Microbial quality of oysters sold in Western Trinidad and potential health risk to consumers

Abstract

The prevalence and characteristics of Escherichia coli and Salmonella spp. as well as counts of E. coli in raw oysters, condiments/spices, and raw oyster cocktails sampled from 72 vendors across Western Trinidad were determined. The microbial quality of the water used in the preparation of raw oysters was also investigated. Of 200 samples each of raw oysters, condiments/spices and oyster cocktails tested, 154 (77.0%), 89 (44.5%) and 154 (77.0%) respectively yielded E. coli. The differences were statistically significant (P = < 0.001; chi square = 62.91). The mean E. coli count per g in the ready-to-eat oyster cocktail ranged from 1.5 x 10(3) +/- 2.7 x 10(3) in Couva to 8.7x10(6) +/- 4.9x10(7) in San Fernando. One hundred and forty-six (73.0%) oyster cocktails contaminated with E. coli had counts that exceeded the recommended standard of 16 per g. Of a total of 590 E. coli isolates from various sources tested, 24 (4.1%), 20 (3.4%) and 69 (11.7%) were mucoid, haemolytic and non-sorbitol fermenters respectively. Twelve (2.0%) isolates of E. coli were O157 strains, while 92 (46.0%) of 200 E. coli isolates tested belonged to enteropathogenic serogroups. Ninety (45.0%) and 73 (36.5%) of 200 water samples contained total coliforms and faecal coliforms respectively, with counts that exceeded 2.2 coliforms per 100 ml. Salmonella spp. were isolated from 7 (3.5%), 1 (0.5%) and 2 (1.0%) of 200 samples each, of raw oysters, condiments/spices and oyster cocktails respectively. Oysters pose a health risk to consumers in Trinidad, particularly from colibacillosis and salmonellosis, and the need for increased public awareness of this hazard cannot be over-emphasized.

Spices and herbs as source of Salmonella-related foodborne diseases

“…Although the intent was not to draw quantitative comparisons between the prevalence of contamination of domestic and imported produce, the different detection rates might reflect differences in conditions during pre-and post-harvest operations. Based on the studies included in the present review (Table 2), Salmonella-contaminated spices and herbs were also detected in surveys from Brazil (Moreira, Lourenção, Pinto, & Rall 2009), Japan (Hara-Kudo et al, 2006), India (Banerjee & Sarkar 2003), Trinidad (Rampersad et al, 1999), and Austria (Kneifel & Berger 1994). In the study of Moreira et al (2009) examining the microbial status of various commodities (basil, bay leaves, black pepper, cinnamon, clove, cumin, dehydrated green onion, dehydrated parsley, oregano) marketed in São Paulo, 13 (5.6%) of 233 samples were positive for Salmonella.…”

Street Vended Food in Developing World: Hazard Analyses

“…Studies done to find out the bacteriological quality of the water used by some street vendors have revealed frequent contamination with coliforms and fecal coliforms [43]. When the street foods in Trinidad and Tobago were analyzed, it was reported found that 35% of foods were contaminated by E. coli while 57.5% of water used by vendors were contaminated by coliforms [26,[44][45][46]. These reports were similar to the findings that the stored water used by consumers and vendors, at the vending site, showed heavy bacteriological contamination of faecal origin [31].…”

Microbial Load and the Prevalence of Escherichia coli, Salmonella spp. and Listeria spp. in Ready-to-Eat Products in Trinidad

“…E. coli O157 has also been isolated from the water supply to rural communities (2.0%) (Welch et al 2000) [13], local delicacies such as oysters (2%) (Rampersad et al 1999) [14] and 'black pudding' (13.6%) (Adesiyun and Balbirsingh 1996 [9]) and from pre-processed cows' milk (0.8%) (Adesiyun et al 2007) [12]. The first case of neonatal septicaemia and meningitis due to L. monocytogenes was reported in Trinidad in 1998, (Ashiru and Bratt 1998) [15] when symptoms appeared three days after a blood transfusion.…”

“…In Trinidad and Tobago, Salmonella spp. have been recovered from oysters, 2.3% (Rampersad et al 1999) [14], black pudding, 8% (Adesiyun and Balbirsingh 1996) [9] and table eggs, 13.0% (Adesiyun et al 2005) [16].…”