Following a read of a recent issue of Stormwater, especially the piece on antidegradation by Stewart Leeth (July/August 2003), felt compelled to write. When we consider degradation, do we also consider creating conditions that harbor pathogens and disease vectors such as mosquitoes?

It seems that there is a potential disconnect between the various disciplines dealing with stormwater. First is the group that, I assume, most often reads this magazine, those with engineering and hydrology backgrounds. Then there is the group that deals with health and epidemiology. Unfortunately, there seems to be a disjointed academic interaction between these two groups. I suspect that this derives from the various perceived missions but unfortunately, there is a crossed logic that comes out of this. I also see this disconnect in interactions with the various planners who are developing these local stormwater plans under the Phase II NPDES requirements.

Various articles in the local media have dealt with recently completed local stormwater plans. Drains and standing stagnant water, although often discussed by these plans, might not be sufficiently considered by the plans' authors with respect to the serious pathogens they can harbor or the habitats they can create for mosquitoes. I'd like to address the question of mosquitoes - especially in light of the recent news on the westward spread of West Nile virus - in a future issue. Here, I will discuss pathogens and, specifically, multiantibiotic resistant bacteria that can be found in stormwater runoff.

In areas of large agricultural operations, there is a growing pressure to use biosolids as land-applied soil amendments. In many cases, the setback for such application is insufficient to preclude wash-off to adjacent riparian areas. Accordingly, the pathogens harbored within biosolids might wind up as part of irrigation return flows or stormwater.

Additionally, within urban areas, the pathogen levels accruing to stormwater runoff are now recognized as major contributors to pollution and disease.

What is less well recognized, however, is that these pathogens often harbor resistance and virulence genes that confer on them a "super bug" status. This genetic material is easily passed between different bacteria and viruses through, among other mechanisms, plasmids. Plasmids are like little cassettes of genetic material that will fit any operating system. Once in the genetic system, they are faithfully replicated. This genetic information can be passed to background soil and water bacteria or viruses. Such transfer merely widens the background exposure for humans, pets, and livestock.

The issue of multiple-antibiotic resistance among pathogens has been considered as a major health issue now for a decade or more by the World Health Organization (WHO). Unfortunately, those outside of the often arcane and closed fraternity of medicine and public health are seldom aware of such issues.

I am a member of a multijurisdictional task group looking at issues related to biosolids, stormwater, and wastewater. In a recent meeting of our task group, one of the members - a wastewater engineer - raised an interesting question relating the survival of pathogens once the material had left the sewer treatment works. The underlying issues involved in this question are very similar for stormwater.

The essence of the question was related to the survival of genetic material - hence, an analysis on the underlying issue of surviving multidrug (antibiotic)-resistant bacteria (MDRB). The question went something like this: "If Staphylococcus aureus are found dead, does that mean that the problem is solved?" The corollary: Are they dead, or merely in the viable but nonculturable state, in a starvation arrested state, or killed from a starvation but otherwise in a recoverable state by sudden nutrient excess in the culture? Additionally, there are issues of the reuptake of naked DNA. Recently, in discussing mobile genetic elements (MGEs), Nielsen and others (2000) demonstrated that DNA was well protected in dead cells and that transforming activity remained. The survival of such material was found to be up to two years. Additionally, these and similar papers demonstrate that growing plants, via their roots, can transfer MGEs to bacteria. The reverse has also been widely demonstrated. Thus, nonpathogens and nonbacteria can serve as reservoirs for maintaining resistance. Pneumococci, for example, can take up naked DNA from the environment (natural transformation from lysed bacteria). Thus, merely finding "dead" bacteria might be no assurance that risk has reached acceptable levels. Further, from the classical work of Griffith (a British medical officer who discovered in 1928 that pathogenic genetic information was transferable from heat-killed bacteria cells to live ones, which provided the first evidence that not only was genetic material heat-stable, but that pathogenesis could be reclaimed from dead bacteria), we know that pathogens can regain virulence from dead bacteria. Additionally, during the above-noted meeting, I mentioned some notes I had taken during a recent medical grand rounds at our teaching hospital. The speaker, an expert on infectious disease, indicated that there is strong medical evidence that about half of the general, nonhospital-community­acquired skin infections in the greater Los Angeles area are now caused by methicillin-resistant Staphylococcus aureus. The April 2003 issue of Skin & Allergy News also had a front-page article on this topic since those in dermatology often stand on the front lines. Prior to 1985, vancomycin resistance in human pathogens had not been described in the literature. A decade later, more than one half of the hospitals in New Jersey contained strains of vancomycin-resistant bacteria. By the end of 1998, one quarter of enterococci isolated from intensive care units across the United States expressed resistance to vancomycin. Recent publications in the medical literature discuss the cost of drug-resistant bacteria. The annual cost in the US was estimated to be upward of $30 billion annually (Dominguez, 2000). Current EPA Class B biosolids, which are applied to agricultural lands, with the allowed fecal coliform counts of 2 x 10/6 per gram, might actually constitute a large aliquot when containing MDRB. This is a worrisome situation when the material is applied to areas with animal or vector access or stormwater runoff potential to riparian areas or irrigation return.

