Great Smokies Diagnostic Laboratory
Darryl Gopaul, Leslie Hart, Brenda Cupp, Martin Lee
St. Joseph's Health Centre London, Ontario Canada and Great Smokies Diagnostic Laboratory, Asheville, North Carolina, USA
Colonizing bacteria in the human gut are necessary in the metabolism of nutrients and food components. One of bacteria's key roles for example, is the digestion of soluble fibers to short chain fatty acids. The numbers and types of organisms present in the stools of humans is of interest in patients with diagnosis of food allergies, malabsorption syndrome, autoimmune disease and in acute and chronic gastrointestinal dysfunction. The purpose of this study was to evaluate the recovery of fecal bacteria by the manual method of plating stools compared to the automated method of spreading stools onto selective media. A total of 15,234 stools were streaked in 1993-1994 using the manual method and 16,923 stools were streaked in 1994-1995 using an automated method (Vista Laboratories Ltd. ISOPLATER). The number of isolates considered potentially pathogenic recovered by the manual method was 5,921 while the number recovered using the ISOPLATER was 9,359 (p<0.001). A significant increase was noted in the recovery of certain organisms: Klebsiella pneumoniae-mucoid strains (13.6% to 20.1%), Aeromonas (0.08% to 0.2%), Proteus vulgaris (1.1% to 1.8%), non-Lactose fermenting E. Coli (0.6% to 0.9%), Pseudomonas (3.7% to 6.5%), Shigella (0.007% to 0.03%), Campylobacter (0.007% to 0.02%), Yersinia (0% to 0.06%), and Vibrio (none to 0.02%) using the ISOPLATER. While one could argue that the increased recovery reflects year-to-year variation, the large number of specimens evaluated suggests that the ISOPLATER automated streaker leads to improved recovery of fecal bacteria as compared to the manual method.
This experiment was to determine which method consistently produced isolated colonies allowing different morphotypes to be observed independently. Our study revealed that the automated streaking by the ISOPLATER consistently yielded isolated colonies decreasing the need for additional isolation steps. The ISOPLATER utilized less labor resulting in cost effective productivity. We also observed a marked increase in the numbers (Chart 1) and varieties of colonies seen (Charts 2 and 3) as well as increasing our recovery of pathenogenic organisms (Chart 4). Other organisms (not shown) displayed a less significant increase in recovery between methods. These a Citrobacter freundii (14.9% to 19.8%), Bacillus species (1.5% to 2.9%), Staph aureus (1.2% to 1.5%), Edwardsiella (0% to 0.006%), Pleisomonas shigelloides (0% to 0.01%) and Beisseria cinerea (0% to 0.006%). Organisms displaying no change or a decrease in recovery were Salmonella (0.1% with both methods), Proteus mirabilis (1.3% to 0.8%) and Citrobacter diversis (0.8% to 0.5%). The large number of specimens evaluated suggests that the ISOPLATER automated streaker leads to improved recovery of fecal bacteria as compared to the manual method.
Aldridge C, P Jones, SF Gibson, JW Lanham, MC Meyer, R Vannest and RA Charles. 1977. Automated Microbiological Detection/Identification System. Journal of Clinical Microbiology. 6:406-413
Davis BD, R Dulbecco, N. Eisen and HS Ginsberg. 1980. Microbiology, 3rd ed. Burgess Publishing Co. MN.
Finegold Sidney M and Baron Ellen Jo. Bailey and Scott's Diagnostic Microbiology, 7th ed. C.V. Mosby Co. St. Louis, Mo. 1986.
Lennette Edwin H. Manual of Clinical Microbiology, 4th ed. ASM. Washington, D.C. 1985
Galland,
& Barrie S (1993). Intestinal Dysbiosis and the Causes of Disease.
J Advancement Med, 6(2), 67-8
