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36 Cards in this Set
- Front
- Back
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Which genus of baceria do not have a cell wall?
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Mycoplasma
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What are the important structural components of bacteria?
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Flagella (some), fimbriae, capsule, cell wall, cytoplasic membrane
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What does 'antigenic' mean?
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Relating to an antigen (A toxin or other foreign substance that induces an immune response in the body, esp. the production of antibodies)
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What is a flagella used for?
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Locomotion, virulence property, antigenic
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What are fimbriae used for?
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Adherence of bacteria, virulence property
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What is virulence?
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The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by the ability of the organism to invade the tissues of the host
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What is a capsule?
AKA? |
Complex polysaccharide that surround some bacteria, prevents desiccation, involved in adhesion, has a virulence property
AKA Glycocalyx |
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Some KIllers Have Pretty Nice Capsules
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Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Neisseria meningitidis, and the yeast Cryptococcus neoformans.
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What are the three types of cell wall?
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Gram positive, gram negative, mycobacterial
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Peptidoglycan is common to which type of cell wall?
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All
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Lipopolysaccharide is common to which type of cell wall? What is it AKA?
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Gram negative only.
AKA Endotoxin |
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Arabinogalactan and mycolic acids are common to which type of cell wall?
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Mycobacterial
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Lipoteichoic acid is common to which type of cell wall?
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Gram positive
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Cell wall components are virulence factors and targets for antibiotics
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The type of cell wall structure correlates with action of some antiobiotics
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What is the cytoplasmic membrane the site of for bacteria?
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Respiratory and transport proteins
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What are endospores? In what generea are they found?
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A structure produced by bacteria that are resistant to adverse environmental conditions. They are found in Bacillus and Clostridium
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Describe the contents of gram-positive cell walls.
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Cytoplasmic membrane covered by a thick layer of peptidoglycan with teichoic acid
Thick layer enables retention of Gram-stain (blue/black) when microscopic smears are treated with alcohol (LEARN!) Peptidoglycan target for antibiotics based on penicillins |
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What kind of antibiotic acts well on peptidoglycan?
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Penicilins
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Describe the contents of gram-negative cell walls
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Thin layer of peptidoglycan
Glycoproteins, porin, lipoprotein Microscopic smears are decolourised by alcohol so are made visible only with red counterstain |
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Describe the contents of mycobacterial cell walls?
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Lipid rich (can't do normal staining), Ziehl-Neelsen stain, if bacteria is decolourised with acid o ralcohol in the cold - stain is retained inside of cell - bacteria described as Acid-Fast Bacilli (AFBs), normally appear red against blue or green bacground from counterstain
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What are Acid-Fast Bacilli?
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Bacteria that ave a mycobacterial cell wall which is stained inside the cell when cold acid/alcohol is added.
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What is the effect of lipopolysaccharide on host defence mechanisms?
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Has an ADVERSE effect:
Activates macrophages to release cytokines (e.g. Tumour necrosis factor) Activates B-cells Activates kallikrein and coagulation cascades ALL LEAD TO SEPTIC SHOCK |
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What is a cytokine?
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A small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system. They are a category of signaling molecules used extensively in intercellular communication
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What is tumour necrosis factor?
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A group of the cytokines family that can cause cell death
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What is a kallikrein? What is its clinical importance?
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Peptidases (enzymes that cleave peptide bonds in proteins), a subgroup of the serine protease family
They are targets of active investigation by drug researchers as possible biomarkers for cancer |
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How are bacteria classified? (3)
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Shape, staining reactions, atmosphere requred for growth
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What are the teichoic and lipoteichoic acids of gram positive cell walls susceptible to?
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Beta lactam antibiotics
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What do teichoic and lipoteichoic acids protect gram positive bacteria from?
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Low humidity (of the skin)
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What is an other name for peptidoglycan?
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Murein
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What is campylobacter jejuni?
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A rod shaped, gram negative microaerophilic bacteria. Food poisoning can be caused by the Campylobacter species
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Which bacteria produce endospores?
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Bacillus and clostridum (e.g. C. diff - very hard to remove)
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What are fungal cell walls mainly composed of?
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Chitin
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What is the Ziehl–Neelsen stain also known as?
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The acid-fast stain
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What is the Ziehl-Neelson stain used for?
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Identifying acid-fast organisms, mainly Mycobacteria (no cell wall).
MYCOBACTERIUM TUBERCULOSIS identification It is helpful in diagnosing Mycobacterium tuberculosis since its lipid rich cell wall makes it RESISTANT TO GRAM STAIN |
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What makes TB resistant to gram staining?
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It has a very lipid rich cell wall
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Mycobacterium Tuberculosis is gram positive/negative
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Neither. It does not retain any bacteriological stain due to high lipid content in its wall
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