C. Vernozy-Rozand

An updated review of Listeria monocytogenes in the pork meat industry and its products

Pork meat and processed pork products have been the sources of outbreaks of listeriosis in France and in other European countries during the last decade. The aim of this review is to understand how contamination, survival and growth of Listeria monocytogenes can occur in pork meat products. This study discusses the presence of L. monocytogenes in raw pork meat, in the processing environment and in finished products. The prevalence of L. monocytogenes generally increases from the farm to the manufacturing plants and this mainly due to cross‐contamination. In many cases, this pathogen is present in raw pork meat at low or moderate levels, but foods involved in listeriosis outbreaks are those in which the organism has multiplied to reach levels significantly higher than 1000 CFU g−1. In such cases, L. monocytogenes has been able to survive and/or to grow despite the hurdles encountered during the manufacturing and conservation processes. Accordingly, attention must be paid to the design of food‐processing equipment and to the effectiveness of the cleaning and disinfecting procedures in factories. Finally, the production of safe pork meat products is based on the implementation of general preventive measures such as Good Hygiene Practices, Good Manufacturing and the Hazard Analysis Critical Control Point.

Long-term survival of Shiga toxin-producing Escherichia coli in cattle effluents and environment: an updated review.

Shiga toxin-producing Escherichia coli (STEC) are one of the most important emergent foodborne pathogens. STEC are common as colonizers in the intestine of healthy cattle and are spread into the environment by fecal shedding or following the surface application of farm effluent on soil. The bacteria can be transmitted to humans through food, such as inadequately cooked ground beef or unpasteurized milk. During the last decade, a wide variety of environmentally related exposures have emerged as new routes of transmission. Major outbreaks due to the consumption of raw fruits and vegetables or accidental ingestion of soil or water contaminated by STEC have been increasingly reported. STEC survival in cattle effluents, soil, plants and water is discussed in the light of new knowledge regarding both biotic and abiotic factors which may affect their survival or enhance their dissemination in the environment. The ability to persist in cattle production environments contributes to the contamination and recontamination of cattle, as well as for human infection. Consequently, effective control strategies must be considered on cattle farms, in order to limit entry of STEC cells into the environment.

Growth and enterotoxin production of Staphylococcus aureus during the manufacture and ripening of Camembert‐type cheeses from raw goats’ milk

Tests were carried out to determine the effect of manufacturing procedures for a Camembert‐type cheese from raw goats’ milk on the growth and survival of Staphylococcus aureus organisms added to milk at the start of the process, and to study the possible presence of staphylococcal enterotoxin A in these cheeses. The initial staphylococcal counts were, respectively, 2, 3, 4, 5 and 6 log cfu ml−1. Cheese was prepared following the industrial specifications and ripened for 41 d. Detection of enterotoxins was done by the Vidas SET test and by an indirect double‐sandwich ELISA technique using antienterotoxin monoclonal antibodies. Generally, numbers of microbes increased at a similar rate during manufacture in all cheeses until salting. During the ripening period, the aerobic plate count population and Staph. aureus levels remained stable and high. There was an approximately 1 log reduction of Staph. aureus in cheeses made with an initial inoculum of Staph. aureus greater than 103 cfu ml−1 at the end of the ripening period (41 d) compared with the count at 22 h. The level of staphylococcal enterotoxin A recovered varied from 1 to 3·2 ng g−1 of cheese made with an initial population of 103–106 cfu ml−1. No trace of enterotoxin A was detected in cheeses made with the lowest Staph. aureus inoculum used in this study.

Evidence for natural horizontal transfer of tetO gene between Campylobacter jejuni strains in chickens.

Aims:  The transfer of tetO gene conferring resistance to tetracycline was studied between Campylobacter jejuni strains, in the digestive tract of chickens.

Growth and survival of non‐O157:H7 Shiga‐toxin‐producing Escherichia coli in cow manure

Aims:  The main objective of this study was to evaluate the behaviour of non‐O157:H7 Shiga‐toxin‐producing Escherichia coli (STEC) strains in cow manure.

Isolation and characterization of Shiga toxin‐producing Escherichia coli strains from raw milk cheeses in France

Aims:  To evaluate Shiga toxin‐producing Eschericha coli (STEC) prevalence in 1039 French raw milk cheeses including soft, hard, unripened and blue mould cheeses, and to characterize the STEC strains isolated (virulence genes and serotypes).

Comparison of three immunological methods for detecting staphylococcal enterotoxins from food

Aims:  Immunologically based assays for the detection of staphylococcal enterotoxins are numerous. These techniques include radio immunosorbent assays and enzyme‐linked immunosorbent assays (ELISA), some of which are available as commercial kits. The purpose of this study was to compare the performances of three commercial immunoassays.

Prevalence of Escherichia coli O157:H7 in industrial minced beef

Aims:  The lack of baseline data on the prevalence of Escherichia coli O157:H7 in retail minced beef in France prompted this survey of industrial minced beef production.

Supplementation of enrichment broths by novobiocin for detecting Shiga toxin‐producing Escherichia coli from food: a controversial use

Aims:  To investigate the assumption that usage of novobiocin (20 mg l−1) in Shiga toxin‐producing Escherichia coli (STEC) enrichment broths could achieve false‐negative results.

Prevalence of verotoxin-producing Escherichia coli (VTEC) in slurry, farmyard manure and sewage sludge in France

Aims: The aims of the present study were to determine VTEC prevalence in manure, slurryand sewage sludge in France and to characterize the VTEC strains isolated (virulence genes and serotype). 
Methods and Results: Seven hundred and fifty‐two samples from 55 farmyard manures, 136 bovine and porcine faeces, 114 slurries, 10 composts, and 437 samples from outflows of sewagewastewater treatment plants were analysed. Twenty‐four percent contained isolates which were PCR positive for stx gene. Twenty‐one VTEC strains were recovered from positive samples by colony hybridization: 76% of them were positive for stx2 gene, 33% for stx1 gene,and 19% for eae gene. One strain belonged to serotype O157:H7 and two others to serogroups O26 and O55, respectively. 
Conclusions: Some of the VTEC strains isolated from environments in France should be considered as potentially pathogenic for humans. 
Significance and Impact of the Study: Appropriate handling or use of manure, slurry andsewage sludge is necessary so that contamination of the environment and food by VTEC can be prevented.