microbiology

• 1.3:1 bacterial:human cells
• microbes affect all life and are 90% of earth's biomass
• Microbes are the earliest forms of life, they cycle carbon, nitrogen, sulphur, hydrogen and oxygen. They regulate and affect plant & animal growth
• We use microbes in food production (bread, cheese, wine), nutrient absorption (bowel flora break down things to produce vitamin k), commercial applications (food and biopharmaceutical production eg insulin)
• There are bacteria, fungi, parasites and viruses cause disease. Historically important cause of death. Modern engineering, immunisation and antibiotics have reduced that impact
• microorganism = life form invisible to the naked eye (bacterium, virus or fungus)
• microbiota (microorganisms of a particular niche or geological period)
• microbiology (scientific study of microorganisms)
• Clinical Microbiology = application of scientific study to the observation and treatment of patients
• Infectious Diseases = disease caused by microorganisms
• Clinical Infectious Diseases = internal medicine subspecialty concerned with patients with infections
• Prehistory-1850 = death in all phases of life common, low life expectancy, infections, trauma, epidemics --> didn't know about microbial life. 1546 - Fracastoro said spores (invisible chemical particles) cause disease
• Robert Hooke --> 1665 first person to observe fungi under magnification, published a book --> coined the term cell
• 1676 - Antony Van Leeuwenhoek invented to first microscope which allowed for observation
• 1796 - Edward Jenner observed milkmaids contracted cowpox but didn't get smallpox, so invented the first vaccine. (inocculation)
• 1847 - semmelweis --> figured out that puerperal fever (childbirth associated infection) is contagious. Vienna General Hospital. Issue was students not cleaning hands between autopsies and examining women in labour. Figured out by morgue worker dying after pricking himself, presenting with same symptoms. Introduced antiseptic hand wash (chlorinated lime) --> infection and mortality fell
• 1853 - john snow --> figured out cholera outbreak in soho region was spread by vomiting and diarrhoea. Traced it to a pump that had cholera nappies in cesspit leaking into waterpipes.
• Louis Pasteur - 1857 - fermentation

  1861 - refutes theory of spontaneous generation

  1885 - anthrax and rabies vaccines
• 1867 - joseph lister cleaned equipment with carbolic acid --> reduction in surgical infection --> invented antiseptic surgery
• Robert Koch - 1876 - found anthrax caused by a bacterium +TB(1882). 1881 introduced pure culture techniques for handling bacteria. 1884 Postulates
• 1892 - Ivanovski - proposed that tobacco mosaic disease was caused by a bacterium or a filterable toxin --> filtered sap was still transmitting disease. 1898 Beijerinck proposed it was spread by a smaller, simpler reproducing particle --> VIRUS
• GOLDEN AGE OF ANTIBIOTIC DISCOVERY --> 1929 fleming penicillin. 1935 Domagk sulphonamides. 1945 duggar isolates tetracycline. 1947 langham isolates chloraphenicol. 1952 bunch and McQuire isolate erythromycin. 1952 kornfield isolates vancomycin
• Age of molecular genetics (1941-present)
• 1944 Lederberg and Tatum determined DNA could be tranferred between bacteria. Important because they're masters of adaptation --> new DNA picked up to instantaneously create a new phenotype = more pathogenic
• 1953 Watson, Crick, Franklin and Wilkins determine DNA structure (double helix)
• 1970 Hamilton Smith reports first restriction enzyme
• 1983 Mullis invents the polymerase chain reaction
• 1995 first complete nucleotide sequence of a bacterial chromosome (haemophilus influenzae)
• 2003 - Human genome project 13 years 3 billion. 2007 - full diploid genome of James D. Watson sequenced in 2 months <$1 million. 2013 - Human genome in a couple of days $2000
• 21st century headed toward a potential post-antibiotic era. 2000 linezolid first new antibiotic in 35 years
• not developing antibiotics fast enough to keep up with antibiotic resistant infections because it is not financially incentivised
• lack of drugs + loss of resistance = antibiotic issues
• Three Kingdom System: Eucaryotes, Procaryotes = archaea (extremity) + bacteria (these cause clinical infections)
• microorganisms important to humans = bacteria, viruses, fungi, parasites, prions (self-replicating proteins)
• Two types of prokaryotes (bacteria) = eubacteria (relevant) and archaeabacteria. Classified according to phenotype (size, shape, biochemical properties) and genotype 16S rRNA genes - very species specific
• bacteria have no membrane bound organelles, no nucleus, single chromosome (circular), haploid, cytoplasmic membrane, periplasmic space, can have an outer membrane, flagellum for attachment
• Gram stain: Gram positive (cytoplasm, cytoplasmic membrane, cell wall = peptidoglycan) THICK vs negative (membrane, peptidoglycan THIN, periplasmic space additional outer membrane). Dye is crystal violet (stains cell wall purple)
• Gram-positive bacteria thick cell wall 50-90% peptidoglycan, stains purple. Gram-negative bacteria thin cell wall 10% peptidoglycan, counterstained pink.
• Viruses contain a single type of nucleic acid (DNA OR RNA, not both), this is surrounded by a capsid (protein coat). May also have an envelope they derive from host cell. They multiply inside living cells using host cell machinery (few enzymes of their own, synthesize capsid that facilitates transfer of nucleic acid into host cell
• Fungi are eukaryotic, multicellular (except yeast). They have setrols in cell membrane and no peptidoglycan --> instead glucans, mannans and chitin in cell walls