Free Powerpoint Templates Page 1 Free Powerpoint Templates Bacterial Classification...
-
Upload
arnold-griffin -
Category
Documents
-
view
225 -
download
0
Transcript of Free Powerpoint Templates Page 1 Free Powerpoint Templates Bacterial Classification...
Free Powerpoint TemplatesPage 1
Free Powerpoint Templates
Bacterial ClassificationAssoc.Prof.Dr.Yeşim Gürol
Free Powerpoint TemplatesPage 2
In this lesson
• Describe bacterial classification:
• List taxon levels
• Define taxonomy and identification
• Describe principles of taxonomy
• Explain classification of bacteria
Free Powerpoint TemplatesPage 3
Taxonomy
Is the science of classification, especially of living organisms, to facilitate research and communication.
Organisms are arranged into taxonomic categories or taxa (singular: taxon), to show degrees of similarities between organisms.
Free Powerpoint TemplatesPage 4
Criteria that drive taxonomy
Although genomic analysis has become the final determinant of taxonomy,demonstration of phenotypic features remains the primary means of applying these classifications in diagnostic microbiology.
Free Powerpoint TemplatesPage 5
Based on certain shared genotypic and phenotypic characteristics bacteria are classified into:
• Family
• Genus
• Species
• Strain
Free Powerpoint TemplatesPage 6
• Genus (plural genera) refers to a group of
bacterial organisms that share in common
several structural, biochemical and physiological traits
• Species refers to a subgroup of organisms
within a genus that share more specific traits
among themselves.• The term strain refers to a pure culture
made up of descendants of a single isolation
Free Powerpoint TemplatesPage 7
Bacterial classification is based on several major properties
• Gram staining (and other stains)
• Morphology
• Metabolic behavior
• Infection patterns
• Intracellular vs extracellular
• Antigenic composition
• DNA sequence
Free Powerpoint TemplatesPage 8
• Natural classification scheme that reflects major differences in cell wall structure and to some extent the mechanisms involved in disease.
• Gram positive (blue): single membrane consisting of a thick peptidoglycan layer – no lipopolysaccharide
Free Powerpoint TemplatesPage 9
• Gram negative (pink): inner and outer membranes, with outer membrane having lipopolysaccharide molecules
Free Powerpoint TemplatesPage 10
• Property discovered by Christian Gram 1883, a Danish botanist, while attempting to differentiate bacteria from human tissue by different staining methods. He noted differences in stain retention by bacteria..
Free Powerpoint TemplatesPage 11
Free Powerpoint TemplatesPage 12
Free Powerpoint TemplatesPage 13
Free Powerpoint TemplatesPage 14
Free Powerpoint TemplatesPage 15
• Gram positive cocci
in clusters
Gram positive cocciin chains
Free Powerpoint TemplatesPage 16
• Gram negative cocci
• Gram negative rods
Free Powerpoint TemplatesPage 17
Morphology
• Rods or cocci
• Curved or spiral
• Filamentous
Free Powerpoint TemplatesPage 18
• Metabolic properties may influence ability type of disease caused but not the only factor
• Aerobe versus anaerobe (microaerophilic, facultative aerobes)
• Anaerobes have a greater propensity to cause abscesses
• Brain, lung, liver, intra-abdominal abscesses
Free Powerpoint TemplatesPage 19
Some correlation between morphology and disease
• Spiral bacteria---Treponemes, Borrelias, Leptospiras, Spirillium tend to cause systemic diseases
Free Powerpoint TemplatesPage 20
• Pathogenic filamentous bacteria
• Actinomyces, Nocardia, Mycobacteria tend to cause chronic diseases
• Gram positive bacteria, Staphylococcus more likely to cause skin infections, Streptococci skin and pneumonia
Free Powerpoint TemplatesPage 21
Free Powerpoint TemplatesPage 22
The ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote
Free Powerpoint TemplatesPage 23
• The general size of a prokaryotic cell is about 1-2 um.
• Note the absence of membrane bound organelles
• There is no true nucleus with a nuclear membrane
• The ribosome's are smaller than eukaryotic cells
• The slime capsule is used as a means of attachment to a surface
• Only flagellate bacteria have the flagellum
• Plasmids are very small circular pieces of DNA that maybe transferred from one bacteria to another.
Free Powerpoint TemplatesPage 24
Free Powerpoint TemplatesPage 25
Free Powerpoint TemplatesPage 26
Free Powerpoint TemplatesPage 27
Free Powerpoint TemplatesPage 28
How does an experienced physician approach bacterial diseases?
