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Antimicrobials Flashcards

(54 cards)

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1
Q

What is an Antimicrobial?

A
  • Drugs/chemicals that kill micro-organisms or inhibit their growth
  • can be used to treat microbial infections
  • most selective of all pharm agents because of selective toxicity
    Most overused and misused therapeutic agents - leads to antimicrobial resistance
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2
Q

What are the different types of antimicrobials?

A

Antibiotics = against bacteria
Antifungals = against fungi
Antivirals = against viruses

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3
Q

What is selective toxicity?

A

Target microbial cells over mammalian cells (thru structural and metabolic toxicity) and cause greater harm to the micro-organisms than the host.

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4
Q

What are the antimicrobial actions?

A

Microbicidal KILL - decrease (immunocompromised preferred)
Microbiostatic PREVENT - remain constant

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5
Q

What are the antimicrobial spectrums of activity?

A

Narrow-spectrum - kills/inhibits narrow range (ex. Penicillin gram +)

Broad-spectrum - kills/inhibits a wide range (ex. Tetracyclines gram +/-, anaerobes, and aerobes)

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6
Q

What are examples of inappropriate antimicrobial use?

A

-antibiotics for viral infections
-inadequate dose/duration
-Rx w/out culture or data
-overuse of unnecessary broad spectrum

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7
Q

What should you consider in optimal antimicrobial therapy?

A

Efficacy, safety, decreasing microbial resistance

  • Organism ID (culture, gram staining, morphology) and susceptibility testing
  • Use of antimicrobial with the narrowest spectrum of activity, at adequate dose and appropriate duration
  • Use of agents in combo if needed (synergistic effect)
  • Consideration of client factors (immune status, age, pregnancy, renal function)
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8
Q

What are antibiotics?

A

Treat infections caused by bacteria that aren’t part of normal flora

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9
Q

What’s the diff b/w mammalian and bacterial cells?

A
  • Bacteria has cell wall
  • Essential metabolic pathways (i.e. synthesizes folic acid)
  • Different macromolecule anabolism (protein synthesis and nucleic acid synthesis) [no nucleus - non-eukaryotic]

(Antibiotics target these!)

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10
Q

What are the mechanisms of action of antibiotics?

A

Inhibition of:

1) Cell wall synthesis
2) Protein synthesis
3) Nucleic acid metabolism
Essential metabolites (folic acid)

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11
Q

Describe the mechanism of cell wall inhibition?

A

Made of peptidoglycan and prevents cell from bursting. If cell wall is fucked with - osmotic pressure = cell lysis.

Interferes with cross linking of peptidoglycan
· Inhibited by glycopeptides (transglycosoylation and transpeptidation)
Inhibited by Beta-lactams (transpeptidation catalysed by penicillin binding proteins)

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12
Q

Describe the mechanism of Beta Lactams

A

Cell wall inhibition - Covalently binds to the active site of penicillin-binding proteins (penicillins and cephalosporins)
BACTERIACIDAL

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13
Q

Describe the mechanism of glycopeptides?

A

Binds to the d-alanyl-D-alinine resides to prevent cell wall synthesis. (Vancomycin)
BACTERIACIDAL

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14
Q

What is gram +?

A

Thick peptidoglycan layer

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15
Q

What is gram -?

A

Thin peptidoglycan layer. Outer layer contains phospholipids and lipopolysaccharides

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16
Q

What’s the deal with penicillin?

A

Cell wall inhibition VIA Beta Lactam
Primarily effective against Gram +
- R side chain determines the class of penicillin (determines: spectrum, susceptibility to acid (route), susceptibility to inactivation (resistance to resistance lol)
- Ends with -cillin
Beta-lactamase enzymes (penicillinase) destroy antibacterial activity causes resistance to penicillin.
Safe in pregnancy, unless anaphylaxis, allergy

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17
Q

What are the classes of penicillin?

A

Class 1: Narrow spectrum, Class 2 : Penicillinase Resistant, Class 3: Extended spectrum

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18
Q

What’s the deal with Narrow Spectrum penicillin?

