Polyphthienoyl trehalose, glycolipids specific for virulent strains of the tubercle bacillus

Phthienoic acids constitute a family of dextro-rotary odd-numbered unsaturated fatty acids isolated exclusively from virulent strains of human and bovine tubercle bacilli. In the bacterial cell they are not free and a search for their linked form in complex wall lipids of Mycobacterium tuberculosis (strain Canetti) showed that they esterified trehalose. Structural elucidation of the major phthienoyl trehalose showed the occurrence of five acyl residues located at 2, 2', 3', 4 and 6' positions of trehalose. The acyl substituents were mainly 2,4,6-trimethyl tetracos-2-enoic acid (C27 phthienoic acid) accompanied by its homologs. In addition to these branched fatty acids, straight-chain C16 and C18 acyls composed about 20% of the substituents. The proposed structure is a new one, both for the mycobacterial-specific glycolipid and for the substituted positions on trehalose. Other minor acyl trehaloses were detected in M. tuberculosis (strain Canetti), differing from the major component by the occurrence of an additional hydroxy fatty acid (3-hydroxy-2,4,6-trimethyl tetracosanoic acid) or by the number of acyl substituents. The major glycolipid presented a weak activity in vitro on mitochondrial oxidative phosphorylation. These glycolipids and phthienoic acids could serve as virulence indicators.

[Dynamics of the shedding of bacterial and ultrafine forms of mycobacteria during the chemotherapy of patients with pulmonary tuberculosis]

The specific features of bacterial excretion by patients with pulmonary tuberculosis in the process of chemotherapy, depending on the duration of treatment, have been studied, and the time-course of the excretion of ultramicro forms of mycobacteria by patients with and without caverns in the lungs in the process of chemotherapy has been followed. The results of the detection of M. tuberculosis ultramicro forms with the use of the biological and bacteriological methods indicate that both these methods are highly effective and informative. The method of the direct reversion of ultramicro forms into coccoid ones in Shkol'nikova's culture medium with 10% of plasma added has proved to be the simplest. The injection of sputum filtrates containing filter-passing (ultramicro) forms of mycobacteria into experimental animals induced the development of specific minor tuberculous inflammation of a productive character without the caseation of granulomas or progressing; such inflammation coursed as a latent lympho-hematogenous process.

[A new method of determining the virulence of nontubercular mycobacteria and weakly virulent Mycobacterium tuberculosis]

A new method for enhancing the sensitivity of white mice to infection with faintly virulent mycobacteria is proposed. The method consists in the sensitization of animals with pertussis monovaccine introduced in a single-intraperitoneal injection 7 days before the infection of animals with the culture under study. The method permitted the detection of residual virulence in all opportunistic mycobacteria under study.

[Comparative effectiveness of different methods for the microbiological study of resected pulmonary tuberculomas]

Wide-range microbiological study (bacterioscopy, inoculation, biological assays) of 114 lung tuberculomas excised from 107 patients has revealed a pronounced variability and sharply decreased viability of mycobacterial populations vegetating in caseous foci. Differences in the frequency and character of the detection of Mycobacterium tuberculosis and their altered forms, arising from the use of three above-mentioned methods of microbiological investigation, were noted. Bacterioscopy proved to be more informative with respect to the detection of the bacterial forms of M. tuberculosis. Biological assay was highly sensitive with respect to the L-forms of M. tuberculosis and permitted the detection of the persisting forms of this infective agent, contained in caseous foci and not detected by the method of inoculations. To evaluate the actual state of the mycobacterial population in the focus of tuberculous lesion, the use of a complex of microbiological methods for the detection of typical and biologically altered forms of M. tuberculosis is necessary.

Virulence for guinea pigs of tubercle bacilli isolated from the sputum of participants in the BCG trial, Chingleput District, South India

This study, conducted in Madras, India and in Madison, Wisconsin, USA, was concerned with the virulence of isolates of Mycobacterium tuberculosis obtained from the sputum of individuals living in the Chingleput district of south India. The following results were obtained. 1. The findings of Mitchison with respect to the predominance of low virulence for guinea pigs among isolates from persons living Madras, were confirmed on isolates from the sputum of residents of the Chingleput district. 2. A high correlation was found between the log10 number of tubercle bacilli recovered from the spleen of guinea pigs infected intramuscularly with 1.0 mg of tubercle bacilli and the root index of virulence. 3. A high correlation was found between the log10 number of tubercle bacilli recovered from the spleen of guinea pigs infected intramuscularly with 1.0 mg of tubercle bacilli and the number recovered from the spleen of guinea pigs infected by the respiratory route with 5-10 tubercle bacilli. 4. Relatively low correlations were found between RIV and the susceptibility of isolates to thiophene-2 carboxylic acid hydrazide or to hydrogen peroxide.

