1. Bacterial Classification and Nomenclature
Dr. Rashad Shawgi Babiker
M.Sc (Microbiology) (UMST)
M.Sc. Stud. (Immunology )
Institute of Tropical Medicine.(SAS)

2. Review Cell Membrane – regulates what comes in and out of the cell
Cell Wall – maintains shape and form
Capsule – found in virulent bacteria, helps evade immune system
What are the two blank areas?

3. Bacterial structure
a. The cell wall may also be surrounded by an organized capsule called a glycocalyx and/or by a loose jelly-like sheath called a slime layer.  b. In parasitic forms, these outer coverings protect the cell from host defenses.
1. Cell wall – keeps cell from bursting or collapsing due to osmotic changes (changes in water)

4. Bacterial structure 2. Flagella is used for movement
3.  Pilli (Fimbrae) help bacteria cling to surfaces
4. Prokaryotes do not have organelles or a membrane bound  nucleus!
5.  Nucleoid region contains a circular loop of DNA
6.  Plasmids are rings of DNA, used in reproduction
7.  Ribosomes in cytoplasm synthesize proteins

5. Outlines Ways for classifying the bacteria (taxonomy & classification)
Phenotyping, serotyping and genotyping
Bacterial nomenclature
Medically important classes

6. Definitions
Classification can be defined as the arrangement of organisms into taxonomic groups (taxa) on the basis of similarities or relationships
Nomenclature is naming an organism by international rules according to its characteristics
Identification refers to the practical use of a classification scheme

7. strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars)
type – a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype)

8. Naming and Classifying Microorganisms
Linnaeus established the system of scientific nomenclature.
Each organism has two names: the genus and specific epithet.

9. Scientific Names
Are italicized or underlined. The genus is capitalized and the specific epithet is lower case.
Are “Latinized” and used worldwide.
May be descriptive or honor a scientist.

10. Scientific Names Staphylococcus aureus
Describes the clustered arrangement of the cells (staphylo-) and the golden color of the colonies (aur-).

11. Scientific Names Escherichia coli
Honors the discoverer, Theodor Escherich, and describes the bacterium’s habitat–the large intestine or colon.

12. Scientific Names
After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet:
Staphylococcus aureus and Escherichia coli are found in the human body. S. aureus is on skin and E. coli in the large intestine.

13. Classification of Bacteria
Light microscope was the original tool.
Initial classification was based on of the shape of the bacterial cells.

14. 4 Main Shapes of Bacteria
Cocci
Bacilli
Spirilla
Spirochetes

15. Four Groups Based on Cell Wall Composition
Gram-positive cells
Gram-negative cells
Bacteria with chemically unique cell walls
Bacteria without cell walls

17. Peptidoglycan
N-acetylmuramic acid
(NAM)
Provides strong, flexible support to keep bacteria from collapsing because of changes in osmotic pressure
N-acetylglucosamine
(NAG)

18. Gram Positive Cell Wall
Consists of
A thick, homogenous sheath of peptidoglycan nm thick
Tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid

19. Gram Negative Cell Wall
Consists of
An outer membrane containing lipopolysaccharide (LPS)
Thin shell of peptidoglycan between inner and outer membranes
Periplasm

21. Gram Negative

22. Gram Positive

23. Bacteria with Chemically Unique Cell Walls
Acid-Fast Cells
Mycobacterium species

24. Rickettsia – Chemically Unique Cell Wall

25. Chlamydia – Chemically Unique Cell Wall

26. Bacteria without Cell Walls - Mycoplasma
Lack a rigid cell wall during their entire life cycle
Smallest known organisms – smallest genomes (other than viruses)
Diameter ranges from 0.15 m to 0.30 m
Do not stain with the Gram stain

27. True bacteria and disease
Modes of access of disease bacteria
a) Access from the air ("strep throat", chlamydias)
b) Access through contamination of food and drink
c) Access through direct contact
- Syphilis and Gonorrhea, Anthrax, Brucellosis
d) Access through wounds
- Tetanus, Gas gangrene
e) Access through bites of insects and other organisms
i) Bubonic plague (the "Black Death")
v) Lyme disease