[Determination of biovars of Brucella melitensis by manometric character: epidemiological value and relation to serovars]. / Détermination des biovars de Brucella melitensis par les caractères manométriques: intérêt épidémiologique et relation avec les sérovars.

As Brucella melitensis is the most frequently encountered Brucella species in human medicine, and as its subdivision into three serovars is insufficient for epidemiological studies, we sought to define a new scheme for biotyping of this species. For this purpose, we studied 94 strains for their oxidative metabolic rates on 32 substrates and their susceptibility to ten antibiotics, and 132 strains for their activities with three enzymes. A taxonomic study on the basis of the 32 oxidative metabolic rates led to the distinction of five biovars which could then be defined by means of the five most discriminating substrates. Among the ten antibiotics tested, only three showed varying patterns of susceptibility. Oxidative metabolic rates were not correlated with these patterns of susceptibility nor with the enzymatic activities. However, a relationship was found between biovar and serovar, especially with regard to the following substrates: meso-erythritol, deoxythymidine, D-galactose and DL-phenylalanine. As shown by correspondence analysis, the repartition of biovars significantly differed among French administrative regions.

[Mathematical model of epidemiology of an anthropozoonose: brucellosis (author's transl)]. / Modélisation mathématique de l'épidémiologie d'une anthropozoonose: la Brucellose.

We are trying to make a model of the epidemiology of Brucellosis by using a two-type branching process. In this text, we are studying the probability of extinction. A complete study on the theory of process with a finite number of types was made by SEVAST'YANOV (1951) [6]. The study of the behaviour of such a process is made with the help of the generating function of the number of infected animals by a single animal. To express this generating function, we start with the same hypothesis as BARTOSZYNSKI [2] (1965) when he makes an interhuman epidemic model by a simple branching process of GALTON-WATSON. However these hypothesis will be modified in order to adapt them to the types of Brucellosis contamination.

[The intracellular multiplication of "Brucella" The theory for an experimental model (author's transl)]. / La multiplication intracellulaire de Brucella (Théorie pour un modèle expérimental)

Brucella melitensis can penetrate and multiply in cells of the BHK21 line. The intracellular bacteria can be counted either by culture after destruction of the cells or by direct examination after staining; in the latter case, the cells are distributed into various classes according to the number of bacteria which they contain. The number of intracellular bacteria increased exponentially and the division time is 12 hours. The intracellular division of the bacteria is independent of the cellular invasion. The infection by bacteria is not a factor related to mortality nor to survival of the cells. Whatever the number of bacteria initially placed on the BHK21 cells (up to 1,000 bacteria per cell), the number of infected cells never increased about 20%, and this indicates that all the cells do not have the same aptitude for the phagocytosis of Brucella. A mathematical model is suggested. Taking all factors into account, the model shows the probability for a certain number of Brucella per cell and, on the other hand, it shows the mean number of Brucella per cell at any particular moment. This model can be used in the case of other bacteria and of other cells, and can be used whenever a precise study of the intracellular multiplication of bacteria is required.