<i>Campylobacter</i> in an Urban Estuary: Public Health Insights from Occurrence, HeLa Cytotoxicity, and Caco-2 Attachment Cum Invasion

Abstract

Aquatic recreation in urban estuaries worldwide is often restricted by fecal pollution. Variability in the occurrence of fecal pathogens and their differential virulence potentials within these estuaries may result in variable public health risks. To address this hypothesis, Campylobacter were isolated from the Yarra River estuary, Australia and then characterized via HeLa cell cytotoxicity and attachment to and the invasion of Caco-2 monolayers. Overall, 54% (n=216) of estuarine samples (water and sediment combined) yielded biochemically confirmed culturable Campylobacter; higher detection was recorded in water (92%, n=90) than in the bank and bed sediments combined (27%, n=126). The seasonality of occurrence was not significant. HeLa cell cytotoxicity revealed that estuarine Campylobacter had low cytotoxin titers; the 95% confidence interval (CI) ranged between 61 and 85, which was markedly lower than the mean value (~386) for the C. jejuni 11168 reference pathogenic strain. The Caco-2 attachment of estuarine Campylobacter isolates (n=189) revealed that the 95%CI for the attachment efficiency of the test strains ranged between 0.09 and 0.1%, with only 3.7% having a higher efficiency than the 5 th percentile value for C. jejuni 11168. None of the estuarine strains exhibited Caco-2 invasion capabilities. In contrast to the common assumption during quantitative microbial/risk assessments (QMRAs) that all environmental strains are pathogenic, the present results revealed that Campylobacter within the Yarra River estuary had very low virulence potential. Since this is the first study to use human epithelial cell lines to characterize estuary-borne pathogens, these results generate valuable insights for a better understanding of the public health risks in urban estuaries that will underpin more robust QMRAs.

Synthesis of blue fluorescent carbon dots and their application in detecting mercury and iodine based on “off–on” mode

“…The concentration of CD we used in cell culture was 0.04 mg·mL −1 , and this concentration is greater than that reported in much of the literature for HeLa cell cultures, meaning it is a relatively large concentration. [ 52–55 ] Although HeLa cells were immersed in the CD solution for 48 h, cells were able to move freely and stayed alive without outside nourishment. More than 95% of the cells were alive, which proved that the synthesized material was not toxic to the cells (Figure 11f).…”

Spatiotemporal variations in the occurrence of Campylobacter species in the Bloukrans and Swartkops rivers, Eastern Cape, South Africa

“…in river systems can vary by region and country as reported in previous studies. For instance, Campylobacter occurrence has been reported to be 25% in Australia [ 40 ], 26 % in Canada [ 41 ], 35.7% in Ghana [ 42 ], 41.5% in India [ 43 ] 46.6%–53.3% in France [ 44 ], 53.3% in Norway [ 45 ] and 91% in the Yarra River estuary, Australia [ 46 ]. Campylobacter occurrence (66.67 %) reported in the Bloukrans River in this study is similar to the 68.7% reported in Nigeria [ 47 ] and 33–63% in Canada [ 48 ].…”