Virulence of tubercle bacilli isolated from patients with tuberculosis in Bangalore, India

This is a study of the virulence of cultures of Mycobacterium tuberculosis isolated from pulmonary and extrapulmonary forms of tuberculosis in patients living in or near Bangalore, India. The findings are as follows: 1. The percentage of cultures recovered from cases of pulmonary tuberculosis in Bangalore classified as being of low, moderate, and high virulence, was the same as that reported by Mitchison et al., in 1960 for isolates obtained from patients in Madras, India. 2. The distribution of the root index of virulence (RIV) of isolates from patients living in the city of Bangalore was significantly different (p less than 0.05) from that of isolates from patients living in rural Bangalore. 3. Even though the number of cultures classified as high virulent was significantly greater in isolates from patients with tuberculosis meningitis compared with those from patients with pulmonary tuberculosis, the data show that 36% of the isolates from the meningitis group were classified as low virulent.

Protection to mice afforded by BCG vaccines against an aerogenic challenge by three mycobacteria of decreasing virulence

Specific pathogen-free mice were vaccinated subcutaneously with 10(7) CFU of BCG Pasteur or BCG Glaxo and 30 or 90 days later, the mice were challenged aerogenically with Mycobacterium tuberculosis (Erdman or South Indian strains) or with M. avium. Both vaccines induced substantial levels of resistance to tuberculosis and tuberculin hypersensitivity. There was no detectable difference in the host response to the three aerogenic challenges which could be related in any way to the immunogenicity of the BCG strain or to the mouse virulence of the challenge organism. These results do not support the hypothesis that the protective activity of BCG vaccines varies, depending upon the virulence of the infecting organism.

Mycobacterium bovis BCG vaccine fails to protect protein-deficient guinea pigs against respiratory challenge with virulent Mycobacterium tuberculosis

Specific-pathogen-free Hartley guinea pigs were maintained on isocaloric-purified diets either adequate (30%) or moderately deficient (10%) in protein. Half of each diet group was vaccinated with viable Mycobacterium bovis BCG. Six weeks later, all animals were challenged by the respiratory route with virulent Mycobacterium tuberculosis H37Rv. At intervals of 1, 2, and 3 weeks postchallenge, guinea pigs from each diet and vaccination group were skin tested with tuberculin and sacrificed. Protein deficiency resulted in loss of tuberculin hypersensitivity. Vaccination with M. bovis BCG protected control animals, as determined by significant reductions in the number of M. tuberculosis H37Rv organisms recovered from lungs, spleen, and bronchotracheal lymph nodes 2 and 3 weeks postchallenge. Based upon the same criteria, the degree of protection afforded protein-deficient animals by M. bovis BCG vaccine ranged from partial (spleen and lymph nodes) to none at all (lungs). Approximately the same numbers of tubercle bacilli were recovered from nonvaccinated guinea pigs in both diet groups. Protein deficiency appears to impair M. bovis BCG-induced immunity while not affecting primary pulmonary infection with virulent M. tuberculosis.

Granuloma formation by muramyl dipeptide associated with branched fatty acids, a structure probably essential for tubercle formation by Mycobacterium tuberculosis

Muramyl dipeptide, which does not induce epithelioid granuloma when injected alone dissolved in phosphate-buffered saline, could induce extensive granulomas in guinea pigs when chemically conjugated with branched, but not linear, fatty acids. Peptidoglycan fragments of Staphylococcus epidermidis could evoke epithelioid granulomas when incorporated in a water-in-oil emulsion. These findings suggest the importance of a lipid bound to muramyl dipeptide for granuloma formation. In view of the fact that mycobacteria uniquely contain large amounts of branched fatty acids, it was proposed that the complex of muramyl dipeptide and branched fatty acids, mostly mycolic acids, is a structure in tubercle bacilli responsible for tubercle formation.

Isolation and identification of mycobacteria from patients with pulmonary tuberculosis

A total of 500 clinically and radiologically positive cases of pulmonary tuberculosis were examined microscopically and culturally for the presence of Mycobacterium tuberculosis. Out of those, 40 percent were found to be positive by ordinary Z.N. stain and 35 per cent by culture. Fluorescent stain proved to be more sensitive than ordinary Z.N. stain, where 62.7 per cent was found to be positive. All the isolated culture when subjected to different biochemical tests for identification of the strains, they all turned out to be Myco. tuberculosis, human type.

