Contribution of Microbiologists: Joseph Lister, Alexander Fleming, Edward Jenner, Lazzaro Spallanzani, Martinus Beijerinck.

1. Joseph Lister

Joseph Lister was a British surgeon and medical scientist. He was born in Essex, England in 1827 in a Quaker family. He is regarded as the father of modern surgery and father of antiseptic surgery.

He obtained the degree of Bachelor of Medicine from University College London in 1852. His main work was concerned with prevention of infection during surgical operations.

He was influenced by Louis Pasteur’s germ theory of disease. It was demonstrated that airborne microbes are responsible for wound infection. This is referred to as antisepsis.

He was the first to use carbolic acid (phenol) as an antiseptic. In 1865 an 11-year-old boy with compound fracture was treated with carbolic acid and the bone was healed without infection.

Strict hygienic methods were introduced by him in operation theatre. Surgeons were required to wash hands and steel instruments were sterilized in carbolic acid solution. Carbolic acid spray was used in the air and antiseptic catgut sutures were introduced. These measures is the basis of modern infection control.

He was also involved in other surgical improvements. He was the second man in England to operate on a brain tumor. Mastectomy techniques was improved and a method to repair kneecaps using metal wire was developed.

He served as Professor of Surgery at Glasgow University, Edinburgh University and King’s College London. His research findings were published in The Lancet in 1867.

Because his methods reduced surgical mortality rate many honours were given to him. He received a baronetcy in 1883 and was elevated to Baron by Queen Victoria in 1897. He was appointed as one of the original members of the Order of Merit in 1902.

His contribution in the field of hygiene and microbiology is remembered. The Lister Institute of Preventive Medicine, Listerine mouthwash and the bacterial genus Listeria were named in his honour.

Contributions of Joseph Lister

• He was known as the father of antiseptic surgery and father of modern surgery. In August 1865 the first surgical operation under antiseptic condition was performed by him. The mortality rate from post operative infections like gangrene and sepsis was reduced from 45–50% to nearly 15% in his surgical ward.
• He was the first to apply Louis Pasteur’s germ theory to surgical practice. The procedures were formed on the principle of “no germs, no infection, no disease”. It was demonstrated that if microbes are excluded infection can be prevented.
• He introduced carbolic acid (phenol) as a chemical disinfectant to destroy germs. Carbolic acid lotions and pastes were applied directly on wounds. Surgical instruments were sterilized in carbolic acid baths and a carbolic acid spray was used in operation room to neutralize airborne pathogens.
• Surgical hygiene standards were established by him. Surgical staff were required to wear clean clothes and use clean gloves. Hands and instruments were washed in 5% carbolic acid solution before and after procedures. These measures is the foundation of modern aseptic technique.
• He introduced absorbable catgut ligatures treated with carbolic acid in 1869. These ligatures were dissolved safely inside the body and internal sepsis was reduced. He was also the second man in England to operate on a brain tumor and mastectomy techniques was improved. A method to repair kneecaps using metal wire was developed.
• He contributed to microbiology and pathology. A pure culture technique using serial dilution was developed by him to isolate specific bacteria. An important paper on inflammation was written explaining how inflamed tissue becomes susceptible to disease. His contribution in surgical science is regarded as very significant.

2. Alexander Fleming

Alexander Fleming was a Scottish physician and bacteriologist. He was born on a farm in Scotland in 1881. He graduated with distinction from St Mary’s Medical School at London University in 1906 and his entire career was devoted to immunology and bacteriology under the guidance of Sir Almroth Wright.

During World War I he served as a captain in the Army Medical Corps. It was observed by him that many soldiers died from uncontrollable infections even after the use of antiseptics. This experience inspired his lifelong search for effective antibacterial agents.

In 1922 lysozyme was discovered by him accidentally. Nasal mucus was transferred onto a Petri dish and after two weeks bacterial growth was inhibited. Lysozyme is an enzyme with mild antibacterial property and it is present in tears, saliva, skin and hair.

On September 28, 1928 penicillin was discovered by him accidentally. A mould (Penicillium notatum) contaminated a Petri dish of staphylococcal bacteria and the surrounding colonies was destroyed. The active mould juice was isolated and this was named as penicillin.

His findings on penicillin were published in 1929. However large scale purification was not achieved by him at that time. Later Howard Florey, Ernst Chain and Norman Heatley extracted and mass produced penicillin and modern medicine was revolutionized.

In 1945 the Nobel Prize in Physiology or Medicine was shared by him with Florey and Chain. He was knighted in 1944 and many honorary degrees was awarded to him. He was also named among the most important people of the 20th century.

In his 1945 Nobel Lecture he warned about misuse of antibiotics. It was cautioned that underdosing can educate microbes to become drug resistant. This warning is considered significant in present antimicrobial resistance crisis.

