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18 Today export countries must adapt those rules and regulations to maintain trade opportunities. It appears that many countries, especially the poorest may face a major problem in meeting food safety standards that are obligatory in a number of importing countries. 2.7 Vibrio 2.7.1 History and Morphology The first Vibrio spp. identified was Vibrio cholera, discovered in 1854 by the Italian physician Filppo Pacini during an outbreak and subsequent investigation in Florence. Pacini detected V. cholerae in all intestinal mucosal samples of fatal victims. John Snow (1813-1858) studied the epidemiology of cholera in several cities of England and found that cholera is spread by the contaminated water and suggested pure water for drinking (Thompson et al., 2004). According to the Bergey’s Manual (Holt et al., 1994) this bacteria is in the family Vibrionaceae and genus Vibrio and has characteristics of straight or curved rods, (0.5-0.8µm in width and 1.4-2.6 µm in length), motility by one or more polar flagella, Gram negative, chemoorganotropic, facultative anaerobic, mesophilic, oxidase positive and sensitive to the vibriostatic agent O/129 (except a few species). Most species grow well at 37°C. Vibrio is distributed worldwide and is found in sea water, fresh water, brackish water and associated with aquatic animals, sediments and feeds (Bhaskar et al., 1998). Large numbers of Vibrio and Photobacterium attach to the external surface of the zooplankton and make bio films. Because of this close association with zooplankton, it is assumed that cholera outbreaks are linked to planktonic blooms and rising sea water temperature due to global warming (Thompson et al., 2004).
19 2.7.2 Biochemical characteristics of Vibrio Biochemical characteristics of Vibrio are used to differentiate the food associated with Vibrio pathogens including Aeromonas hydrophila and Plesiomonas shigelloides that belong to the family Vibrionaceae (Table 6) (Kaysner, 2000). Thiosulfate citrate-bile salt agar (TCBS) is a selective medium for the isolation of Vibrio (Thompson et al., 2004). Vibrio organism’s ability to ferment sucrose and a colour change of the colony helps to differentiate Vibrio spp. Sucrose positive, yellow colonies on TCBS agar are characteristics of V. cholerae, V. fluvialis, V. furnissii, V. alginolyticus, V. metschnikovii. While V. parahaemolyticus, V. mimicus, V. vulnificus and V. hollisae are sucrose negative and produced green colour colonies. Table 6: Biochemical characteristics of the Vibrionaceae commonly encountered in seafood V. alg V. cho V. flu V. fur V. hol V. me V. mi V. parh V. vul A. TCBS agar Y Y Y Y NG Y G G G Y G Oxidase + + + + + - + + + + + Arginine dihydrolase Lysine decaboxylase Growth in (w/v): - - + + - + - - - + + + + - - - + + + + V + 0% NaCl - + - - - - + - - + + 3% NaCl + + + + + + + + + + + 6% NaCl + - + + + + - + + + - 8% NaCl + - V + - V - + - - - 10% NaCl + - - - - - - - - - - Growth at 42 o C Acid from: + + V - nd V + + + V + Sucrose + + + + - + - - - V - D-Cellobiose - - + - - - - V + + - Lactose - - - - - - - - + V - Arabinose - - + + + - - + - V - D-Mannose + + + + + + + + + V - hy P. sh
Page 1 and 2: 2.1 Shellfish culture CHAPTER II LI
Page 3 and 4: 7 constant over the years while cul
Page 5 and 6: 9 Pathogenic bacteria associated wi
Page 7 and 8: 11 Listeriosis, and other pathogens
Page 9 and 10: Coastal water Shrimp Bangladesh (Co
Page 11 and 12: Table 4: Cholera pandemics Pandemic
Page 13: 17 parahaemolyticus should be Kanag
Page 17 and 18: 21 2.7.4 Genotypic characteristics
Page 19 and 20: 23 Clinical strains of V. parahaemo
Page 21 and 22: 2.8 Human pathogenic Vibrio 2.8.1 V
Page 23 and 24: 27 Vibrio spp. display similar bioc
Page 25 and 26: 29 host and effluent from the conta
Page 27 and 28: 31 elimination of Edwardsiella tard
Page 29 and 30: A. Cooling and freezing 33 Rapid an
Page 31: 2.10.3 Consumer education 35 Consum

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