L12 Medically Important Bacteria 2 PDF

Intro to Agricultural Microbiology COMMONWEALTH OF AUSTRALIA PHAR2921 Copyright Regulation WARNING This material has been...

Intro to Agricultural Microbiology COMMONWEALTH OF AUSTRALIA PHAR2921 Copyright Regulation WARNING This material has been reproduced and communicated to you by or on behalf of the University of Sydney pursuant to Part VBof the Copyright Act 1968 (the Act). Medically-important The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this Bacteria Part 2. material by you may be the subject of copyright protection under the Act. Gram Positives Do not remove this notice Dr. Angela Sun [email protected] Page 370 Diversity of bacteria – Gram positives Learning Outcomes. Be able to… Discuss the importance of bacteria in medicine and human disease, with specific reference to examples Name six different medically-relevant Gram-positive bacteria (and one G-ve), and describe: - their phylogeny - their microscopic morphology - their normal habitat - the human disease(s) caused - any distinctive/ unique features Page 371 Diversity of bacteria – Gram positives Relevant Unit of Study learning outcomes LO1: understand the microbial world and its relationships with other forms of life and the environment LO2: describe and understand organism structures, functions, and bio-relationships (in humans and the environment) of major microbial groups (e.g., bacteria, fungi, viruses, protozoa) LO3: for each microbial group, describe the pathological processes of infection in humans Page 372  Phylogenetic tree of the Bacteria Bacteroidetes Tree based on alignment of 16S rRNA sequences Bacteroidetes Spirochaetes Verrucomicrobia Deinococcus/ Green sulfur Thermus bacteria Planctomycetes Green non-sulfur bacteria Chlamydia  Cyanobacteria Thermotoga Actinobacteria  Firmicutes  Thermodesulfobacterium Nitrospira  Proteobacteria Aquifex     Bacterial names shown are phylum -level groups Page 373 Tree adapted from Brock Both Gram + and – bacteria are medically-important –Chlamydiae GRAM Chlamydia NEGATIVE – Firmicutes Bacillus Clostridium Lactobacillus GRAM BACTERIA Staphylococcus POSITIVE Streptococcus – Actinobacteria Mycobacterium Page 374  Chlamydia Aerobic, heterotrophic, G-ve cocci Obligate intracellular parasites of humans & animals Cause sexually-transmitted disease and eye infection Cannot be grown on agar, small genome (1 Mb) consistent with host-dependence An ‘energy parasite’ – dependent on host cells for ATP and other metabolites Chlamydia in eukaryotic cells, x7000 Phillips DM, Swenson CE, Schachter J. Ultrastructure of Chlamydia trachomatis infection of the mouse oviduct. J Ultrastruct Res. 1984 Sep;88(3):244-56. doi: 10.1016/s0022-5320(84)90122-9. PMID: 6544879.  Chlamydia C.trachomatis Causes urethritis (STD) and trachoma (eye infection) Prescott Can you get chlamydia from Koala? Hypertrophy of eyelids in trachoma Chlamydia is serious pathogen for koalas Chlamydia Virulence factors – unusual cell wall allows growth inside phagocytes – has no peptidoglycan → intrinsic resistance to all antibiotics targeting PG. http://microbialcell.com/researcharticles/2019a-bugalhao-microbial-cell/ Gram positive bacteria: Phlyum Firmicutes, Phylum Actinobacteria Distinguished from Gram negatives by thicker peptidoglycan and lack of outer membrane Divided into Firmicutes (Low GC) and Actinobacteria (High GC) groups; “GC” means %GC content of DNA Firmicutes - facultative anaerobic rods or cocci - some make endospores Actinobacteria - aerobic rods or filaments, - some make exospores (eg. Streptomyces, see antibiotics lecture) Page 377 Firmicutes: Gram-positive rods May be facultatively anaerobic or strictly anaerobic Contain both normal flora and pathogenic species – Lactobacillus Normal flora – Bacillus primarily soil organisms some are pathogens – Clostridium Bacillus anthracis Page 378 Bacillus Facultative anaerobic, heterotrophic, G+ve rods Ubiquitous in environment, esp. soil Transient flora on skin Older / starving / stressed cells make endospores Page 