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bacteria

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bacteria

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    1. Bacteria Professor Mark Pallen

    3. Importance of Bacteria Life is microbial! (to the first approximation) Micro-organisms colonise every environment on earth >80% of life’s history was bacterial You have more bacterial cells than human cells Microbes play a key role in the biosphere Pathogenic microbes globally are the most important cause of human disease and death

    4. Importance of Infection Decisive role in history Still major cause of death and misery worldwide Public anxieties Meningitis, Food poisoning Mad cow disease Emerging infections Hospital Infection Antibiotic-Resistant Superbugs

    5. Microbes in History

    6. Microbes in History

    7. Microbes in the News

    8. Microbes in the News

    9. Microbes in the News

    10. Microbes in the News

    11. Differences between Bacterial and Human Cells Bacterial cells No nucleus No intracellular organelles (but ribosomes) No introns (nearly) No junk DNA Plasmids, bacteriophage Human cells Nucleus Intracellular organelles (ribosomes subtly different) Introns Lots of junk DNA Viruses

    12. Tree of Life

    13. Size matters

    14. Bacterial cells

    15. Differences between bacteria and viruses Viruses Obligate intracellular parasites No ribosomes DNA or RNA, not both seen by EM 10-100s of genes Tangled phylogeny Bacteria Usually free-living, but can be parasites Ribosomes DNA and RNA seen by LM 100s-1000s of genes Natural phylogeny

    16. The Gram stain procedure

    20. Bacterial Growth Solid media or liquid media Agar plates, slopes, broth culture Atmosphere: Aerobic, anaerobic or microaerophilic Facultative or obligate anaerobes Usually at 37 degrees C Most clinically important bacteria grow overnight, or within a few days Mycobacteria can take months Some can not be grown

    21. Gram-Negative Rods Enteric Bacteria E. coli Salmonella Shigella Yersinia Pseudomonas Proteus Vibrio cholerae Klebsiella pneumoniae

    22. Gram-Negative Rods Fastidious GNRs Bordetella pertussis Haemophilus influenzae Campylobacter jejuni Helicobacter pylori Legionella pneumophila Anaerobic GNRs Bacteroides fragilis Fusobacterium

    23. Gram-Negative Cocci Neisseria gonorrhoeae The Gonococcus Neisseria meningitidis The Meningococcus Both Gram-negative intracellular diplococci

    24. Gram-positive Cocci Staphylococci Catalase-positive Gram-positive cocci in clusters Staphylococcus aureus coagulase-positive Staph. epidermidis and other coagulase negative staphylococci

    25. Gram-Positive Cocci Streptococci Catalase-negative Gram-positive cocci in chains or pairs Strep. pyogenes Strep. pneumoniae Viridans-type streps Enterococcus faecalis

    26. Gram-Positive Rods Clostridia Anaerobes C.perfringens C. tetani C. botulinum C. difficile Bacillus cereus Aerobe Listeria monocytogenes Faculative anaerobe

    27. Non-Gram-stainable bacteria Unusual gram-positives Spirochaetes Obligate intra-cellular bacteria

    28. Unusual Gram-positives Mycoplasmas Smallest free-living organisms No cell wall M. pneumonia, M. genitalium Mycobacteria Acid-fast bacilli, stained by Ziehl-Neelsen stain M. tuberculosis M. leprae M. avium

    29. Spirochaetes Thin spiral bacteria Viewable by phase-contrast microscopy or silver stain Treponema pallidum Borrelia burgdorferi Leptospira

    30. Obligate intracellular bacteria Rickettsia Coxiella burneti Chlamydias C. trachomatis C. pneumoniae C. psittaci

    31. Outline Importance of bacteria Nature of bacteria Classification of bacteria Gram-positive versus Gram-negative Rods and Cocci Aerobic versus anaerobic

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