Classification of Bacteria

1. Classification of Bacteria

2. Taxonomy The science of classification

3. Haeckel’s 3 Kingdoms • Plant • Animal • Protista

4. Carl Woese’s 3 Domains Based on rRNA nucleotide sequencesWhy use this as a basis for classification?

6. Organisms in the 3 Domains • Eukarya - kingdoms: plantae, animalia, fungi, protists • Archaea - prokaryotes • Bacteria - prokaryotes

7. 2 Types of Prokaryotic Cells • Eubacteria • cell walls contain peptidoglycan • different nucleotide sequences in rRNA • different membrane lipids • Archaebacteria • no peptidoglycan • rRNA • lipids • live in extreme environments ex. Thermoacidophiles Extreme halophiles Methanogens http://www.ucmp.berkeley.edu/archaea/archaea.html

8. Comparison of Archaea, Bacteria & Eukarya

9. Naming organisms (nomenclature) Binomial system uses 2 names Genusspecies ex. Bacillus subtilis ex. Clostridium tetani ex. Staphylococcus aureus Is tubercle bacillus the scientific name of an organism or a common name?

10. 3. Phylogenetic Classification • An evolutionary arrangement of species. • Sharing a recent ancestor as in plants and animals (fossil records) • In bacteria? • Possible by Molecular Methods • Genetic Homology: • Base composition (GC ratio) • Nucleic acid hybridisation. • Ribosomal RNA (rRNA) sequence analysis • Protein profiles and amino acid sequences

11. PURE CULTURE: • Populations of individuals all derived from the same single organism. • STRAIN: • A Group of Pure Cultures Derived from a Common Source and Thought to be the Same. • SPECIES: • A Group of Closely Similar Strains.

12. INTRASPECIES CLASSIFICATION • Biotypes • Biochemical properties. • Serotypes • Antigenic features. • Phage Types • Bacteriophage susceptibility. • Colicin Types • Production of bacteriocins.

13. Species of bacteria - “population of cells with similar characteristics” Strain of bacteria - “group of cells derived from a single cell” ex. Staphylococcus aureus 13578

14. Naming of microorganisms. • Governed by international rules • Rules published in the International Code of Nomenclature of Bacteria. • The International Journal of Systematic Bacteriology

15. Rules for the Nomenclature of Microorganisms • There is only one correct name for an organism. • Names that cause error or confusion should be rejected. • All names in Latin or are latinized. • The first word (genus) is always capitalized. • The second word (species or specific epithet) is not capitalized. • Both genus and species name, together referred to as species, are either underlined or italicized when appearing in print. • The correct name of a species or higher taxonomic designations is determined by valid publication, legitimacy of the name with regard to the rules of nomenclature, and priority of publication.

16. Nomenclature • Casual or Common Name: • e.g. "typhoid bacillus" • Scientific or International Name: • Salmonella typhi • Salmonella london • Staphylococcus aureus • Clostridium tetani • Mycobacterium bovis • Borrelia burgdorferi

17. Classification vs. Identification Techniques • Bergey’s Manual of Determinative Bacteriology uses: • microscopic appearance • biochemical reactions • growth requirements • serology • phage typing • Classification or identification??

18. Biochemical Tests

19. Serology Slide Agglutination Test

20. Phage Typing

21. Bergey’s Manual of Systematic Bacteriology establishes phylogenetic relationships by: • amino acid sequencing • protein analysis • rRNA sequencing – ribotyping • Why is rRNA rather than other types of RNA used? • Chapter 10 • nucleic acid hybridization Classification or identification??

