Prevalence of Foodborne Pathogens in Freshwater Fish in Latvia

Abstract

The aim of this study was to detect the prevalence of Salmonella spp., Listeria monocytogenes, and Yersinia enterocolitica in freshwater fish in Latvia. In total, 235 samples, including freshly caught fish from fives lakes (n = 129) and fish from retail markets (n = 106), were collected from April 2014 to December 2014 in Latvia. Samples were tested according to International Organization for Standardization methods. No Salmonella spp. were found in fresh fish from lakes or in commercially available fish. In contrast, the overall prevalence of L. monocytogenes and Y. enterocolitica in freshwater fish was 13% (30 of 235) and 14% (34 of 235), respectively, and no significant difference between the prevalence of L. monocytogenes and Y. enterocolitica was observed (P > 0.05). All Y. enterocolitica isolates belonged to the nonpathogenic 1A biotype. Molecular serotyping of L. monocytogenes revealed that the most distributed serogroup was 1/2a-3a (65%), followed by 1/2c-3c (25%), 1/2b-3b (5%), and 4b, 4d, 4e (5%). The prevalence of L. monocytogenes and Y. enterocolitica in freshwater lake fish was 2% (2 of 129) and 3% (4 of 129), respectively. In contrast, the prevalence of L. monocytogenes and Y. enterocolitica in fish at retail markets was 26% (28 of 106) and 28% (30 of 106), respectively. In retail samples, 9 of 58 positive fish contained both L. monocytogenes and Y. enterocolitica. In general, differences in the prevalences of L. monocytogenes and Y. enterocolitica in retail samples were significantly higher than those in freshly caught fish (P < 0.05). The results of this study indicate that freshwater fish could be an important source of Y. enterocolitica and L. monocytogenes for consumers in Latvia.

Occurrence, Antibiotic Resistance, and Population Diversity of Listeria monocytogenes Isolated From Fresh Aquatic Products in China

“…Serotype 4b, 1/2a, and 1/2b account for 95% of the strains isolated from human listeriosis ( Cartwright et al, 2013 ; Althaus et al, 2014 ). In this study, the majority of L. monocytogenes belonged to serogroup I.1 (serotype 1/2a, 38.89%), II.2 (serotype 1/2b, 34.72%), and III (serotype 4c, 22.22%), which is consistent with the previous results obtained in fish from several countries ( Fallah et al, 2013 ; Jamali et al, 2015 ; Terentjeva et al, 2015 ). Wang et al (2015) reported serotype 1/2b (belonged to ST87 and ST3) with a frequency of 64.3% of L. monocytogenes was predominant in human listeriosis cases in China, similar results was also reported in Zigong, Sichuan province, conducted by Wang et al (2018) , indicating potential hypervirulent isolates were present in aquatic products in China.…”

The microbial safety of fish and fish products: Recent advances in understanding its significance, contamination sources, and control strategies

“…Similarly, a study in Iran reported that 14.16% of retail rainbow trout were positive for L. monocytogenes compared to the 4.16% positive rate of fish samples collected from ponds on fish farms (Rezai, Ahmadi, & Salimi, 2018). Listeria monocytogenes was detected in 26% of retail and 2% of wild‐caught freshwater fish in Latvia (Terentjeva et al., 2015). Fish skin is considered one primary contamination source.…”

Microbiological quality of farmed grass carp, bighead carp, Siberian sturgeon, and wels catfish from Eastern Poland

“…The International Commission on Microbiological Specification for Foods suggests microbiological criteria for fresh fish (only aerobic plate count and E. coli ) ( 8 ), but these are not legally enforced and the lack of legislated safety criteria creates potential health risk for consumers. The necessity of monitoring contamination of food fish caused by pathogenic bacteria has been confirmed by other authors ( 13 , 23 , 30 , 31 ).…”

“…Food fish contain bacteria pathogenic to humans, like Listeria monocytogenes , Salmonella spp., Staphylococcus aureus , and Escherichia coli ( 3 , 12 , 13 , 23 , 28 , 30 , 31 ), and therefore consumption may be entailed risk for consumers. The consumption of raw or insufficiently heat-treated fish causes most outbreaks of food poisoning ( 13 ).…”