This study was undertaken to establish a typing scheme for Listeria monocytogenes. A total of 823 strains, isolated in France from 1958 to 1978, were studied; 69.4% of these belonged to serotype 4. Using a set of 20 phages, the lytic activity, frequency and specific character of these phages were estimated and phage typing carried out. We were able to define a phage typing system for L. monocytogenes using 12 principal phages and 3 secondary phages. In order to discriminate phages types within serotype 1, the phages 1, 3, 4, 5, 6 and 7 were used, and for phage types within serotype 4, the phages 10, 11, 14, 15, 16 and 17. Secondary phages 8, 9 and 20 had a weak lytic activity, but their specificity was very high. The lytic patterns obtained with the phages 9 and 20 were restricted to strains of serotype 5. We established a complete correlation between the lytic pattern of phages 1 to 8 and serotype 1, just as there was a correlation between the lytic pattern of phages 10 to 19 and serotype 4. Using the set of 20 phages we were able to type 645 of 823 strains of L. monocytogenes. Thus we were able to type 78.4% of all the strains examined. This percentage was very different according to the serotype of the strains tested: 88% of strains of serotype 4 and 57% of strains of serotype 1. With this set of phages 552 of 645 typable strains could be subdivided into 8 principal phagetypes: 3 types within the serotype 1 and 5 others in serotype 4. This phage typing system can be used in some epidemiological situations, in taxonomic investigations or as bacterial markers.

Animals↗

PubMedDate not supplied

[Human brucellosis in Benin: results of a serological survey among exposed workers].

A serological survey was carried out in Bénin in order to assess the rate of brucellosis infection among exposed workers (workers in slaughtering-houses and breeders). 221 sera were tested with rose Bengale test, Wright sero-agglutination test, indirect immunofluorescence test and counter-immuno electrophoresis (brucelline). The percentage of positive sera among exposed workers is 17,7%. The rose Bengale and immunofluorescence tests combination permits complete detection of positive sera. These results suggest the existence of human brucellosis in Bénin and shows the necessity of a national control programme adapted to the socio-economic problems of this country.

Abattoirs↗

PubMedDate not supplied

[Isolation and characterization of "Listeria monocytogenes" bacteriophages (author's transl)].

Fifteen L. monocytogenes phages are isolated from lysogenic strains without induction and are selected for phage-typing. Four of these phages are produced by strains belonging to serotype 1/2a and 1/2b, eight by strains 4b and three other phages respectively by strains 4ab, 4g and 3c. Electron micrographs of 5 of these phages show isometric heads with non contractile tails. They belong to morphological group B of Bradley. Rabbits are immunized with 7 bacteriophages and all the phages are studied by neutralization tests with these 7 antisera. This study seems complex nevertheless it is possible to distinguish four antigenic groups: A, B, C, and D. The lytic spectrum of each phage is usually restricted to strains of the serotype from which that phage is obtained. It appears that a good correlation exists between phage sensitivity and serological type of the strains. With this first set of fifteen phages, 159 of 214 (74,3%) strains of L. monocytogenes can be classified in more than 21 types but it appears that some new phages obtained from strains of serotype 1/2 must be isolated in the future. Our data indicate that these phages can be used as a phage-typing scheme for L. monocytogenes.

Antigens, Viral↗

PubMedDate not supplied

Hyperimmunization of rabbits with Australia antigen.

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Adjuvants, Immunologic↗

PubMedDate not supplied

[Fosfomycin resistance in Staphylococcus saprophyticus and other species of coagulase-negative staphylococci].

Susceptibility of 121 isolates of coagulase-negative staphylococci to two antimicrobial agents, novobiocin and fosfomycin, was determined using the agar dilution method. Isolates included 45 strains of Staphylococcus saprophyticus, 26 strains of S. cohnii and S. xylosus, 24 strains of S. epidermidis and 26 strains of S. hominis, S. capitis, S. warneri and S. auricularis . The minimal inhibitory concentration average of fosfomycin for S. saprophyticus differed (p less than 0.001) from that other for novobiocin-resistant staphylococci (S. cohnii and S. xylosus) and for S. epidermidis (p less than 0.001). Out of 45 isolates of S. saprophyticus, 42 were resistant to fosfomycin. The results were very heterogeneous with regard to fosfomycin for all of the other coagulase-negative staphylococci. Resistance to fosfomycin, like resistance to novobiocin, could be used as a presumptive test for the identification of S. saprophyticus.

Anti-Bacterial Agents↗

PubMedDate not supplied

Experimental infection of mice with Listeria monocytogenes and L. innocua.

Swiss mice were infected with two Listeria strains: L. monocytogenes strain 10401, serovar 4b, and L. innocua strain 390, serovar 6a. Bacteria were inoculated by intravenous, subcutaneous or oral routes, and then enumerated in the spleen. The splenic infection was studied comparatively for these three inoculation routes with both strains. Strain 390 caused a splenic colonization only after intravenous inoculation. For the 10401 strain, the peak of infection appeared on the 3rd day after inoculation; the intravenous route was the most efficient to kill mice, the subcutaneous one the most efficient to obtain a reproductible sublethal infection; the oral route infected regularly only with doses higher than 10(7) bacteria. A splenomegaly appeared only in mice infected with strain 10401. Estimation of Listeria strain pathogenicity depended more on the measure of bacterial count in the spleen on the 3rd day of infection than on LD50. To be able to compare quantitatively the pathogenicity of L. monocytogenes and L. innocua, it seemed impossible to use only one dose of bacteria and to inoculate through one route.

Animals↗