Beach sand as a source of faecal indicator organisms

Brandão, João

http://hdl.handle.net/10400.18/5296

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Authors

Brandão, João

Abstract(s)

Microbial life in beach sands research began in Bacteriology with Roger Fujioka of the University of Hawai'i and in Mycology with Laura Rosado, of the Portuguese National Institute of Health. Since then, many reports and scientific papers have been published on the subject. The number of publications in this area is currently increasing exponentially, most of which addressing methodological approaches and weaving considerations on the microbiome characterization and influence on human health. Levels of bacteriological indicators of bathing water quality are of concern due to run-offs and tide retractions. Clear and precise guidance on the subject, however, has been lost in time. It should serve as a working basis for regulators and research. Global warming and climate change also bring a regional de-characterization of the microbiota, due to the geographic expansion of endemic microbes. These bring along unexpected illnesses diagnosed with some degree of unexpectedness or difficulty by local clinicians. The following three points are currently of high relevance in sand contaminants: A. Sampling, representativeness and analytical methods: sand is patchy, not a homogeneous or a fluid system. In 2015, an open letter was published, as a result of a meeting of experts, from several scientific areas converging in one posture towards the issue of sand contaminants. During this meeting, it was decided that sampling should be evaluated, and that levels of relevance and clinical expression or influence of the quality of adjacent waters should stratify analytical methods. A basic analytical snapshot of the level of contamination of sand (sanitation), is inexpensive and its feasibility leads to easy transfer between laboratories. This allows it to become current practice and to integrate the process of quality regulation and public health protection. However, in pathogen detection situations, epidemiological outbreaks or over-dominance of unexpected and persistent microbial agents, the health risk or socio-economic implications should be assessed, and the causes identified, in order to be controlled or eradicated. There is present need to define levels of analysis in order to adopt the recommendation of the open letter, excluding neither classic nor molecular methodologies (namely, next generation sequencing, which allows the characterization of full microbiomes). B. Biological groups indigenous to beach sand, the definition or relevance of indicators and pathogens, and their forms of detection and counting, are being published without any methodological equivalence or biological relevance. The lack of regulation and international standards for the evaluation of contaminants in sand is generating a logistical nightmare for those who want to make interregional comparisons. A quantitative microbial risk assessment based on the clinical and safety aspects of several agents and biological groups is in order to pre-structure international regulation. Fecal indicator and other pathogenic or opportunistic bacteria from intertidal sands, as well as dry sand contamination resulting from animal shedding or direct sand / soil life, will be included in these groups; Enteric and respiratory viruses propagated through the environment (intertidal sands); Pathogenic, opportunistic and allergenic fungi; Parasites; and forms of allochthonous life as a consequence of sand nourishment. Considerations on environmental resistome of sand should not be excluded. C. Implications of climate change in sand / soil microbiome Extreme weather events, global warming and migration of endemic species are current factors that will dictate future risk assessments.