22. DNA Hybridization

23. Identification vs. Classification

24. Spirochetes Axial filaments for motility Examples: Treponema pallidum - syphillis Borrelia burgdorferi - Lyme disease Leptospira interrogans - leptospirosis

25. Axial Filaments Movement of spirochetes Structure Filament Hook Basal body Ex. Treponema pallidum Bundles of fibrils that arise at the end of the cell beneath the outer sheath & spiral around the cell

26. Campylobacterjejuni • microaerophilic • motile vibrio • Gram negative • animals esp poultry & cattle • grows @ 42oC • most commonly identified bacterial cause of diarrhea in world (CDC) • unpasteurized milk • food

27. Pseudomonasaeruginosa • Gram negative aerobic rod • “bacillus of blue-green pus” • pyocyanin pigment • fermented grape smell • normal flora • skin & intestine • unusual carbon sources • antibiotic resistant • infections • wound, ear, urinary, respiratory, burns

28. Gram negative aerobic cocci Neisseria meningitidis Branhamella catarrhalis Neisseria gonorrhoeae in pus

29. Enterobacteriales Family- enterobacteriaceae Non-pathogens • Escherichia • Klebsiella • Proteus • Serratia • Etc. Describe the microscopic appearance of these organisms.

30. Enterobacteriaceae cont’d Pathogens • Salmonella (typhi) • typhoid fever • Shigella (dysenteriae) • bacillary dysentery • Yersinia (pestis) • bubonic plague All members of Enterobacteriaceae are facultative anaerobes. Meaning? Can you see why the family, enterobacteriaceae, has been referred to as the Colon-typhoid-dysentery group? Can you differentiate the pathogens from the non-pathogens microscopically?

31. Vibrionales Shape? Facultatively anaerobic Vibrionaceae Vibriocholerae

32. Hemophilusinfluenzae • Aerobic Gram negative rod • Normal flora in intestine and respiratory tract • Most common cause of meningitis in children • Hib vaccine • Also causes otitis media, pneumonia, epiglottitis Why is the name of this organism misleading? What can you learn from the name?

33. Bacteroidaceae - Bacteroides fragilis • Gram negative anaerobic rods • Found in the human intestine & mouth • 95% of the bacteria in a stool specimen & 20% of the weight! • One billion per gram of feces! • Most common anaerobe isolated from infections • appendicitis, peritonitis, complicate abdominal surgery

34. Rickettsia & ChlamydiaGram negative obligate intracellular parasites Rickettsia transmitted to humans by insects & ticks Ex. Rickettsia rickettsii - Rocky Mountain spotted fever

35. Chlamydia Not transmitted by insects Causes: 1.Trachoma - world’s leading infectious cause of blindnessMiddle East, North Africa, India Chlamydia trachomatis 2.Non-gonococcal urethritis common std in U.S.

36. Chlamydia psittacicauses: 1. Psittacosis (“parrot fever”) 2. Ornithosis Chlamydia pneumoniae - pneumonia

37. Mycoplasmas • No cell wall • pleomorphic • penicillin sensitive or resistant? • Smallest free-living organisms • Microscopic fried-egg colonies • Ex. Mycoplasma pneumoniae

38. Gram Positive Cocci Staphylococcus Streptococcus Micrococcusluteus

39. Staphylococcusaureus • Gram positive cocci, clusters • Yellow pigment • Causes • common food poisoning • surgical wound infections • resistance • toxic shock syndrome

40. Streptococcuspyogenes • Gram positive cocci in chains • Diseases • pharyngitis (sore throat) • scarlet fever * • erysipelas * * look for a description of this disease

41. Endospore-Forming Gram Positive Rods • Bacillales - Bacillus • aerobes or facultative anaerobes • common in soil • ex. Bacillus anthracis, Bacillus subtilis • Clostridiales - Clostridium • obligate anaerobes • found in soil • diseases • tetanus (Clostridium tetani), botulism (C. botulinum),gas gangrene (C. perfringens)

42. Spore-Forming Organisms Clostridium tetani - Gram stain Bacillus cereus - spore stain

43. Corynebacterium Characteristics of Corynebacterium sp.: • pleomorphic Gram positive rod • metachromatic granules • unusual arrangements • palisades • Chinese letters • C.diphtheriae causes diphtheria

44. Mycobacteria Characteristics of Mycobacterium sp. • Gram positive small rods • acid-fast • mycolic acid complexed with peptidoglycan (waxy) • diseases: • tuberculosis • leprosy (M. leprae) Acid-fast stain of sputum showing Mycobacterium tuberculosis

45. Streptomycetes Characteristics of Streptomyces: • mold-like bacteria • branching, spores • produce geosmin • soil smell • several species produce antibiotics • ex. streptomycin