Investigation and characterization of Shiga toxin‐producing Escherichia coli present in mussels from harvesting areas in Galician southern Rias (NW Spain)

Abstract

Shiga toxin‐producing Escherichia coli are a known cause of serious illnesses, and a major public health concern. The coastal environment is the receptacle of agricultural and urban wastewater effluents, thus STEC can be present. In the current study their occurrence and prevalence in mussels (Mytilus galloprovincialis) cultured in the southern Rias of Galician was assessed. This region is interesting due to its economic importance as Galicia produces the 98% of the mussels cultured in Spain, being this country the third world producer. From June 2012 until September 2013, 241 mussel samples were collected, being 112 positive for eae and 17 also positive for stx1,2. An increase was observed in the winter months for both genes, which seemed correlated with a generalized decrease in water salinity. Serotype O157:H7 was not detected, but one isolate resulted resistant to six antibiotics, denoting the presence of multidrug resistant bacteria in this área. Practical applications A critical step for adequate risk assessments is the evaluation of potential threats. In this sense, very few microbiological parameters are analyzed in bivalve molluscs, being many human pathogens not assayed. Shiga toxin‐producing Escherichia coli was detected for the first time in mussels harvested in Galicia, a region of critical importance worldwide for the mussel industry. This study highlights that additional studies to better characterize the microbial populations of this important region are still needed, and furthermore, that measures to control microbial pathogens, such as depuration, must not be taken lightly.

An Evaluation of the Pathogenic Potential, and the Antimicrobial Resistance, of Salmonella Strains Isolated from Mussels

“…Caution must be taken when extracting conclusions related to the abundance as, due to the fact that certain areas are more productive, more samples were analyzed. In line with this, in previous studies, a bias existed towards the Ria of Arousa, due to a higher number of samples harvested and analyzed from this area, as a consequence of having a higher production [12,13]. The current study adds to the others previously published, informing the presence of different pathogens in this economically important area, and highlighting the importance of depuration for the safety of the consumers.…”

“…Mussel samples, harvested in the Rias of Arousa and Vigo (Figure 1), were analyzed from 2012 to 2016. The samples were collected, as previously reported [12]. Briefly, the mussels were collected from the rafts, placed in sterile bags and transported under refrigeration to the laboratory.…”

“…Previous studies have already reported the presence of pathogenic bacteria in this economically important mussel production area. These studies included pathogenic Vibrio and Campylobacter species, as well as Shiga toxin-producing Escherichia coli, thus highlighting the importance of screening for additional microorganisms, which can pose a risk for consumers [12][13][14]. In addition to these studies, Salmonella spp.…”