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Rapid confirmation of Listeria monocytogenes isolated from foods by a colony blot assay using a digoxigenin-labeled synthetic oligonucleotide probe.

ABSTRACT: An oligodeoxyribonucleotide probe based on the sequence of a 321-bp internal fragment of the msp gene encoding a major secreted polypeptide of Listeria monocytogenes was labeled with digoxigenin by using terminal deoxynucleotidyl transferase. The specificity of the digoxigenin-labeled probe was determined by dot blot assays. The probe reacted with all strains of L. monocytogenes tested (12 of 12 strains representing five serotypes). The probe did not react with any other Listeria species or with other gram-positive bacteria (Brochothrix, Erysipelothrix, Corynebacterium, Rhodococcus, Lactobacillus, Leuconostoc, Bacillus, Staphylococcus, and Streptococcus). The probe was used to develop a colony blot assay for the rapid confirmation of L. monocytogenes on Listeria-selective agars which had been streaked with food enrichment cultures. Forty-eight food samples were tested by conventional culture and DNA colony blot assay. The sensitivity and specificity of the DNA colony blot were 100 and 97%, respectively.

SUBMITTER: Kim C

PROVIDER: S-EPMC183440 | biostudies-other | 1991 Jun

REPOSITORIES: biostudies-other

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Rapid confirmation of Listeria monocytogenes isolated from foods by a colony blot assay using a digoxigenin-labeled synthetic oligonucleotide probe.

Kim C C Swaminathan B B Cassaday P K PK Mayer L W LW Holloway B P BP

Applied and environmental microbiology 19910601 6

An oligodeoxyribonucleotide probe based on the sequence of a 321-bp internal fragment of the msp gene encoding a major secreted polypeptide of Listeria monocytogenes was labeled with digoxigenin by using terminal deoxynucleotidyl transferase. The specificity of the digoxigenin-labeled probe was determined by dot blot assays. The probe reacted with all strains of L. monocytogenes tested (12 of 12 strains representing five serotypes). The probe did not react with any other Listeria species or with ...[more]

PMID: 1908203

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Project description:The prevalence and levels of Listeria monocytogenes in retail raw foods covering most provincial capitals in China were studied with testing of 1036 samples of vegetables, edible mushrooms, raw meat, aquatic products and quick-frozen products from September 2012 to January 2014. The total prevalence of Listeria monocytogenes was 20.0% (207/1036), and the most probable number (MPN) values of 65.7% of the positive samples ranged from 0.3 to 110 MPN/g. Geographical differences were observed in this survey, and the results of both qualitative and quantitative methods indicated that the levels in the samples from North China were higher than those in the samples from South China. A total of 248 isolates were analyzed, of which approximately half belonged to molecular serogroup 1/2a-3a (45.2%), followed by 1/2b-3b-7 (30.6%), 1/2c-3c (16.1%), 4b-4d-4e (5.2%) and 4a-4c (2.8%). Most of the isolates carried hly (100%), inlB (98.8%), inlA (99.6%), inlC (98.0%) and inlJ (99.2%), and 44.8% of the isolates were llsX-positive. Seventeen epidemic clones (ECs) were detected, with 7 strains belonging to ECI (2.8%) and 10 belonging to ECIII (4.03%). Resistance to clindamycin (46.8%) was commonly observed, and 59 strains (23.8%) were susceptible to all 14 tested antibiotics, whereas 84 (33.9%) showed an intermediate level of resistance or were resistant to two or more antibiotics, including 7 multi-resistant strains that exhibited resistance to more than 10 antibiotics. The data obtained in the present study provides useful information for assessment of the possible risk posed to Chinese consumers, and this information will have a significant public health impact in China. Furthermore, the presence of virulence markers, epidemic clones, as well as the antibiotic resistance amongst the isolates strongly implies that many of these strains might be capable of causing listeriosis, and more accurate treatment of human listeriosis with effective antibiotics should be considered. This research represents a more full-scale and systematical investigation of the prevalence of L. monocytogenes in retail raw foods in China, and it provides baseline information for Chinese regulatory authorities that will aid in the formulation of a regulatory framework for controlling L. monocytogenes with the aim of improving the microbiological safety of raw foods.

Dataset Information

Rapid confirmation of Listeria monocytogenes isolated from foods by a colony blot assay using a digoxigenin-labeled synthetic oligonucleotide probe.

Publications

Rapid confirmation of Listeria monocytogenes isolated from foods by a colony blot assay using a digoxigenin-labeled synthetic oligonucleotide probe.

Similar Datasets

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