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Biomedical subjects

M T Montagna

Publications and source records attributed to M T Montagna.

5 recordsLinked to original sources

[Antibacterial activity of fosfomycin in chronic kidney infections].

Authors have carried out a retrospective study in vitro on the bacteria isolated from renal parenchyma and stones in patients with CPN associated to kidney stones. Results show a different inhibitory action of the some antibiotics to Proteus, E. coli and P. aeruginosa. Fosfomycin inhibits the growth of bacteria in a wide range of concentration (50-1000 microgram/ml). A prospective study in vivo shows an excellent therapeutic action of fosfomycin in recurrent urinary infections, and a very good one in CPN and in some forms associated to kidney stones.

Adult

[Researches on the production of inhibitory substances by strains of "N. meningitidis" (author's transl)].

The possibility to produce some inhibitory substances has been researched in 85 strains of N. meningitidis belonging to different serogroups. By the double layer agar method, 9 of these strains have inhibited the growth of one or more indicator strains. We had the best results at 37 degrees C and 30 degrees C in tests made incubating 3 producer strains in different experiment conditions; the "Brain heart infusion agar" and the "Heart infusion agar" were the best and fittest culture media, used for the production of these substances. Several attempts to get the production of bacteriocins in liquid culture media have always given negative results, both by spontaneous growing and by ultraviolet irradiation and mitomycin induction. We were able to get 3 among these substances from as many strains of N. meningitidis (from the 85 tested) in the supernatant, only growing the strains in soft agar and centrifuging these growths. So these 3 bacteriocins had inhibited the growth of the 92% of the tested N. meningitidis, but they were inactive towards 296 bacterial strains belonging to Gram-positive and Gram-negative species (including the 15 strains of Shigella and E. coli given as indicators in the research of colicins), 70 strains of Mycoplasma and 9 L-forms of Pr. mirabilis and of St. aureus. Only 3 L-forms obtained from as many strains of N. meningitidis resulted to be inhibited by the three bacteriocins.

Bacteriocins

[Report on Citrobacter strains having antigenic relationship with "E. coli", and their characteristics (author's transl)].

During a research done on the diffusion of enteropathogenic E. coli in a children's community, 24 strains of Citrobacter have been isolated. By agglutination and agar-gel diffusion techniques, they looked to have some somatic antigens in common with those serogroups of enteropathogenic E. coli. The results were as follows: 14 strains were correlated with the serogroup O111; 9 strains with the serogroup O125 and 1 strain with the serogroup O55. The isolation of these strains has been made at the same period when we have found out the E. coli of homologous serogroups, even if they didn't belong to the same subjects. The colicine typing and sensibility to antibiotics tests made both on Citrobacter strains and on E. coli ones of homologous serogroups haven't pointed out other characteristics of identity. Furthermore, antigenic relationships between the 24 strains of Citrobacter and different serogroups of Salmonella have been demonstrated, that is: the strains containing the somatic antigen O111 were correlated with the serogroup O35; the strains having the somatic antigen O125, with the serogroup O6, 14, 24 and the strain containing the somatic antigen O55, with the serogroup O50. The presence of these strains in normal subjects only, gives a further witness that their role in enteric infections remains to be demonstrated.

Anti-Bacterial Agents

[Researches on some biochemical and serological properties and on the sensitivity to antibiotics of L-forms of "Proteus" (author's transl)].

The possibility to keep some biochemical reactions of the parent strains (urease-positive, glucose fermentation, phenylalanine-deaminase-positive, H2S but not indol production) was demonstrated in 5 L-forms, obtained from as many strains of Pr. mirabilis and in 1 L-form, isolated from a vaginal secretion and identified as belonging to the same species. The indirect hemagglutination technique, made by the sonicated antigen in 3 of the 6 L-forms with Proteus OXK antiserum, resulted positive in titers varying from 1:128 to 1:1024. Crossed tests made with antisera for different bacterial species (e. coli, Shigella, klebsiella, ecc.) and of Mycoplasma (M. hominis, M. orale, M. salivarium, M. fermentans, M. arthritidis) put in evidence aspecific reactions only in 1.3% of the bacterial antisera. On the contrary, all 5 antisera for Mycoplasma were able to agglutinate the sensitized erythrocytes at titers quite analogous to that of the homologous antiserum. The sensitivities to various antibiotics of the 6 L-forms and the parent strains has been determined. All of L-forms were more resistent to the tetracycline than L-forms of other bacterial species. On the basis of te results got by biochemical and serological tests, we confirm the necessity to make use of both the groups of tests, in order to identify the L-forms of recent isolation.

Anti-Bacterial Agents

[Researches on some properties of inhibitory substances produced by strains of "N. meningitidis" (author's transl)].

Some properties of three inhibitory substances produced by as many strains of N. meningitidis have been studied. All these substances appeared to be completely destroyed by proteolytic enzymes (trypsin and pronase) and to be very heat-stable; they were insensitive to ultraviolet light and they were stable pH 2-10; filtration through filters of different porosity (Seitz, Berkefeld, millipore membranes) resulted in loss of the inhibitory effect constantly. On the basis of these results and on their specific action specific action, it is possible to class these substances among bacteriocins ("meningocins") at low molecular weight.

Bacteriocins