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L Sula

Publications and source records attributed to L Sula.

At least 37 records · Page 2Linked to original sources
PubMed1973

WHO cooperative studies on the phage-typing of mycobacteria. 1. Phage lysis of Czechoslovak and Italian strains of Mycobacterium tuberculosis.

Although phage-typing of some pathogenic microbes-e.g., Escherichia coli and the genera Salmonella, Staphylococcus, and Streptomyces-is in routine use, little progress has yet been made in the phage-typing of mycobacteria, chiefly because mycobacteriophages possess a polyvalence that prevents the reliable identification of individual species of mycobacterium. Furthermore, laboratories cannot compare their results because they employ different methods and culture media and also because the phages used cannot be accurately identified. It has been shown that internationally reproducible results can be obtained for M. tuberculosis by selecting suitable mycobacteriophages and sensitive culture media, and by using a standardized technique of phage-typing. Under these conditions, phage lysis may be utilized to classify strains of M. tuberculosis.

Bacteriophage Typing↗
PubMed1971

Cultivation of the Douglas strain of Mycobacterium lepraemurium in continuous culture.

Cultivation of Mycobacterium lepraemurium in cell-free media has not yet been successful, perhaps because of deterioration of the nutritional quality of the medium with prolonged incubation at 37 degrees C. Trials with a continuous culture technique, involving regular change of a simple liquid medium prepared from human placenta, demonstrated active fission of the Myco. lepraemurium cells. Abundant growth in the form by macroscopically visible colonies has not been achieved even after prolonged incubation up to 8 months.

Bacteriological Techniques↗
PubMed1970

The microstructure of colonies of the Connaught BCG strain.

It has previously been shown that there is a certain correlation between the biological properties of BCG strains-properties on which their immunogenicity and allergenicity depend-and the macroscopic appearance of the growth of these colonies on solid and liquid media. To investigate this phenomenon in greater detail, the author examined the microstructure of colonies of the Connaught BCG strain grown on both solid and liquid media. Colonies were fixed in agar, embedded in paraffin, sectioned and stained by the Ziehl-Neelsen technique.A striking finding was the alternation of acid-fast and non-acid-fast zones in colonies grown on bovine-serum agar or Ogawa egg medium; the strata nearest the surface of the solid media were usually more acid-fast than were the deeper strata. Colonies grown in Sula's liquid medium, on the other hand, showed no such stratification and were equally acid-fast at all points. These differences may be the result of genetic factors or of the different nutritional conditions provided by solid and liquid media.

Bacteriological Techniques↗
PubMed1970

Studies with the light microscope and electron microscope of lung macrophages in rabbits inoculated with an attenuated stain of Mycobacterium microti.

One of the main difficulties in trying to standardize BCG vaccine or to develop a new antituberculosis vaccine with no allergenic properties is the lack of a suitable protection test. The virulence of the challenge strain, the dosage, and the period of observation of the animals are factors that complicate the standardization and reproducibility of any protection test involving animals. On the other hand an ultramorphological test based on the macrophages obtained from immunized animals would eliminate many of the variable factors.With this in mind, pulmonary macrophages of rabbits immunized with attenuated "MP" strain of Mycobacterium microti were examined in ultrathin sections prepared from lung specimens taken from rabbits under general anaesthesia. In comparison with normal rabbits, increased numbers of immune macrophages were found and they contained larger numbers of lysosomal bodies, mitochondria, and Golgi bodies. Quantitative assessment of these differences in ultrastructure by the application of gradient centrifugation may lead to the elaboration of a simpler test for assaying the protective values of antituberculosis vaccines.

Animals↗
PubMed1969

A comparative study of special agar medium (Redmond) and simple agar medium for the phage-typing of mycobacteria.

Phage-typing is an important technique for classifying mycobacteria and optimum conditions for growth are required to bring the organisms into the logarithmic phase of growth needed for their exposure to phages. The quality of the media used for growing the strains selected for typing is therefore important.Comparative trials on the propagation of 3 different mycobacterial phages (MyF(1)-P/58; MyF(2)-P/59, both isolated in Prague, and GS4E, supplied by W. B. Redmond, Atlanta, Ga., USA) on ATCC 607 and S(1)P (scotochromogen) mycobacterial strains grown on RVA (Redmond) medium and on simple N-1 agar, with and without albumin, were undertaken. The results showed that the Redmond medium is very sensitive for growing atypical strains but not for multiplying phages. The lytic plaques were less developed on this medium and the metabolic activity of the phages-as shown by the absence of a positive tellurite phenomenon-was impaired. Further comparative trials with slowly growing mycobacteria are in progress.

