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Enterococci in Water

Fluorogenic Substrate Method for the Detection and Quantitation of Enterococci in Marine Water


PHL Location

Central Laboratory, Lake Charles Laboratory, Shreveport Laboratory

CPT Code



Enterolert Test, Enterolert Most Probable Number Technique

Brief Description of Test

After incubation the diluted sample with reagent added is examined for fluorescence in the wells of the IDEXX Enterolert Quanti-tray / 2000. A table is referenced to find the Most Probable Number (MPN) of Enterococci present in the sample.

Possible Results

MPN / 100ml    (colony forming units / 100ml)

Reference Range

< 10 to  > 2005       

Specimen Type

Beach water

Specimen Container(s):

250 ml polycarbonate sample bottle

Minimum volume accepted:

200 ml

Collection Instructions

Samples should be collected by personnel trained in proper collection technique according to the Louisiana BEACH Program Sample Collection Standard Operating Procedures.

Storage and Transport Instructions

Samples should be placed on ice to ensure a temperature from 1-4ºC and delivered to the testing laboratory AS SOON AS POSSIBLE since sample analysis must begin within 6 hours after collection.

Causes for Rejection

  • Sample submitted over 6 hours from collection time.
  • Sample totally immersed in water during transport.
  • Sample less than 1ºC or greater than 10ºC upon receipt.
  • Sample with no ID or missing collection date or time.
  • Sample leaking or insufficient volume.
  • Sample frozen.
  • Sample submitted in an inappropriate container.

Limitations of the Procedure

Samples must be delivered to the lab within 6 hours of collection. The initiation of sample analysis must begin within 2 hours of receipt within the laboratory. The sample must be read within 24 to 28 hours. The lack of fluorescence after 28 hours is a valid negative test, but fluorescence after 28 hours is an invalid positive test result.

Interfering Substances



  1. Quanti-Tray Insert & MPN Table, IDEXX Laboratories, One IDEXX Dr., Westbrook, Maine
  1. Louisiana’s BEACH Program Quality Assurance Project Plan, Louisiana DHH OPH, Robert Wagner Ph.D., Quantitative Ecological Services, Version 1, 12 / 21 / 03.
  1. Fluorogenic Substrate Method for the Detection and Quantitation of Enterococci in Marine or Fresh Water, Enterolert Most Probable Number Technique, Standard Operating Procedures, DHH OPH Division of Laboratories, Version: October 2003.