A Comparison of the Multiple Tube Fermentation Method and the Colitag Method for the Detection of Waterborne Coliform Bacteria J Julie Hsieh Abstract Recreational water quality is an important issue in public health because of problems including diarrhea that are caused by fecal contamination Constant monitoring for Escherichia coli E coli an indicator organism for such contamination is a way to reduce human exposure This research project was designed to determine if the Colitag method for detecting E coli is as reliable as the Multiple Tube Fermentation MTF method which is currently the technique approved by the U S Environmental Protection Agency From September 2000 to March 2001 identical water samples were taken approximately once a week from Strawberry and Codornices Creeks in Berkeley California to perform both tests simultaneously The Colitag method was found to be as sensitive as the MTF method in detecting fecal coliforms in recreational water Statistical analysis of parallel test results showed a strong linear correlation of 0 87 between the two methods which held up well at both high and low fecal coliform counts Because only 24 hours are required to obtain results from the Colitag method compared to 96 hours for the MTF method the former is preferable Saving three days means that monitoring agencies could respond faster to sudden increases in E coli and could therefore take immediate corrective action to ensure the public safety Introduction Strawberry Creek which runs through the campus of the university of California at Berkeley represents an irreplaceable natural resource that is highly valued by both the university and the community at large The riparian corridors provide essential places for educational recreational social and individual activities Charbonneau 1987 Therefore the water quality of the creek is extremely important for human health especially since the creek is used by many students for educational and recreational purposes ranging from college students who study it in Biology 1B at UC Berkeley Moser 1999 to elementary school students who come to play and picnic there Charbonneau 1987 In past years the water quality of the creek has caused great concern among members of the university community and their neighbors An article in the student newspaper the Daily Californian July 2 1973 p 6 reported that fecal bacteria were contaminating the north fork of the creek from sources in the north Berkeley hills This caused concern in the community because fecal bacteria can cause human disease and illness Baker and Herson 1999 Another article in the paper eight years later November 2 1981 p 1 reported that the creek was being used as a sewer contaminated by urban runoff chemicals and sewage With recent efforts to improve the water quality of the creek the levels of fecal coliform and Escherichia coli E coli detected in the creek have decreased dramatically Over the last century scientists around the world have tried to come up with an easy affordable and accurate way of monitoring the quality of drinking and recreational water Chang 2000 pers comm One way to determine water quality is to measure the presence of E coli which is the main member of a large bacterial family Enterobacteriace which is composed of faculatively anaerobic Gram negative rods that live in the gastrointestinal tract of most warmblooded animals Edberg et al 1997 The presence of E coli in normal human intestines and feces has led to using the bacteria in nature as an indicator of fecal pollution in water Edberg et al 1997 Most E coli strains are harmless but several cause diarrhea In severe cases people especially children and the elderly have died from ingesting water or food contaminated with E coli AWWA Research Committee 1999 The current standard method for monitoring members of the coliform group in water is the Multiple Tube Fermentation MTF technique which is certified by the U S Environmental Protection Agency USEPA Clesceri et al 1998 However this method has the disadvantage of requiring up to 96 hours to obtain results When a large quantity of pathogens is present in recreational water it would be ideal to inform the public of this as soon as possible But since the MTF technique is so slow people may become sick from contact with recreational water before test results are released to them Another disadvantage of this technique is that it is not E coli specific but instead measures all fecal coliforms In 1986 USEPA recommended using E coli as the indicator organisms instead of fecal coliforms for monitoring recreational water because the former give a more accurate measurement However this recommendation has not been widely accepted since the MTF method has been around for almost 100 years as a way to measure fecal coliforms When agencies are used to monitoring water with the same method for a long time it is hard to get them to try new methods The Colitag technique Chang 2000 pers comm on the other hand has neither of these disadvantages It detects only E coli and it yields results in only 24 hours The purpose of the present research project therefore is to compare the results obtained from these two different methods to see if the Colitag method works as well in detecting fecal coliforms in recreational water as the MTF technique Samples were taken not only from Strawberry Creek but also from Codornices Creek which flows through UC Berkeley s Married Students Housing Village in Albany The second creek was added to the study because many children of all ages play nearby and may be at risk from contacting the water Lee and Lee 2000 Another reason for testing this creek was to increase the range of fecal coliform levels tested by both techniques because Codornices Creek has historically had higher counts of fecal coliform than Strawberry Creek Maranzana 2000 pers comm Methods Strawberry Creek is divided into two main branches the north and south forks The confluence of the two forks is located in Eucalyptus Grove at the western edge of the central campus about 400 feet east of Oxford Street Figure 1 Codornices Creek runs nearby UC Berkeley s Married Students Housing Village in Albany between Ninth Street and Gilman Street Figure 1 Exactly the same sampling methods were used at Codornices Creek as at Strawberry Creek The two sites were chosen because UC Berkeley s office of environment health and safety already uses them for weekly monitoring Figure 1 Sampling Sites of Strawberry
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