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Survey of Microbes Part I: Important prokaryotes

Survey of Microbes Part I: Important prokaryotes. SHAPES: ____________ – spherical, ball shaped ____________ - rod _________________ – helical, comma (vibrio), twisted rod (spirillum, rigid with lophotrichous flagella), spirochete (flexible with periplasmic flagella) Also…

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Survey of Microbes Part I: Important prokaryotes

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  1. Survey of MicrobesPart I: Important prokaryotes

  2. SHAPES: • ____________ – spherical, ball shaped • ____________ - rod • _________________– helical, comma (vibrio), twisted rod (spirillum, rigid with lophotrichous flagella), spirochete (flexible with periplasmic flagella) • Also… • intermediate shapes like coccobacillus • cells can be thin (filamentous) • Cells can be pleomorphic (species can have >1 form such as Corynebacterium diphtheriae) But first… a word on shape, arrangement and size

  3. arrangements of bacteria • Pairs (2 like diplococci, diplobacilli) • Tetrads (4 cells in packet) • Sarcinae (balls or blocks of 8, 16, 32 cells) • Chains (streptococci; streptobacilli) • Clusters (Micrococcus, Staphylococcus) • Palisades arrangement (Corynebacteria)

  4. streptococci diplobacillus spirochete spirillum

  5. size

  6. Bacterial Taxonomy Based on Bergey’s Manual Bergey’s Manual of Determinative Bacteriology – five volume resource covering all known prokaryotes Classification based on genetic information –phylogenetic Two domains: Archaea and Bacteria Five major subgroups with 25 different phyla 7

  7. Major Taxonomic Groups of Bacteria Domain ____________ – primitive, adapted to extreme habitats and modes of nutrition Domain Bacteria: Phylum Proteobacteria – Gram-negative cell walls Phylum Firmicutes – mainly gram-positive with low G + C content Phylum Actinobacteria – Gram-positive with high G + C content 8

  8. Figure 4.27 Universal phylogenetic tree 9

  9. IMPORTANT GRAM POSITIVE BACTERIA

  10. Soil bacteria: • Bacillus • Clostridium (some pathogens) • Lactic acid bacteria: Lactococcus, Lactobacillus, Acidophilus • Several human pathogens: • Staphylococcus (S. aureus) • Streptococcus (S. pyogenes, S. pneumoniae) • Mycobacterium (M. leprae and M. tuberculosis) • Corynebacterium • Listeria monocytogenes • Others: • Propionibacterium • Streptomyces • Mycoplasma! (no cell wall, but it’s grouped with G+) Important Gram positive bacteria

  11. 1a.) Gram + cocci • Genus: staphylo=“grape clusters” • S. epidermidis – opportunistic pathogen; no virulence factors; natural flora • S. aureus – hemolytic, coagulase, invasive; flora of the nose but still a pathogen • Many diseases: endocarditis, pneumonia, meningitis, arthritis, intoxications such as ______________________ and food poisoning; more often cuteneous: • pimples/boils/abscesses/carbuncles, pink eye • scalded skin syndrome, • impetigo. Staphylococcus

  12. BOIL Strep. pyogenes? IMPETIGO SCALDED SKIN SYNDROME CARBUNCLE Endocarditis

  13. 1a.) Gram + cocci --Staph Pathogenic effects: mostly associated with ________________________ Prevents bacteria from being cleared from host • Diagnostic marker • localized clotting • Kills leukocytes so • that bacteria are • not phagocytosed • Form pus and acne Virulence factors of Staph

  14. Current estimate: >60% of hospital acquired S. aureus infections are MRSA Many strains are MDR!!

  15. Percentage of Staphylococcus aureus isolates resistant to methicillin in national surveys, United States, 1999–2004. TSN, The Surveillance Network (data include hospital infections); NNIS, National Nosocomial Infections Surveillance System (data include only intensive care units); SENTRY, includes only skin and soft tissue infections. (source: Klein et al. 2007. EID)

  16. Hospitalizations and Deaths Caused by Methicillin-Resistant Staphylococcus aureus, United States, 1999–2005 Figure 1. Estimated methicillin-resistant Staphylococcus aureus (MRSA)–related hospitalization rates, United States, 1999–2005. Rates are no. MRSA-related discharges/1,000 hospitalizations. Error bars represent 95% confidence intervals. (source: Klein et al. 2007. EID)

  17. 1a.) Gram + cocci • Group A Strep = ____________ • Strep throat, pharyngitis • Secondary: Scarlet fever (systemic rash); Rheumatic fever (heart valves, arthritis) • Cuteneous infections: Impetigo (older children), pyoderma, acne, Erysipelas – AKA “St. Anthony’s Fire”; Toxic shock syndrome • ________________________ ; “flesh eating bacteria” • All are mediated by various virulence factors – esp. ____________ Streptococcus

  18. 1a.) Gram + cocci --Strep Strep throat Strawberry tongue – Scarlet fever

  19. 1a.) Gram + cocci --Strep • Streptococcal toxic shock syndrome (STSS), causes blood pressure to drop rapidly and various organs to fail. About 20% of patients with necrotizing fasciitis and more than half of those with STSS will die. Generally, the mortality rate for other forms of invasive group A streptococcal disease is 10-15%. Streptococcus