Organ system approach•Which bacteria cause disease in a certain location
Gram stain approach•What does the gram stain show--used to treat empirically before cultures are completed•Requires that one is able to get a gram stain which is not always the case
Free Powerpoint TemplatesPage 29
Organ system approach • Meningitis
Pneumococci, Meningococci, Hemophilus influenzae, Listeria
• Sinusitis
Pneumococci, H. influenzae, Moraxella• Acute otitis media
Pneumococci, H. influenzae, Moraxella• Pharyngitis
Group A streptococci
These are all aerobic bacteriaThese are all aerobic bacteria
Free Powerpoint TemplatesPage 30
Now add in the Gram stain
Gram negative rods seen in CSF in meningitis
•H. influenzae
Gram positive cocci in meningitis •Pneumococcus
Gram positive cocci in sinusitis •Pneumococcus or Staphylococcus
Gram stain may suggest the organism --clusters or diplococci?
Free Powerpoint TemplatesPage 31
• Pneumonia • Pneumococcus, H. influenzae
• Pleural cavity • Pneumococcus, Staphylococcus
• Endocarditis • Streptococcus, Staphylococcus,
Enterococci
Free Powerpoint TemplatesPage 32
• Pneumonia-sputum gram stain• Gram positive diplococci as predominant
organism• Likely organism Pneumococcus--the most common gram positive
cocci found in pneumonia
• Therapy• Endocarditis-blood culture positive• Gram positive cocci on the stain• Maybe Streptococci, Enterococci, or Staphylococci
• Treatment decision made on this basis- Vancomycin +
Free Powerpoint TemplatesPage 33
The three phylogenetic lineages of cells (Domains according to comparative
rRNA sequences)
• Bacteria
• Archae
• Eukarya
Free Powerpoint TemplatesPage 34
Free Powerpoint TemplatesPage 35
• Bacteria :Prokaryotic
• Archae :Prokaryotic
• Eukarya :Eucaryotic
Free Powerpoint TemplatesPage 36
Free Powerpoint TemplatesPage 37
Free Powerpoint TemplatesPage 38
Free Powerpoint TemplatesPage 39
• Eukaryotic (Greek for true nucleus)
• Prokaryotic (Greek for primitive nucleus)
Free Powerpoint TemplatesPage 40
Procaryotic cells
• Bacteria
• Archae
Free Powerpoint TemplatesPage 41
Bacteria
• The smallest cells
• Visible only with the aid of a microscope
• The smallest bacteria: Mycoplasma,Chlamydia and Rickettsia-0.1-0.2 micrometer
• Larger bacteria: many microns in length
Free Powerpoint TemplatesPage 42
Most bacterial cells
• Approximately 1 micrometer in diameter
• Visible by light microscope
• Resolution: 0.2 micrometer
Free Powerpoint TemplatesPage 43
Free Powerpoint TemplatesPage 44
Microscopes
• Light:– Bright-field– Dark-field (Treponema pallidum-
Syphilis_Frengi)– Fluorescence– Phase contrast (details of the living
cell)
• Electron
Free Powerpoint TemplatesPage 45
Major characteristics of Eucaryotic and prokaryotic cell
Eucaryote Prokaryote• Size >5 μm 0,5-3 μm• Nuclear structure : Nucleus classic membrane no membrane Chromosomes
strands of DNA single sircular DNAdiploid genome haploid genome
Free Powerpoint TemplatesPage 46
Eucaryote Prokaryote• CytoplasmicStructuresMitokondria + -Golgi bodies + -Endoplasmic reticulum + -Ribosomes 80S(60S+40S) 70S(50S+30S)Cytoplasmic membrane with sterols no sterol
Free Powerpoint TemplatesPage 47
Differences between Procaryotes
• Bacteria differ:
-morphology (size, shape, stainig characteristics)
-metabolic
-antigenic and
-genetic characteristics
Free Powerpoint TemplatesPage 48
Procaryotic cells
• Size:micrometer(μm)
10 -6 meter
Free Powerpoint TemplatesPage 49
• Size:
-the smallest bacteria:
Mycoplasma : 0.3 μm
Nanobacteria: 0.2-0.05 μm
Escherichia coli:2-6 μm
Spirochetes: 500 μm
red blood cell:7 μm
Free Powerpoint TemplatesPage 50
Free Powerpoint TemplatesPage 51
Free Powerpoint TemplatesPage 54
Dark-field (Treponema pallidum-Syphilis_Frengi)
Free Powerpoint TemplatesPage 55
Free Powerpoint TemplatesPage 56
Free Powerpoint TemplatesPage 57
Free Powerpoint TemplatesPage 58
Free Powerpoint TemplatesPage 59
Free Powerpoint TemplatesPage 60
Free Powerpoint TemplatesPage 61
Free Powerpoint TemplatesPage 62
Free Powerpoint TemplatesPage 63
Free Powerpoint TemplatesPage 64
Free Powerpoint TemplatesPage 65
Biochemical reactions are used to classify
Sequencing