Is it safe to eat raw seafood? Prevalence of Salmonella in some seafood products sold in Alexandria markets.

BACKGROUND: Salmonella is a significant microbial hazard in seafood. Salmonella-contaminated seafood usually looks and smells normal; it is therefore essential that every effort is made toward the rapid detection of Salmonella as an important criterion in quality control of seafood. AIMS: This study aims to determine the percentage of Salmonella in some Egyptian seafood sold in Alexandria markets and to study the validity of Chromagar Salmonella Plus (CASP) agar versus xylose lysine desoxycholate and Salmonella-Shigella agar for the isolation and identification of Salmonella in seafood. MATERIALS AND METHODS: Two hundred and twenty-five samples of three seafood types, shrimp, gandofli, and river mussel (om-elkhloul) were studied. Samples were selectively enriched in Rappaport-Vassiliadis and tetrathionate broth, and then plated onto the aforementioned plating media for the detection of Salmonella. RESULTS: In total, Salmonella was detected in 9.8% of the samples. The sensitivity and specificity of the media used varied according to the media and enrichment broth combinations used. The CASP and Rappaport-Vassiliadis combination yielded the best sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 95.45, 100, 100, 99.5, and 99.5%, respectively. CONCLUSION AND RECOMMENDATION: CASP was more accurate than xylose lysine desoxycholate and Salmonella-Shigella in the detection of Salmonella from seafood samples. We recommend that CASP medium should be tested against more Salmonella-positive samples before it is used as a screening plating medium for Salmonella in seafood.

Evaluation of two enrichment broths, three plating media and ELISA technique for the isolation of salmonella from dairy products.

Salmonella is one of the most important food-borne pathogens that can be transmitted through the consumption of contaminated milk and milk products. Early detection of Salmonella in food is important for food safety. Two selective media, brilliant green agar (BGA) and xylose lysine desoxycholate (XLD) agar are commonly used in diagnostic laboratories for the isolation of Salmonella, often after enrichment of the samples in a broth before plating on the solid medium. Recently, a new medium called CHROmagar Salmonella (CAS) has become available for the rapid detection of Salmonella. In the present study, we compared this new medium with BGA and XLD for the isolation of Salmonella from 160 dairy products samples (80 ice cream and 80 kariesh cheese samples) with enrichment in Rappaport- Vassiliadis (RV) and tetrathionate (TT) broth. TECRA Unique Salmonella ELISA test was used. Only one sample was positive for Salmonella, which appeared on each of CAS and XLD agars, after enrichment using RV but not TT. This was associated with a sensitivity and specificity of (100 %, 92.45%), (100%, 93.71%) and (0 %, 100%) for each of CHROmagar Salmonella, XLD and BGA respectively. TECRA Unique Salmonella test yielded the highest sensitivity and specificity among all used methods; it had 100% sensitivity with 100% specificity.

Bacteriological quality of some dairy products (kariesh cheese and ice cream) in alexandria.

The present study estimated the total viable bacterial density, total and faecal coliforms, and E. coli in Kariesh cheese and ice cream. The study included 160 ice cream and kariesh cheese samples (80 samples each). Ice cream samples were 47 packed (33 cup and 14 stick) and 33 open samples while kariesh cheese samples were 62 open, 18 packed samples (8 of known brand and 10 of unknown brand). Samples were collected from supermarkets, shops and street vendors. All samples were analyzed for enumeration of total viable heterotrophic bacteria using standard pour plate method, and for the determination of the total coliforms, fecal coliforms and E. coli using multiple tube dilution method. Ice cream samples, showed that the total bacterial count was >/=1.5x105 cfu/g in 26 (32.5%) samples, total coliforms were >/= 10 MPN/g in 36 (45.0%) samples, fecal coliforms were detected in 45 (56.3%) samples ,and E. coli was detected in 34 (42.5%). kariesh cheese samples, showed a total coliforms of >/= 10 MPN/g in 54 (67.5%) samples, while fecal coliforms were detected in 64 (80%) samples, and E. coli was detected in 60 (75%). It is recommended to use and implement immediate regulatory measures like good manufacturing practices as well as distribution and retail storage practices for ensuring microbiological safety of ice cream and kariesh cheese.