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Nonculturable but still viable and potentially pathogenic
Zbl. Bakt. 279, 154-156 (1993) © Gustav Fischer Verlag, Stuttgart· Jena . New York
Editorial
Nonculturable but Still Viable and Potentially Pathogenic RITA R. COLWELL Department of Microbiology, University of Maryland, College Park, MD 20742, USA Received February 5, 1993
In recent years it has been revealed that microorganisms which are not cultured but can be detected by means of fluorescent antibody or gene probes do remain intact, metabolizing and potentially pathogenic. The techniques of fluorescent monoclonal antibody were introduced for pathogenic organisms only in the last decade. The work done with Vibrio cholerae provides the most dramatic of these examples. In the early 1980s from our work with pathogens in the environment, we determined that Vibrio cholerae could be detected by means of fluorescent antibody (6) and therefore could be the source of the epidemics of cholera in cholera endemic areas. In fact, we were able to demonstrate a seasonality of the fluorescently labelled cells even though they could not be cultured, showing peaks in their incidence at which time outbreaks of disease would occur and the ability to occasionally culture the Vibrio cholerae from water sources and other environmental sources would ensue. The viable but nonculturable phenomenon as it was then defined was reviewed by Roszak and Colwell (4). They summarized information known for several decades about survival of microorganisms in the environment and the suspected retention of viability of these organisms and potential pathogenicity, particularly in food microbiology studies where "resuscitation" methodologies were developed. In any case, the ability to induce infection in volunteers who were fed viable but nonculturable Vibrio cholerae (1) provided primary evidence of the potential pathogenicity for humans. Some recent studies done with divers diving in polluted waters have demonstrated that there is a colonization of divers and their gear with pathogens encountered in polluted waters. Importantly, sero-conversion was detected in the divers, even though overt symptomatic disease was not manifested. Thus, an area of medical microbiology, medical microbial ecology, needs to be developed for better understanding of chronic
Nonculturable but Still Viable and Potentially Pathogenic
155
diseases and the sporadicity of disease outbreaks, particularly those that are water and food borne. Research in medical microbiology (medical microbial ecology) will require a completely new view of the environment as a source of pathogens and the kinds of clinical infections arising by exposure to environmental pathogens. The route of infectivity, other than direct person-to-person transmission, usually of the virulent type, includes the potential for either non-expressed clinical infections or low grade infection, by transmission of pathogens surviving in, or adapted to, the environment. Epidemiology has developed as a science but it has neglected incorporation of the principles of ecology. The understanding and knowledge accrued over the years by microbial ecologists on distribution of microorganisms in the environment, influenced by such environmental parameters as temperature, pressure, salinity, nutrient availability, etc., coupled with known effects of seasonality and microorganism-microorganism interactions, strongly suggest that epidemiology would benefit greatly from incorporation of these principles to provide an improved understanding of environmental pathogens. The evidence that has been accumulated for cholera is similarly increasing in volume for Legionella, Campylobaeter, and Helieobaeter. The evidence is now compelling (2,3) for environmental sources of Campylobaeter jejuni, and Legionella pneumophila and the long term survival of Helieobaeter pylori in the environment (5). Thus, there are very important lessons to be learned by clinicians from microbial ecology. The basic principles of ecology (both macro and micro) and an understanding of the progression of the transmission of disease from environmental sources suggest epidemics and the infection process itself may be a function of the physiological condition of the infecting organism, i. e., passaging through human or animal systems, as opposed to emerging directly from environmental adaptation to infection of the warm blooded animal, both domestic and human, means there is much to be learned in considering the environment as a source, a mediator, and an influence on the disease process and on the spread of disease amongst both domesticated animals and humans. Clearly, the viable but nonculturable phenomenon and its exploration has elucidated another set of parameters and perhaps a new perspective and a polyphasic system for medical microbiology.
References 1. Colwell, R. R., M. L. Tamplin, P. R. Brayton, A. L. Gauzens, B. D. Tall, D. Harrington, M. M. Levine, S. Hall, A. Hug, and D. A. Saek: Environmental aspects of V. eholerae in transmission of Cholera. In: Advances in Research on Cholera and Related Diarrhoeas, 7th ed. by R. B. Saek and Y. Zinnaka, pp. 327-343. K. T. K. Scientific Publishers, Tokyo (1990) 2. Paszko-Kolva, c., M. Shahamat, H. Yamamoto, T. Sawyer, J. Vives-Rego and R. R. Colwell: Survival of Legionella pneumophila in the Aquatic Environment. Microb. Ecol. 22 (1991) 75-83 3. Rollins, D. M. and R. R. Colwell: Viable but nonculturable stage of Campylobaeter jejuni and its role in survival in the natural aquatic environment. Appl. Environ. Microbiol. 52 (1986) 531-538 4. Roszak, D. B. and R. R. Colwell: Survival strategies of bacteria in the natural environment. Microbiol. Rev. 51 (1987) 365-379
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R. R. Colwell
5. Shahamat, M., U. Mai, C. Paszko-Kolva, M. Kessel and R. R. Colwell: Use of autoradiography to assess viability of Helicobacter pylori in water. Appl. Environ. Microbiol. (1993) April issue 6. Xu, H.-S., N. C. Roberts, L. B. Adams, P. A. West, R.J. Siebling, A. Hug, M.1. Hug, R. Rahman and R. R. Colwell: An indirect fluorescent antibody staining procedure for detection of Vibrio cholerae serovar 01 cells in aquatic environmental samples. J. MicrobioI. Meth. 2 (1984) 221-231 Dr. Rita R. Colwell, Dept. of Microbiology, University of Maryland, College Park, MD 20742, USA