Susceptibility of Mycobacterium intracellulare to hydrogen peroxide

The susceptibility to H2O2 of 5 strains of Mycobacterium intracellulare and both catalase-positive (TMC 102) and negative (TMC 303) strains of M. tuberculosis, H37RV, was tested at pH 7.0 and 4.0. All strains of M. intracellulare were significantly more resistant to this oxygen metabolite than were the two M. tuberculosis strains, even though the catalase activity of M. tuberculosis TMC 102 was higher than most M. intracellulare strains. Even the catalase negative (Eggeman) strain of M. intracellulare showed greater resistance to 0.2% H2O2 than M. tuberculosis H37RV (TMC 102). This suggests that M. intracellulare is protected from H2O2 damage by factors additional to their catalase activity.

[Characteristics of the filterable forms of Mycobacterium tuberculosis and their significance in pathology]

The results of the present investigation indicate that antituberculosis therapy for a period of 6 months leads to qualitative changes in M. tuberculosis population. This is manifested by the appearance of the filterable forms of M. tuberculosis in pathological material. At the same time these forms retain the initial pathogenicity of M. tuberculosis and induce not only tuberculous, but also nonspecific inflammation. Among the population of these filterable forms organisms carrying the genetic information of the species and capable of replication processes have been detected.

[The etiological agent of tuberculosis]

Author points out the reduced virulence of M. tuberculosis, that shows itself in a lower number of sputum smears and cultures positive for acid-fast bacilli and in a quick bacteriologic conversion of these cases. The most important test is again sputum smear with demonstration by microscope. No doubt that the use of antitubercular chemotherapy helped this paradoxical return to experimental methods employed by Koch, but on the other hand this use aided in forming some bacterial resistances. Author reminds that M. tuberculosis is supplied with particular characteristics, partly connected with its high lipidic contents. From this diversity as regards other bacteria rises also the difficult discovery of new efficacious antitubercular drugs.

Disruption of phagosomal membranes of normal alveolar macrophages by the H37Rv strain of Mycobacterium tuberculosis. A correlate of virulence

The H37Rv and H37Ra strains of Mycobacterium tuberculosis were incubated with normal rabbit alveolar macrophages and examined by electron microscopy at 5 to 6 and 18 to 24 h of incubation. At the 18- to 24-h incubation interval, 60 to 100% of the endocytosed organisms of the H37Rv strain disrupted the phagosomal membranes and appeared free in the cytoplasm of the macrophages. In contrast, the H37Ra strain lacked this putative virulence characteristic, and greater than 99% of the organisms appeared within intact phagosomes. Heating the organisms of the H37Rv strain abrogated to a large extent, but not completely, their capacity to disrupt phagosomal membranes. In the course of the interaction of organisms of the virulent H37Rv strain with phagosomal membranes of normal rabbit alveolar macrophages, adherence of the phagosomal membrane to the surface of the organisms was a prominent feature that was followed by fragmentation and apparent disintegration of the membrane. This potential virulence characteristic could explain why there is essentially no resistance expressed in the lung during the early postinfectious period of primary infection to M. tuberculosis.

Immunological mechanisms controlling mycobacterial infections

After a brief review of the present knowledge about cell mediated immunity mechanisms involved in controlling mycobacterial diseases, variations of the immune responses to mycobacterial diseases in man and in experimental animals models are described. Related factors involved in the variations of the BCG vaccination effectiveness against human tuberculosis are presented according to present hypotheses on varying potency of BCG strains and influence of previous sensitization with non tuberculous mycobacteria. Also new hypotheses concerning qualitative differences in immune responses to mycobacteria in humans are discussed in association with information suggesting that tuberculosis, as other granulomatous chronic infectious diseases, is a disease in which an immune spectrum can be described with a significant modulation of T and B lymphocyte mediated responses. Evidence obtained in murine experimental models, using BCG infection in inbred and recombinant mice, demonstrated the existence of at least two genes which are able to control the induction and expression of CMI after mycobacterial infection. One of them, being not linked with the major histocompatibility complex gene (non H2), controls the natural non specific activity of the mononuclear phagocytic system and the other, linked with H2 complex, is able to modulate the level of CMI in responsive mice. Collective or individual antituberculosis strategies must be reconsidered following this finding.

Bacteriophage typing of strains of Mycobacterium tuberculosis from Nepal

One hundred strains of Mycobacterium tuberculosis isolated from cases of pulmonary tuberculosis in Nepalese villagers were typed with the World Health Organization set of bacteriophages. The number of strains in the 3 major phage types A, I, and B were 19, 53, and 28 respectively. This distribution is significantly different from those described in other geographical regions. In particular there was a relatively low incidence of type A strains and, in common with South India, there was a high proportion of type I strains. All the strains in this study were resistant to 5-Furan-2 carbonic acid hydrazine and 34 were highly resistant to isoniazid. Representative strains of the 3 phage types, including 4 isoniazid-resistant type I strains, did not differ in their virulence in the guinea pig; thus the type I strains found in Nepal may not be of the same origin as those of this phage type from India which are usually attenuated in the guinea pig. This study provides further evidence for the existence of geographical differences in the types of tubercle bacilli.

