Pseudomonas Aeruginosa: Assessment of Risk from Drinking Water
THE ISSUE
Pseudomonas aeruginosa is a bacterium that is naturally found in
many types
of drinking water. For example, it is a violation of European regulations
to
have Pseudomonas aeruginosa present in a 250 ml sample of bottled
water.
However, no such regulation exists in the United States. Apparently,
the
Pseudomonas aeruginosa regulation in Europe originated as a quality
control
issue and not as a health effects issue. During the last decade,
a number of
papers have appeared that have indicated that Pseudomonas aeruginosa
from
drinking water is a health threat. However, it is not considered
a health threat
by those in the clinical microbiology or infectious diseases communities.
Therefore, an assessment of health risk to humans from Pseudomonas
aerugi-
nosa from drinking water was conducted.
RESEARCH STRATEGY
A practicing infectious disease physician (Dr. Catherine Hardalo,
Yale
University) and a medical microbiologist (Dr. Stephen Edberg,
Yale University)
collaborated to perform the health risk analysis of Pseudomonas
aeruginosa
from drinking water. An extensive literature search was conducted
and col-
leagues were consulted.
MAJOR FINDINGS AND SIGNIFICANCE
Pseudomonas aeruginosa is a ubiquitous environmental bacterium.
It can be
recovered, often in high numbers, in common food, especially
vegetables.
Moreover, it can be recovered in low numbers in drinking
water. A small per-
centage of clones of Pseudomonas aeruginosa possess the required
number of
virulence factors to cause infection. However, Pseudomonas
aeruginosa will
not proliferate on normal tissue but requires previously
damaged organs.
Further narrowing the risk to human health is that only certain
specific hosts
are at risk, including patients with profound neutropenia,
cystic fibrosis,
severe burns, and those subject to foreign device installation.
Other than these
very well defined groups, the general population is refractory
to infection with
Pseudomonas aeruginosa. Because of its ubiquitous nature
it is not only
impractical to eliminate Pseudomonas aeruginosa from our
food and drinking
water but attempts to do so would produce disinfection byproducts
more
hazardous than the species itself. Moreover, because there is no
readily avail-
able sensitive and specific means to detect and identify
Pseudomonas aerugi-
nosa available in the field, any potential regulation governing
its control would
not have a defined laboratory test measure of outcome. Accordingly,
attempts to
regulate Pseudomonas aeruginosa in drinking water would not
yield public
health protection benefits and could, in fact, be counterproductive
in this regard.
Hardalo, C. and Edberg, S.C., Pseudomonas aeruginosa: Assessment
of Risk from Drinking
Water, Critical Reviews in Microbiology, 23(1):47-75 (1997).
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