Food Protection Trends - September/October 2020 - 317

TABLE 1. Quantity and frequencies of aerobic-mesophilic bacteria (AMB), total coliforms
(TC), fecal coliforms (FC), and E. coli in bottled purified water samplesa
Microorganism
Group

Minimum

Median

Maximum

Frequency (%)

AMB
TC
FC
E. coli

1.12
<1.1
<1.1
<1.1

3.18
1.1
<1.1
<1.1

6.45
>8
>8
4.6

20 (100)
11 (55)
6 (30)
2 (10)

n = 20. Minimum, median, and maximum values are in log CFU/mL for AMB and in MPN/100 mL for TC, FC, and E. coli.

a

TABLE 2. Microbiological indicators for which bottled purified water samplesa were
outside the 041 Guideline
Microorganism group

No. of samples outside of the 041 Guidelineb* (%)

Only AMB
Only TC
Both AMB and TC
Total

7 (35)
5 (25)
6 (30)
18 (90)

n = 20.
*Guideline that establishes that purified water bottled must not exceed the limit of 2 log CFU/mL (100 CFU/mL) of AMB and the
presence of TC must not be detectable in any 100 mL (<1.1 MPN/100 mL).

a
b

In this study, all water samples contained AMB, and 13
(65%) of them were outside the 041 Guideline: 7 (35%)
samples exceeded the maximum allowed limit for only
AMB and 6 (30%) samples exceeded both indicators (AMB
plus TC; Table 2). These results were higher (0 to 33.3%)
than those reported by Abd El-Salam et al. (1) in Egypt,
Igbeneghu and Lamikanra (15) in Nigeria, Osei et al. (28)
in Ghana, and Venkatesan et al. (38) in India. In general, a
high concentration of AMB can be taken as an indication of
deterioration in water quality and as a sign of the presence
of human pathogenic microorganisms (23, 39). A high
level of AMB in water indicates the potential presence of
(opportunistic) pathogens such as Aeromonas, Klebsiella, and
Pseudomonas (39) that can spread disease to humans (23)
and importantly to immune-compromised persons whose
risk of severe infections is high (15).
Other bacterial groups commonly used to monitor water
quality are TC of which FC are a subset and E. coli is the
most important species. If one of these groups is detected,
it means that a contamination of fecal origin has occurred,
and some of these microorganisms can potentially cause
disease (40). TC should be absent immediately after
disinfection, and the presence of these organisms indicates

inadequate treatment (40). In our study, 55% of the water
samples in total were positive for TC. Our results are
higher than the results reported for Egypt, Nigeria, and
Nepal (25 to 28.6% of samples) (1, 15, 29). Our results
differ from those reported by Venkatesan et al. (38) in
Chennai, India, who reported that none of the bottled
water samples analyzed contained TC. Regarding FC
and E. coli, we identified 30 and 10% of positive samples,
respectively. Our results differ from the results reported
for Egypt, Uganda, Nepal, and India, where none of the
purified water samples were found to be positive for
FC and E. coli (1, 13, 29, 38). A high concentration of
bacteria in bottled water may occur through carriers such
as introduced flakes of human skin (29). For this reason,
we recommend that water plant workers be checked
constantly to identify asymptomatic carriers of enteric
bacterial pathogens. The high percentage of bottled water
samples outside of the guidelines may be due to inefficient
disinfection processes by the purification plants. The
introduction of microorganisms might also occur during
the processing or handling of water (29) or from a lack of
stringent treatment of containers before filling with the
purified water (27). Therefore, frequent monitoring by

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