These bacteria are thus able to colonize animals, including humans, through ingestion. There are indications within the literature of E. coli O157:H7 being able to travel up the vascular system in lettuce and celery (Solomon et al., 2002; Wachtel et al., 2002). Since lettuce is eaten raw, the risk should be clear to most. One will remember that this bacteria sent children and their parents desperately seeking new kidneys. Once ingested, the shiga containing plasmids may be transferable to normal flora and later to pathogenic bacteria found in humans or animals, making later treatment with particular antibiotics ineffective. Additionally, one finds that there is a remultiplication of bacterial numbers within standing sludge, biosolids, or compost. Thus, the current Part 503 limits on biosolid marker organisms might have little bearing on the ultimate numbers. Stormwater managers need to appreciate such issues. Even if these materials are composted prior to land application, the issue might not be solved. During composting, the mesophiles can transfer genetic information to thermophiles. The archaea, which are extreme thermophiles, are recognized as a separate third domain of life together with the bacteria and eukarya.

Transfer of plasmids to bacteria from archaea has been demonstrated (Cannio et al., 2001; Ruepp et al., 2000; Horiike et al., 2002; Cohen et al., 2003; Koonin et al., 2003). Thus, in theory, it may be possible to develop an MDRB that can survive temperatures found within composting. Furthermore, there is experimental evidence that even when disrupted by radiation, these ancient organisms can reassemble (Jolivet et al., 2003; DiRuggiero et al., 1997). This, from a theoretical perspective, raises questions of the eventual failure of pasteurization. Hassen and others (2001) found that gram-positive bacteria, especially micrococcus, spores of bacilli, and fungal propagules, survived and reached high concentrations in compost. Not only that, "the appearance of gram-negative rods (opportunistic pathogens) during the cooling phase may represent a serious risk for the sanitary quality of the finished product intended for agronomic reuse."

Harmless gut and soil bacteria have become reservoirs for multiresistance plasmids, which may be gained from pathogens or where there are other commensals that contained the shared genetic information. For example, Levy (1992) found that the resistance in gut bacteria of cattle moved to gut bacteria of mice having access to the same area, then from the mice to pigs, chickens, and flies. He notes a Dutch study that followed bacteria from animals to the human food chain and entered the consumer's kitchen. In other cited examples, he noted the distinct relationship between MDRB in animals and thence to humans attending them, even though the humans neither used antibiotics nor ate the animals. Levy's work is not new. The world has changed, yet are we coming full circle? Relatively speaking, from a historical perspective, we recently began to understand the germ theory. Then we developed sanitation. During the early 20^th century, infection often led to amputations and death from infections following childbirth. In the 1930s, we saw the development of antibiotics, and that was soon followed by antibiotic resistance. Then came multiple-antibiotic resistance. We have relied upon antibiotics to the extent that we have dropped our guard on many areas, including sanitation of stormwater. Unfortunately, in the interim, pathogens have been busily at work defending their genetic cache. Stormwater professionals now need to appreciate that is no longer merely silt and hydraulics but also the need to look at stormwater as a transport mechanism for pathogens and their genetic material.

