Evaluation of Colilert-18 for the detection of coliforms and Escherichia coli in tropical fresh water.
OBJECTIVE
To evaluate the suitability of Colilert-18 in detecting Escherichia coli and total coliforms in tropical freshwater samples.


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%.


CONCLUSIONS
The high false-positive rate of Colilert-18, tempers its value for E. coli detection when used for tropical freshwater samples.
Chao
W L
WL
Department of Microbiology, Soochow University, Shih Lin, Taipei, Taiwan. wlchao@mail.scu.edu.tw
D000362:Agar; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli / Q000145:classification / Q000302:isolation & purification*; D005189:False Positive Reactions; D005618:Fresh Water / Q000382:microbiology*; D014329:Tropical Climate
D000362:Agar