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Microbiology > 6. Antimicrobial Agents > Flashcards

6. Antimicrobial Agents Flashcards

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Biology 101 flashcards
1
Q

What is an antibiotic?

A

A chemical substance produced by microorganisms or chemical synthesis that, in low concentrations, inhibit the growth of other microorganisms

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2
Q

What are the criteria that have to be met in order for an antibiotic to be used?

A 
Selective toxicity
No allergic reactions
Soluble in body fluids
Capable of penetrating infected tissue
Do not readily develop resistance
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3
Q

What is broad spectrum vs. Narrow spectrum?

A

Broad - affects both gram negative and gram positive bacteria

Narrow - affecting only gram negative OR gram positive

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4
Q

What is bactericidal vs. bacteriostatic?

A

Bactericidal - kills the bacteria

Bacteriostatic - prevents bacteria from multiplying

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5
Q

What is an antimicrobial agent?

A

A type of chemotherapeutic agent used specifically for the treatment of infectious diseases

Most are antibiotics

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6
Q

What are the different types of mode of action?

A

Inhibitors of:

  • cell wall synthesis
  • protein synthesis
  • DNA and RNA synthesis
  • cell membrane function
  • other metabolic processes
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7
Q

What are beta-lactam antibiotics?

A

Antimicrobials that inhibit cell wall synthesis

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8
Q

What are the two major groups of beta-lactam antibiotics?

A

Penicillins

Cephalosporins

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9
Q

What is the prototype compound for natural penicillins?

A

Penicillin G or Benzylpenicillin

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10
Q

What is the spectrum for natural penicillins?

A

Narrow

Gram positive

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11
Q

What is the resistance to natural penicillins?

A

Are inactivated or sensitive to the enzyme Beta-lactamase, which opens the beta-lactam ring making the antibiotic useless

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12
Q

What is the clinical use for natural penicillins?

A

Penicillin G destructive to gastric acid and cannot be taken orally
Penicillin V can be taken orally

Are often given in combination with other drugs to improve absorption and retention abilities

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13
Q

Does class concept apply to natural penicillins?

A

Yes, test results from one antibiotic apply to all antibiotics of that class

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14
Q

What are the semisynthetic beta-lactamase resistant penicillins?

A

Oxacillin
Methicillin
Cloxacillin

Mainly used to treat staphylococcal infections, have a narrow gram positive spectrum
Cloxacillin commonly used, more stable, class concept applies
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15
Q

What is the bacterial resistance to semisynthetic penicillins?

A

Is due to altered penicillin binding proteins in their cell walls that prevent the antibiotic from binding

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16
Q

What are the aminopenicillins?

A

Ampicillin

Broad spectrum, both gram positive and negative
Susceptible to beta-lactamase
Amoxicillin used clinically as it has better absorption and excretion
Class concept applies

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17
Q

What are anti-pseudomonal penicillins?

A

Primarily directed towards the resistant psedudomonas aeruginosa
Broad spectrum
Inactivated by staphylococcal beta-lactamase
Expensive, used if other antibiotics are resistant
Class concept does not apply

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18
Q

What are the two groups of anti-pseudomonal penicillins?

A

Carboxy penicillins
- carbenicillin

Ureidopenicillins
- mezlocillin, azlocillin

19
Q

What are the two agents used, that when given in combination with beta-lactam antibiotics, the beta-lactamase enzyme is inhibited?

A

Clavulanic acid eg. Amoxicillin-clav, Ticarcillin-clav

Sulbactam

20
Q

What are cephalosporins?

A

A beta-lactam antibiotic
First produced from a fungus
Broad spectrum

21
Q

What is the first generation of cephalosporins?

A

Include cephlaothin, cefazolin, cephalexin

More expensive
Class concept generally applies
Injected, but cephalexin can be taken orally

22
Q

What is the second generation of cephalosporins?

A

Includes cefaclor, cefonicid, cefotiam, cefotetan, cefamandole, ceforanide

Broad spectrum, increased against gram negative but decreased against gram positive
None are effective against pseudomonas
Class concept does not apply

23
Q

What is the third generation of cephalosporins?

A

Include cefixime, cefotaxime, ceftizoxime, cefoperazone, cefazidime, ceftriaxone

Broad spectrum, less against gram positives but more against enterobacteriaceae and pseudomonas
Class concept does not apply

24
Q

What is the fourth generation of cephalosporins?

