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  • Author: Hristo Daskalov x
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Abstract

The aim of this study was to collect actual data concerning the frequency of contamination with Listeria monocytogenes of some raw dried cured vacuum packed sausages, which are very popular in Bulgaria produced from Oct. 2004 till May 2008. 148 vacuum-packed samples were taken from 9 different food business operators during all seasons of the year. The samples were analyzed according to the USDA method for meat foods. Ten specimens were positive for presence of Listeria monocytogenes, which is equal to 6,75% of all tested samples. In two other raw dried cured sausages L. welshimeri and L.innocua were found, but these species are not pathogenic for consumers. In the period before the official implementation of the HACCP system (01.01.2006) in Bulgaria, 52 samples were examined and 5 Listeria monocytogenes isolates were found (~10%). 2,5 years after the HACCP implementation, 96 specimens from the same meat factories were tested and 5 Listeria monocytogenes isolates (5,2%) were detected. Samples taken from lots, produced in winter time were contaminated with Listeria monocytogenes more often (7 of all 10) than specimens taken during other seasons. Data was discussed through the point of view of the effectiveness of hygienic practices and HACCP system application. Also, application of the ‘microbiological criterion’ set in the COMMISSION REGULATION (EC) No 2073/2005 for ready-to-eat foods unable to support the growth of L. monocytogenes was considered.

Abstract

This paper presents an outbreak provoked by methicillin-resistant strains of coagulase-positive S. aureus (CPS), produced staphylococcal enterotoxins (se) in pig meatballs and potato salad consumed from 70 people in the village Mamarchevo, Bulgaria. Eighteen women aged 50 to 70 years, and two children aged 4 and 5 years have demonstrated a severe malaise with vomiting and indigestion. Two food samples and isolates of CPS were received in the laboratory of Bulgarian Food Safety Agency. Both samples were found to have a high level of CPS. The level of S. aureus contamination in the potato salad was 8.3 logs CFU/g and 7.7 logs CFU/g in roasted meatballs, which was a significant reason to doubt the production of the toxin. The samples were analyzed according to the European Screening Method v5 using mini VIDAS SET2. The results showed a presence of staphylococcal enterotoxin (TV 2.67 for meatballs and TV 3.27 for potato salad), which was the reason for the ensuing food intoxication. EURL CPS applying quantitative indirect sandwich-type ELISA confirmed the presence of sea, sec and sed in the potato salad and sea and sed in the roasted meatballs. Two CPS isolates were confirmed as S. aureus by a species-specific 23S rRNA targeted PCR test. Real-time PCR method detected sea, sed, seg, sei, sej, and ser genes in S. aureus strains, found in both matrixes. Multiplex PCR method proved the existence of the mecA gene in both S. aureus strains. Resistance to cefoxitin (>16 mg/L), penicillin (>2 mg/L), kanamycin (64 mg/L) and sulfamethoxazole (>512 mg/L) was found.