Observations on the use of a medium detecting β-glucuronidase activity and lactose fermentation for the simultaneous detection of Escherichia coli and coliforms

Walter, K.S.; Fricker, E.J.; Fricker, C. R.

doi:10.1111/j.1472-765x.1994.tb00901.x

Cited by 12 publications

(5 citation statements)

References 4 publications

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“…c d r may not cleave methyl umbelliferyl glucuronide on initial isolation. In this study we have seen no evidence of that and in other studies we have demonstrated that > 98% of the I.. c d i isolated in the 'I'hanics water area are glucuronidase positive (Fricker and Fricker 1904). T h e benefits of presence/absence testing are.…”

Section: Discussioncontrasting

confidence: 66%

A preliminary study of the use of Colilert for water quality monitoring

Cowburn

Goodall

Fricker

et al. 1994

Lett Appl Microbiol

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The Colilert presence/absence test has been compared with membrane filtration using membrane lauryl sulphate broth for the detection of coliforms and Escherichia coli in a number of different types of water. Colilert appears to give results which are essentially the same as those obtained by membrane filtration whilst taking considerably less time to perform. The data generated in this study are in agreement with a large number of studies published in the United States and suggest that a large comparative study with drinking water samples is warranted.

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Section: Discussioncontrasting

confidence: 66%

A preliminary study of the use of Colilert for water quality monitoring

Cowburn

Goodall

Fricker

et al. 1994

Lett Appl Microbiol

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“…The authors noted that all of these colonies were found on membranes from samples of raw water and speculated that the ‘crowded’ plates were the cause. Walter et al. (1994) also noted a reduction in the numbers of E. coli detected when using MLGA (as compared to MLSB) but could find no correlation with the number of colonies growing on the membrane.…”

Section: Discussionmentioning

confidence: 89%

“…The authors noted that all of these colonies were found on membranes from samples of raw water and speculated that the 'crowded' plates were the cause. Walter et al (1994) also noted a reduction in the numbers of E. coli detected when using MLGA (as compared to MLSB) but could find no correlation with the number of colonies growing on the membrane. More recently, Fricker et al (2008b) reported on the b-d-glucuronidase activity of cultures of E. coli isolated from water using lactose and b-d-glucuronidase-based methods and found false negative reactions in 12-27% of cultures examined with MLGA.…”

Section: Discussionmentioning

confidence: 89%

“…Thus, 19 of a total of 233 E. coli isolates (8AE2%) recovered on MLGA failed to produce typical green colonies. Subsequently Walter et al (1994) found that MLGA detected E. coli in fewer samples than did membrane lauryl sulfate broth (MLSB) which is essentially the same medium as MLGA but without the added glucuronide, suggesting a higher rate of false negative colonies. In the study described by Fricker et al (2008b), false negative reactions were seen in between 12 and 27% of E. coli isolates.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the cause of false negative β-d-glucuronidase reactions in culture media containing fermentable carbohydrate

Fricker¹,

Warden²,

Eldred³

2010

Letters in Applied Microbiology

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Aims: To explain the basis for false negative β‐glucuronidase reactions seen with culture media containing lactose as a carbon and energy source. Methods and Results: Escherichia coli strains were assessed for their reactions in culture media containing a β‐d‐glucuronidase substrate either with or without lactose. An assay was developed to test for the expression of β‐d‐glucuronidase at pH 5·0 and pH 7·2. Strains of E. coli that gave false negative glucuronidase reactions on media containing lactose generally expressed lower concentrations of the enzyme β‐d‐glucuronidase than strains that gave positive results, although the difference was by no means consistent. Most strains that were negative on lactose‐containing media expressed virtually no β‐d‐glucuronidase activity at pH 5·0. Examination of colonies on Membrane lactose glucuronide agar (MLGA) from lightly polluted water showed that c. 10% of the E. coli present failed to yield green colonies on MLGA. Conclusions: E. coli that failed to produce green colonies on MLGA produced lower levels of β‐d‐glucuronidase than did strains that formed green colonies, the difference being greater at pH 5·0 than pH 7·2. The false negative rate for E. coli 10% which is similar to that experienced in the study that originally described MLGA. Significance and Impact of the Study: Strains of E. coli that fail to produce typical colonies on MLGA might produce lower concentrations of the enzyme β‐d‐glucuronidase. Whilst the enzyme activity is sufficient to be detected at pH 7·2, fermentation of lactose significantly lowers the pH of the medium and can result in reduced enzyme activity and therefore lack of detection. The false negative rate of c. 10% would be difficult to detect in routine laboratories as it would represent 1% or less of yellow colonies being identified as E. coli (assuming E. coli accounts for 10% of the total coliform population in drinking water).

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“…Traditional methods for the identification and detection of bacteria and parasites in water are based on cultural and immunochemical techniques which are slow, inefficient and often unreliable, with routine tests for bacteria taking 18 h or more to perform ( Cowburn et al . 1994 ; Walter et al . 1994 ; Nieminski et al .…”

Section: Introductionmentioning

confidence: 99%

In situ reverse transcription for the specific detection of bacteria and protozoa

Prescott¹,

Fricker

1999

Lett Appl Microbiol

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A .M . P R ES CO T T A ND C .R . F R IC KE R . 1999. In situ hybridization experiments with oligonucleotide probes directed against the 16S and 18S rRNA molecules have been used successfully to identify specific organisms in mixed microbial populations. However, there are limitations in applying these techniques to environmental samples. In the present study we have examined the possibility of using in situ reverse transcription as an alternative to hybridization methods for the rapid detection of Escherichia coli and the waterborne parasite Cryptosporidium parvum. Following fixation and permeabilization of the cells,extension reactions were performed with species-specific primers, AMV reverse transcriptase and either cy3-AP3-dUTP or fluorescein-11-dUTP at 45°C for 45 min. The cells or oocysts were then filtered onto Costar metallic membrane filters and images captured with a CCD camera. The results have shown that this technique can successfully detect E. coli cells and C. parvum oocysts in under 2 h.

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Observations on the use of a medium detecting β-glucuronidase activity and lactose fermentation for the simultaneous detection of Escherichia coli and coliforms

Cited by 12 publications

References 4 publications

A preliminary study of the use of Colilert for water quality monitoring

A preliminary study of the use of Colilert for water quality monitoring

Understanding the cause of false negative β-d-glucuronidase reactions in culture media containing fermentable carbohydrate

In situ reverse transcription for the specific detection of bacteria and protozoa

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