Microbial pathogens that pose a human health risk in water may be autochthonous (native) or allochthonous (non-native) to aquatic environments. Water-associated pathogens can infect humans via various portals of entry, including wounds and ingestion of water, or food grown in water that contains pathogens. The research foci in my laboratory include the ecology of an autochthonous aquatic pathogen, Vibrio vulnificus, and the fate of allochthonous enteric pathogens in aquatic habitats.
V. vulnificus infections are usually acquired via wound infections, or by consumption of undercooked shellfish (particularly oysters). These infections may progress to septicemia in immunocompromised individuals, making V. vulnificus among the most lethal bacterial pathogens once infection is established. Evidence is accumulating that some V. vulnificus strains, and perhaps lineages, are more virulent than others. The allochthonous enteric pathogens that “invade” aquatic habitats when fecal material enters the water range from viruses (e.g. enteroviruses) to bacteria (e.g. Campylobacter) to protozoa (e.g. Cryptosporidium), and generally infect humans when water is consumed or accidentally ingested, but also may be transmitted by food that has been contaminated via the water. Because the possible range of pathogens that could be carried to water in feces or sewage includes literally hundreds of different types across the microbial spectrum (with viruses at the small end and worms at the large end), we use fecal indicator bacteria (FIB) such as Escherichia coli and enterococci to provide a warning that fecal contamination has occurred, which elevates the risk to humans who use the water. The FIB surrogates are used to regulate water quality in the drinking water, recreational water, and even water-grown food areas, such as shellfish.
The FIB that are currently approved for regulatory use for the purposes mentioned above are shed in the feces of most animals, including humans, thus, they provide no information about the source of fecal contamination. Such information is essential for accurate risk assessment and for remediation of waters whose quality is “impaired” (below regulatory standards). However, some microorganisms are relatively specific to the gastrointestinal tracts/feces of certain hosts, unlike the FIB. Such host-specific microorganism can be used as specific tracers, or markers, of fecal contamination from particular host types in water. This research area is known as microbial source tracking (MST), and detection of the marker is frequently accomplished by PCR, or, more recently, by quantitative PCR (qPCR).
This seminar will discuss development of MST methodology, laboratory and field validation of emerging methods, and specific examples from field studies. It will also discuss the distribution of V. vulnificus strains in Gulf of Mexico oysters and tissues, and our hypothesis that at least one of the V. vulnificus lineages with relatively greater virulence potential is preferentially distributed in aquatic habitats with poor water quality.
Please contact Anita Wright (firstname.lastname@example.org) for additional information.