Pharmacology Lecture 5_Gram Positive Bacteria

Question 1

What are the three antibiotic susceptibility tests

Answer 1

1) Broth dilution - cultured bacteria is placed in test tubes and different amounts of antibiotic are applied to each tube. The lowest consentration of antibiotic that reduces the amount of bacteria present is the minimal inhibitory consentration (MIC)
2) Anti microbial gradient - a dish of cultured bacteria has strips infused with varying concentrations of antibiotic inserted. A tear drop shaped area of inhibited bacteria growth will form around the strip. The pointy end of the drop will be the MIC
3) Disk Diffusion - this is similar to anti microbial gradient only disks with individule consentrations are applied.

Question 2

Which of the two Gram positive bacteria discuessed in calss are possitive with the catalase test?

Answer 2

Staphylococci

Question 3

What are the two Gram positive bacteria cocci that were discuessed in class?

Answer 3

Staphylococci and Streptococci

Question 4

What are two of the virulance factors of Staph. Aureus

Answer 4

Many adhesion factors (cell membrane binding proteins) and exotoxic exoproteins.

Question 5

What is the significance of biofilms in the disease process

Answer 5

Biofilms are large stucture and very hard to treat. Becasue they are large, they tend to resist the immune system. Biofilms become large and unstable so they send free bacteria into the body. a Biofilm on a heart valve would allow the bacteria to constantly seed the blood with bacteria.

Question 6

Describe Conjugation, transformation, and transduction

Answer 6

Conjugation - genetic material (typically plasmids) is exchanged between bacteria through the pili (basically bacterial sex)

Transformation - Genetic material is picked up from the enviornment and incorporated into the genome of a bacteria or stored as a plasmid.

Transduction - New genetic information is aquired through infection by a bacteriaphage

Question 7

Describe Beta, alpha, and gamma hemolysis of streptocossus

Answer 7

Beta - full hemolysis, blood augar has become clear
Alpha - partial hemolysis, blood augar is turned green
Gamma - no hemolysis, blood augar is unchanged

Question 8

What are the 4 general mechanisiums of antibiotics

Answer 8

1) Inhibition of protein synthesis
2) Inhibit DNA and RNA synthesis
3) Interfere with cell wall
4) Inhibit energy metabolism

Question 9

What bacteria strain is indicated by a possitive coagulase test?

Answer 9

Staphylococus Aureus