A

Injected
Active against non-penicilinase producing Gram + an some Gram -
Penicillin G p used in group B strep, effective against streptococci

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19
Q

What’s the deal with Penicillinase Resistant penicillin?

A

Cell wall inhibition

Not as effective against other infections as pen G or pen V
cloxacillin, dicloxacillin (ORALLY ADMIN restricted for use against staphylococci) - MASTITIS

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20
Q

What’s the deal with extended spectrum penicillin?

A

NOT penicillinase-resistant
**Ampicillin (usually parenteral - non GI); **amoxicillin (oral)
Combined with clavulanic acid (irreversible inhibitor of penicillinase)
Active against gram+, but major use gram -
Many strains resistant due to overuse

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21
Q

What’s the deal with cephalosporins?

A

Cef-
Cell wall inhibition VIA beta lactam
Structural relatives of pen (so if someone anaphylactic against pen shouldn’t be prescribed ceph 5%)
Two R groups so more can be made
Classified by 5 generations Narrow —-> Broad *effectiveness against Beta lactamases and against Gram (-)
**Gen 1 = **Cefazolin, **Cephalexin (gram +, ok gram -)
** Gen 3 = ** Cefixime (gram -)

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22
Q

Describe the mechanism of glycopeptides?

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A

Cell wall inhibition.
Bind to D-alanyl-D-alanine residues (binds to amino acid)
Bactericidal
(Vancomycin)

23
Q

What’s the deal with Vancomycin?

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A

Cell wall inhibition via glycopeptides
Injected
Gram +
Last line treatment of prophylaxis of Group B strep and serious life threating infections not responsive to other antibiotics
Side effects: turn red

24
Q

Describe the mechanism of protein synthesis inhibition?

Study These Flashcards
A

Fuck with 30s or 50 s subunits (not in mammalian cells), messing with ribosomal activity

(Aminoglycosides, Tetracyclines = 30 s) ( Macrolides, Clindamycin = 50 s)

