History of Microbiology

• • • • • History of Microbiology Prehistory – 1850 (before microbial life was known) o Death in all phases of life was common, low life expectancy, infections with trauma, epidemics o 1546 – Fracastoro proposed that invisible particles cause disease o 1676 – Antony Van Leeuwenhoek invented the first microscope o 1796 – Edward Jenner created the first vaccine (smallpox) o 1847 – Semmelweis proposed that puerperal fever is a contagious disease ▪ Infection was related to students not effectively cleaning their hands between performing autopsies and examining women in labour ▪ Introduced antiseptic hand wash using chlorinated lime (infection + mortality rates fell) 1853 – John Snow (Father of Epidemiology) traced the source of a cholera outbreak to the Broad Street drinking water pump in Soho, London o Sudden epidemic with immediate digestive problems (cramps, vomiting, diarrhoea) o Face, feet and hands shrivelled – died in less than a day o Probably spread by vomiting and diarrhoea Pasteur: 1857 – fermentation, 1861 – refutes theory of spon gen, 1885 – immunisation against rabies 1867 – Joseph Lister invents antiseptic surgery Robert Koch: 1876 – anthrax due to a bacterium, 1881 – introduces pure culture techniques for handling bacteria, 1882 – identifies causative agent of tuberculosis, 1884 – Koch’s postulates Discovery of viruses • 1892 – Ivanovski proposed that tobacco mosaic disease was caused by a bacterium or a filterable toxin however filtered sap still transmitted disease to healthy plants • 1898 – Beijerinck proposed that the disease was caused by a reproducing particle much smaller and simpler than a bacterium → demonstrated that the infectious agent in filtered sap could reproduce Antibiotic discovery • 1929 - Fleming discovers the first antibiotic penicillin • 1935 - Domagk discovers sulphonamides • 1945 - Duggar isolates tetracycline • 1947 - Langham isolates chloramphenicol • 1952 - Bunch and McQuire isolate erythromycin • 1952 - Kornfield isolates vancomycin Age of molecular genetics (1941 – present) • 1944 – Lederberg and Tatum determined that DNA could be transferred between bacteria • 1953 - Watson, Crick, Franklin and Wilkins determine the structure of DNA • 1970 - Hamilton Smith reports first restriction enzyme • 1983 - Mullis invents the polymerase chain reaction • 1995 - The first complete nucleotide sequence of a bacterial chromosome is reported o Haemophilus influenzae • 2003 - Human Genome Project complete → 13 years and $3 billion • 2007 - Full diploid genome of James D. Watson sequenced → 2 months and <$1 million • 2013 - Human genome in a couple of days ($2000) 21st century – potential post-antibiotic era • 2000 - FDA approves linezolid, the first new antibiotic class in 35 years • In a recent survey of infectious disease specialists 60% reported encountering infections resistant to every antibiotic e.g. Klebsiella pneumoniae, MRSA Classifying microorganisms • Three-kingdom system (no longer used) – bacteria, archaea, eucaryota • Today: bacteria, viruses, fungi, parasites, prions Bacteria • Two types of prokaryotes (bacteria) → eubacteria and archaeobacteria • Classified on basis of: o Phenotype – size, shape, biochemical properties… o Genotype – 16S rRNA genes Gram stain reactions • Gram positive bacteria = thick cell wall (50-90% peptidoglycan) → stains purple • Gram negative bacteria = thin cell wall (10% peptidoglycan) → stains pink