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Flashcards in micro poop 2. Deck (50):
1

What factors must be considered in choosing an antimicrobial agent?

identity of infecting organism, information about the susceptibility of the infecting organism, factors specific to the patient

2

What is empiric theory?

the application of knowledge of the organisms most likely to cause infection in a given clinical setting and its most likely susceptibility to an antibiotic

3

Why is knowing the susceptibility of the organism important in choosing an antibiotic?

organisms exhibit intrinsic or innate resistance to certain antibiotics so you won’t consider these, while some are universally susceptible to certain antibiotics

4

What factors to the patient are important to consider when choosing an antibiotic?

history of previous reactions, age (gastric acidity changes with age - important for orally ingested), pregnancy, renal/hepatic function, site of infection

5

pharmacokinetics

encompasses all the ways that the body manipulates a drug, including absorption, distribution, metabolism, and excretion

6

pharmacodynamics

describes the biochemical and physiologic effects of the drug and its metabolism of action on the bacteria

7

bacteriostatic

antimicrobial agents that inhibit the growth and/or reproduction of the infecting agent, but fail to actually kill the agent

8

Why is bacteriostatic typically better than bacteriocidal?

normal defenses typically destroy the microorganism

9

What are examples of bacteriostatic agents?

macrolids (erythromycin), clindamycin, sulfamethoxazole, trimethoprim, tetracyclines, chloramphenicol

10

bacteriocidal

antimicrobial agent that is capable of causing irreversible damage or death to the organism

11

What are examples of bacteriocidals?

b-lactam antibiotics (penicillins and cephalosporins), vancomycin, aminoglycosides, fluoroquinolones

12

What is a factor that can influence if a antimicrobial is bacteriostatic or bacteriocidal?

antimicrobial concentration at the site of action - can be bacteriostatic at low concentrations and bactericidal at high concentrations

13

MIB

Minimal bacteriocidal concentration - the lowest concentration which prevents the organism from multiplying

14

broad spectrum antibiotics

active against wide range - usually both gram positive and gram negative

15

When are broad spectrum typically used?

empirically prior to identifying the causative bacteria (wide differential and potentially serious illness)

16

narrow spectrum antibiotic

active against a select group of bacterial types

17

What are the five mechanisms antibiotics inhibit/kill bacteria?

interfere with cell wall synthesis, protein synthesis, cytoplasmic membrane function, nucleic acid synthesis, metabolic pathway

18

What are antibiotics that interfere with cytoplasmic membrane function tricky?

all organisms have a cytoplasmic membrane

19

What antibiotics interfere with cell wall?

beta lactams (penicillin, cephalosporin, carbapenems, monobactams), vancomycin, bacitracin

20

What antibiotics interfere with cell membrane?

polymyxins

21

What antibiotics interfere with folate synthesis?

sulfonamides, trimethoprim

22

What antibiotics interfere with DNA gyrase?

quinolones

23

What antibiotics interfere with RNA polymerase?

rifampin

24

What antibiotics interfere with ribosome subunits?

macrolides, clindamycin, linezolid, cholamphenicol, streptogramins, tetracyclines, aminoglycosides

25

What is the mechanism of action for inhibitors of cell wall synthesis?

interfere with peptidoglycan sheet synthesis and murrain assembly

26

What are the beta-lactams?

PCCM (P-in, C-in, C-em, M-am) penicillin, cephalosporin, carbapenem, monobactam

27

How do beta lactams work?

bind at the active site of the transpeptidase enzyme that cross-links the peptidoglycan strands, irreversibly inhibiting the enzyme - formation of cell wall is prevented (non toxic to human)

28

What is the general structure of a penicillin? What group does it belong to?

house with an attached garage, beta lactams that block cell wall synthesis

29

How are cephalosporins categorized?

by generation - each generation exhibiting increased spectrum of activity as well as increased resistance to destruction by beta=lactamase enzymes

30

What is the structure of a cephalosporin?

weird house with attached garage

31

What are the third and fourth generation cephalosporins more targeted towards?

gram negative bacteria

32

carbapenems

cell wall inhibition - active against all pathogenic organisms and resistant to destruction by the extended spectrum beta lactamases

33

What is the structure of a carbapenem?

house with both attached and detached garage

34

What is the only antibiotic that works against MRSA?

vancomycin

35

What is the method of action for vancomycin?

blocks residues instead of cleaving like penicillin - prevents crosslinking

36

What bacteria are vancomycin effective against?

gram-positive bacteria (including MRSA) - gram negative resistant due to LPS porons

37

What is used for people who are allergic to penicillin? What is the method of action?

inhibitors of protein synthesis - infere with formation of 30S complex, 70S ribosome, or block elongation process

38

aminoglycosides - method of action and danger of these drugs

inhibit protein synthesis - causes misreading of mRNA —> therapeutic level is high, near toxic level - need to stop and give kidneys a rest

39

linezolid - method of action and when should it be used

inhibit protein synthesis - should only be used against gram + bacteria that are resistant to other antibiotics

40

macrolids

bacteriostatic - block protein synthesis

41

lincosamides

similar to macrolids - inhibit protein synthesis

42

chloramphenicol - method of action and when should it be used

inhibits protein synthesis - VERY TOXIC - should only be used against salmonella

43

tetracyclines

inhibit protein synthesis - static in nature, immune system must be able to clear the bacteria

44

quinolones/fluorquinolones

inhibition of DNA synthesis - esp inhibiting DNA gyrases/topoisomerases required for supercoiling DNA

45

metronidazole

inhibition of DNA synthesis

46

rifampin

inhibition of RNA synthesis

47

bacitracin

inhibition of RNA transcription

48

What is trimethoprim used in combination with?

sulfamethoxazole

49

trimethoprim

prevention of synthesis of folic acid

50

sulfonamides and dapsone

prevents synthesis of folic acid