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23 Cards in this Set
- Front
- Back
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Characteristics of Bacteria
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Prokaryotic organisms.
No internal membranes or organelles 2 cell wall types: gram (+) and gram (-) Unicellular or colonial. Both intracellular and extracellular pathogens |
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Bacterial Classification:
Phenotypic & Genotypic characteristics |
Phenotypic:
-Shape, gram stain, acid-fast stain, spores, metabolic functions, 02 requirements Genotypic: -DNA homology, 16S RNA sequences, whole genome seq., unique DNA probes. |
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Bacteria structures, shapes
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-Cocci = spheres
-Strepto = chains -Staphylo = grape-like clusters -Diplo = pairs |
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Cocci (spheres)
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-Neisseria gonorrhoeae
-Streptococcus pyogenes -Staphylococcus aureus |
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Diplococci
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-Gonococci
-Pneumococci |
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Bacterial Shapes (cont.)
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Bacilli = rods
Spirals = Helically coiled Vibrios = Curved rods (V. cholerae) Endospore = Spore forming |
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Bacilli Examples
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-Escherichia coli
-Klebsiella pneumoniae -Salmonella typhi |
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Spirals examples
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Treponema pallidum
Borellia burgodorferi |
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Endospore forming bacteria
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Clostridium tetani
Bacillus anthracis |
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Surface structures of bacteria
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Flagella: locomotion
Pili/Fimbriae: adhesion or DNA transfer Capsules: adhesion, antiphagocytic, antigenic |
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What are the following structures used for in bacteria?
1.Mycolic Acid 2.Cell wall 3.Lipopolysaccharide |
1. to protect against dessication.
2. Composed of peptidoglycan, which provides osmotic stability. 3. toxic to the host and antigenic (found in gram (-)) |
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Flagella
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Locomotion
Composed of flagellin Antigenic, used in typing bacteria (i.e. H antigen in E.coli O157H7) |
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Pili / Fimbriae
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-Fimbriae are thin fibers covering the surface of some bacteria, assist in adherence to surfaces.
-Sex pili are hollow fibers used for the transfer of bacterial chromosome during conjugation |
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Bacterial Capsules
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-Adhesive
-Resist drying. -Protection against antimicrobial agents. -protection against phagocytosis by leukocytes. |
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What are the 3 most common causes of bacterial meningitis that have capsules?
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-Streptococcus pneumoniae
-Neisseria meningitidis -Haemophilus influenzae |
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Mycolic Acids
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-Composed of long chain fatty acids
-Protect against desiccation. -Confer the property of acid-fast staining. Fuchsia coloured. (mycobacteria and Nocardia) |
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what is Lipopolysaccharide (LPS)
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-LPS is attached to outer membrane of the cell wall of gram-negative bacteria.
O antigen + core + Lipid A O antigen used to serotype gm(-) rods for epidemiology studies Lipid A is highly toxic part of LPS embedded in the outer lipid bilayer. |
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Effects of Lipid A
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-Shock
-multiple organ failure -Hemorrhage -Disseminated Intravascular coagulation -Death |
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Bacterial Endospores
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-bac. sporulation occurs almost exclusively in gram + bacteria.
-Spores are a dorman form of life and produced when conditions prevent vegetative cell growth. -spores are resistant tokilling by physical and chemical agents |
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Bacterial Plasmids
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-Autonomously replicating, extrachromosomal genetic elements.
- composed of small circular DNA. - Code for antibiotic resistance, toxin production bacteriocin production and enzymes. -plasmids are major mechanism for transfer of antibiotic resistance between bacteria. |
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Botulinum toxin
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-created by Clostridium botulinum
-Decreased ACh release at the neuromuscular junction (flaccid paralysis) -Heat sensitive toxin -Intoxication by preformed toxin in food. |
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Cholera toxin & E.coli Enterotoxin
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Activates adenylate cyclase, which increases cAMP in intestinal villi resulting in diarrhea.
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Staphylococcal Enterotoxin
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-produced by certain strains of S.aureus
-Resistant to heat and digestive enzymes. -Stimulates peristalsis, vomiting and interleukin-1 release. |