He was known as a modest and patient person. He was married twice and had one son. In 1955 he died suddenly due to coronary thrombosis and his ashes were interred in St Paul’s Cathedral in London.

Contributions of Alexander Fleming

• In 1922 lysozyme was discovered by him. It is an enzyme which possess weak antibacterial property and is present in tears, saliva, mucus, skin, hair and fingernails. It was demonstrated that natural substances in the body can inhibit bacterial growth.
• In 1928 the first antibiotic was discovered accidentally by him. A mould (Penicillium notatum) contaminated a Petri dish containing Staphylococcus aureus and the surrounding bacteria was inhibited. The active mould juice was isolated and this was named as penicillin.
• By the discovery of penicillin the antibiotic era was initiated. Infectious diseases which were previously fatal such as pneumonia, meningitis, diphtheria, gonorrhea and syphilis was treated successfully. This discovery is regarded as major advancement in modern medicine.
• In 1945 while receiving the Nobel Prize he warned about the danger of antibiotic resistance. It was cautioned that exposure of microbes to non lethal quantity of penicillin can educate bacteria to become resistant. This warning is considered as foundation of antimicrobial stewardship.

3. Edward Jenner

Edward Jenner was an English country physician. He was born in Berkeley, Gloucestershire in 1749. He is regarded as the father of immunology and pioneer of vaccination because the first scientifically validated vaccine was developed by him.

He was aware of the local belief that dairymaids who suffered from cowpox do not get smallpox. This theory was tested scientifically by him. In May 1796 an 8-year-old boy, James Phipps, was inoculated with material from a cowpox lesion and later he was exposed to smallpox. The boy did not develop the disease and protective power of vaccination was proved.

The term vaccination was coined by him from the Latin word vacca meaning cow and vaccinia meaning cowpox. In his 1798 publication the term virus was also used to describe transmission of cowpox. He was also the first to describe the allergic reaction known as anaphylaxis.

In 1798 further experiments were carried out by him and it was discovered that vaccine can be transferred from one vaccinated person to another. This method is referred to as arm-to-arm vaccination. By this method large scale distribution of vaccine was made possible without dependence on natural cowpox outbreak.

He was also a natural scientist and studied under John Hunter. He was elected as Fellow of the Royal Society for his observations on nesting behaviour of cuckoos. Studies on animal hibernation and bird migration was also conducted and the first Plesiosaurus fossil was discovered by him.

His contribution in general medicine was also significant. An improved method for preparing tartar emetic was devised by him. He was likely the first physician to associate angina with hardening of arteries and to describe rheumatic heart disease.

His interest extended beyond medicine. Inspired by hot air balloon demonstration he constructed and launched a hydrogen balloon which flew about 12 miles. He also enjoyed playing violin and writing poetry.

Despite receiving honours and financial awards he did not try to enrich himself. A one room hut called the Temple of Vaccinia was built in his garden where poor people were vaccinated free of cost.

His work laid the foundation of modern immunology and prophylactic medicine. Later vaccines against polio, measles and influenza were developed on similar principle. In 1980 smallpox was declared eradicated globally and his contribution is remembered.

Contributions of Edward Jenner

• In 1796 the first scientific smallpox vaccine was developed by him. It was observed that milkmaids who suffered from cowpox do not get smallpox. An 8-year-old boy, James Phipps, was inoculated with cowpox matter and later exposed to smallpox and the boy was protected.
• By the deliberate and scientific use of vaccination the foundation of modern immunology was laid. It was demonstrated that infectious disease can be controlled by prior exposure to mild form of pathogen. Later vaccines against polio, measles and rabies were developed on similar principle.
• The word vaccination was coined by him from vacca meaning cow. The term virus was also used by him to describe infectious agent. He was the first to describe the allergic hypersensitivity reaction which was referred to as anaphylaxis.
• He discovered that the vaccine can be transferred from pustule of one vaccinated person to another. This is referred to as arm-to-arm vaccination. By this method large scale global distribution of vaccine was made possible even without natural cowpox outbreak.
• He improved the preparation of tartar emetic (potassium antimony tartrate). It was also observed by him that angina is associated with hardening of arteries and rheumatic heart disease was described accurately.
• He was elected as Fellow of the Royal Society in 1789 for his observation on nesting behaviour of cuckoo bird. It was noted that newly hatched cuckoo pushes out the eggs and chicks of foster parents. Studies on hibernation of hedgehogs and dormice was carried out and evidence of bird migration during winter was published.
• As a fossil hunter the first Plesiosaurus fossil on Stinchcombe Hill in England was discovered by him. This discovery contributed in geology and paleontology.
• Inspired by balloon flights in France a hydrogen balloon was built and launched by him which flew about 12 miles. He was likely the first person to fly a balloon in Britain.

