Epidemiology and Infection

Table of Contents - 1999 - Volume 123, Issue 02  


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

F. S. RAMPERSAD a1, S. LALOO a1, A. LA BORDE a1, K. MAHARAJ a1, L. SOOKHAI a1, J. TEELUCKSINGH a1, S. REID a1, L. McDOUGALL a1 and A. A. ADESIYUN a2c1
a1 School of Medicine, Faculty of Medical Sciences, University of the West Indies, St Augustine, Trinidad and Tobago
a2 School of Veterinary Medicine, Faculty of Medical Sciences, University of the West Indies, St Augustine, Trinidad and Tobago

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=[less-than-or-eq, slant]0·001; χ2=62·91). The mean E. coli count per g in the ready-to-eat oyster cocktail ranged from 1·5×103±2·7×103 in Couva to 8·7×106±4·9×107 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.

(Accepted April 23 1999)


Correspondence:
c1 Author for correspondence.

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