TH. PART: BACTERIOLOGY Q37-46

Question 1

(Q37) Beta-lactams

Beta lactams includes 4 groups which are:

Answer 1

1. Penicillins
2. Cephalosporins
3. Carbapenams
4. Monobactams

Question 2

(Q37) Beta-lactams

When and by who was penicillin discovered?

Answer 2

In 1928 by Alexander Flaming

Question 3

(Q37) Beta-lactams

What does all 4 groups of beta-lactams have in common?

Answer 3

All have a beta-lactam ring in the structure

Question 4

(Q37) Beta-lactams

What is mechanism of penicillin?

Answer 4

Inhibit synthesis of bacterial cell wall by binding to PBP (penicillin binding proteins)

Question 5

(Q37) Beta-lactams

What are 3 reasons for antibiotic resistancy?

Answer 5

1) Penicillinases: Prevent penicillin from binding to PBS by binding to PBS itself.
2) Due to altering PBS.
3) Porins (in G- bacteria): Sends penicillin out of bacteria.

Question 6

(Q38) Cephalosporins

Mechanism of cephalosporins?

Answer 6

Disrupt synthesis of peptidoglycan layer (cell wall syntesis).

Question 7

(Q38) Cephalosporins

Mostly used for G+ or G- bacteria?

Answer 7

G-

Question 8

(Q38) Cephalosporins

How many generations is it of cephalosporins and what are they?

Answer 8

5 generations
Gen. 1 = for G+ bacteria (e.g. KEFLEX)
Gen. 2 = Fewer targets
Gen. 3 = More effective against G- bacteria
Gen. 4 = Used only for more severe infections, both G+ and G-
Gen. 5 = Treats penicillin resistant bacteria like MRSA. E.g in USA only 1 type og 5th generation cephalosporin is available.

Question 9

(Q38) Cephalosporins

What fungi is cephalosporins produced by?

Answer 9

Cephalosporium

Question 10

(Q39) Macrolides

What is the suffix macrolides always ends with?

Answer 10

-thromycin

Question 11

(Q39) Macrolides

Name 3 examples of macrolides:

Answer 11

Erythromycin, azithromycin, clarithromycin

Question 12

(Q39) Macrolides

What is mechanism of macrolides?

Answer 12

Inhibit protein synthesis by inhibition of bacterial 50S ribosomal subunit. Inhibit growth of bacteria but is not bactericidal.

Question 13

(Q39) Macrolides

Which bacteria are macrolides usually used agains?

Answer 13

Macrolides are active against most aerobic and anaerobic G+ bacteria. Usually not G- bacteria. (some G- strains are sensitive like pasteurella, haemophilus and neisseria.)

Question 14

(Q39) Macrolides

Why are macrolides often in site of infection?

Answer 14

They are actively concentrated within LEUKOCYTES and are therefore transported into the site of infection

Question 15

(Q40) Lincosamides

Another name for lincosamides?

Answer 15

Clindamycin

Question 16

(Q40) Lincosamides

Mechanims of lincosamides?

Answer 16

Inhibits 50S ribosomal subunit -> supress protein synthesis.

Question 17

(Q40) Lincosamides

What tissue is clindamycin extra good at penetrating?

Answer 17

Bone

Question 18

(Q40) Lincosamides

What bacteria does it treat well?

Answer 18

G+ aerobes (e.g. streptococcus, staphylococcus, but not enterococcus).

Clindamycin is approved for use in cats and dogs for treatment of infected wounds, abscesses, and dental infections. (MSD manual)

Question 19

(Q40) Lincosamides

What bacteria does it not treat well?

Answer 19

G- aerobes. Don’t work at all.

Question 20

(Q41) Aminoglycosides
What suffix(es) does aminoglycosides always end with?

Answer 20

• mycin, -micin and -cin

exeption: thromycin is a macrolide

Question 21

(Q41) Aminoglycosides

4 examples of aminoglycosides:

Answer 21

1) streptomycin
2) gentamicin
3) tobramycin
4) amikasin

Question 22

(Q41) Aminoglycosides

Are aminoglycosides used alone?

Answer 22

Almost always used with another type of AB (so to widen the specter).

Question 23

(Q41) Aminoglycosides

What bacteria is it used against?

Answer 23

G- aerobes like E. coli, klebsiella and pseudomonas.

Question 24

(Q41) Aminoglycosides

What bacteria is it NOT used against?

Answer 24

G+ aerobes and never any anaerobes

Question 25

(Q41) Aminoglycosides

Work by what mechanism?

Answer 25

By binding to 30S ribosome, thereby inhibiting protein synthesis. Are bactericidal.

Also have a post antibiotic effect by causing suppression of bacterial growth after removal of anitbiotic.

Question 26

(Q42) Chloramphenicols

Work by what mechanism?

Answer 26

Binds to the 50S subunit on ribosome, supressing protein syntheisis.

Question 27

(Q42) Chloramphenicols

What can a high dosage affect?

Answer 27

Can interfere and reduce mitochondrial protein in mammalian cells

Question 28

(Q42) Chloramphenicols

What bacteria does it kill? Give 1 example.

Answer 28

Effective against a wide variaty og G+ and G- bacteria. Is very effective agains Salmonella typhi.

Question 29

(Q42) Chloramphenicols

What spectre of bacteria is it known to be extra good at?

Answer 29

Anaerobic spectrum

Question 30

(Q42) Chloramphenicols

Bacteristatic or bactericidal?

Answer 30

Usually bacteristatic, but can be bactericidal at higher dosage for some species.

Question 31

(Q43) Tetracyclins

Treats what?

Answer 31

All tetracyclines are about equally active and typically have about the same broad spectrum, which comprises both aerobic and anaerobic gram-positive and gram-negative bacteria, mycoplasmas, rickettsiae, chlamydiae, and even some protozoa (amebae). Tetracyclines generally are the drug of choice to treat rickettsiae and mycoplasma.

Question 32

(Q43) Tetracyclins

Work by what mechanism?

Answer 32

Binds to bacterial 30S ribosome subunit and mRNA preventing ribosomal translation.