This report compares the enterococci count on samples obtained with Azide NutriDisk (AND) (sterile, dehydrated culture medium) and Slanetz & Bartley (SB) medium when exposed to a variable in incubation time and temperature. Three experiments were performed to examine the recovery of enterococci on AND and SB media using membrane filtration with respect to: (a) incubation time; (b) incubation temperature; and (c) a combination of the two. Presumptive counts were observed at 37, 41, 46 and 47 °C and at 20, 24, 28 and 48 h. These were compared to AWWA standard method 9230 C (44 °C, 44 h). Samples were confirmed using Kanamycin Aesculin Azide (KAA) agar. Friedman's ANOVA and Students t-test analysis indicated higher enumeration of enterococci when grown on AND (p=0.45) than SB (p=<0.001) at all temperatures with a survival threshold at 47 °C. Significant results for AND medium were noted at 20 h (p=0.021), 24 h (p=0.278) and 28 h (p=0.543). The study concluded that the accuracy of the AND medium at a greater time and temperature range provided flexibility in incubator technology making it an appropriate alternative to SB medium for monitoring drinking water using field testing kits in developing countries.
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Research Article|
August 01 2006
Analysis of enterococci using portable testing equipment for developing countries – variance of Azide NutriDisk medium under variable time and temperature
S. Godfrey;
*Water and Sanitation Project, UNICEF, Madhya Pradesh, India
E-mail: sgodfrey@unicef.org
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K. Toop;
K. Toop
***Water, Engineering and Development Centre, Dept of Civil and Building Engineering, Loughborough University, Loughborough, UK
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C. Francis
C. Francis
**CREH Analytical, Leeds, UK
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Water Sci Technol (2006) 54 (3): 127–134.
Citation
S. Godfrey, J. Watkins, K. Toop, C. Francis; Analysis of enterococci using portable testing equipment for developing countries – variance of Azide NutriDisk medium under variable time and temperature. Water Sci Technol 1 August 2006; 54 (3): 127–134. doi: https://doi.org/10.2166/wst.2006.458
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