25
What's the deal with Aminoglycosides?
Protein synthesis inhibitor Injected Irreversibly binds to 30s - misreads mRNA codes Aerobic gram - Bactericidal
26
What are the adverse effects of aminoglycoside?
Ototoxicity (damage to inner ear) - irreversible partial or total hearing loss Avoid in pregnancy And damage to kidneys
27
What's the deal with Tetracyclines?
Protein synthesis inhibitor Reversibly bind to 30s - prevents binding of rTNA to mRNA Bacteriostatic Broad spectrum - many gram + and - strains, but many have developed resistance Reserve for specific indications: Lyme, chlamydia
28
What are the adverse effects of Tetracyclines?
GI discomfort Effects on calcified tissue - bone deposits/teeth **Avoid in pregnancy, lactating ppl, and children under 8 yo - permanent teeth discolouration an temporary inhibition bone growth
29
What' the deal with macrolides?
Protein synthesis inhibitor Reversibly bind to 50s subunit - inhibit translocation Bacteriostatic Many Gram + and some Gram - **ERYTHROMYCIN Can be used in pregnancy - alternative to penicillin, safe w limited toxicity **AVOID ERYTHROMYCIN ESTOLATE in preg - hepatotoxicity Adverse effect: GI discomfort
30
What’s the deal with Clindamycin**?
Protein synthesis inhibitor Reversibly binds to 50s subunit - inhibits translocation Bacteriostatic Gram+ and some Anerobic gram - strains Alternative to pen Bacterial Vaginosis Adverse effect - inflammation of colon
31
Describe the mechanism of Nucleic Acid Metabolism Inhibition?
Target enzymes of bacterial DNA replication - DNA gyrase (topoisomerase II) and topoisomerase IV - not in mammalian cells IV - facilitates DNA replication II and IV - reduce tension of DNA coil (Fluoroquinolones, Metronidazole, Nitrofurantoin)
32
What's the deal with Fluoroquinolones?
Ciprofloxacin most widely used Usually not first defence Many gram - and some gram + UTIS, respiratory and intestinal tract, lungs, skin, bones Interfere with DNA gyrase (topoisomerase II) and topoisomerase IV Bactericidal Well tolerated
33
Adverse effects of Fluoroquinolones?
GI discomfort Tendon rupture ****Arthropathy - avoid in 1st trimester and use caution under 18 yo
34
What's the deal with **Metronidazole?
Anaerobic bacteria Bactericidal Converted to reactive metabolite by proteins in anaerobic bacteria Good for treatment of BV
35
What's the deal with **Nitrofurantoin?
Converted to a reactive metabolite causing damage to DNA Good for UTIs Can cause hemolytic anemia in neonates Avoid in late pregnancy, neonates, and lactating ppl
36
Describe the mechanism of Essential Metabolite Inhibition
Fuck w/ synthesis of folic acid Bacteria must make folic acid (mammalian cells obtain from diet) Bacteriostatic Inhibits enzyme needed to make folic acid (Sulfonamides and Trimethoprim) Broad spectrum Gram + / -, resistance S and T usually administer together - co-trimoxazole UTI an resp infections
37
What's the deal with Sulfonamides?
Essential metabolite inhibition VIA enzyme inhibition Enzyme = dihydropteroate synthase (DHPS) - 1st step of folic acid Adverse effects - Hypersensitivity Kernicterus in neonates - bilirubin induced brain damage Avoid late preg, neonates, lactating ppl
38
What's the deal with Trimethoprim?
Essential metabolite inhibition VIA enzyme inhibition Enzyme = dihydrofolate reductase - 2nd step folic acid 50,000 x more active against the bacterial version Adverse effects- Megaloblastic anemia Avoid first trimester of pregnancy = increase in neural tube defects
39
Common indications for antibiotics in midwifery?
UTIs, Intrapartum prophylaxis group B streptococcus, Mastitis, Prophylaxis of ophthalmia neonatorum, BV
40
UTIs treatments?
Amoxicillin (most common), cephalexin, Nitrofurantoin (avoid late preg), Cefizime (once a day)
41
Group B Strep Proph?
Order of Preference: Penicillin G Ampicillin Cefazolin Clindamycin Vancomycin
42
Mastitis treatment?
Cephalexin Cloxacillin or Dicloxacillin Co-amoxiclav Clindamycin
43
Ophthalmia Neonatorum proph?
Erythromycin ointment 1 hour after birth
44
BV treatment?
Metronidazole Clindamycin
45
What's the difference b/w mammalian and fungal cells?
Fungal - cell membrane (ergosterol instead of CHO) and Cell wall (made from chitin and beta-glucan)
46
Method of Action for Cell membrane disruption in antifugals?
Interferes w/ ergosterol or ergosterol synthesis (Polyenes and Azoles)
47
What's the deal with Polyenes?
Includes **nystatin (topical, systemically toxic) Treats candida in mouth (thrush), esophagus, skin, vagina Disrupt cell membrane of fungal cells
48
What's the deal with Azoles?
Disrupt cell membrane of fungal cells (fungal enzyme 14 - alpha - demethylase (P450) ) Most widely used antifungal 2 Groups (1) Imidazoles (**Miconazole, **clotrimazole) (2) Triazoles Topical or systemically Treat candida infections, athletes foot, ringworm, systemic fungal infections AVOID SYSTEMIC AZOLES IN PREGNANCY
49
What's Candidiasis?
Aka Yeast infection - yeasts from genus Candida
50
Treatment for Candidiasis?
(TOPICAL) Clotrimazole Miconazole
51
Treatment for thrush?
Nystatin
52
Nipple infection treatment
Miconazole or Clotrimazole All purpose nipple ointment (antifungal and anti-inflammatory) Nystastin cream
53
Treatment of Herpes
HSV -1 cold sores HSV 2 - genital herpes Suppressive proph with history of recurrent genital herpes 36 weeks till delivery Acyclovir Valaciclovir (less doses)
54
Drug risk classification?
A and B considered safe in preg X - never use!

Pharmacology (4 decks)

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