Bacteria associated with false-positive most-probable-number coliform test results for shellfish and estuaries

Hussong, David; Damaré, J. M.; Weiner, Ronald M.; Colwell, Rita R.

doi:10.1128/aem.41.1.35-45.1981

Cited by 19 publications

(5 citation statements)

References 53 publications

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“…Bacterial analysis of the first 26 water samples revealed false-positive rates of 19 and 15% for total coliform and E. coli detection, respectively. False-positive reactions obtained by the traditional MTF method applied to marine water have been previously documented (11). Non-E. coli isolates recovered from yellow, fluorescent tubes did not fluoresce upon reinoculation, suggesting that they were not the original cause of fluorescence.…”

Section: Discussionmentioning

confidence: 81%

Evaluation of colilert-marine water for detection of total coliforms and Escherichia coli in the marine environment

Palmer

Tsai

Lang

et al. 1993

Appl Environ Microbiol

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A test that allows for early detection of fecally contaminated coastal water would enhance public health protection. Colilert-Marine Water (Colilert-MW; Environetics, Branford, Conn.) is a rapid 24-h test that has recently been developed to detect total coliforms and Escherichia coli in coastal water. We performed a premarketing evaluation of the Colilert-MW product, testing it in parallel with the multiple tube fermentation (MTF) method for 86 coastal water samples in southern California. Statistical analysis was performed by using paired t tests and linear regression. Bacterial isolates were evaluated by biochemical and genetic analysis. The results of this study showed a strong correlation between the traditional MTF and the Colilert-MW method for detection of total coliforms (r = 0.95) and E. coli (r = 0.89) in ocean water samples. Paired t-test results indicated that the Colilert-MW and MTF were equivalent in detecting E. coli and that the Colilert-MW may be more sensitive in the detection of total coliforms. We conclude that Colilert-MW would be a useful tool with which to monitor coastal beach water.

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Section: Discussionmentioning

confidence: 81%

Evaluation of colilert-marine water for detection of total coliforms and Escherichia coli in the marine environment

Palmer

Tsai

Lang

et al. 1993

Appl Environ Microbiol

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“…In addition, the MPN assay is susceptible to bacterial interference (1,18,25); falsenegative reactions (absence of gas production in the presence of coliforms) may occur at the presumptive, confirmed, and completed stages of the MPN analysis (13). Other factors, such as synergistic gas production from lactose by noncoliforms (20), cultivation of anaerogenic and non-lactose-fermenting E. coli strains (4), and the presence of lactose-fermenting noncoliforms (23,24), have contributed to the inefficiency of E. coli detection methodologies.…”

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confidence: 99%

Fluorogenic assays for immediate confirmation of Escherichia coli

Feng¹,

Hartman²

1982

Appl Environ Microbiol

254

116

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Rapid assays for Escherichia coli were developed by using the compound 4methylumbelliferone glucuronide (MUG), which is hydrolyzed by glucuronidase to yield a fluorogenic product. The production of glucuronidase was limited to strains of E. coli and some Salmonella and Shigella strains in the family Enterobacteriaceae. For immediate confirmation of the presence of E. coli in most-probable-number tubes, MUG was incorporated into lauryl tryptose broth at a final concentration of 100 ,ug/ml. Results of both the presumptive test (gas production) and the confirmed test (fluorescence) for E. coli were obtained from a variety of food, water, and milk samples after incubation for only 24 h at 35°C. Approximately 90% of the tubes showing both gas production and fluorescence contained fecal coliforms (they were positive in EC broth incubated at 45°C). Few false-positive reactions were observed. The lauryl tryptose broth-MUG-mostprobable-number assay was superior to violet red bile agar for the detection of heatand chlorine-injured E. coli cells. Anaerogenic strains produced positive reactions, and small numbers of E. coli could be detected in the presence of large numbers of competing bacteria. The fluorogenic assay was sensitive and rapid; the presence of one viable cell was detected within 20 h. E. coli colonies could be distinguished from other coliforms on membrane filters and plates of violet red bile agar if MUG was incorporated into the culture media. A rapid confirmatory test for E. coli that is amenable to automation was developed by using microtitration plates filled with a nonselective medium containing MUG. Pure or mixed cultures containing E. coli produced fluorescence within 4 h (most strains) to 24 h (a few weakly positive strains).

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“…As a matter of fact, the variations in the profile of relative frequencies of bacterial species (for instance, in consideration of climatic conditions as well as physicochemical characteristics of the water) undoubtedly influence the selectivity patterns of the two procedures. The results obtained by either fecal coliform method will be greatly affected by the incidence of false-positive or false-negative findings (12,22,27).…”

Section: Discussionmentioning

confidence: 99%