TEXTBOOK OF MICROBIOLOGY ~ WITH VIROLOGY AND IMMUNOLOGY

Author: Vladimir Markov

Editor's Note: This textbook is important contribution to the development of bulgarian medical science. The titular, Prof. Vladimir Markov (1883-1958), was graduate in Veterinary Medicine but served at university position in Medical Faculty, Sofia University. Besides his numerous publications in microbiology and epidemiology, this particular textbook was issued in six editions for purposes of student education. This manuscript from 1946 was the last one we believe was edited by the author himself, while next versions were expurgated by collaborators at BAS. It is interesting to report in this book the personal efforts of V. Markov to keep up-to-date with rapidly developing international scholarship in the late 1940s, and because of the difficult post-war years. On scientific level, most of the microbiological methods he had described are linked to cultivation and staining techniques. Also interesting to follow is the collaboration of Prof. V. Markov with another outstanding representative of interwar academic science in Bulgaria, doyen of bacteriology Prof. Stefan Angelov, ditto.

INTRODUCTION TO SECOND EDITION

Modern medical microbiology has become an extensive science which cannot be fitted into the framework of a textbook, and this makes it quite difficult to compile a teaching guide. During the last few years those sciences that previously represented only small sections of microbiology such as genetics, immunology and virology have developed into independent sciences.

In the scope of a textbook for students it is impossible to give complete information on all the causative agents which are known to medical science, and also on comprehensive methods of investigation of bacterial and viral infections.

The second edition of the textbook on microbiology with virology and immunology has been revised in accordance with the curriculum accepted in Sofia University. New data from bulgarian and foreign literature have been added to the textbook, which, to a certain degree, supplement many chapters.

In this edition the sections 'pathogenic mycoplasmas' and 'viruses' have been completely re-written. Besides, recent data have been added to those chapters dealing with the theory of the formation of antibodies, antitoxin and neutralization reaction of toxin, serotherapy, seroprophylaxis and vaccines.

Taking into account the complexity of the problem, that is, to give the main sections in general and special microbiology briefly and in an up-to-date form, the author during the preparation of this edition resorted to the help of distinguished international microbiologists and epidemiologists.

Many valuable consultations and advice helped to eliminate the drawbacks in the manuscript, and they helped with necessary corrections and addenda.

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NOTES ON HISTORY OF MICROBIOLOGY

Metchnikoff s study of the problems of phagocytosis was the starting point for the appearance of a number of works which demonstrated that in the defence reactions of the body an important role is played by certain substances in the blood serum, secreted by special cells under the influence of microbes and their toxins (P. Ehrlich, R. Pfeiffer, J. Bordet, and others).

In 1888 the French scientists E. Roux and A. Yersin established that the causative agent of diphtheria produces a biological toxin, and they determined its importance in the development of the disease. In 1890 the German scientist, E. Behring, and the Japanese, S. Kitasato, by means of successive injections of small doses of tetanus and diphtheria toxin into animals, prepared the corresponding immune sera which could protect the animals from lethal poisonings with toxins. At the Pasteur Institute, Roux obtained an anti-diphtheric serum and used it for treating diphtheria in children. These discoveries provided the basis for the production of medicinal sera against botulism, anaerobic infections, venomous snake bite, etc.

German scientist P. Ehrlich (1854-1915) created the theory of humoral immunity from which arose a prolonged difference of opinion dividing the scientists into two schools: supporters of Ehrlich and his opponents headed by Metchnikoff. The controversy stimulated a rapid series of investigations on the problems of immunity, the results of which were of great practical importance. More improved laboratory diagnostic methods of infectious diseases were devised, and vaccines were obtained against enteric fever, cholera, plague, and other diseases. Due to widespread discussions, it was established that insusceptibility to infectious diseases depends on cellular as well as humoral immunity. In 1908 both Metchnikoff and Ehrlich were awarded the Nobel prize for elaborating the science of immunity.

The scientists who discovered the causative agents of a number of infectious diseases have performed great services for the advancement of medical microbiology. One of them was D. Ivanovsky (1864-1920), who laid the foundations for the study of a new field in biology, the study of viruses. In 1892, while working on the problem of tobacco mosaic disease which had caused great damage to tobacco plantations, Ivanovsky established that this disease, widespread in the Crimea, is produced by a virus which has a high virulence and a strictly selective activity. This discovery showed that organisms exist together with the cellular forms which are invisible in ordinary light microscopes. They pass through filters of small pore size and lack a cellular structure.

Within six years after the discovery, M. Beijerinck confirmed similar data as that obtained by the russian scientist. Due to the outstanding investigations of Beijerinck, Loeffler, and Frosch in 1897 the virus aetiology of foot-and-mouth disease was established. Later on, the causative agents of many virus infections of man, animals and plants were discovered and studied.

In the 20th century very important investigations were made in the field of specific prophylaxis of infectious diseases. In 1924-1925, G. Ramon devised a method for the preparation of anatoxins (toxins rendered non-toxic by formalin). With their help immunization against diphtheria and tetanus was successfully carried out. Vaccine preparations were received from live, but attenuated, causative agents of tuberculosis (Calmette and Guerin, 1919), plague (Girard and Robic, 1931), yellow fever (Taylor, 1936), tularaemia (Gaisky, 1939), and a number of other vaccines.

Investigations which permitted the practical introduction of salvarsan (Ehrlich), bacteriophages (D'Herelle), sulphonamides (Domagk and others), penicillin (Fleming, Chain, Florey), and other antibiotics are highly appraised and it is due to the application of these drugs that modern medicine achieved great success in the treatment of infectious diseases.

The development in the last thirty years of the genetics of micro-organisms and viruses, as a result of which the biochemical mechanisms of heredity and variation were revealed, should be considered a new stage in microbiology.

The successes of microbiology contributed immensely to the development of the study of infectious diseases, epidemiology, virology, immunology, surgery, hygiene, etc. It can be said without exaggerating that at present there is no medical science which could have progressed without the development of microbiology.