standard precautions of infection control for intraoral radiography, and that gas sterilization of plates after each day's clinical use is a potential solution. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 457-462)