Occurrence of Vibrios in Frozen Seafoods and Survival of Psychrotrophic Vibrio cholerae in Broth and Shrimp Homogenate at Low Temperatures

Abstract

Pathogenic vibrios are important etiologic agents in tropical regions and have been frequently recovered from seafoods and aquacultured foods. In this study, commercially frozen seafoods including peeled shrimps and fish and shrimp dumplings were examined. Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio cholerae and Vibria fluvialis were recovered at 36.0%, 15.8%, 14.9% and 13.2%, respectively. A number of psychrotrophic vibrios were selected and their survival in tryptic soy broth (TSB) supplemented with 1% sodium chloride (NaCl) (TSBS medium) and shrimp homogenate at 4°C and −30°C were studied. Two psychrotrophic non-O1 V. cholerae (laboratory stocks no 128 and 129) survived well at these low temperatures. Counts decreased by about 1 log/ml in TSBS medium at 4°C for 6 days and 3 log/ml at −30°C for 3 days. Shrimp homogenate provided better protection than TSBS medium for psychrotrophic V. cholerae at −30°C. Survival of V. cholerae at low temperatures was further increased by the addition of 0.5% of heated pyrophosphate and metaphosphate, probably by decreasing the lethality of the cold injury to the cells. Measures should be taken to minimize the risk from pathogenic vibrios in frozen seafoods, especially if phosphates are used and psychrotrophic strains are present.

Prevalence of Vibrio parahaemolyticus in seafoods and their processing environments as detected by duplex PCR

“…Vibrio parahaemolyticus is considered as one of the major food‐borne pathogens because of its high recovery from fresh seafood products, refrigerated seafoods and even frozen items 14, 29, 30. The bacterium can cause gastroenteritis in humans as a result of consumption of contaminated seafood products in the summer months 12, 31.…”

The use of the so‐called ‘tubs’ for transporting and storing fresh fishery products

“…In the majority of studies, a reduction of Vibrio counts (from 0.5 to 4 log 10 ) within the first 3 days was reported. V. cholerae showed a 1 log 10 decrease after 4 days in prawns stored at 1.5°C and in shrimps at 4°C (Wong et al., ; Januario and Dykes, ) and between 3 and 4 log 10 decrease after 3 days in crab and shrimp homogenates stored at 7°C. As regard to V. parahaemolyticus , two studies report no substantial variations of counts in sheep head porgy and bigeye snapper stored at 4°C over 5 and 28 days, respectively (Vasudevan and Venkitanarayanan, ; Pattanayaiying et al., ) and one described growth (~ 2.5 log 10 in 4 days) in sea bass at 4°C (Provincial et al., 2013a).…”

“…• Yes: retain • No: exclude Table A.3: Long list of bacteria, viruses and parasites as biological hazards and the result of the selection based on the two criteria: (1) evidence of causing human illness and being associated with fresh fishery products and (2) evidence of survival and/or growth within the range of À3°C to 7°C. Those included in the assessment are shown in bold Reily and Hackney (1985), Corrales et al (1994), Wong et al (1995), Magalhaes et al (2000), Johnston and Brown (2002), Vasudevan et al (2002), Januario and Dykes (2005), Vasudevan and Venkitanarayanan (2006) Table A.4: Long list of histamine-producing bacteria as biological hazards and the result of the assessment against the two criteria: (1) evidence of causing human illness associated with fresh fishery products and (2) evidence of biogenic amines production within the range of À3°C to 7°C. Those included in the assessment are shown in bold Background information on selected hazards…”

“…Reply to question 3: Y Badhey et al (1986), Telzak et al (1990), Weber et al (1993), Sobel et al 2007), Horowitz (2010, Leclair et al (2013), Walton et al (2014) G (evidence of toxin production) Riedo et al (1994), Betts andGaze (1995), Farber et al (2000), Miya et al (2010) Reily and Hackney (1985), Corrales et al (1994), Wong et al (1995), Magalhaes et al (2000), Johnston and Brown (2002), Vasudevan et al (2002), Januario and Dykes (2005)…”

Dondurulmuş Deniz Ürünlerinde Vibrio spp.’nin İlmiğe Dayalı İzotermal Amplifikasyon (Loop Mediated Isothermal Amplification, LAMP) Yöntemiyle Belirlenmesi

“…cholerae'nın belirlenmesi amacıyla yapılan ompwA gen bölgesinin tespitine yönelik LAMP reaksiyonunda ise izolatların hiçbirinde V. cholerae bulunamamıştır. Benzer şekilde V. choleare'nın tespit edilmediği çalışmalar (23,37) olduğu gibi mikroorganizmanın farklı düzeylerde kontaminasyon varlığını bildiren çok sayıda araştırma da (32,38,39) Araştırma sonuçlarına göre Vibrio spp. pozitif örneklerde en çok identifiye edilen tür V. parahaemolyticus ve daha sonra V. vulnificus şeklinde olmuştur.…”