379 Bacillus spore stain shows endospores (green) and vegetative cells (red) Bacillus B. anthracis Causes anthrax: highly infectious and deadly disease Usually zoonotic: transmitted from animals (cattle, sheep) Possible bioterrorism agent due to stable endospores Plasmid-encoded virulence factor: exotoxin 1. “protective antigen” heptamer: makes pore in target cell 2. “edema factor” and “lethal factor”: enter cell, disrupt signalling pathways → Anthrax exotoxin – three secreted proteins work together to kPagiell380cells  Bacillus “Anthrax” can present in three different ways: Cutaneous: common, ~20% mortality Gastrointestinal: rare, ~50% mortality Pulmonary: rare, ~80% mortality All potentially treatable with antibiotics: eg. ciprofloxacin cutaneous anthrax, eschar lesion Page 381 pulmonary anthrax, lung necrosis Bacillus SMHPa1ge3382/2/97 Clostridium Anaerobic, heterotrophic, G+ve rods with endospores Habitat: Soil, human and animal gut Some species are normal flora, some are pathogens Pathogenic clostridia make potent exotoxins - C. tetani → tetanus - C. botulinum → botulism Phase contrast microscopy of C.tetani. Note refractive endospores that cause terminal swelling of cells Page 383 Cranston, 1947 Clostridium C.tetani Tetanus: muscle rigidity, death due to respiratory failure Virulence factor: tetanospasmin, an exotoxin Requires deep wounds to multiply (NB. anaerobic!) Common-source disease, not a contagious disease Source: soil / manure, inoculated into puncture wound “Tetanus Following Gunshot Wounds," 1809. By the surgeon and artist Sir Charles Bell, the painting depicts a soldier suffering from tetanus. Tetanospasmin is a neurotoxin : blocks transmission of ‘relaxation’ signal to muscles → body rigidity, death from respiratory paralysis  Clostridium C. botulinum Causes botulism, a dangerous type of food poisoning (common-source disease) Lives in soil. Spores enter food chain, persist thru processing, germinate in food (anaerobic, neutral pH) Virulence factor: botulinum toxin (BOTOX) – the most deadly poison known, lethal dose ~1 microgram before after Despite extreme toxicity, BOTOX Botulinum causes flaccid paralysis of is used in cosmetic mePdagiec38i5 ne muscles - opposite to tetanospasmin  Lactobacillus L. acidophilus Facultative anaerobic, heterotroph, G+ve non-sporing rods Normal flora of mouth, gut, vagina; non-pathogenic Probiotic effect? Competition with pathogens in gut Cheese + yoghurt production: lactic acid fermentation Lactobacillus  gram stain as probiotic → Page 386 Prescott Gram-positive cocci All are non-motile, and either aerobic or facultative Contain both normal flora and pathogenic species Medically-important genera: – Staphylococcus Normal flora / potential pathogens – Streptococcus Staphylococcus aureus  normal flora here pathogen here → Page 387 Staphylococcus Facultative anaerobic, heterotrophic, G+ cocci - clumps. Habitat: human-associated, either as normal flora (skin, nose) or as pathogens (wound infection) Tough cell wall makes Staph. resistant to physical stress (eg. desiccation) → long survival in environment Resistant to salt – trait needed to survive on skin & nose Staphylococci on mannitol-salt agar: S.epidermidis: non-mannitol fermenting (red) S.aureus: mannitol-fermenting (yellow) Page 388  Staphylococcus S.aureus “Golden Staph” Opportunistic pathogen Infections: wound infections, boils, impetigo, toxic shock Nosocomial spread – hospital strains antibiotic resistant Morphology arrangement – Staph vs Strep Strep: chains →  Staph: clusters Cranston Brock Impetigo: skin infection of children, Page 389 S.aureus and/or Streptococcus.pyogenes Staphylococcus S.aureus “Golden Staph” Virulence factors: coagulase, exotoxins Coagulase as a diagnostic test https://microbiologyinfo.com/coagulase-test-principal-procedure-types-interpretation-and-examples/ Streptococcus Facultative anaerobic, heterotrophic, G+ve cocci in chains Habitat: mouth and gut of animals and humans Beneficial streptococci: –S.thermophilus: yoghurt + cheese production, normal