Comparative characterization of Listeria monocytogenes isolated from Portuguese farmhouse ewe's cheese and from humans. 2006

Pedro Leite, and Rui Rodrigues, and Mass Ferreira, and Graça Ribeiro, and Christine Jacquet, and Paul Martin, and Luisa Brito
Laboratório de Microbiologia, Instituto Superior de Agronomia, Tapada da Ajuda 1349-017 Lisbon, Portugal.

In order to investigate the possible relationships between Listeria monocytogenes strains isolated from farmhouse ewe's cheese and clinical strains collected, in partially overlapping dates, from the same geographical area in Portugal, a total of 109 isolates from seven ewe's cheese manufactures (n=94) and from humans (n=15) were characterized by serotyping, RAPD, PFGE and allelic analysis of the virulent actA gene. Serotyping indicated the presence of four different serovars: 1/2a, 1/2b, 1/2c and 4b. The 15 clinical isolates were either serovar 4b (86.7%) or serovar 1/2b (13.3%). Among the 94 isolates from cheese and related environments the serovars prevalence was 1/2a (1.1%), 1/2b (17.0%), 1/2c (12.8%) and, unexpectedly, 4b (69.1%). Based on results obtained with PFGE typing of the strains, 25 genotypes were identified, 10 from farmhouses and 15 from human cases. Isolates from serovars 1/2a and 1/2c were assigned to single genotypes, respectively. Within serovars 1/2b and 4b three and 20 genotypes were established, respectively. RAPD typing of the isolates rendered 18 types indicating the lack of accuracy of the primers used in strain differentiation within serovar 4b. The actA gene typing of the strains showed a prevalence of actA gene type I (90.4%) compared with the rest of the strains that were all actA gene type II (9.6%). In spite of the fact that all the farmhouses were completely independent, the distribution of L. monocytogenes genotypes, intra and inter cheese manufactures, was relatively homogeneous, suggesting the existence of resident strains. In contrast, among human isolates there was a great genetic diversity. There was no common genotype between L. monocytogenes implicated in the cases of listeriosis and these cheese-related isolates, suggesting the absence of a causal relationship.

UI MeSH Term Description Entries
D008088 Listeriosis Infections with bacteria of the genus LISTERIA. Listeria Infections,Infections, Listeria,Infection, Listeria,Listeria Infection,Listerioses
D008089 Listeria monocytogenes A species of gram-positive, rod-shaped bacteria widely distributed in nature. It has been isolated from sewage, soil, silage, and from feces of healthy animals and man. Infection with this bacterium leads to encephalitis, meningitis, endocarditis, and abortion.
D008565 Membrane Proteins Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors. Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D010802 Phylogeny The relationships of groups of organisms as reflected by their genetic makeup. Community Phylogenetics,Molecular Phylogenetics,Phylogenetic Analyses,Phylogenetic Analysis,Phylogenetic Clustering,Phylogenetic Comparative Analysis,Phylogenetic Comparative Methods,Phylogenetic Distance,Phylogenetic Generalized Least Squares,Phylogenetic Groups,Phylogenetic Incongruence,Phylogenetic Inference,Phylogenetic Networks,Phylogenetic Reconstruction,Phylogenetic Relatedness,Phylogenetic Relationships,Phylogenetic Signal,Phylogenetic Structure,Phylogenetic Tree,Phylogenetic Trees,Phylogenomics,Analyse, Phylogenetic,Analysis, Phylogenetic,Analysis, Phylogenetic Comparative,Clustering, Phylogenetic,Community Phylogenetic,Comparative Analysis, Phylogenetic,Comparative Method, Phylogenetic,Distance, Phylogenetic,Group, Phylogenetic,Incongruence, Phylogenetic,Inference, Phylogenetic,Method, Phylogenetic Comparative,Molecular Phylogenetic,Network, Phylogenetic,Phylogenetic Analyse,Phylogenetic Clusterings,Phylogenetic Comparative Analyses,Phylogenetic Comparative Method,Phylogenetic Distances,Phylogenetic Group,Phylogenetic Incongruences,Phylogenetic Inferences,Phylogenetic Network,Phylogenetic Reconstructions,Phylogenetic Relatednesses,Phylogenetic Relationship,Phylogenetic Signals,Phylogenetic Structures,Phylogenetic, Community,Phylogenetic, Molecular,Phylogenies,Phylogenomic,Reconstruction, Phylogenetic,Relatedness, Phylogenetic,Relationship, Phylogenetic,Signal, Phylogenetic,Structure, Phylogenetic,Tree, Phylogenetic
D011174 Portugal A country in southwestern Europe, bordering the North Atlantic Ocean, west of Spain. The capital is Lisbon. Madeira Island,Portuguese Republic
D012150 Polymorphism, Restriction Fragment Length Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment. RFLP,Restriction Fragment Length Polymorphism,RFLPs,Restriction Fragment Length Polymorphisms
D002611 Cheese A nutritious food consisting primarily of the curd or the semisolid substance formed when milk coagulates. Cheeses
D004587 Electrophoresis, Agar Gel Electrophoresis in which agar or agarose gel is used as the diffusion medium. Electrophoresis, Agarose Gel,Agar Gel Electrophoresis,Agarose Gel Electrophoresis,Gel Electrophoresis, Agar,Gel Electrophoresis, Agarose
D005260 Female Females
D005506 Food Contamination The presence in food of harmful, unpalatable, or otherwise objectionable foreign substances, e.g. chemicals, microorganisms or diluents, before, during, or after processing or storage. Food Adulteration,Adulteration, Food,Adulterations, Food,Contamination, Food,Contaminations, Food,Food Adulterations,Food Contaminations

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