To conclude, the following thought is paraphrased from the statement by the WHO's chief of communicable disease, David Heymann, before the US Senate hearing on the spread of communicable disease, in 2001:

Some microbes have accumulated resistant genes to virtually all currently available drugs. Thus, these have the potential to cause untreatable infections. Accordingly, such diseases might have no effective cures over the next 10 years unless there is some uncharacteristic breakthrough in drug therapy. Therefore, if current trends continue, many important medical and surgical procedures, including cancer therapy, bone marrow and organ transplant, hip and knee replacement, and perhaps coronary bypass surgery, could no longer be undertaken without undue risk of unstoppable infection.

Cannio, R., P. Contursi, M. Rossi, and S. Bartolucci. "Thermoadaptation of a mesophilic hygromycin B phosphotransferase by directed evolution in hyperthermophilic Archaea: selection of a stable genetic marker for DNA transfer into Sulfolobus solfataricus." Extremophiles, 5(3):153-59. 2001.

Cohen, G.N. et al. "An integrated analysis of the genome of the hyperthermophilic archaeon Pyrococcus abyssi." Mol Microbiol., 47(6):1495-512. 2003.

DiRuggiero, J. et al. "Repair of extensive ionizing-radiation DNA damage at 95 degrees C in the hyperthermophilic archaeon Pyrococcus furiosus." J Bacteriol., 179(14):4643-645. 1997. (These investigators looked at the capacity of the hyperthermophile Pyrococcus furiosus to repair DNA by measuring survival at high levels of 60Co gamma-irradiation. They noted that while the P. furiosus 2-Mb chromosome was fragmented into pieces ranging from 500 kb to shorter than 30 kb at a dose of 2,500 Gy, it was fully restored upon incubation at 95°C.)

Dominguez, E.A. et al. "A pilot study of antibiotic cycling in a hematology-oncology unit." Infection Control and Hospital Epidemiology, Vol. 21, Suppl. 1, pp 4-8. 2000.

Hassen et al. Bioresour Technol, 80(3):217-25. 2001.

Horiike, T., K. Hamada, and T. Shinozawa. "Origin of Eukaryotic Cell Nuclei by Symbiosis of Archaea in Bacteria supported by the newly clarified origin of functional genes." Genes & Genetic Systems, 77(5):369-76. 2002.

Jolivet, E. et al. "Physiological Responses of the Hyperthermophilic Archaeon 'Pyrococcus abyssi' to DNA Damage Caused by Ionizing Radiation." J Bacteriol., 185(13):3958-961. 2003.

Koonin, E.V. et al. "The rhomboids: a nearly ubiquitous family of intramembrane serine proteases that probably evolved by multiple ancient horizontal gene transfers." Genome Biol., 4(3):R19. 2003.

Levy, S.B. The Antibiotic Paradox: How Miracle Drugs Are Destroying the Miracle. Plenum Press, New York. 1992.

Nielsen, K.M., K. Smalla, and J.D. van Elsas. "Natural Transformation of Acinetobacter sp Strain BD413 with Cell Lysates of Acinrtobacter sp., Pseudomonas fluorescens, and Burkholderia cepacia in Soil Microcosms." Appl Environ Microbiol, 66(1):206-12. 2000.

Ruepp, A. et al. "The genome sequence of the thermoacidophilic scavenger Thermoplasma acidophilum." Nature, 407(6803):508-13. Sept. 28, 2000.

Solomon, E.B., S. Yaron, K.R. Matthews. "Transmission of Escherichia coli O157:H7 From Contaminated Manure and Irrigation Water to Lettuce Plant Tissue and Its Subsequent Internalization." Appl Environ Microbiol, 68(1):397-400. 2002.

Wachtel, M.R., L.C. Whitehand, and R.E. Mandrell. "Association of Escherichia coli O157:H7 with Preharvest Leaf Lettuce upon Exposure to Contaminated Irrigation Water." J. Food Prot., 65(1):18-25. 2002.

Edward McGowan has a degree in medicine and a doctorate related to water-quality control. He was the US Agency for International Development regional environmental officer for the eastern and southern half of Africa, an area covering 22 nations. In that capacity, he interacted with numerous governments, various United Nations agencies, WHO, US Department of Agriculture, USEPA, international donors, and US Foreign Service staff on issues of water quality and public health.

SW November/December 2003