Classification
•the arrangement of organisms into taxonomic groups (taxon / taxa) on the basis of similarities or relationships.•Biochemical
•Physiologic•Genetic•morphologic
Nomenclature
• Naming an organism by international rules.
• International Committee on Systematic Bacteriology
• Bergey’s Manual of systematic Bacteriology
• Taxonomic Ranks• Kingdom Prokaryotae
• Division Gracilicutes• Class Scotobacteria• Order Eubacteriales• Family Enterobacteriaceae • Genus Escherichia• Species Escherichia coli• Subtype Escherichia coli O157:H7
Classification• Species
• group of individual isolates or strains sharing a high degree of similarity in many independent features
Criteria for Classification • cell shape• Specialized structures (spore, flagella)• Staining ( Gram)• Characteristic pigments• Extracellular enzymes ( hemolysis )
• Characteristic metabolic functions (biochemical tests)
• Sensitivity to antibiotics• Molecular biology (comparing genes or genomes)
Phylogenetic Classification• Common ancestor
• Close phylogenetic relatedness : recent ancestor
• No fossil record exist for bacteria
• There is considerable genetic diversity among bacteria
• G + C content
• DNA-DNA hybridization
• DNA sequencing
• Based on molecular phylogeny, prokaryotes fall into two major groups.
• the Eubacteria
• the Archaebacteria,
• Progeny
• Clone
• Colony
• Epidemiology
• Outbreaks
• Clonality
• Practical purposes (genetically identical)
• Biotyping
• Serotyping
• Morphotyping
• Bacteriophage typing
• Bacteriocin typing
• Antimicrobial susceptibility testing
Subtyping
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