Micro 02

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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  


   

 
 

 
 

 

 

 
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