Revista de la Asociacion Argentina de Microbiologia最新文献

The use of acid cheese whey as an essential substrate for the production of alkaline protease was studied by growing Bacillus subtilis NRRL 3411 on different conditions of aereation. The maximum enzymatic activity of 17 000 proteolytic units was obtained in the following conditions: 200 RPM, air flow of 1 v/v minutes (KLa 37 h-1), separate sterilization of the medium components and periodical additions of peptone.

The data presented confirm previous evidence of delayed hypersensitivity in mice following infection with Junin virus. Adaptive transfer of sensitized cells from adult mice which had received 5 Junin virus injections into preinfected newborn mice shortened their survival by 72 hours. It was clear, however, that the development of the immunological mechanism in adult mice occurred under certain conditions. This evidence was confirmed by the observations that the induction of cell-mediated immunity and the response of sensitized lymphocytes to viral antigens appeared to be related to multiple injections of the virus. On the other hand, the sensitized cells were present in adult mice by day 9 and vanished 60 days after the infection. These results revealed the difference between the lymphoid cells from adult mice in the early and the late stages of immunity. The implications of these results in the development of the fatal neurological disease induced by the Junin virus in newborn mice are discussed.

Several aspects of the appearance and development of delayed hypersensitivity in mice infected with Junin virus are described. The results obtained showed that the development of the immunological mechanisms occurs irrespective of age. Spleen cells of donor mice inoculated with one i.p. dose of Junin virus had a poor cytotoxic activity, as demonstrated by 51Cr release and adoptive immunity procedures. Spleen cells treated with anti-theta serum and complement did not strikingly affect the development of Junin virus disease in mice. This demonstrated the capacity of T lymphocytes to influence the course of the viral infection of newborn mice adoptively transferred with immune spleen cells. No difference were detected in the virus titer in the brains of transferred and control animals, this fact suggests that immune T lymphocytes are not involved in Junín virus clearance.

The susceptibility of adult male goats to Brucella ovis infection was studied. Fifteen goats and fifteen rams both of ages ranging from 22 to 34 months were inoculated conjunctivally with 10(9) cells of B. ovis strain recently isolated from a case of ram epididymitis. Five goats and five rams were killed 78 days after inoculation and similar groups were killed at two month intervals thereafter. B. ovis was recovered from semen of a male goat, 33 and 61 days after inoculation. The five goats sacrificed 78 days after inoculation contained Brucella in their organs. The semen and the tissues of the two other groups remained culturally negative throughout the observation period. Seven cultures were obtained from the semen of 14 rams used comparatively as inoculated controls. Epididymitis was clinically observed only in one male goat although under six presented macroscopic lesions. Seven rams out of the 15 inoculated showed clinical symptoms of epididymitis. Antibodies detectable by complement fixation and immunodiffusion disappeared 80 days after inoculation in goats, while rams reacted during the 189 days period of observation. It is concluded that the B. ovis infection in male goats is transient and the role that they may play in the epizootiology of the disease is negligible.

The present study was carried out with 111 multiresistant pathogenic strains of enterobacterias isolated from different sources with increased resistance to three or more antibiotics. Among the identified species are included E. coli, Shigella sp., Salmonella oranienburg, Klebsiella pneumoniae and Citrobacter freundii. In general, the minimal inhibitory concentration of antibiotics was above 100 microgram/ml and in some cases it was superior to 1000 microgram/ml. Resistance transfer factors were detected in 72% of the strains; 33% movilized the complete pattern of resistance and 67% did it partially because some of the determinants were not transfered. The Citrobacter strains show a high frequency of transference (10(-1)), while for the others species it was in the order of 10(-2)--10(-3). The use of a multi-inoculator allows to perform in a simple way the preliminar evaluation about the presence or absence of R transfer factors in multiresistant strains. This technique has shown good correlation with the data obtained by the usual dilution and plating method.

Addition of beta-lapachone to the epimastigote (culture) form of Trypanosoma cruzi, suspended in saline, buffered-isotonic medium (pH 7.2), determined the appearance of large amounts of H2O2 in the suspension medium, as measured spectrophotometrically by formation of the H2O2 horse radish peroxidase complex. Under similar conditions, alpha-lapachone did not induce H2O2 formmation. Using NADH as electron donor, beta-lapachone (not alpha-lapachone) increased significantly the rate of H2O2 generation by epimastigote homogenates and the same occurred with NADPH, although in a reduced extent. Similar results were obtained with the isolated mitochondrial and microsomal fractions although with the latter NADPH was more effective than NADH as electron donor for beta-lapachone reduction and peroxide generation. The distribution of peroxide generation in epimastigote fractions would indicate that about 92% of the beta-lapachone dependent formation of peroxide occurred in the mitochondria, and 8% in the endoplasmic reticulum. The growth of epimastigotes was inhibited 95% by 1 microgram/ml beta-lapachone, a concentration that determined maximal rate of H2O2 production. Since H2O2 and other intermediates of oxygen reduction such as O2- (superoxide anion) and OH (hydroxyl radical) are lethal to cells and tissues, it is possible that the effect of beta-lapachone on T. cruzi proliferation in vitro was mediated by H2O2 and related free radicals.