Postgraduate Researchers in Science Medicine Conference 2005: Abstracts
Potential pathogenic microorganisms transmitted via dental impressions.
G Rodger, S. Parker, GJ Pearson, RL Taylor, J Verran
Objectives: To assess the microbial contamination of dental impressions arriving at dental laboratories.
Methods: Thirty two impressions were swabbed, at random. Swabs were transferred into 2ml sterile reduced transport fluid (RTF) (Syed & Loesche 1972) and vortexed for 30 seconds. Dilutions were plated out onto Mannitol salt agar ( MSA), Sabouraud dextrose agar ( SAB), Columbia agar (plus 5% horse blood - CBA) and R2A agar. Inoculated plates were incubated at 37±1°C for 24-48 hours ( MSA, CBA and SAB); 37±1°C plus 5% CO2 for 24-48 hours ( CBA) and 23±1°C for 5-7 days (R2A).
Preliminary identification was based on colony morphology, haemolytic reaction, Gram-staining and biochemical reactions. Further identification was performed using API 20 NE and API STAPH ( BioMérieux, France) identification kits. The germ-tube test was performed on yeast isolates.
Results: Twenty nine of the thirty two impressions were contaminated, only one uncontaminated impression was labelled as having been disinfected. Preliminary identification was performed on three hundred and forty four different colony morphologies. The proportions of positive cocci, negative rods, positive rods and yeasts were 68.02%, 12.5%, 10.17% and 9.30% respectively.
Conclusion: It appears not all impressions arriving at dental laboratories are disinfected.
Syed , S.A. Loesche, W.J. (1972) Applied Microbiology 24 (4), 638-644
Gillian Rodger, Biological Sciences, Manchester Metropolitan Univeristy, Loxford Tower, Lower Chatham Street, Manchester
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