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Evaluation of Colilert‐18 for the detection of coliforms and Escherichia coli in tropical fresh water
Author(s) -
Chao W.L.
Publication year - 2006
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2005.01814.x
Subject(s) - escherichia coli , biology , agar , food science , microbiology and biotechnology , veterinary medicine , bacteria , gene , biochemistry , medicine , genetics
Aims: To evaluate the suitability of Colilert‐18 in detecting Escherichia coli and total coliforms in tropical freshwater samples. Methods and Results: Target organisms were isolated from yellow‐fluorescent and yellow wells of Colilert‐18/Quanti‐Tray using m‐TEC agar and m‐ENDO LES agar respectively. All the selected isolates were first identified based on their fatty acid methyl ester profile. Isolates showing contradictory results to that of the Colilert‐18 procedure were re‐identified using API 20E strips. A total of 357 isolates, 177 from yellow‐fluorescent wells and 180 from yellow wells, were identified. Conclusions: The false‐positive and ‐negative rates for E. coli detection using Colilert‐18 were 36·4% and 11%, respectively, while for coliform detection the false‐positive rate was 10·3%. Significance and Impact of the Study: The high false‐positive rate of Colilert‐18, tempers its value for E. coli detection when used for tropical freshwater samples.