Eco-Sensa Colieco-18 test media for E. coli and coliform detection

Introduction

The Colieco-18 test simultaneously detects total coliforms and Escherichia coli using ONPG and MUG as indicators.

• Coliforms: β-galactosidase metabolizes ONPG, turning samples from colorless to yellow.

• E. coli: β-glucuronidase metabolizes MUG, producing bright blue fluorescence under UV light.

• Because E. coli has both enzymes, positive samples show both yellow color and fluorescence.

Detection capability: 1 cfu/100 mL within 18–28 hours, even in the presence of up to 10⁶ heterotrophic bacteria per 100 mL .

Test Kit Specifications

• Packaging: 100 tests/box

• Storage: 2–25 °C, away from light

• Shelf life: 12 months

Procedures

Presence/Absence (P/A) Test

1. Add the contents of one packet to a sterile, transparent, non-fluorescent vessel containing 100 mL of water sample.

2. Cap and shake well.

3. Incubate at 36 ± 2 °C for 18–28 hours.

4. Read results according to the Result Interpretation Table.

MPN-Tray Enumeration Test

1. Add one packet to a sterile vessel with 100 mL of water sample.

2. Cap and shake well.

3. Pour mixture into a 51-well or 97-well MPN tray and seal with an MPN tray sealer.

4. Incubate sealed tray at 36 ± 2 °C for 18–28 hours.

5. Record number of positive wells and use the provided MPN table to calculate the Most Probable Number .

Result Interpretation

Usage Instructions

• Open a Colieco-18 packet by unfolding in the opposite direction along the crease.

• A slight color tinge may appear when added to water sample (this is normal).

• Best read results within 18–28 hours. If positive appears after 28 hours, disregard.

• Weak color reactions: judge as positive if equal to or darker than comparator.

• Reagent is normally light yellow; do not use if clumped or darker.

• If sample water is colored, use a blank control or dilute.

• Undissolved particles are normal and do not affect performance.

• Only sterile water may be used as diluent — do not use buffers or oxidants.

• When testing tap water, add sodium thiosulfate to neutralize chlorine.

• Check fluorescence using 365-nm UV lamp in a dark room, within 5 inches of sample. Direct light away from eyes .

Quality Control

For each batch, run quality control using:

1. Positive controls

   • E. coli ATCC 25922 / WDCM 00013

   • Klebsiella variicola ATCC 31488 / WDCM 00206

2. Negative control

   • Pseudomonas aeruginosa ATCC 10145 / WDCM 00024

3. Blank control

   • Reagent + 100 mL sterile water incubated 28 h = no color change

4. QC performed according to ISO 11133:2014