สถาบันวิจัยวิทยาศาสตร์สาธารณสุข

NATIONAL INSTITUTE OF HEALTH OF THAILAND

Food pathogens in ready-to-eat traditional thai fermented products (Fermented shrimp, Fermented Crab and Fermented fish)

Authors : Aroon Bangtrakulnonth* , Nopharat Manrim* , Chaiwat Pulsrikarn* , Pathom Sawanpanyalert* and Adisorn Swetwiwathana**

 

Affiliations:    *National Institute of Health, Department of Medical Science
** Proposed Faculty of Agricultural Industry, King Mongkut’s Institute of
Technology Ladkrabang
 
 Source:       Food Journal (1) January – March 2004
 
Language:     English
 
Abstract:
 
Three hundred samples of thai traditional fermented products [34 samples of fermented shrimp, 66 samples of fermented fish (pla-jom), 100 samples of fermented fish (pla-ra) and 100 samples of fermented crab] sold in retailed markets around Bangkok and Nonthaburi were investigated for pH, salt percentage and pathogenic microorganisms such as Salmonellae, Shigellae, Escherichia coli O157 : H7, Vibrio cholerae, V. parahaemolyticus, Staphylococcus aureus and Bacillus cereus. The results revealed that the average pH of fermented shrimp, fermented fish (pla-jom), fermented fish (pla-ra) and fermented crab was 4.02, 4.26, 4.79 and 7.44 respectively, while the average salt percentage from each aformentioned fermented product was 8.06, 8.75, 14.85 and 15.23 respectively. Results in detection of pathogenic microorganisms from the products indicated that 21 samples (7.00 %) were found contaminated with food pathogens. Among these positive pathogenic microorganisms samples, Salmonellae revealed to be the most detectable pathogen of these fermented products (3.00 %) [from one sample of fermented shrimp (S. Paratyphi B var. java), one sample of pla-ra (S. Rissen), 3 samples of pla-jom (S. Bredeney, S. Hadar and S. Hvittingfoss) and 4 samples of fermented crab (S. Hvittingfoss, S. Stanley, S. Braederup and S. enterica subsp. enterica 41:b:-), following by V. parahaemolyticus (2.67 %) [from 6 samples of fermented crab and 2 samples of pla-jom] and B. cereus (1.33 %) [from 3 samples of fermented shrimp and one sample of pla-ra]. Shigellae, V. cholerae, S. aureus and E. coli O157 : H7 were not detected in any of these samples. The pH of Salmonellae, V. parahaemolyticus andB. cereus positive samples was between 4.11 – 7.88, 4.11 – 4.48 and 3.79 – 4.86 respectively, and the salt percentage of each pathogenic positive samples was between 1.37 – 16.89, 3.27 – 17.41 and 6.69 – 17.17 % respectively. Determination of antimicrobial susceptibility of contaminated gram positive pathogens against a panel of 9 antibiotics implied that all detected serovar of Salmonellae and all strains of V. parahaemolyticus were sensitive to most of studied antimicrobial agents except S. Hadar resisted to Nalidixic acid and Tetracycline, S. Braenderup resisted to Nalidixic acid, Tetracycline and Co-trimoxazole, and all detected strains of V. parahaemolyticus resisted only to ampicillin.