A

Includes cefipime, cefipriome

Broad spectrum
Selection for antimicrobial susceptibility testing varies

25
Q

What is Aztreonam?

A

Other beta-lactam antibiotic
Attaches to penicillin binding proteins and disrupts cell wall synthesis
Ineffective against gram positives
Effective against enterobacteriaceae and psudomonas that are resistant to other antibiotics

26
Q

What is imipenem?

A 
Belongs to a class called carbapenems
Bactericidal - binds to proteins of the cell wall causing bacterial cells to elongate and lyse
Broad spectrum
27
Q

What is Vancomycin?

A

NOT a beta-lactam antibiotic but still inhibits cell wall synthesis
Belongs to a class called glycopeptides
Not affected by beta-lactamase
Bactericidal
Narrow gram positive spectrum
Used to treat when other antibiotics are resistant
Have toxic side effects such as hearing loss

28
Q

What are the four groups of antibiotics that inhibit bacterial protein synthesis?

A

Macrolide
Chloramphenicol
Tetracyclines
Aminoglycosides

29
Q

What is erythromycin?

A

Belongs to the group macrolides
Binds to ribosomal sub units
Usually bacteriostatic
Narrow mainly gram positive spectrum, some gram negatives

30
Q

What is clindamycin?

A

Similar to Erythromycin
Better absorption and penetration properties
Better for treating anaerobic infections
Associated side effect of diarrhea

31
Q

What is Chloramphenicol?

A

Bacteriostatic, inhibits protein synthesis
Broad spectrum
Small molecule
Serious toxic effects - gray syndrome in infants, aplastic anemia, dose-related marrow depression
Used for treatment of typhoid and meningitis

32
Q

What are Tetracyclines?

A 
Inhibit protein synthesis, prevent the binding of tRNA to mRNA 
Bacteriostatic 
Broad spectrum 
Resistance is common 
Treats chlamydia, acne, mycoplasma
Taken orally, not given to children
33
Q

What are Aminoglycosides?

A

Inhibit protein synthesis, bactericidal
Ineffective in treating anaerobic infections
Synergistic action with beta-lactum antibiotics
Movement affected by magnesium and calcium ions
Broad spectrum
Toxic to kidneys, damage to eights cranial nerve

34
Q

What are some Aminoglycosides currently in use?

A 
Kanamycin
Gentamicin
Tobramycin
Amikacin
Netilmicin
Spectinomycin 
Class concept does not apply
35
Q

What are some antimicrobials that inhibit DNA and RNA synthesis?

A

Fluoroquinolones
Nalidixic Acid
Metronidazole (Flagyl)

36
Q

What are Floroquinolones?

A

Belong to a class called Quinolones
Bind to DNA gyrase enzymes, inhibit nucleic acid synthesis
Bactericidal
Broad spectrum including enterobacteriaceae
Toxic - irreversible cartilage and skeletal damage

37
Q

What is Nalidixic Acid?

A

Belong to the class Quinolone
Broad spectrum
Treats urinary tract infections

38
Q

What is Metronidazole?

A

Effective against anaerobic infections
Breaks up DNA strands - bactericidal
Treats protozoan parasitic infections

39
Q

What are Polymyxins?

A 
Inhibits cell membrane function 
Belong to polypeptides 
Bind to cell membranes causing leakage of cell contents -  bactericidal 
Toxic - kidneys and nerves 
Narrow gram negative spectrum

Include polymixin B and polymixin E

40
Q

What are some antimicrobial agents that inhibit other metabolic cell processes?

A

Sulfonamides
Trimethoptim
Nitrofurantoin

41
Q

What are Sulfonamides?

A 
Antimicrobial agents NOT antibiotics 
Synthetic 
Prevent the synthesis of folic acid, work by competitive inhibition 
Bacteriostatic 
Broad spectrum, inexpensive
Treat urinary infections 
Synergistic action with trimethoprim
42
Q

What is Trimethoprim?

A

Interferes with folic acid, using competitive inhibition
Broad spectrum
Often used with sulfonamide and the combination is called cotrimoxazole
Used for urinary tract infections

43
Q

What is Nitrofurantoin?

A

Synthetic
Belongs to a group called Nitrofurans
Mode of action not clear - may damage DNA, protein, translation enzyme
Broad spectrum
Treats urinary tract infections
Can be both bactericidal and bacteriostatic

Microbiology (7 decks)

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