flora Page 390 Streptococcus Harmful streptococci: –S.pyogenes: scarlet fever – contagious, mostly affects young children –S.pneumoniae: pneumonia https://www.nhs.uk/conditions/scarlet-fever/ Gram stain of sputum from pneumonia case: note G +ve cocci in pairs and short chains Page 390 Streptococcus S.pneumoniae Can cause pneumonia and meningitis Characteristic alpha-haemolysis reaction on blood agar: Virulence factors: capsule, haemolysin – encapsulated strains are 100,000 x more virulent! S.pneumoniae, blood agar S.pyogenes, blood agar Page 391 alpha-haemolysis (greening) beta-haemolysis (clearing) Streptococcus S.pneumoniae Virulence factors: capsule, haemolysin – encapsulated strains are 100,000 x more virulent! Actinobacteria: Streptomyces, Mycobacterium Aerobic Gram positive filaments or rods – Streptomyces Makes antibiotics – Mycobacterium Causes tuberculosis Streptomyces colonies powdery surface diffusible pigments Page 392 Mycobacterium Actinobacteria Aerobic, heterotrophic, G+ve rods Mycolic acids in cell wall → waxy layer → ‘acid fast’ stain Wax protects against stresses, incl. immune system. Pathogenic species ─ M.tuberculosis: tuberculosis (TB) ─ M.leprae: leprosy Page 393 SEM: Irregular rods in palisades  Mycobacterium M.tuberculosis Obligate pathogen of humans – no environmental reservoir One of the “Big 3” killer diseases of humanity Chronic infection of lungs: fever, coughing, weight loss Can be grown in vitro, but slow-growing and fastidious Virulence factors: ─ waxy cell wall gives resistance to many stresses, eg. antibiotics, macrophage Wrinkly colonies of M.tuberculosis on Lowenstein-Jensen agar Putting it all together…The Bacteria Classified by phenotype (morphology, nutrition, physiology) or by phylotype (ribosomal RNA seq.) Habitats and metabolism are exceedingly diverse Lack true organelles and true multicellularity, but can have complex structures, differentiation, life cycle Pathogens occur in many bacterial genera, can be closely related to normal flora, even same species. “Medically-significant” bacteria include pathogens, but also normal flora, and antibiotic-producers Page 395  References Prescott ‘Microbiology’, Ch 19 – 24, 39 Madigan et al. ‘Brock. Biol.of Microorgs’ Ch 12, 26, 27 Picture credits Cranston, L.R. (1947) Atlas of Bacteriology http://www.textbookofbacteriology.net/Bacillus.html http://webs.wichita.edu/mschneegurt/biol103/lecture20/anthrax_hand.jpg http://www.rcsb.org/pdbstatic/education_discussion/molecule_of_the_month/images/1acc-heptamer.gif http://www.weilovna.cz/tmp/tetanus.jpg http://www.rnceus.com/biot/botul.html http://microbes.historique.net/images/bot.jpg http://www.shorelaser.com/ClinPix/BTXPERI0.JPG http://mataglap.com/Images/sgng/nose.jpg http://www.textbookofbacteriology.net/S.pneumoniae.html http://webdb.dmsc.moph.go.th/ifc_nih/a_nih_1_001c.asp?info_id=933 http://www.keepfit.org.uk/images/yabs19.jpg http://www.masterviews.com/images/fruit_salad_03_by_Carin.jpg http://microbewiki.kenyon.edu/index.php/Image:Throat.jpg http://www.nlfb.de/boden/bilder/actinomycesk.jpg http://www.birthcontrol4u.com/poster.jpg http://images.usatoday.com/tech/_photos/2005/12/09/lice180.jpg http://i44.photobucket.com/albums/f38/DjJasonG/chlamydia.jpg http://biology.kenyon.edu/Microbial_Biorealm/bacteria/gram-positive/mycoplasma/Mhyo_cilia.gif Page 396 Picture credits…cont… http://www.acadweb.wwu.edu/courses/envr429-rm/Robin/images/envr429/6_anabaena_400x.jpg http://www.mdbc.gov.au/subs/information/mfat/images/species/algae.jpg http://en.wikipedia.org/wiki/Cyanotoxin http://www.ippc.orst.edu/dir/microbial/bt/crystal.gif http://www.igmors.u-psud.fr/images/Streptocolonie1.jpg http://web.umr.edu/~microbio/BIO221_2002/Methanobacterium_thermoautotrophicum_files/... http://genomenewsnetwork.com/articles/04_02/m_acetivorans_seq.shtml http://opm.phar.umich.edu/phpthumb/phpThumb.php?src=../images/proteins/1py6.gif&w=250&h=300 http://www.spacedaily.com/images/life-pyrococcus-furiosus-bg.jpg http://www.sanger.ac.uk/Projects/S_coelicolor/gfx/h4tkm1m.gif Page 397