From: "Edo McGowan" <edo_mcgowan@hotmail.com>
To: Audra.Morse@coe.ttu.edu
CC: samy.suissa@clinepi.mcgill.ca, eideditor@cdc.gov
Subject: Resistabnce and sewage
Date: Fri, 06 Jul 2007 19:02:52 +0000
To: Editor EID
Fm: Dr Edo McGowan
Re: Comments on Antimicrobial Drugs and Community-acquired Methicillin-Resistant Staphlococcus
aureus, United Kingdom
Both Schneider-Lindner, et al and Morse & Jackson, from different perspectives discuss resistance. It
should be clear from the paper by Morse & Jackson (see below) that resistance once in reclaimed water, if
difficult to control. This is amplified by the work of Pruden, et al--- Emerging Contaminants: Studies in
Northern Colorado. Environ. Sci. Technol.; (Article); 2006; 40(23); 7445-7450.
Thus even with fairly sophisticated systems, as noted in the Morse & Jackson paper, antibiotic resistance
proves to be a problem in recycled/reclaimed water. Based on recent microbiology tests here in Santa
Barbara, the state’s Title 22 recycled/reclaimed water which is used for irrigation of parks and other city
areas, including golf courses, does contain multi-drug resistant bacteria.
The paper by Schneider-Lindner discusses the enhanced risk of acquiring MRSA when there is a history of
antibiotic use. Sjolund et al. (2005) [Emerging Infectious Diseases (Vol. 11, # 9, Sept 2005 @ p. 1389 et
seq] indicated that resistance in the normal flora, which may last up to four-years, might contribute to
increased resistance in higher-grade pathogens through interspecies transfer.
Sjolund et al go on to note that since populations of the normal biota are large, this affords the chance for
multiple and different resistant variants to develop. This thus enhances the risk for spread to populations of
pathogens. Furthermore, there is crossed resistance. For example, vancomycin resistance may be
maintained by using macrolides.
One wonders if the advancing trend in resistance noted by Schneider-Lindner, et al might not be
augmented by common cultural practices found in many communities? The growing need to spare drinking
water sees a rapid advancement in the use of recycled/reclaimed water.
In California, Title 22 recycled/reclaimed water is produced under a specified set of criteria established by
the state’s Department of Health Services, but the bulk of the studies were done circa 1977. The criteria
developed for Title 22 are applicable to processes for the entire state. Thus, if multi-antibiotic resistance is
found in one system (Santa Barbara), it should be easily noted in others using the same criteria. Viable but
non-culturable (VBNC) states rapidly recover and thus lab tests used by Title 22, which do not test for
VBNC, have been shown to vastly under report actual numbers. This under reporting is often by several
magnitudes.
The indicators used in this process are vegetative bacteria easily killed by low-level disinfection, yet the
standards do allow a certain number to remain (again ignoring VBNC). This strategy completely ignores the
fact that more robust pathogens, those that would require high-level disinfection such as required for semi-
critical medical devices, will survive and probably in greater numbers. Thus any assurance that this water is
safe by using low-level disinfection susceptible indicators needs serious review.
Because the issue of viable but non-culturable bacteria is not recognized by Title 22, and with rapid
regrowth of the VBNC bacteria, one can see how a community might be sprinkling quite a bit of antibiotic
resistance around the town through the use of recycled/reclaimed water. How much of this may have been
a part of the backdrop for the levels found by Schneider-Lindner?
Additionally, astonishingly high levels of bacteria can exist within biofilms od the delivery pipes. These may
exceed 10/9th CFU/sg cm/individual types of bacteria. These biofilms shed and thus what may show as
acceptable levels one day may be completely out of compliance on another when the biofilm is disrupted.
This issue has plagued tracking of Legionella, which are easily established within pipes carrying nutrient
rich recycled/reclaimed water.
Now, the issue is not between health and the need to conserve water---rather it is between what is safe and
what is not. Until the medical community sits up and recognized this, the problem of community acquired
antibiotic resistance may continue.
Since 2002, or 2003, our teaching hospital has been making it a rule to give vancomycin before certain
surgical procedures. Vancomycin, not a benign drug by any stretch of the imagination, was until recently
held in reserve as the drug of last resort. Using vancomycin in this way may carry resistance to the sewers
and thus contribute to advancing levels of drug resistant pathogens within a community. Its use as a routine
prophylactic will see more rapid development of resistance and flushing it to sewers will see it picked up
and redistributed via recycled/reclaimed water back into the community’s environment. Think we might have
a revolving door?
Here is the problem. The standards in most areas are badly dated. The typical indicators used may not be
reflective of what is actually there. The literature is very clear---coliform counts are not necessarily
reflective of the public health risks.
I am suggesting that a scientifically valid review be undertaken. CDC should, with the assistance of EPA,
have the capacity to undertake such an analysis. The results should be made available for review. There is
basically nothing wrong with the use of recycled/reclaimed wastewater if it is properly treated. The operative
word and issue at hand is PROPERLY. Current standards appear not to be protective.