Opsonization of two different streptococcal group A type 12 strains was investigated. The strains differed only in M protein presence. It was observed that after the treatment of bacteria with fresh normal rabbit serum M positive strains bind to their surface IgG only whereas M negative strains solely some complement components. These results may suggest that streptococci lacking M protein are able to activate complement by alternate pathway.
Many plant diseases belonging to the yellows group are believed to be caused by wall-free prokaryotes resembling mycoplasmas, which are spread by leafhopper vectors. Im most cases the evidence for mycoplasma aetiology rests upon the finding by electron microscopy of mycoplasma-like bodies in phloem tissue of diseased plants, coupled in some cases with symptom remission following treatment of plants with tetracyclines. The only plant-pathogenic mycoplasmas which have so far been cultured are the spiroplasmas (motile, helical, filamentous mycoplasmas) which cause citrus stubborn, corn stunt and probably a small number of other plant diseases. Spiroplasma citri (the citrus stubborn agent) can infect members of many plant families, and disease symptoms suggest that the organisms produce toxins. Phytotoxic substances have been detected in, and partially purified from spiroplasma cultures. The corn stunt spiroplasma does not produce toxins and probably affects plants by interfering with hormone metabolism.
Crude juices of garlic (Allium sativum), onion (Allium cepa) and shallots (Allium ascalonicum) were tested in an agar diffusion test for their growth inhibitory effect on five gram negative and three gram positive bacterial species and two yeast species. All test organisms were inhibited by garlic juice, whilst onion and shallot juice showed no effect upon gram negative bacteria. Garlic juice was investigated in more detail. Addition of complex-forming agents and organic matter to the crude juice reduced its activity on all test organisms. Volatile substances showed a strong inhibitory activity after exposure for 8 hours or longer at 23 degrees C or 37 degrees C. Minimal inhibition concentrations determined in a dilution test were found to be high for gram negative bacteria and low for both yeast species. The D-values of the different test organisms in undiluted garlic juice were calculated. P. aeruginosa had a very low D-value, whilst the bacteriostatic concentration was high. This indicates a large concentration exponent of crude garlic juice for this organism. The opposite was found for S. aureus. In view of the strong antibiotic properties and the complete absence of development of resistance further investigation upon the principles of the antimicrobial activity of juices from Allium species merits consideration.
Mastomys natalensis chronically infected with Toxoplasma gondii strain ALT over two months were treated with sulfamethoxypyrazine-pyrimethamine for 10 and 25 days. 72 hours after discontinuation of therapy the animals were sacrificed. The brains were removed and, following corresponding preparation, studied for the presence of the parasite and structural changes of cysts by light and transmission electron microscopy. More or less pronounced structural changes could be found in cyst walls, bradyzoites, and in particular in the endodyogeny stages. The degree of damage proved to be proportional to the intensity of the bradyzoite metabolism. The combination of drugs used was capable of passing the cyst membrane as long as the bradyzoites maintained their metabolism irrespective of its intensity. In cysts with a largely dormant metabolism that had been subject to therapy, no micromorphological differences of the ultrastructure could be recognized when compared with untreated controls of identical age; these cysts could not be influenced by treatment.
Normal ICR mice were injected intraperitoneally with 0.5 ml of thioglycollate broth or 5 x 10(8) heat-killed Pasteurella multocida vaccine and the number of polymorphs, lymphocytes and macrophages in the peritoneal washout suspensions were determined at intervals up to 72 hours. The stimulated mice were challenged intraperitoneally with opsonized or unopsonized P. multocida at increasing time intervals and the rate of growth by the organisms in the washout suspension was determined up to 60 minutes later. The opsonized bacilli were taken up by the 6 hr. exudate cells (50-60% PMNs) and their growth inhibited more effectively than when the 72 hr exudate cells were tested (only 10% PMNs). When the challenge inoculum was introduced into the peritoneal cavities of mice stimulated 6 hrs previously with 5 x 10(8) heat-killed P. multocida vaccine, up to 80% of the bacilli were inactivated over a 30 minute period. However, when 72 or 250 hr peritoneal exudate cells were tested, the inoculum was not inactivated, but showed an increasingly lethal effect.
Serological studies with soluble and particulate antigens of Cl. perfringens type A revealed that enterotoxin and spore antigens could be used as a suitable marker for epidemiological studies. 94% of the food poisoning strains of Cl. perfringens type A could be grouped into 3 groups with the help of 2 enterotoxin-specific sera and 90% in 4 groups with antispore sera. Heat-sensitive strains were found to be antigenically more homogenous than the heat-resistant ones. Sera raised against spores of heat-resistant strains could not agglutinate spore of any of the heat-sensitive strains. Similarly no spores of heat-resistant strains were agglutinable by serum raised against spores of heat-sensitive strains. On the basis of typing efficiency the two antigen, viz enterotoxin and spore antigens were used in the serogrouping scheme proposed for the epidemiological investigation of food poisoning with Cl. perfringens type A. Used together, enterotoxin and spore agglutinogen form an antigenic formula for each strain showing the serogroup to which it belongs.
A method for a simple preparation of Salmonella flagellar antigen is described. The antigen is sufficiently pure to elicit high titered H antibodies of 12,800-51,200 and O titers of less than 50. Highly motile Salmonella test strains are grown on 0.8% swarm agar and harvested with 0.05 n HCl which solubilizes the flagella. The suspension with a pH of 1.5 is kept at 4 degrees C. over night and then centrifuged at 49,000 g for 60 min. The supernatant is neutralized and precipitated with ammonium sulfate at 2/3 saturation. The resulting polymeric flagellin is submitted to a zone electrophoresis on Pevikon. Strips are cut from the "cake" and eluted. The H antigen is found on the anodic side, the O antigen remains near the trough or migrates slightly cathodically. Form 20 plates enough flagellin is collected fro the immunization of 50-100 rabbits. The Latex test proved to be especially suited for the checking of the H antigen.
In a screening study of surface waters, the authors were successful in culturing NCV in 2/3 of cases. Since these organisms are incapable of multiplication in open waters and yet were present in water samples in considerable amounts, it was postulated that they persisted in certain forms of aquatic life. To elucidate this question, the intestinal contents and in some cases, the bile of a total of 110 animals belonging to 17 different bird, fish, and frog species from different habitata were examined. From these animals, 51.8% were found to be carriers of NCV and 7.3%, of salmonella. Additionally, 4.5-15.5% were found to carry Aeromonas, Plesiomonas, Staphylococcus aureus, and Pseudomonas aeruginosa. Fish and frogs were found to offer NCV organisms possibilities to persist while migratory birds such as stock ducks import them even from tropical areas. When compared with the results of studies performed, salmonella carriers among Danube fish were found to have increased in number.
128 M- and 15 T-typed strains of A-streptococci were investigated in respect of their streptolysin O production. The peak of streptolysin O production was reached after the logarithmic growth-phase and persisted for more than 24 h. The strains were classified in very weak 44% (0-1,0 E/ml), weak 30% (1,5-3,0 E/ml), medium 21% (4-8,0 E/ml) strong 5% (12-48 E/ml), 9 strains (7%) produced no detectable streptolysin O. The amount of streptolysin O necessary for antigen stimulation is discussed. A connection of growth character and enzyme production was not observed.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：