L11 Medically Important Bacteria Part 1 PDF

Intro to Agricultural Microbiology PHAR2921 COMMONWEALTHOFAUSTRALIA Copyright Regulation...

Intro to Agricultural Microbiology PHAR2921 COMMONWEALTHOFAUSTRALIA Copyright Regulation WARNING Medically-important This material has been reproduced and communicated to youbyor onbehalf of the University of Sydney pursuant to Part VBof the Bacteria Part 1. CopyrightAct 1968(the Act). Thematerial in this communication may be subject to copyright Gram negatives under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under theAct. Donotremovethis notice Dr. Angela Sun [email protected] Page 345 Diversity of bacteria – Gram negatives Learning Outcomes. Be able to… Discuss the importance of bacteria in medicine and human disease, with specific reference to examples Name eight different medically-relevant Gram- negative bacteria, and describe: - their phylogeny - their microscopic morphology - their normal habitat - the human disease(s) caused - any distinctive/ unique features Page 346 Diversity of bacteria – Gram negatives 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 347 Revision: How are Bacteria Classified? Phenetic (phenotype): – Gram reaction and morphology – Carbon sources, energy sources – Electron acceptors (eg. aerobic/anaerobic) Phylogenetic (genotype): – Ribosomal RNA sequence – Other DNA, RNA, protein sequence Page 348 Classification of bacteria… In *this* 2-lecture set, the bacteria will be organised by their phylogeny – a systematic approach Phenotypes will be discussed also, where this is important for identification or pathogenicity In some cases, systematics agrees with phenotype, eg. all endospore formers are Gram positive In other cases, the classifications disagree, eg. anaerobic growth occurs in diverse bacteria Both approaches are useful – it depends on the question being asked ! Page 349  Phylogenetic tree of the Bacteria Tree based on alignment   Bacteroidetes 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 350 Tree adapted from Brock Diverse Gram-negative bacteria can cause disease Proteobacteria Phylum Escherichia Genus Salmonella Vibrio Pseudomonas Neisseria Rickettsia Bacteroidetes Bacteroides Spirochaetes Treponema Page 351 Escherichia Facultative anaerobic, heterotrophic, G-ve rods Found in gut of humans and animals Part of family Enterobacteriaceae: contains many other pathogens: Salmonella, Klebsiella, Yersinia Widely used in microbiology as a model organism (E. coli) Motile by peritrichous flagella Polar flagellum Peritrichous flagella. eg. Pseudomonas eg. E.coli Page 352 Escherichia E.coli Most strains are normal flora, and beneficial eg. E.coli K12 biosynthesizes vitamin K Some strains pathogenic; these are food or water- borne pathogens O157 – infection by animal food, O111 Symptoms - diarrhoea, fever Virulence factors: endotoxin (all G-), enterotoxin (some) Salmonella Facultative anaerobic, heterotrophic, G-ve rods Normal flora in animal gut, pathogenic to humans S.enterica: food-borne infection, self-limiting diarrhoea S.typhi: water-borne, typhoid fever, potentially fatal Virulence factors: endotoxin, enterotoxin, cytotoxin Salmonella enterica False-colour transmission electron micrograph peritrichous flagella → motile! Page 354 Identifying Enterobacteriaceae Selective + differential agars for identifying Enterobacteriaceae E.coli on XLD Salmonella on XLD - lactose positive - lactose negative - H2S negative - H2S positive Vibrio Facultative anaerobic, heterotrophic, G-ve curved rods Motile, various flagella arrangements Habitat is primarily marine, but can cause gut infection V. cholerae The most pathogenic Vibrio species – causes cholera: severe diarrhoea -> transmission – virulence factor: cholera toxin (an exotoxin) – common in sewage contamination Page 355 TEM of V.cholerae; curved cell, polar flagellum, bundles of pili Vibrio V. cholerae Transmission usually by faecal contamination of water → How do the symptoms of cholera help its transmission? V.cholerae is more rarely a food-borne disease (seafood) SMH 16/3/98 Page 356 Pseudomonas Aerobic, heterotrophic G-ve rods, motile (polar flag.) Ubiquitous in soil and water, opportunistic pathogens Large genome (6 Mb) → Metabolically versatile P. aeruginosa Nosocomial infection (hospital acquired) – esp. burns. Virulence factors: innate antibiotic resistance (low membrane permeability), haemolysin, proteases P.aeruginosa infection  from contact lens in burned skin tissue → Page 357 Pseudomonas P. aeruginosa Virulence factors innate antibiotic resistance (low membrane permeability) Haemolysin Proteases Page 357 Pseudomonas P. aeruginosa Aust. Doctor 19/10/01 eg. Nosocomial infection: P. aeruginosa transmitted * from nurse’s finger nail to many heart surgery patients Metabolic versatility helps P.aerug. to colonise diverse niches (eg. fingernail, heart) * P.aeruginosa infections are common, but person- person transmission is rare Page 358 Neisseria Aerobic, heterotrophic, G-ve diplococci Habitat: mammalian mucous membranes Carrier - Back of throat, nose Pathogenic species – N. gonorrhoeae → Causes ??? – N. meningitidis → Causes ??? Page 359 https://microbenotes.com/differences-between-neisseria-meningitidis-and- neisseria-gonorrhoeae/ Neisseria Virulence factors – capsule: evasion of immune response – fimbriae: adhesion to tissues Pathogenic species – N. gonorrhoeae → gonorrhoea – N. meningitidis → meningitis (meningococcal disease) N.meningitidis cells adhering to cilia in the respiratory tract SEM Neisseria N.meningitidis Meningitis: inflammation of meninges (membrane around brain) → fever, rash, headache, confusion, death Serious, rapidly progressing disease – needs rapid diagnosis and treatment (antibiotics) Analysis: microscopic examination of CSF Crystal violet stain: both white blood cell nuclei and Neisseria cells appear purple Neisseria Lumbar puncture to white bloPao d cell ge 360 obtain cerebrospinal fluid Neisseria N.gonorrhoeae Gonorrhoea: a sexually transmitted disease collect urethral Diagnose by microscopic the happy couple exudate (pus) examination Safranin : epithelial cells Neisseria and Neisseria appear pink Note adherence of epithelial Neisseria cells to the cell epithelial cells Page 361 Rickettsia Aerobic, heterotrophic, G-ve, coccobacilli Cannot be grown in vitro – only in tissue culture. Bacteria are very dependent on host metabolism Intracellular parasites of arthropods – eg. fleas, lice, ticks Small ‘degenerate’ genome (1 Mb) → specialised lifestyle Related to mitochondrion – significance? Zoonotic Rickettsia inside a eukaryotic cell (from tick) Light micrograph, with carbol fuschin stain Page 362 1 m  Rickettsia Transmission to humans occurs via bites or faeces of arthropods → various fever diseases R.prowazekii → epidemic typhus – headache, fever, rash (up to 50% mortality) – overcrowded conditions → transmitted by body louse – virulence factors: adhesin, phospholipase Human body louse Pediculus humanus is a vector for spreading R.prowazekii Page 363 SEM Bacteroides Obligate anaerobe, heterotrophic, G –ve rods Normal flora, but can be opportunistic pathogens Bacteroides are most abundant cells in human body Several beneficial species: digestion of carbohydrates, exclude pathogens by competition (Salmonella) Bacteroides Gram stain Capsule stain→ Page 364 Bacteroides B.fragilis Opportunistic pathogen: cause infection if it escapes the gut eg. abcesses, septicemia, appendicitis Virulence factors: capsule, antibiotic resistance Salyers et al.(1995) J.Bact 177:5727 donor cell recipient cell Tcr: tetracycline resistance Exc: excision Tra: Transfer Int: integration Treponema Anaerobic, heterotrophic, G-ve, spirochaetes. Obligate parasites, require animal cells for growth Dark field microscopy of spirochaetes Spirochaete cell structure Page 366  Use axial filament for structure and corkscrew motility Great to move through viscous fluid Treponema T.pallidum Causes Syphilis: a sexually transmitted disease (STD) Effects: 10: chancres, 20: rash, 30: nervous system damage Can’t be grown in standard media ‘Degenerate’ small genome (1 Mb) they’re at it again! collect sample from Page 367 Silver stain of T.pallidum cells chancres (sores) References Prescott ‘Microbiology’, 6th ed. Ch 21-22 Madigan et al. ‘Brock. Biol.of Microorgs’ Ch 12, 26, 27 Picture credits http://commtechlab.msu.edu/Sites/dlc-me/zoo/Pf07002.jpg http://www.globalhealth.org/view_top.php3?id=228 http://www.ebc.ee/MOLBIO/ribosome.jpg http://images.amazon.com/images/P/0683006037.01._SCLZZZZZZZ_.jpg http://www.science-shop.de/buecher/cover/138/13831227N.jpg http://www.bergeys.org/images/Bergey.gif http://www.jcn.co.uk/images/01-04-16-01.jpg http://www.nrc-cnrc.gc.ca/education/images/bio/gallery/bac_legionella.jpg http://www.bnr.nl/blobs/anp/28507.jpg http://www.gynae-centre.co.uk/images/Couple1.jpg http://www.boltonlgb.co.uk/images/stds/gonorrhea-1.jpg http://nfs.unipv.it/nfs/minf/dispense/immunology/pertox1.jpeg http://textbookofbacteriology.net/B.pertussisGram.jpeg http://en.wikipedia.org/wiki/Klebsiella http://www.cdc.gov/ncidod/dvbid/images/bubo.jpg http://www.cdfe.org/cholera.jpg http://remf.dartmouth.edu/images/BacteriaCholeraTEM/image/o395_wt_cholera_wild_type.jpg http://www.ecbt.org/images/HibL.jpg http://www.brown.edu/Courses/Bio_160/Projects1999/bmenin/images/H.influenzae.gif http://vietsciences.free.fr/khaocuu/nguyenlandung/images/Bacteroides.jpg http://www.festered.com/vd.jpg http://biology.kenyon.edu/Microbial_Biorealm/bacteria/leptospira/humanlepto.jpg Page 368 Picture credits…cont… commtechlab.msu.edu/sites/dlc-me/zoo/zdrs0232.jpg www.apsnet.org/online/Archive/1998/cepacia.jpg http://www.kbfi.ee/upl/pildid/ecotox/CuO_1h.jpg http://www.ufz.de/data/8250 www.nsf.gov/news/mmg/media/images/squid1_f1.jpg www.vet.uga.edu/VPP/clerk/otis/Fig4.jpg http://commtechlab.msu.edu/sites/dlc-me/zoo/zdrr0101.jpg http://ag.udel.edu/plsc/events/img/Rhizobium-in-pea-plant2.jpg http://www.ehleringer.net/Biology_5470/Images/rhizobium.gif www.nre.vic.gov.au/.../VIDA+clover+roots.jpg Schultz et al. (1999) Science 284:493 Page 369