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36 Cards in this Set

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Which genus of baceria do not have a cell wall?
Mycoplasma
What are the important structural components of bacteria?
Flagella (some), fimbriae, capsule, cell wall, cytoplasic membrane
What does 'antigenic' mean?
Relating to an antigen (A toxin or other foreign substance that induces an immune response in the body, esp. the production of antibodies)
What is a flagella used for?
Locomotion, virulence property, antigenic
What are fimbriae used for?
Adherence of bacteria, virulence property
What is virulence?
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
What is a capsule?
AKA?
Complex polysaccharide that surround some bacteria, prevents desiccation, involved in adhesion, has a virulence property

AKA Glycocalyx
Some KIllers Have Pretty Nice Capsules
Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Neisseria meningitidis, and the yeast Cryptococcus neoformans.
What are the three types of cell wall?
Gram positive, gram negative, mycobacterial
Peptidoglycan is common to which type of cell wall?
All
Lipopolysaccharide is common to which type of cell wall? What is it AKA?
Gram negative only.
AKA Endotoxin
Arabinogalactan and mycolic acids are common to which type of cell wall?
Mycobacterial
Lipoteichoic acid is common to which type of cell wall?
Gram positive
Cell wall components are virulence factors and targets for antibiotics
The type of cell wall structure correlates with action of some antiobiotics
What is the cytoplasmic membrane the site of for bacteria?
Respiratory and transport proteins
What are endospores? In what generea are they found?
A structure produced by bacteria that are resistant to adverse environmental conditions. They are found in Bacillus and Clostridium
Describe the contents of gram-positive cell walls.
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
What kind of antibiotic acts well on peptidoglycan?
Penicilins
Describe the contents of gram-negative cell walls
Thin layer of peptidoglycan
Glycoproteins, porin, lipoprotein
Microscopic smears are decolourised by alcohol so are made visible only with red counterstain
Describe the contents of mycobacterial cell walls?
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
What are Acid-Fast Bacilli?
Bacteria that ave a mycobacterial cell wall which is stained inside the cell when cold acid/alcohol is added.
What is the effect of lipopolysaccharide on host defence mechanisms?
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
What is a cytokine?
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
What is tumour necrosis factor?
A group of the cytokines family that can cause cell death
What is a kallikrein? What is its clinical importance?
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
How are bacteria classified? (3)
Shape, staining reactions, atmosphere requred for growth
What are the teichoic and lipoteichoic acids of gram positive cell walls susceptible to?
Beta lactam antibiotics
What do teichoic and lipoteichoic acids protect gram positive bacteria from?
Low humidity (of the skin)
What is an other name for peptidoglycan?
Murein
What is campylobacter jejuni?
A rod shaped, gram negative microaerophilic bacteria. Food poisoning can be caused by the Campylobacter species
Which bacteria produce endospores?
Bacillus and clostridum (e.g. C. diff - very hard to remove)
What are fungal cell walls mainly composed of?
Chitin
What is the Ziehl–Neelsen stain also known as?
The acid-fast stain
What is the Ziehl-Neelson stain used for?
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
What makes TB resistant to gram staining?
It has a very lipid rich cell wall
Mycobacterium Tuberculosis is gram positive/negative
Neither. It does not retain any bacteriological stain due to high lipid content in its wall