Antimicrobials 1 and 2

Question 1

Define antibiotic and antimicrobial

Answer 1

Antibiotic: technically a naturally produced chemical from a microorganism. Antibacterial: drugs to treat bacterial infections

Question 2

Define bacteriostatic and bactericidal

Answer 2

Static stops growth so immune system can catch up. Cidal kill bacteria. Best for life-threatening or when immune systems broken.

Question 3

Principles of Antimicrobial Therapy Flowchart.

Answer 3

Insert chart.

Question 4

Betalactams

Answer 4

Only work when the cells are actively dividing

Question 5

Penicillin pyramid

Answer 5

Penicillin most narrow, amoxicillin/ampicillin more, pipercillin most. Cloxacillin on the side only fights staph, some strep. Tunnels = add another drug to amoxicillin/pipercillin. Insert Picture.

Question 6

General facts Cephalosporins

Answer 6

From mold. Blocks cross linking of peptidoglycan, activate autolytic enzymes. Gram -ve coverage increases with generation, gram +ve decreases. No Listeria, no Enterococcus, no coagulase negative staphylococci

Question 7

Generations of cephalosporins

Answer 7

1. Good gram +ve cocci, some gram -ve rod; 2. Good gram +ve cocci, more gram -ve; 3. Not great staph, good strep, even more gram -ve; 4. Good gram +ve, most gram -ve

Question 8

Names of drugs in the generations of cephalosporins

Answer 8

1st: Cefazolin, cephalexin (po). 2nd: Cefuroxime, cefprozil. 3rd: (all T’s) Cefotaxime, ceftazidime, ceftriaxone, cefixime (po). 4th: cefepime

Question 9

Monobactams

Answer 9

Aztreonams. No anaerobes covered.

Question 10

Carbapenems

Answer 10

Imipenem and meropenem (fewer side effects) - cover almost all diseases.

Question 11

Vancomycin

Answer 11

NOT A BETA LACTAM. Acts on early peptidoglycan wall synthesis

Question 12

Bacitracin

Answer 12

NOT A BETA LACTAM. Acts by inhibiting the precursors from getting to the site of peptidoglycan wall synthesis. Only used as a cream/topical agent because of side effects

Question 13

Summary of the drugs that affect cell wall

Answer 13

The cell wall active agents are the penicillins, the cephalosporins, the carbapenems, aztreonam and vancomycin. Penicillins – penicillin tree. Cephalosporins – ceph cycle. Aztreonam only gram negs. Carbapenems - gorillacillin. Vancomycin and bacitracin– only gram pos

Question 14

Protein inhibitors

Answer 14

Need to be actively transported into cell - therefore don’t work well on anaerobes.

Question 15

Aminoglycosides

Answer 15

Protein inhibitor. Gut gram negatives, bacteriocidal.

Question 16

Macrolides/Erythromycins

Answer 16

Protein inhibitor. Mycoplama, chamydia, gram +ve, and respiratory gram -ve . Bacteriostatic.

Question 17

Clindamycin

Answer 17

Protein inhibitor. Bacteriostatic. Common for dental and gyne. Gram positive aerobe and anaerobe

Question 18

Chloramphenicol

Answer 18

Protein inhibitor. Bacteriostatic. Rarely used due to side effects - affect bone marrow and mitochondria.

Question 19

Tetracycline, doxycycline, tigecyclin

Answer 19

Protein inhibitor. Bacteriostatic. Good coverage. Deposit on bones and teeth, can stain.

Question 20

Linezolid

Answer 20

Protein inhibitor. Bacteriostatic. Acts on ribosome. Good for highly resistant gram +ve infections (superbugs)

Question 21

Drugs that affect nucleic acid synthesis.

Answer 21

Work on proteins that affect nucleic acids ie ribosomes, gyrase, other enzymes, etc.

Question 22

Quinolones

Answer 22

Inhibit enzymes for supercoiling (gyrase, etc). 1: rare. 2. Ciprofloxacin (urinary, diarrhea, gram +ve). 3. Levofloxain (pneumonia from community, mostly gram +, some gram -). 4. Gemifloxacin (powerful).

Question 23

Metronidazole

Answer 23

Affect nucleic acid synthesis. Converted to active form by anaerobic or parasites. May be cancerous.

Question 24

Rifampin

Answer 24

Inhibits RNA polymerase. Used in combination for mycobacteria. Prophylaxis against N meningitidis.

Question 25

Antimetabolites

Answer 25

Binary fission requires cofactors like THF and folic acid. Antimetabolites block these.

Question 26

TMP/SMX

Answer 26

Antimetabolites. No anaerobes. coverage good

Question 27

Cytoplasmic membrane agents

Answer 27

Polymyxin - alters permeability; Good for gram -ve rods. Daptomycin - distrupts CM; reserved for highly resistant gram +ve cocci

Question 28

How can bacteria become resistant?

Answer 28

Acquire genes via 3 mechanisms: Conjugation (plasmid). Bacteriophage transduction. Transformation (extracellular DNA)

Question 29

What are the resistance mechanisms?

Answer 29

Block target, change target, fake (different metabolic pathway), attack (breakdown before it can bind), efflux pump