488 Modern Food Microbiology
Utility for Water
The prediction of fecal coliforms in water by the enumeration of their phages has been shown to be feasible by some investigators
34,42,47,92 and not feasible by others. In a study of coliphages and fecal and total
coliforms in natural waters from 10 cities, a linear relationship was found between the two groups.
91
Because bacteria and viruses possess different properties relative to their persistence in the environment, coliphages have attracted interest from those interested in indicators of enteroviruses,
especially in water. The inability of the coliform index to predict correctly the presence of enteric
viruses in waters has been reported by a number of investigators. The survival of coliphages in water
has been shown to parallel that of human enteric viruses.
80 In a study of approved waters for oyster
harvesting along the Gulf Coast, neither E. coli nor coliform levels were predictive of the presence
of enteroviruses in oysters.
25 In recreational waters considered to be acceptable and safe by coliform
standards, enteroviruses were detected 43% of the time and 35% of the time in waters acceptable for
shellfish harvesting.
27 In a study of open waters along the North Carolina coast, enteric viruses were
isolated from 3 of 13, 100-g clam samples from open beds, and 6 of 15 were positive from closed
beds.
91 A well-documented outbreak of human hepatitis A was traced to the consumption of oysters
taken from open waters.
69
In a study comparing coliphages, total coliforms, fecal coliforms, enterococci, and standard plate
counts on water from different treatment processes, coliphages correlated better with enteroviruses
than either of the other groups noted.
84 When secondary sewage effluents were tested for male-specific
coliphages, up to 8,200 plaque-forming units (pfu) were found,
33 but how assays for male-specific
coliphages compare to the more traditional assay methods is unclear. Because some coliphages have
been reported to have their natural habitat in environmental waters, their numbers may not correlate
directly with fecal pollution.
78 Male-specific coliphages are more indicative of fecal pollution of waters
than total coliphages because they do not form F-pili at temperatures less than 30
◦ C, and thus cannot
infect their F+ host cells.
79 In a later study of 1,081 samples consisting of feces from humans and
11 animal species in addition to human-associated wastewaters, male-specific phages appeared to be
the indicator of choice for assessing the potential presence of human enteric viruses in estuarine and
marine environments impacted by wastewater sources.
12 Although the 11 animal species contained
male-specific phages, the numbers were generally low.
Similar to coliphages, Bacteroides fragilis phages are found in waters that contain high levels of
human fecal waste. While their numbers tend to be lower than coliphages, they are more specific to
human feces. In one study, they were not found in significant numbers in slaughterhouse wastewaters
or in waters that contained fecal matter from wildlife only.
87 These investigators showed that B. fragilis
phages multiplied only under anaerobic conditions.
The double-stranded DNA (dsDNA) phages of Vibrio vulnificus along with their host cells have
been found in a variety of oyster tissues and fluids, and the phages were more abundant and diverse in
molluscan shellfish than in other habitats, suggesting their possible use as indicators of V. vulnificus
presence.
17 In another study, it was found that the organism was lowest in oysters during the month of
January–March and highest during the summer and fall months when numbers per gram were 10
3 –10
4
and the V. vulnificus phages were also present in highest numbers during that period.
18
Regarding human enteric viruses, not only can at least some survive better in water than coliforms,
but viruses also tend to be more resistant to destruction by chlorine. Whereas chlorine destroyed
99.999% of fecal coliforms, total coliforms, and fecal streptococci in primary sewage effluents, only
85–99% of viruses present were destroyed in one study.
53
When four phages were compared by heating, drying, and ClO 2 exposure, hepatitis A virus was
found to be more resistant than poliovirus I and small round RNA (MS2) and DNA (X174)
Utility for Water
The prediction of fecal coliforms in water by the enumeration of their phages has been shown to be feasible by some investigators
34,42,47,92 and not feasible by others. In a study of coliphages and fecal and total
coliforms in natural waters from 10 cities, a linear relationship was found between the two groups.
91
Because bacteria and viruses possess different properties relative to their persistence in the environment, coliphages have attracted interest from those interested in indicators of enteroviruses,
especially in water. The inability of the coliform index to predict correctly the presence of enteric
viruses in waters has been reported by a number of investigators. The survival of coliphages in water
has been shown to parallel that of human enteric viruses.
80 In a study of approved waters for oyster
harvesting along the Gulf Coast, neither E. coli nor coliform levels were predictive of the presence
of enteroviruses in oysters.
25 In recreational waters considered to be acceptable and safe by coliform
standards, enteroviruses were detected 43% of the time and 35% of the time in waters acceptable for
shellfish harvesting.
27 In a study of open waters along the North Carolina coast, enteric viruses were
isolated from 3 of 13, 100-g clam samples from open beds, and 6 of 15 were positive from closed
beds.
91 A well-documented outbreak of human hepatitis A was traced to the consumption of oysters
taken from open waters.
69
In a study comparing coliphages, total coliforms, fecal coliforms, enterococci, and standard plate
counts on water from different treatment processes, coliphages correlated better with enteroviruses
than either of the other groups noted.
84 When secondary sewage effluents were tested for male-specific
coliphages, up to 8,200 plaque-forming units (pfu) were found,
33 but how assays for male-specific
coliphages compare to the more traditional assay methods is unclear. Because some coliphages have
been reported to have their natural habitat in environmental waters, their numbers may not correlate
directly with fecal pollution.
78 Male-specific coliphages are more indicative of fecal pollution of waters
than total coliphages because they do not form F-pili at temperatures less than 30
◦ C, and thus cannot
infect their F+ host cells.
79 In a later study of 1,081 samples consisting of feces from humans and
11 animal species in addition to human-associated wastewaters, male-specific phages appeared to be
the indicator of choice for assessing the potential presence of human enteric viruses in estuarine and
marine environments impacted by wastewater sources.
12 Although the 11 animal species contained
male-specific phages, the numbers were generally low.
Similar to coliphages, Bacteroides fragilis phages are found in waters that contain high levels of
human fecal waste. While their numbers tend to be lower than coliphages, they are more specific to
human feces. In one study, they were not found in significant numbers in slaughterhouse wastewaters
or in waters that contained fecal matter from wildlife only.
87 These investigators showed that B. fragilis
phages multiplied only under anaerobic conditions.
The double-stranded DNA (dsDNA) phages of Vibrio vulnificus along with their host cells have
been found in a variety of oyster tissues and fluids, and the phages were more abundant and diverse in
molluscan shellfish than in other habitats, suggesting their possible use as indicators of V. vulnificus
presence.
17 In another study, it was found that the organism was lowest in oysters during the month of
January–March and highest during the summer and fall months when numbers per gram were 10
3 –10
4
and the V. vulnificus phages were also present in highest numbers during that period.
18
Regarding human enteric viruses, not only can at least some survive better in water than coliforms,
but viruses also tend to be more resistant to destruction by chlorine. Whereas chlorine destroyed
99.999% of fecal coliforms, total coliforms, and fecal streptococci in primary sewage effluents, only
85–99% of viruses present were destroyed in one study.
53
When four phages were compared by heating, drying, and ClO 2 exposure, hepatitis A virus was
found to be more resistant than poliovirus I and small round RNA (MS2) and DNA (X174)