Comparative Evaluation of Different Methods to Detect Bacterial

Comparative evaluation of different methods to detect bacterial contamination in
recreational waters. RACHAEL LOGSDON*, Department of Biological Sciences,
Northern Kentucky University, Highland Heights, KY 41099.
Banklick Creek, a major watershed in the Northern Kentucky area, is also part of the
local combined sewer system. Concerns about pollution, odors and the possible
emergence of water borne diseases have been voiced about the creek. Investigation done
in the summer 2006 found inconsistencies in each of the testing methods, making further
evaluations of the test methods a necessity. This project was designed to compare the
different methods used in fecal coliform testing and to monitor the variations in the water
quality of Banklick Creek as it flows from Doe Run Lake to Pioneer Park. In this study,
four common methods of testing water for fecal bacterial contamination were evaluated:
the Manja test, Coliscan Easygel´âó, Most Probable Number (MPN/MUG), and Millipore
filtration using different selective media. Each test’s cost, consistency and reliability were
compared. Water inoculated with E.coli, Klebsiella pneumoniae, Citrobacter freunde,
Enterobacter aerogenes, Salmonella typhi, Enterococcus faecalis and Bacillus subtilus
were used as controls. The water of Banklick Creek was also monitored with the same
methods, as was water of a control stream Grassy Creek that is not part of a combined
sewer system.