Comparative study of the lipid composition of particular pathogenic and nonpathogenic species of Mycobacterium

A comparative study was undertaken of lipid composition of Mycobacterium tuberculosis H(37)Rv and H(37)Ra, M avium, M phlei, and M 607. Neutral lipids and phosphatides constituted about 55 and 25 percent of the total lipids, respectively. Seven different phosphatides were isolated and identified in varying proportions in all of the above species of mycobacteria. These were polyglycerophosphatide, phosphatidic acid, phosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol dimannoside, and phosphatidylinositol pentamannoside. Choline-containing phosphatides and cholesterol (steroids) were not detected in lipids of any of the five species under these defined experimental culture medium and growth conditions. Interestingly enough, neutral lipids of M tuberculosis (H(37)Rv and H(37)Ra) contained a higher percentage of diglycerides than monoglycerides, whereas in the other species (M avium, M phlei, and M 607) the monoglyceride content exceeded that of the diglycerides. It appears that the lipid composition of mycobacteria can be an additional useful parameter in distinguishing pathogenic from nonpathogenic species of mycobacteria.

Role of lipid content and hydrogen peroxide susceptibility in determining the guinea-pig virulence of Mycobacterium tuberculosis

Among isoniazid-sensitive strains of Mycobacterium tuberculosis, strong associations were found in 56 strains of phage type A and I from India, Burma and East Africa between attenuation in the guinea-pig, a low content of strongly acidic (SAL) and sulphatide (SL) lipids, the presence of the attenuation indicator (AI) lipid and phage type I, suggesting that lipid content might mediate attenuation. However, 22 strains of phage type B and I from Iran and Britain also had low contents of SAL and SL but were highly virulent. Although the finding of a strong association in all 78 strains between attenuation and H2O2 susceptibility in vitro supports other evidence that attenuation is often due to increased susceptibility to H2O2 secreted by macrophages, an alternative mediator of virulence probably exists since 8 of the strains were attenuated and also resistant to H2O2. Identification of South Indian attenuated strains for epidemiological purposes by in vitro tests would be best achieved by the presence of AI, H2O2 susceptibility and, if the strains originated in or near India, by phage type I.

Lipid composition and virulence of Mycobacterium tuberculosis H37Rv

The total lipids increased with decrease in total phospholipids in Mycobacterium tuberculosis H37Rv grown at 30 degrees as compared to 37 degrees. Oleic and elaidic acid supplemented to the growth medium resulted in a higher total lipid and phospholipid content, but the content was lower in cells grown in the presence of palmitoleic acid. Cellular content of mannophosphoinositides decreased, whereas that of phosphatidylethanolamine and cardiolipin increased at the lower temperature. A decrease in mannophosphoinositides and an increase in cardiolipin were noted with all fatty acid supplements; however, phosphatidylethanolamine behaved differently. The unsaturated to saturated fatty acids ratio increased at low temperature with oleic and elaidic acid supplements, but it decreased with palmitoleic acid. Cells from media supplemented with palmitoleic acid were found to be most virulent to guinea-pigs. Possible correlation of altered lipid composition and virulence of M. tuberculosis H37Rv has been discussed.

Koch's Tubercle Bacillus - a centenary reappraisal

The tubercle bacillus discovered by Robert Koch in 1882 was termed Mycobacterium tuberculosis in 1886. This organism was later found to be only one of many acid fast bacilli, some of which caused diseases resembling tuberculosis in various animals and some lived freely as saprophytes. The strains associated with disease were also referred to as tubercle bacilli and in later years those which differed in their properties from Koch's original isolates were given separate species names. Modern taxonomic methods have enable the species within the genus Mycobacterium to be carefully defined. The use of such methods has shown that the strains called M. tuberculosis, M. bovis, M. microti and M. africanum belong to a single evolutionary unit or species. It is therefore recommended that the latter three species names should be discarded and that the variants should be regarded as types of M. tuberculosis. The term "tubercle bacilli" had been applied to the variants of M. tuberculosis and also to quite distinct species of acid fast bacilli such as M. avium. It is therefore necessary to define the term "Tubercle bacillus" whenever it is used. The "classical" subdivisions of M. tuberculosis are based on simple cultural properties and pathogenicity in mammalian hosts. More recent methods enable other important subdivisions to be made. These include three major phage types of the human strains and two variants of the bacillus is therefore one of a heterogeneous group of acid fast bacilli which can, nevertheless, be seen to belong to the evolutionary distinct species Mycobacterium tuberculosis.