Occurrence of Listeria monocytogenes in soft and semi-soft cheeses in retail outlets in Sweden

Comparative Analysis of Extracellular and Intracellular Proteomes ofListeria monocytogenesStrains Reveals a Correlation between Protein Expression and Serovar

“…For example, in dried sausage processing plants, the majority of the L. monocytogenes isolates were of serogroup 1/2 (49.5% of serovar 1/2a, 13.0% of serovar 1/2b, and 19.0% of serovar 1/2c) whereas only 8.0% of the isolates were of serovar 4b (35). Similar observations on Listeria strains isolated from soft and semisoft cheeses were made (20). Consequently, it was suggested that serovar 4b strains have a higher epidemic potential than serogroup 1/2 strains and that the serogroup 1/2 strains are better adapted to survive in food plants than serovar 4b strains.…”

Bacteriophage biocontrol ofListeria monocytogeneson soft ripened white mold and red-smear cheeses

“…However, it should be realized that this finding does not diminish its effectivity or affect its applicability in commercial cheese production, since the initial contamination levels actually found on soft-ripened cheese are usually very low. 6,9 Nevertheless, it is also important to note that phage application during soft cheese production and ripening must be precisely timed to correlate with the possible time point(s) of Listeria entry into the product. If phage would only be applied late in the ripening phase, i.e., after bacterial growth has been initiated (after day 3 to 6), the bacterial population may have reached higher cell densities which might reduce efficacy of phage treatment.…”

“…[2][3][4][5][6][7][8][9][10] Soft-ripened cheeses seem to be more frequently contaminated than semi-hard or hard cheeses, 9,11 although there are some contrary reports. 6 Soft cheeses provide appropriate growth conditions for Listeria, 12,13 not only because of the psychrotrophic and halotolerant nature of the organism, 14 but also because they are commonly consumed as they are, i.e., without any bactericidal treatment (cooking, heating) to eliminate contaminations introduced throughout the production and ripening period. The significant pH increase during the surface ripening of these dairy products also strongly supports growth of Listeria species.…”

Survival of pathogens in "Graviera Kritis" cheese made with raw and pasteurized milk

“…Furthermore, the bacteriocin nisin produced by certain strains of Lactococcus lactis subsp lactis, commonly found in raw milk (Tzanetakis 1992), has been found to be effective against Listeria monocytogenes (Clevelant et al 2001). The prevalence of Listeria monocytogenes in retail raw milk cheeses ranged from 0.9% at 2004 in the UK (Little et al 2008) to 42.4% in Sweden during 1994 (Loncarevic et al 1995), but Debuyser et al (2001) found a higher incidence of Listeria monocytogenes in cheeses made from pasteurized (8%) versus raw (4.8%) milk. In Greece, the prevalence of Listeria monocytogenes in ovine and caprine herds that were suspected to suffer from meningoencephalitis was 19.3 and 36.9%, respectively (Giannati-Stefanou et al 2006).…”