M
ColiPAT kit for early detection of coliforms in water
Ashish Tambi , Urmila Brighu and A. B. Gupta
ABSTRACT
Determining the microbial quality of drinking water by assessing the presence/absence (P/A) or
enumeration of indicator bacteria continues to be widely practiced worldwide. However, rapid tests
are required for microbiological water quality assessment so that the information is available in the
shortest possible time for initiating a timely intervention. Traditional methods for the enumeration of
indicator bacteria are not only expensive but also need trained personnel. We have developed a
low-cost kit,
M
ColiPAT, and have validated its application for detection of coliforms in drinking water
using the IDEXX Colilert-18 Quanti tray method.
M
ColiPAT kit medium was able to detect coliforms
down to a level of 3.1 MPN/100 ml within 10.5 hours. The sensitivity and specificity of the kit were
95.45% and 100% respectively.
M
ColiPAT is found to be reliable and accurate for the detection of
coliforms in drinking water.
Ashish Tambi (corresponding author)
Urmila Brighu
A. B. Gupta
Department of Civil Engineering,
Malaviya National Institute of Technology,
Jaipur, 302017 Rajasthan,
India
E-mail: ashishtambi006@gmail.com
Key words | coliforms, Colilert, indicator, most probable number, rapid detection, water
INTRODUCTION
Microbiological quality monitoring of source and treated
drinking water is essential for the timely control of water-
borne diseases. The monitoring of water quality should be
rapid and reliable to protect consumers against the
spread of water-borne diseases (Fiksdal & Tryland ).
Ideally, the occurrence and number of all pathogens in
drinking water should be monitored, however, it is not feas-
ible to assess the levels of pathogens in drinking water in
routine analysis. The presence of pathogens is relatively
low as compared to that of other microorganisms and
these are present only under specific environmental con-
ditions (Wildeboer et al. ). Indicator organisms have
been widely used to assess the microbiological quality of
drinking water rapidly (Landre et al. ; Edberg et al.
). The indicator organisms most commonly used are
coliform bacteria, faecal coliform bacteria, and enterococci.
Coliforms include members of the family Enterobacteria-
ceae, e.g. Escherichia spp., Enterobacter spp., Klebsiella
spp., and Citrobacter spp. Members of the coliform group
are aerobic and facultative anaerobic, Gram-negative,
non-spore forming rod-shaped bacteria that ferment lactose
with gas production within 48 hours at 35
C(APHA ).
Coliforms are present in large numbers in faeces of humans
and other warm-blooded animals and therefore accepted as
an indicator of faecal contamination.
The standard tests employed for the assessment of the
coliform group include: multiple-tube fermentation tech-
nique (MTF), membrane filter (MF) technique or the
enzymatic substrate coliform test (Kodaka et al. ),
which are expensive and require trained laboratory person-
nel. Conventional methods used for the assessment of the
bacteriological quality of drinking water require 18–24
hours to detect the contamination. Confirmation of these
results requires another 1–2 days or longer (Ashbolt et al.
). Further, lack of access to laboratories is an obstacle
to the provision of microbiologically safe drinking water to
many communities and people worldwide (Bain et al. ).
Rapid methods based on detection and quantification of
waterborne pathogenic bacteria in water have been devel-
oped such as real time or quantitative polymerase chain
871 © IWA Publishing 2020 Water Supply | 20.3 | 2020
doi: 10.2166/ws.2020.008
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