Lysogenicity as a tool for bacteriophage typing ofSalmonella Paratyphi B

Summary and Conclusions The serological identity of the phage produced by a spontaneously lysogenic strain ofS. paratyphi B depends on the bacterial type of that particular strain. The frequency of the phenomenon of spontaneous lysogenicity is such, in the case ofS. paratyphi B, that it can be utilised as a tool for typing.It is clear, however, that the possibilities of the method are limited. Firstly, types exist that do not as a rule produce bacteriophages. Secondly, alysogenic strains may exist of types that as a rule are lysogenic.Therefore the method can be utilised only together with, and as a check upon, a system of phage reactions.In Holland the types Kampen and Leeuwarden are frequent types, that can readily be recognised by the identity of the phages they produce. This is sufficient to justify the use of the method.The relation shown between true lysogenicity and bacterial types may be of theoretical interest. Perhaps it will be possible in this way to relate every existing phage to a bacterial type. The theoretical aspects will, however, be discussed elsewhere.     

The pathogenicity of strains of Salmonella paratyphi B and Salmonella java

AIMS: To relate the diseases caused by strains of Salmonella paratyphi B and S. java to pathogenic mechanisms expressed by these bacteria for the purpose of organism discrimination. METHODS AND RESULTS: Epidemiological data relating to cases of disease caused by strains of S. paratyphi B and S. java, isolated over a 10-year period, were analysed with respect to patients' symptoms, particularly those involving enteric fever. Strains of S. paratyphi B and S. java were also examined for a range of known pathogenic mechanisms. Infection with S. paratyphi B involved pyrexia in 12.5% of patients compared with 2.2% of patients infected with S. java. These organisms could not be differentiated based on the pathogenic properties examined. CONCLUSIONS: Strains of S. paratyphi B appear not to be a major cause of enteric fever but primarily a cause of gastroenteritis, in common with S. java. Both organisms express similar pathogenic mechanisms, and strains of S. java are probably d-tartrate utilizing variants of S. paratyphi B. SIGNIFICANCE AND IMPACT OF THE STUDY: Strains of S. paratyphi B are very closely related organisms, primarily causing gastroenteritis. From this study it would appear that strains of S. paratyphi B are not a major cause of enteric fever.     

Phenomena in mixed cultures ofSalmonella paratyphi B; serological changes and adaptations of the bacteriophage; incomplete natural phages; transformation of phage types

Summary The phenomenon that natural phages are only released in mixed cultures and are not found in pure cultures of bacterial strains has been discussed. It was described how an infecting phage absorbs material from the natural phage in the bacterium and the other way round, that the natural phage absorbs material from the infecting phage. Hereby the bacteriophages can change serologically. Simultaneously the bacteriophage can be adapted. The phenomenon that natural phages are only released in mixed cultures is in some cases explained by assuming that the prophage is incompletely present in the bacterium and is completed by material from an infecting phage.     

The formation of bacteriophages in mixed cultures by recombination of genetic elements; characterisation of phage types ofSalmonella paratyphi B by phage reactions and lysogenic properties

Summary It was shown that bacteriophages, generated in mixed cultures of strains ofS. paratyphi B of different types are formed by recombination of elements from both strains. The characteristics of the bacteriophages found depend upon the “phage type” of the strains inoculated in the medium. Types ofS. paratyphi B can be characterised by a combination of phage reactions and lysogenic properties.     

Typing ofSalmonella weltevreden strains by means of lysis patterns of symbiotic phages

A typing scheme forSalmonella weltevreden using the lysogenicity and lysis patterns of their carried phages is presented. Six strains ofS. weltevreden were selected for use as indicator strains for recognizing the lysis patterns of the carried phages. Two hundred and forty-five strains were examined and 207 were grouped in concurrence with the 15 lysis pattterns obtained out of 64 theoretically possible. Lysis pattern I (all 6 indicator strains lysed by the carried phage) included 24.5% of the strains. Thirty-eight strains (15.5%) were grouped as untypable because their lysates did not lyse any of the indicator strains. No correlation could be established between the lysis patterns of carried phages and the host and geographic distribution ofS. weltevreden.     

Acquisition of iron from transferrin bySalmonella paratyphi B

The ability ofSalmonella paratyphi B to obtain iron from human, bovine, and rabbit transferrin was studied. All three transferrins restored the growth potential for otherwise ironstarvedS paratyphi B producing enterobactin. No exogenous siderophore was needed for growth to occur. A non-enterobactin-producing derivative ofS. paratyphi B was unable to acquire iron from transferrin, and transferrin did not restore the growth potential of the organism. Sequestering the transferrin fromS. paratyphi B in dialysis tubing did not affect the ability of the transferrin to supply iron to the organism.     

Surface K antigen in Salmonella paratyphi B.

It was established by agar immunoelectrophoresis that Salmonella paratyphi B lysate contains a large number of soluble antigens which display a varying degree of serological specifity as well as different diffusion and electrophoretic mobility. Salmonella paratyphi B was found to possess, apart from specific O and H antigens, a surface K antigen. This is a distinct antigen having strict serological specificity. Purified K antigen displayed anodic mobility in immunoelectrophoresis. A detailed study of K antigen properties in cultures treated by different methods as well as immunochemical investigations of purified K antigen showed that the surface K antigen of S. paratyphi B differs from its O, M, Vi, H and other known antigens in terms of basic characteristics.