4. Lazzaro Spallanzani

Lazzaro Spallanzani was an Italian priest, physiologist and biologist. He was born in Scandiano, Italy in 1729 and was often referred to as Abbé Spallanzani. He served as professor at the universities of Reggio, Modena and Pavia and later directed the natural history museum at Pavia.

He is widely known for his experiments against spontaneous generation theory. Nutrient broth was boiled for long time and hermetically sealed in glass flasks and it remained sterile. It was proved that microbes are introduced from air and not produced by any vital force.

He also observed that different microorganisms have different heat sensitivity. They were classified into superior animalcula and lower class animalcula based on resistance to heat. His sterilization experiments laid the foundation for food preservation methods and later work of Louis Pasteur.

He was the first to demonstrate that fertilization requires physical contact of ovum and spermatozoa. The first successful in vitro fertilization was performed using frogs and artificial insemination was carried out in a dog. However he believed in preformation theory and thought that embryo is already formed inside the egg.

He studied digestion through various experiments. It was demonstrated that digestion is a chemical process and not only mechanical grinding. The solvent action of gastric juice was proved by him through experiments on animals and on himself.

In 1793 experiments were conducted on bats. It was observed that blinded bats can fly and avoid obstacles in darkness. When ears were blocked navigation was disturbed and it was concluded that bats depend on hearing rather than vision.

He also contributed in respiration and anatomy. It was established that connective tissues exist between veins and arteries and role of heartbeat in arterial pulse was explained. Later experiments showed that tissues absorb oxygen and release carbon dioxide which is referred to as parenchymatous respiration.

He studied regeneration in worms, amphibians and snails. It was concluded that regenerative capacity is proportional to age and younger organisms regenerate more effectively. He also studied microscopic organisms called Tardigrada in 1777 which are resistant extremophiles.

Contributions of Lazzaro Spallanzani

1. He provided the first systematic rebuttal of spontaneous generation theory. Broth was boiled extensively and when the flask was hermetically sealed microbes did not reappear. It was demonstrated that microbes are carried by air and this laid the foundation of sterilization and modern food canning process.
2. He discovered that digestion is mainly a chemical process rather than only mechanical grinding of food. Experiments were conducted on animals and even on himself to study gastric juice. It was shown that stomach juice has solvent action on food substances.
3. He was the first to show that fertilization requires both ovum and spermatozoa. The first in vitro fertilization was performed using frogs. Artificial insemination of a viviparous animal was also achieved when a dog was impregnated successfully.
4. Through experiments on bats it was observed that blinded bats can still fly and avoid obstacles. It was concluded that bats navigate by sense of hearing and not by eyes. This discovery explained animal echolocation.
5. After observing regeneration in worms, frogs and snails a principle was established. This is referred to as Spallanzani’s law of regeneration. It was stated that regenerative power is proportional to age and younger organisms regenerate more effectively than older ones.
6. He made important discoveries in respiration and circulation. It was demonstrated that tissues absorb oxygen and release carbon dioxide which is referred to as parenchymatous respiration. The role of heartbeats in creating arterial pressure was explained and connective tissues between veins and arteries was established.
7. He also contributed in geology and volcanology. Marine fossils found on mountains were studied by him. He ventured inside active volcanoes like Vesuvius, Etna and Stromboli to observe gas explosions and lava composition.

5. Martinus Beijerinck

Martinus Beijerinck was a Dutch microbiologist and botanist. He was born in Amsterdam in 1851. He studied chemistry at the Technical School of Delft and later earned his doctorate from the University of Leiden in 1877 and much of his career was devoted to teaching and research.

He is regarded as one of the founders of virology. In 1898 it was demonstrated by him that tobacco mosaic disease is caused by an infectious agent smaller than bacteria. Because it passed through bacteria proof filters and multiplied only in living plants it was named as virus and described as contagium vivum fluidum.

He developed the enrichment culture technique. This is a method by which specific microorganisms are isolated from mixed samples by adjusting nutrients and incubation conditions. This technique is regarded as fundamental in microbiology.

He made important discoveries in biological nitrogen fixation. It was shown that certain bacteria convert atmospheric nitrogen into forms usable by plants. Rhizobium from root nodules of legumes and Azotobacter, a free living nitrogen fixing bacterium was isolated by him.

He discovered that some bacteria can use sulfate instead of oxygen in anaerobic respiration. The first sulfate reducing bacterium, Spirillum desulfuricans, was isolated and this organism is now known as Desulfovibrio desulfuricans.

By studying the role of non pathogenic microbes in natural cycles he contributed in the development of microbial ecology. The importance of microbes in carbon, nitrogen and sulfur cycles was emphasized.