  20. PYODERMA (S. aureus or S. pyogenes)

  21. 1a.) Gram + cocci --Strep • ____________ : due to secretion of many enzymes and toxins including: • ____________ : lyse red blood cells • ____________ : breaks down collagen (cement of connective tissue: helps organism spread) Virulence factors of Strep

  22. 1a.) Gram + cocci --Strep • ________________________: causes dental caries (cavities) • ____________________________ (often called pneumococcus) • carried in upper respiratory tract and nasopharynx of humans • 15% of children and 5% of adults are “carriers” • grow in pairs (NOT in long chains) • most common cause of pneumonia and otitis media (middle ear infection) Other pathogenic Streptococci

  23. 1b.) Gram + rods --Clostridium • ____________ ____________ (cannot grow in oxygen) • rod shaped bacteria • contain ____________ : resistant to heat and chemicals; spores are introduced into injury or anaerobic wound or ingested (botulism) • spores germinate and active bacteria multiply Clostridium

  24. 1b.) Gram + rods --Clostridium • C. tetani: ____________ • neurotoxin: called tetanospasmin (a dot the size of a period-kills 30!) • blocks muscles relaxation: muscles spasm and contract • contractions: tear muscles/cause compression fraction of vertebrae • death from spasms of respiratory muscles • vaccine (DPT): inactivated toxin used to stimulate antibodies • C. difficile: ____________ ____________ • often caused when antibiotic therapy alters microflora in intestines • and allows for growth of this organism • C. perfringens: causes ______________________ (severe tissue death); also foodborne diarrhea Medically important species

  25. C. botulinum: ____________________ . • grows in anaerobic environments (canned foods): discard bulging cans! • Produces toxin: MOST potent of ALL toxins: specific for nerve endings (synapses) • Blocksacetylcholine (neurotransmitter): nerve impulses blocked! • Botulism disease progression: • Initialsymptom: blurredvision and nausea flaccidparalysis: respiratory and cardiac failure • slowrecovery: nerve endings regenerate; respiratory support: antibiotics are of no use! • Prevention: Toxin is destroyed by boiling and nitrites in food prevent bacterial growth • A word about commercial use of BOTOX: • prevent wrinkles – maybe, BUT… • strasbismus: crossed eyes • blephorospasm: inability to keep eyelids open Medically important species

  26. commonly found in soil • produces ____________ Medically important species of Bacillus • ____________________: anthrax disease of cattle, sheep and humansTwo forms of anthrax: • ____________(skin): transmitted through a break in the skin • cause pustule or lesions: tissue dies, crusts and falls off • systemic (bloodstream): shock/ collapse • ____________(pulmonary): transmitted by inhaling anthrax spores • starts as pneumonia, high fever then septicemia, respiratory distress, death • biowarfare agent: spores can be spread in aerosols • no spread from persontoperson! • penicillin effective if given early Bacillus

  27. Cutaneous anthrax – note BLACK lesions Anthrax sepsis due to inhalation anthrax (now involving eye) Woman was exposed to animal hides; Pennsylvania 2006 Inhalation anthrax on x-ray; Patient died next day.

  28. 1b.) Gram + rods --Bacillus • Bacillus ____________ : food poisoning often from starchy food especially rice • Bacillus thuringiensis: insect pathogen produces delta endotoxin in crystal form insect eats toxin crystals and dies • sold for plant treatment as pesticide • transgenic plants engineered to produce toxin • Bacillus subtilis: produces bacitracin • Bacillus polymyxa: produce polymixin Bacillus (cont’d)

  29. 1b.) Gram + rods Mycobacterium ____________________________________ Acid-fast stain – mycolic acid; Slow growing • Leprosy:mainly affects the skin, peripheral nerves, upper respiratory tract. • discovered by G.A. Hansen in 1873; first bacterium to be identified as causing disease in man. • contagious, but not widespread because 95% of the population have competent immune systems. • TB: causes tubercles in lungs, bones; poor health, crowding plays a role (communicable); • leading cause of death in the world from a single infectious disease! • affects 1.7 billion people/year which is equal to one-third of the entire world population! Mycobacterium

  30. TB – cavitation, and calcified tubercle

  31. 1b.) Gram + rods --others • ___________________ - C. diphtheriae: causes diphtheria – DPT vaccine -pseudomembrane on tonsils -strong toxin – can destroy heart • ______________________– food poisoning; outbreak in hot dogs; intracellular pathogen Other pathogens

  32. Pseudomembrane: necrosis, plasma, fibrin and bacteria Pallisades arrangement of Corynebacterium Can be pleiomorphic

  33. Propionibacterium, Brevibacterium - swiss cheese, bacterial acne, stinky feet; propionic acid and sulfur compounds • Streptomyces - antibiotic production: • erythromycin, neomycin, streptomycin, tetracycline • ____________– normal flora in gut and vagina • found in yogurt, cheeses (mozzarella, cheddar, provolone) Nonpathogenic, but important!

  34. naturally lack a cell wall • stabilized by sterols, resistant to lysis • extremely small (0.1 – 0.5 µm) • range in shape from filamentous to coccus or doughnut shaped • ____________ ____________ • Mycoplasma ____________ – atypical pneumonia in humans (“walking pneumonia”) ____________

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