ENUMERATING <i>LISTERIA MONOCYTOGENES</i> IN FOOD: A PROBLEM OF LOW NUMBERS

Besse, Nathalie Gnanou; Colin, P.

doi:10.1111/j.1745-4581.2004.tb00052.x

Cited by 7 publications

(2 citation statements)

References 68 publications

(60 reference statements)

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“…The selective agents in the media may have inhibited the growth of stressed cells, or the target pathogens may have been outgrown by the background flora of the milk (5,6,41,67). Direct plating also may not detect target organisms present at low levels, even though they were detected with other methods (5,41,59).…”

Section: Detection Of Target Pathogens By Direct Platingmentioning

confidence: 99%

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Detection and Enumeration of Four Foodborne Pathogens in Raw Commingled Silo Milk in the United States

Jackson

Erten

Maddi

et al. 2012

Journal of Food Protection

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A nationwide survey was conducted to obtain qualitative and quantitative data on bacterial contamination of raw commingled silo milk intended for pasteurization. The levels of total aerobic bacteria, total coliforms, Enterobacteriaceae, Escherichia coli, and Staphylococcus aureus were determined using the TEMPO system. The prevalence rates and levels of presumptive Bacillus cereus, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. were determined in 214 samples. B. cereus was detected in 8.91% of samples, at 3.0 to 93 CFU/ml. E. coli O157:H7 was detected in 3.79 to 9.05% of samples, at <0.0055 to 1.1 CFU/ml, depending on the assay utilized. Salmonella spp. were recovered from 21.96 to 57.94% of samples, at <0.0055 to 60 CFU/ml. L. monocytogenes was detected in 50.00% of samples, at <0.0055 to 30 CFU/ml. The average log-transformed counts of total viable bacteria were slightly lower in samples containing no pathogens. No correlation was observed between the levels of organisms detected with the TEMPO system and the presence or levels of any pathogen except E. coli O157:H7. A higher average log-transformed count of total viable bacteria was observed in samples positive for this organism. The high prevalence rates of target pathogens may be attributed to a variety of factors, including detection methods, sample size, and commingling of the milk in the silo. The effects of commingling likely contributed to the high prevalence rates and low levels of target pathogens because of the inclusion of milk from multiple bulk tanks. The high prevalence rates also may be the result of analysis of larger sample volumes using more sensitive detection methods. These quantitative data could be utilized to perform more accurate risk assessments and to better estimate the appropriate level of protection for dairy products and processing technologies.

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Section: Detection Of Target Pathogens By Direct Platingmentioning

confidence: 99%

“…More sensitive detection procedures were required to accurately isolate and enumerate low levels of pathogens in the present study. Enrichment steps allow for recovery and growth of organisms to detectable levels, and the MPN method allows for more accurate enumeration (5,9,41,67).…”

Section: Detection Of Target Pathogens By Direct Platingmentioning

confidence: 99%

Detection and Enumeration of Four Foodborne Pathogens in Raw Commingled Silo Milk in the United States

Jackson

Erten

Maddi

et al. 2012

Journal of Food Protection

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Enumeration of Listeria monocytogenes at Low Contamination Levels in Several Food Matrices Using a Membrane Filtration Method

et al. 2009

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For the enumeration of Listeria monocytogenes in cold-smoked salmon, a sensitive enumeration method, based on membrane filtration followed by transfer of the filter on a selective medium, has been recently developed. An evaluation of this method was performed with several categories of foods likely to be contaminated with L. monocytogenes. The results obtained with the technique were compared with those from the reference EN ISO 11290-2 method and found to provide more precise results in the enumeration of L. monocytogenes from both artificially and naturally contaminated products. In most cases, the filtration method enabled a greater quantity of food to be examined (from around 0.5 to 14 g, instead of 0.01 to 0.1 g with the reference EN ISO 11290-2 method), thus greatly improving the sensitivity of the enumeration.

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