Classification of Bacteria

The science of classification Taxonomy The science of classification

Haeckel’s 3 Kingdoms Plant Animal Protista

Carl Woese’s 3 Domains Based on rRNA nucleotide sequences Why use this as a basis for classification?

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

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

Comparison of Archaea, Bacteria & Eukarya

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

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

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.

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

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

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

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.

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

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

Biochemical Tests

Slide Agglutination Test Serology Slide Agglutination Test

Phage Typing

rRNA sequencing – ribotyping 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??

DNA Hybridization

Identification vs. Classification

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

Movement of spirochetes 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

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

Pseudomonas aeruginosa 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

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

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

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?

Vibrionaceae Vibrio cholerae Vibrionales Vibrionaceae Vibrio cholerae Shape? Facultatively anaerobic

Hemophilus influenzae 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?

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

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

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

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

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

Gram Positive Cocci Staphylococcus Streptococcus Micrococcus luteus

Staphylococcus aureus Gram positive cocci, clusters Yellow pigment Causes common food poisoning surgical wound infections resistance toxic shock syndrome

Streptococcus pyogenes Gram positive cocci in chains Diseases pharyngitis (sore throat) scarlet fever * erysipelas * * look for a description of this disease

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)

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

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

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

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