Editorial
Nonculturable but Still Viable and Potentially Pathogenic RITA R. COLWELL Department of Microbiology, University of Maryland, College Park, MD 20742, USA Received February 5, 1993
In recent years it has been revealed that microorganisms which are not cultured but can be detected by means of fluorescent antibody or gene probes do remain intact, metabolizing and potentially pathogenic. The techniques of fluorescent monoclonal antibody were introduced for pathogenic organisms only in the last decade. The work done with Vibrio cholerae provides the most dramatic of these examples. In the early 1980s from our work with pathogens in the environment, we determined that Vibrio cholerae could be detected by means of fluorescent antibody (6) and therefore could be the source of the epidemics of cholera in cholera endemic areas. In fact, we were able to demonstrate a seasonality of the fluorescently labelled cells even though they could not be cultured, showing peaks in their incidence at which time outbreaks of disease would occur and the ability to occasionally culture the Vibrio cholerae from water sources and other environmental sources would ensue. The viable but nonculturable phenomenon as it was then defined was reviewed by Roszak and Colwell (4). They summarized information known for several decades about survival of microorganisms in the environment and the suspected retention of viability of these organisms and potential pathogenicity, particularly in food microbiology studies where "resuscitation" methodologies were developed. In any case, the ability to induce infection in volunteers who were fed viable but nonculturable Vibrio cholerae (1) provided primary evidence of the potential pathogenicity for humans. Some recent studies done with divers diving in polluted waters have demonstrated that there is a colonization of divers and their gear with pathogens encountered in polluted waters. Importantly, sero-conversion was detected in the divers, even though overt symptomatic disease was not manifested. Thus, an area of medical microbiology, medical microbial ecology, needs to be developed for better understanding of chronic
Nonculturable but Still Viable and Potentially Pathogenic
155
diseases and the sporadicity of disease outbreaks, particularly those that are water and food borne. Research in medical microbiology (medical microbial ecology) will require a completely new view of the environment as a source of pathogens and the kinds of clinical infections arising by exposure to environmental pathogens. The route of infectivity, other than direct person-to-person transmission, usually of the virulent type, includes the potential for either non-expressed clinical infections or low grade infection, by transmission of pathogens surviving in, or adapted to, the environment. Epidemiology has developed as a science but it has neglected incorporation of the principles of ecology. The understanding and knowledge accrued over the years by microbial ecologists on distribution of microorganisms in the environment, influenced by such environmental parameters as temperature, pressure, salinity, nutrient availability, etc., coupled with known effects of seasonality and microorganism-microorganism interactions, strongly suggest that epidemiology would benefit greatly from incorporation of these principles to provide an improved understanding of environmental pathogens. The evidence that has been accumulated for cholera is similarly increasing in volume for Legionella, Campylobaeter, and Helieobaeter. The evidence is now compelling (2,3) for environmental sources of Campylobaeter jejuni, and Legionella pneumophila and the long term survival of Helieobaeter pylori in the environment (5). Thus, there are very important lessons to be learned by clinicians from microbial ecology. The basic principles of ecology (both macro and micro) and an understanding of the progression of the transmission of disease from environmental sources suggest epidemics and the infection process itself may be a function of the physiological condition of the infecting organism, i. e., passaging through human or animal systems, as opposed to emerging directly from environmental adaptation to infection of the warm blooded animal, both domestic and human, means there is much to be learned in considering the environment as a source, a mediator, and an influence on the disease process and on the spread of disease amongst both domesticated animals and humans. Clearly, the viable but nonculturable phenomenon and its exploration has elucidated another set of parameters and perhaps a new perspective and a polyphasic system for medical microbiology.
References 1. Colwell, R. R., M. L. Tamplin, P. R. Brayton, A. L. Gauzens, B. D. Tall, D. Harrington, M. M. Levine, S. Hall, A. Hug, and D. A. Saek: Environmental aspects of V. eholerae in transmission of Cholera. In: Advances in Research on Cholera and Related Diarrhoeas, 7th ed. by R. B. Saek and Y. Zinnaka, pp. 327-343. K. T. K. Scientific Publishers, Tokyo (1990) 2. Paszko-Kolva, c., M. Shahamat, H. Yamamoto, T. Sawyer, J. Vives-Rego and R. R. Colwell: Survival of Legionella pneumophila in the Aquatic Environment. Microb. Ecol. 22 (1991) 75-83 3. Rollins, D. M. and R. R. Colwell: Viable but nonculturable stage of Campylobaeter jejuni and its role in survival in the natural aquatic environment. Appl. Environ. Microbiol. 52 (1986) 531-538 4. Roszak, D. B. and R. R. Colwell: Survival strategies of bacteria in the natural environment. Microbiol. Rev. 51 (1987) 365-379
156
R. R. Colwell
5. Shahamat, M., U. Mai, C. Paszko-Kolva, M. Kessel and R. R. Colwell: Use of autoradiography to assess viability of Helicobacter pylori in water. Appl. Environ. Microbiol. (1993) April issue 6. Xu, H.-S., N. C. Roberts, L. B. Adams, P. A. West, R.J. Siebling, A. Hug, M.1. Hug, R. Rahman and R. R. Colwell: An indirect fluorescent antibody staining procedure for detection of Vibrio cholerae serovar 01 cells in aquatic environmental samples. J. MicrobioI. Meth. 2 (1984) 221-231 Dr. Rita R. Colwell, Dept. of Microbiology, University of Maryland, College Park, MD 20742, USA