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21 Cards in this Set

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What do G+ and G- bacteria have in common?
They both possess peptidoglycans in their cell walls. These are made of repeating disaccharide units cross linked with amino acids.
The enzyme that catalyzes this linkage is called transpeptidase.
In Gram neg organisms, the penicillin must pass through channels known as porins. TRUE/FALSE
TRUE. The penicillin beta lactam ring binds to and competitively inhibits the transpeptidase enzyme. Cell wall synthesis is arrested.
Name one way a Gram neg bacteria defends itself against penicillin.
It does this by preventing the penicillin from penetrating the cell layers by altering the porins. Gram neg bacteria have an outer lipid bilayer around their peptidoglycan layer.
Both G+ and G- bacteria can have beta lactamase enzymes that cleave the C-N bond in the beta lactam ring. TRUE/FALSE
TRUE.
Gram + bacteria(staph aureus) secrete the beta lactamase(penicillinase), and try to intercept the antibiotic outside the peptidoglycan wall. TRUE/FALSE
TRUE. Gram neg bacteria, have beta lactamase enzymes bound to their cytoplasmic membranes, destroy the beta lactam penicillins locally in the periplasmic space.
What is another way that bacteria can defend themselves against the penicillins?
Bacteria can alter the molecular structure of the transpeptidase so that the beta lactam antibiotic will not be able to bind.
Methicillin resistant Staph. aureus(MRSA) defends itself in this way.
What are the 5 types of penicillin?
1. Penicillin G
2. Aminopenicillins
3. Penicillinase resistant penicillins
4. Anti Pseudomonal penicillins
5. Cephalosporins
What is penicillin G?
This is the original penicillin, discovered by Fleming. He noted that the mold Penicillium notatum produced a chemical that inhibited Staph. aureus. It was first used in 1941.
Regarding Anti-Pseudomonal penicillins, what are the three categories of this class?
1. Carboxypenicillins
2. Ureidopenicillins
3. Monobactams
Cephalosporins is a widely used group of antibiotics that have a beta lactam ring, and are resistant to beta lactamases. TRUE/FALSE
TRUE. Many bacteria produce cephalosporinases, making them resistant to many of these drugs.
How is Pen G normally given?
It is usually given IM or IV. It is usually given in a crystalline form to increase its half life.
Pen V is an oral form of penicillin. TRUE/FALSE
TRUE. It is acid stable in the stomach. It is given for Strep pharyngitis caused by group A beta hemolytic streptococcus.
List some facts about Aminopenicillins.
1. They hit more Gram neg organisms.
2. Bind better to transpeptidase.
3. Inhibited by penicillinase
4. They are used for: E. coli, Proteus salmonella Shigella.
5. IV ampicillin is commonly used with other antibiotics such as Aminoglycosides(gentamicin), especially for severe urinary tract infections.
List three Penicillinase Resistant Penicillins.
1. Methicillin
2. Nafcillin
3. Oxacillin
These are usually given IV. methicillin was good for staphylococcal infections, but because of interstitial nephritis side effects, it is no longer used in the US.
When is Nafcillin used?
It is the drug of choice for serious Staphylococcus aureus infections such as cellulitis, endocarditis and sepsis.
What are the Anti-Pseudomonal Penicillins?
These have expanded G- coverage, especdially pseudomonas aeruginosa. They may be used against Bacterioides fragilis.
List 2 carboxypenicillins, and 2 Ureidopenicillins.
CarboxyP: Ticarcillin
Carbenicillin
UreidoP: Piperacillin
Mezlocillin
List 3 Beta Lactamases Inhibitors.
1. Clavulonic acid
2. Sulbactam
3. Tazobactam
These enzymes are inhibitors of beta lactamase. They can be given with penicillins.
Amoxicillin and Clavulanic acid=Augmentin
Ticaricillin and Clavulanic acid=Timentin
Ampicillin and Sulbactam=Unasyn
Piperacillin and Tazobactam=Zosyn
TRUE/FALSE
TRUE.
There are more than 20 different kinds of cephalosporins. TRUE/FALSE
TRUE.
Cephalosporins have a new basement molecule makes the beta lactam ring much more resistant to beta lactamases.
A new R group side chain allows for double the manipulations in the lab.
There are 1st/2nd/3rd generations.
A new Cephalosporin has been classified as a 4th generation antibiotic because it has greta Gram _ coverage like the 3rd generation, but also has good G+ coverage. TRUE/FALSE
TRUE.