Abstract
Vibrio parahaemolyticus is the leading cause of seafood-associated bacterial gastroenteritis worldwide. Although different studies have focused on its pattern of variation over time, knowledge about the environmental factors driving the dynamics of this pathogen, within the Chilean territory, is still lacking. This study determined the prevalence of total and pathogenic V. parahaemolyticus strains (tdh and/or trh genes) in mussels (Mytilus chilensis) collected from two natural growing areas between 2017 and 2018, using selective agar and PCR analysis. V. parahaemolyticus was detected in 45.6% (93/204) of pooled samples from the Valdivia River Estuary. The pathogenic strains carrying the tdh and/or trh gene were detected in 11.8% (24/204): tdh in 9.8% (20/204), trh in 0.5% (1/204), and 1.5% (3/204) presented both genes. In Reloncaví Fjord, V. parahaemolyticus was detected in 14.4% (30/209) of the samples, pathogenic V. parahaemolyticus carrying the trh gene was detected in 0.5% (1/209) of the samples, while the tdh gene was not detected in the samples from this area. The total count of mauve-purple colonies typical of V. parahaemolyticus on CHROMagar was positively associated by multivariate analysis with area, water temperature, and salinity. Similarly, V. parahaemolyticus detection rates by PCR had a positive correlation with the area and water temperature. The chances of detecting total V. parahaemolyticus in the Valdivia River Estuary are significantly higher than in the Reloncaví Fjord, but inversely, during spring-summer months, the interaction factor between the area and temperature indicated that the chances of detecting V. parahaemolyticus are higher in the Reloncaví Fjord. Interestingly, this period coincides with the season when commercial and natural-growing shellfish are harvested. On the other hand, pathogenic V. parahaemolyticus tdh+ was significantly correlated with an increase of water temperature. These environmental parameters could be used to trigger a warning on potential hazard, which would influence human health and economic losses in aquaculture systems.
Highlights
Vibrio parahaemolyticus is a Gram-negative halophilic bacterium, ubiquitous in marine and estuarine environments (Joseph et al, 1982; Su and Liu, 2007; Raszl et al, 2016)
A longitudinal study was realized between January 2017 and May 2018 from two natural extraction areas of mussels (Mytilus chilensis) in the southeastern Pacific coast of Chile (Valdivia River Estuary in the Los Ríos Region and the Reloncaví Fjord in the Los Lagos Region) (Figure 1)
There was no statistical difference in water temperature between sample sites, but statistical differences were found between sampled months
Summary
Vibrio parahaemolyticus is a Gram-negative halophilic bacterium, ubiquitous in marine and estuarine environments (Joseph et al, 1982; Su and Liu, 2007; Raszl et al, 2016). Gastroenteritis caused by V. parahaemolyticus has been reported worldwide This bacterium is the principal foodborne pathogen associated with the consumption of raw or undercooked seafood in Asia and the United States (Martinez-Urtaza et al, 2004; Su and Liu, 2007; Newton et al, 2012; Wu et al, 2014). In Chile, V. parahaemolyticus is considered an important human pathogen, which in 1997 was associated with a large outbreak in Antofagasta, northern Chile, causing more than 300 cases. It was responsible for several outbreaks between 2004 and 2010 in Puerto Montt, southern Chile, with more than 5,000 cases reported. This region is one of the main shellfish-producing areas, mainly of Mytilus chilensis (González-Escalona et al, 2005; Fuenzalida et al, 2006; García et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