He was elected to the Royal Netherlands Academy of Arts and Sciences in 1885 and received the Leeuwenhoek Medal in 1905. A virology prize and the bacterial genus Beijerinckia were named in his honour.

He never married and believed that science and marriage are incompatible. He was known for strict and eccentric lifestyle and died in 1931 at the age of 79.

Contributions of Martinus Beijerinck

• He is regarded as the father of virology. In 1898 it was demonstrated by him that the agent causing Tobacco Mosaic disease can pass through porcelain filter which retains bacteria. The pathogen was described as contagium vivum fluidum and the term virus was coined to distinguish it from bacteria. It was also stated that it can multiply only inside living host cells.
• He developed the enrichment culture technique which is also referred to as selective culture. By manipulating nutrients and incubation conditions specific microorganisms were isolated from complex environmental samples. This method revolutionized microbiology and is widely used for microbial isolation.
• He made important discoveries in biological nitrogen fixation. It was shown that certain soil bacteria convert atmospheric nitrogen into usable forms for plants. Rhizobium (initially named Bacillus radicicola) was isolated from root nodules of legumes and Azotobacter such as Azotobacter chroococcum was also discovered as free living aerobic nitrogen fixing bacterium.
• He discovered bacterial sulfate reduction. It was demonstrated that some bacteria use sulfate as terminal electron acceptor instead of oxygen in anaerobic respiration. The first sulfate reducing bacterium, Spirillum desulfuricans (now Desulfovibrio desulfuricans) was isolated by him.
• By emphasizing that microbes act as geochemical agents in recycling nitrogen, sulfur and carbon he helped in founding microbial ecology. The environmental role of non pathogenic microorganisms was clearly established.
• Using enrichment techniques he isolated various important microorganisms including Lactobacillus species, sulfur oxidizing bacteria and green algae. He also studied lactic acid bacteria and yeast and contributed in understanding of microbial fermentation which benefited dairy and alcoholic beverage industries.

6. Ronald Ross

Ronald Ross was a British medical doctor and scientist. He was born in 1857 and later served in the Indian Medical Service. His work is mainly associated with the study of malaria and its transmission.

Before his research the cause of malaria was believed to be bad air from marshy places. On August 20, 1897 while working in Secunderabad the malaria parasite was identified inside the gut of an Anopheles mosquito. This day is referred to as Mosquito Day.

It was proved that the malaria parasite develops inside the mosquito and is present in the salivary glands. During mosquito bite the parasite is injected into the human host. This demonstrated that mosquito is the vector of malaria and not the marsh air.

Because of this discovery the prevention strategy was changed. Control of mosquito by draining stagnant water and use of mosquito nets was emphasized. These measures is considered as major step in control of malaria.

In 1902 the Nobel Prize in Physiology or Medicine was awarded to him for his work on malaria. He became the first British Nobel Laureate.

He was born in Almora and much of his research work was conducted in Calcutta and Secunderabad. His contribution in tropical medicine is regarded as very significant.

He also contributed in mathematics and literature. Pathometry which is the mathematical study of spread of infectious disease was developed by him. He wrote poetry, novels and plays and was also skilled in painting and music.

Contributions of Ronald Ross

• In 1897 the transmission of malaria was discovered by him. On August 20, 1897 in Secunderabad pigmented malaria parasites were identified in the stomach wall of an Anopheles mosquito which had fed on an infected patient. This discovery is referred to as Mosquito Day.
• Later through experiments on birds it was demonstrated that the parasite moves from the gut of mosquito to the salivary glands. During the bite the parasite is injected into the human host. It was proved that malaria is transmitted by mosquito and not by bad air or contaminated water.
• Because of this discovery the global strategy of malaria control was shifted from only treatment to vector control. Targeting and reducing mosquito population was emphasized. This is considered as scientific foundation of modern malaria prevention.
• He was pioneer in applying mathematics to infectious diseases. This field was referred to as pathometry. Mathematical models using differential equations were developed to describe relationship between mosquito population, human population and rate of infection.
• It was proposed by him that complete elimination of mosquito is not necessary. If the mosquito density is reduced below a critical level the transmission cycle can be broken. This concept is referred to as threshold theory.
• His mathematical work was later refined into the Ross-Macdonald model. This model is still used in studying mosquito borne diseases like dengue, Zika and West Nile virus. His contribution in mathematical epidemiology is regarded as very significant.
• He also contributed in public health and sanitation. Manuals were written on organizing mosquito brigades to drain stagnant water and apply oil to kill larvae. Malaria surveys and prevention programmes were conducted in Sierra Leone, Mauritius, Greece, Cyprus and Suez Canal zone.
• He served as professor at Liverpool School of Tropical Medicine and later founded the Ross Institute and Hospital for Tropical Diseases in London. His contribution in tropical medicine and public health is remembered.

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