J. Marks

Thin-layer chromatography of mycobarcterial lipids as an aid to classification: Technical improvements: Mycobacterium avium, M. intracellulare (Battey bacilli)

Abstract Lipid analysis by thin-layer chromatography supports the contention of Tsukamura that M. avium, M. intracellulare and M. scrofulaceum are closely related. There is in these species a useful correspondence between serotype and lipid pattern. The latter may be used to identify species and types provided that reference strains are examined in parallel.

A study of the ‘anonymous’ mycobacteria: I. Introduction; colonial characteristics and morphology; Growth rates; Biochemical tests

Summary For the purpose of the present investigation ‘anonymous’ mycobacteria were defined as acid- and alcohol-fast bacilli distinct from tubercle bacilli which had been isolated from human morbid material. The colonial characteristics and morphology, together with certain cultural and biochemical properties, were studied of 114 strains obtained from sputum. The collection was divided into ‘pathogenic’ strains isolated repeatedly and ‘casual’ strains isolated only once. A group associated with pneumoconiosis was separated from other pathogenic strains for separate analysis. One-third of the casual strains and slightly more than half of the pathogenic strains differed from tubercle bacilli in their pigmentation. Also of diagnostic value were emulsifiability, cell length and the degree of cord formation in certain cultural conditions. The cultural and biochemical procedures found most useful to distinguish the anonymous mycobacteria and tubercle bacilli were subculture at 25°C. on egg medium and the arylsulphatase, catalase and niacin tests. None were adequate to distinguish pathogenic and casual strains of anonymous mycobacteria.

The design of sensitivity tests on tubercle bacilli

Summary There is evidence that low degrees of drug resistance are important clinically in tuberculosis but their detection incurs the risk of misdiagnosing some sensitive strains as resistant. It is suggested that this risk may be reduced if test titrations are referred to an index of the normal behaviour of sensitive strains rather than to a single concurrent titration of a standard strain. An index termed the ‘modal resistance’ is denned for this purpose. Strains with four or more times the modal resistance may be diagnosed as resistant on a single titration with reasonable safety.

A Study of the " Anonymous " Mycobacteria. III. Problems of Classification and Diagnosis; Practical Recommendations.

Summary The results of the previous two papers of the series have been considered and practical recommendations made for identifying anonymous mycobacteria in diagnostic work. It is suggested that initial cultures may be adequately screened by a combination of microscopical examination; exposure of the primary culture and a subculture to light at 37° C, a test for resistance to thiosemicarbazone and subculture at 25° C.

Notes on the ziehl-neelsen staining of sputum

Abstract When the incidence of tuberculosis is low, it is possible to save time and labour by making films of concentrates of sputum prepared for culture, 8 per double slide. Each positive is checked by a repeat film on the remainder of the original specimen. A tilting rack is described which makes staining easier and more efficient.

Classification of the mycobacteria in relation to clinical significance

Abstract A new method of classifying the mycobacteria met in human material has been designed for the needs of clinical bacteriology. It is based first on temperature requirements and then on oxygen preference and/or pigmentation. Supporting evidence is provided by the Tween-hydrolysis test and drug sensitivity.

A ‘stepped pH’ technique for the estimation of pyrazinamide sensitivity

Summary A variety of conditions are necessary in pyrazinamide sensitivity tests in order to cater for strains of different growth characteristics. A technique is described which employs stepped pH levels in two complementary media. Only one drug concentration is required.

Low-grade sensitivity to tuberculin in school children

Summary Comparative Heaf multiple puncture tests were carried out on 2,464 children with mammalian tuberculin on one arm and one of a number of antigens from anonymous mycobacteria on the other. The latter antigens were prepared from a photochromogen, a group of scotochromogens, a locally isolated slow growing non-chromogen, the Battey bacillus and a fast growing non-chromogen. The pattern of cross-reaction found in unvaccinated children highly sensitive to tuberculin and/or the anonymous antigens used resembled that seen in children previously vaccinated with BCG, suggesting, in agreement with epidemiological evidence, that high degrees of sensitization usually result from tuberculous infection. A good deal of the low grade sensitivity to tuberculin in unvaccinated children appeared to result from sensitization by bacilli of the Battey-avian group. The evidence in respect of photochromogen sensitization was ambiguous, but the fast growing nonchromogen and the scotochromogens examined appeared not to be implicated.

A study of the 'anonymous' mycobacteria. II. Drug sensitivity; pathogenicity; hypersensitivity.

Summary The sensitivity of anonymous mycobacteria to various antituberculous drugs was determined in order to find reactions helpful in their recognition and also as a guide to possible chemotherapy. Sensitivity to streptomycin, isoniazid, viomycin and cycloserine varied. All the strains examined were resistant to PAS (1 μg./ml.), pyrazinamide (40 μg./ml.) and, except for photochromogens, to thiosemicarbazone (10 μg./ml.) also. Most photochromogens had a limited degree of virulence for guinea-pigs, a property absent in typical scotochromogens and present in only a minority of nonchromogens. In the last group, virulence for guinea-pigs was partially correlated with probable pathogenicity for man, low catalase activity, slow growth and resistance to the lethal effect of acid. A skin reaction of hypersensitivity is described which may be helpful in distinguishing anonymous mycobacteria from tubercle bacilli.

Transient colonization of the respiratory tract by mycobacteria in South Wales

Abstract Rapidly-growing mycobacteria are cultured from the sputum of miners in South Wales with unusual frequency; repeated isolates are obtained in about a quarter of the cases, sometimes over long periods. The chief species identified are M. peregrinum and M. fortuitum . No immediate illness appears to result from the presence of the organisms; but it is suspected that they can provide an antigenic stimulus and consequently may have long-term effects. The phenomenon is thought to be due to depression of normal clearing mechanisms by coal-dust but the reason for its special prevalence in South Wales is uncertain. Schnellwachsende Mykobakterien lieβn sich ungewohnlich oft aus dem Sputum sudwali-sischer Bergleute zuchten. Wiederholte Isolierungen gelangen bei mehr als einem Viertel aller Falle, manchmal uber langere Zeit. In erster Linie waren M. peregrinum and M. fortuitum vertreten. Das Vorhandensein dieser Erreger fuhrt anscheinend nicht zu manifester Erkrankung, aber es wird ein Antigeneffekt vermutet, der durchaus auf lange Sicht Konsequenzen haben kann. Das Phanomen wird als Folge des durch Kohlenstaub beeintrachtigten normalen Reinigungsmechanismus in den Luftwegen angesehen. Die Ursachen fur das haufige Auftreten dieser Erreger in Sudwales ist unbekannt.