7. 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?
8. 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
9. • 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.
11. Species of bacteria - “population of cells
with similar characteristics”
Strain of bacteria - “group of cells
derived from a single cell”
ex. Staphylococcus aureus 13578
12. • Naming of microorganisms.
• Governed by international rules
• Rules published in the International Code of
Nomenclature of Bacteria.
• The International Journal of Systematic
Bacteriology
13. 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.
14. 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
15. Classification vs. Identification
Techniques
Bergey’s Manual of Determinative Bacteriology uses:
• microscopic appearance
• biochemical reactions
• growth requirements
• serology
• phage typing
Classification or identification??
23. Axial Filaments
Movement of spirochetes
Bundles of fibrils that arise at the end of the cell beneath the
outer sheath & spiral around the cell
Ex. Treponema
pallidum
Structure
Filament
Hook
Basal body
24. 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
30. 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?
31. 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
33. Chlamydia
Not transmitted by insects
Chlamydia trachomatis
Causes:
1.Trachoma - world’s leading
infectious cause of blindness
Middle East, North Africa, India
2.Non-gonococcal urethritis
common std in U.S.
