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Z - Micro 02
Micro 02
Question | Answer |
---|---|
Bacteria are diploid or haploid? | Haploid |
Bacteria have nuclear membrane? | No |
What is bacterial genetic transformation? | Naked DNA released during cell lysis --> bind to cell wall of competent bacteria (has structures on cell wall that can bind and take up the fragments) of the same species or closely related --> DNA incorporated into the genome (must have enough homology) |
How can genetic transformation be used for genetic mapping? | The frequency of two traits being passed on together depends on the distance apart on the genome. The closer they are, the more likely they will be passed on together. |
what is a bacteriophage? | Virus that infects bacteria |
Virulent phage vs. temperate phage | virulent lyses and kills bacteria (generalized transduction); temperate incorporates the DNA into its own genome (specialized transduction) |
What is prophage? | "temperate" piece of viral DNA that infects bacteria and is incorporated into the bacterial genome |
Transformation - how much homology required? | Need to be of the same species because the DNA fragments taken in need to be incorporated into the recipient's genome. |
Generalized transduction - how much homology required? | virulent phage injected --> destroys bacterial genome (some pieces of bacterial genome left) --> bacterial genome packaged into capsid --> injected into another bacteria --> if there is HOMOLOGY, then bact chrom is incorporated into new bacteria. |
Conjugation - how much homology required? | Can occur between unrelated bacteria (sex pili required) |
Transposons - how much homology required? | No DNA homology required; this genetic material can move between different bacterial genera |
Lysogenic immunity | prophage (temperate phage that is incorporated into bacterial genome) blocks a subsequent infection by a different phage |
Lysogenic conversion | when gene is transferred from one bacteria to another by specialized transduction and incorporated into genome of new bacteria |
What is the major mechanism for transfer of antibiotic resistance? | Conjugation because can occur between unrelated bacteria |
What do F plasmids look like? | circular, double stranded |
What is an Hfr cell? | bacterial cell that just received an F plasmid incorporates that F plasmid into its own genome |
What is an F' plasmid? | F plasmid from an Hfr cell that gets excised, but now with a part of that bacteria's chromosome as well -- so now have DNA from two different bacteria |
You have gram positive cocci -- if you see bubbles on a catalase test (slide with H2O2), what do you have? | Staph |
On a blood agar plate testing for hemolysis, if you see a clear zone around a plated colony, what do you know? | B hemolytic (lyse all the RBC's around the colony with Streptolysins O and S); could be strep pyogenes or GBS) |
On a blood agar plate testing for hemolysis, if you see a green zone around a plated colony, what do you know? | a hemolytic (only partially lyse the RBC's so the green is a Hb metabolite that's released into the area) |
What are the encapsulated bacteria? | Some Killers Have Pretty Nice Capsules. Strep pneumoniae, Klebsiella pneumoniae, Hemophilus influenza, Pseudomonas aeruginosa, Neisseria meningitidis, Cryptococcus neoformans |
M protein | on Strep pyogenes. Protein that blocks Macrophage action -- inhibits activation of complement and protects from phagocytosis. Weakness because B cells create abs to the M protein. |
Streptolysin O | Enzyme that is responsible for B hemolysis. Is inactivated by O2. ASO titer measures anti-streptolysin O antibodies to confirm recent infection. |
Impetigo | a vesicular blistered eruption, most common in children that becomes crusty and flaky, found around the mouth. Caused by strep pyogenes. |
What is the treatment for infection by strep pyogenes? | Penicillin G |
What does clindamycin do for infection by strep pyogenes? | shuts down streptococcal metabolism and blocks toxin production |
Baby BEL | neonatal meningitis: GBS, E. coli, Listeria monocytogenes |
Endocarditis - subactue and acute | Subacute: Strep viridans. Acute: Staph aureus |
Which Strep most likely to cause abscess in brain or abdominal organs? | Strep viridans - intermedius. |
Which Strep most likely to cause colon cancer? | Strep bovis |
What is resistance mechanism for Strep group D against Vancomycin? | Change d-ala-d-ala to d-ala-lactate! |
Strep in UTI's and biliary tract infections | Enterococcus faecalis |
Lancet shaped dipplococci | Strep pneumoniae |
What is the major virulence factor of pneumococcus? | polysaccharide capsule |
What are the two main lab tests used to ID pneumococcus? | Quellung (abs bind to capsular antigens --> capsule swells); optochin (S. pneum growth will be inhibited, while S. viridans will continue to grow) |
Most common cause of pneumonia in adults | Strep pneumoniae (typicl community acquired pneumonia) |
Most common cause of otitis media in children | Strep pneumoniae |
Most common cause of bacterial meningitis in adults | Strep pneumoniae |
Most common cause of septic arthritis in children and elderly (over 50) | Staph aureus (infection of synovial membrane in joints - synovial fluid will reveal infective organisms) |
What two organisms most likely are the cause of skin infections? | Strep pyogenes and staph aureus |
What is treatment for infection with MRSA (methicillin-resistant staph aureus) | Methicillin is penicillinase-resistant drug. Can use vancomycin. |
Infection from foley catheters or IV lines | Staph epi |
Infection of prosthetic devices | Staph epi |
Gold on sheep blood agar | Staph aureus |
Can you use Penicillin G for staph infections? | No because staph makes penicillinase, which inactivates penicillin G. |
What is coagulase and what does it do? | In staph aureus. activates prothrombin --> causes blood to clot around the org --> protects against phagocytosis |
Protein A | In Staph aureus. Binds the Fc portion of IgG --> prevent opsonization |
Food poisoning by Staph aureus lasts how long? | Grows in food --> that food is ingested --> 12 to 24 hrs. |
Infection of umbilicus in neonate | Staph aureus, scalded skin syndrome |
UTI's in sexually active young woman | Staph saprophyticus |