Agar↗
PubMed1968

Comparative trials with different decontaminating agents for growing Mycobacterium tuberculosis from sputum specimens.

A reliable culture technique for mycobacteria to enable precise taxonomic and biological identification to be made, e.g., virulence and sensitivity or resistance to the major and minor antituberculosis drugs, is one of the basic requirements of efficient and economic tuberculosis control measures. Several of the methods employed for this purpose have been studied systematically. Many of these methods make use of various detergents, especially quaternary ammonium bases in different combinations, which possess strong bacteriostatic or bacteriocidal properties and decontaminate sputum samples without, however, affecting the viability of mycobacteria.A series of experiments to study the effect of sodium lauryl sulfate and of pancreatin, both in combination with sodium hydroxide, and of a new detergent, di-isobutal-naphthalin-sulfonate (Nekal Bx) on the growth of mycobacteria in liquid and solid media were carried out. As a control technique, the processing of samples of pathological material with hydrochloric acid and sodium hydroxide was studied.On the basis of these experiments, the sodium lauryl sulfate method proved to be promising, both for the rapid growth and characterization of the colonies, and for producing the lowest contamination rate in cultures. However, none of the 4 techniques was sensitive enough under the experimental conditions to demonstrate mycobacteria in sputum samples containing few organisms.

Anti-Bacterial Agents↗
PubMed1967

The lipid substances and cytopathic effects in man of BCG strain "Copenhagen" and attenuated vole bacillus strain "Prague".

Both virulent and attenuated acid-fast micro-organisms (including BCG) may provoke in the infected or vaccinated host cytopathic effects characterized by the formation of specific granulation tissue or caseous necrosis. The mycobacterial antigens responsible for these reactions are localized in the lipid substances which are not essential for eliciting immunity to tuberculosis.The lipid contents of 3 mycobacterial strains (BCG-Prague, BCG-Copenhagen, and MP-Prague-the latter an attenuated strain of Myco. microti) were repeatedly analysed during the period 1964-66. The latter 2 strains-of high and low lipid content respectively-were injected intradermally into 2 tuberculin-positive human volunteers and their cytopathic effects studied. The local reaction to MP-Prague was minimal and healed completely after 1 month; severe ulcerous reactions requiring 4 months to heal were observed with BCG-Copenhagen.Electron-microscopic investigation of ultrathin sections showed marked differences in the surface structure of these strains, indicating that they had different ways of disintegrating in vivo.The authors suggest that mycobacterial strains with a low lipid content and established immunogenicity may be more valuable for tuberculosis prophylaxis than BCG or other attenuated mycobacteria.

BCG Vaccine↗
PubMed1965

The phage tellurite zonal phenomenon as a criterion for the differentiation of slowly growing Mycobacteria.

Formerly, only Mycobacterium tuberculosis, Myco. bovis and Myco. avium were recognized as the main acid-fast micro-organisms responsible for producing delayed-type sensitivity to tuberculoproteins and for causing tuberculosis.Recently, many other slowly growing acid-fast micro-organisms have been isolated and recognized as potential human pathogens. The differentiation of these strains is much more difficult than that of the "typical" ones, however, and calls for new techniques. One such technique is the phage-typing of mycobacteria. Phage studies have revealed a hitherto unknown phenomenon-namely, that the lytic plaques produced by phages on slowly growing mycobacteria (whether sensitive or resistant to the major antituberculosis drugs) display, at the boundary with the non-lysed culture, a zone of irregular width formed by mycobacteria that have lost their ability to reduce potassium tellurite to metallic tellurium. By contrast, the lytic plaques produced by phages on rapidly growing mycobacteria with strong tellurite reactivity always display a sharp line of demarcation between the plaque and the non-lysed culture.The studies described in the present paper have shown that the tellurite zonal phenomenon provides a reliable criterion for the differentiation of slowly growing mycobacteria.

Bacteriophage Typing↗