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Bacteriology > Antimicrobial Therapy > Flashcards

Antimicrobial Therapy Flashcards

1
Q

Antimicrobial agent vs Antimicrobial drug

A

An antimicrobial is an agent that kills all microorganisms (i.e. fungi, bacteria etc) or stops their growth.
Antibiotic- A drug used to treat bacterial infections.

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2
Q

Antimicrobial agent

A
  • suppress growth and multiplication

- kill organism

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3
Q

Natural Antibiotic - drug

A

Penicillin derived from fungi
Antibiotics can also be derived from other bacteria e.g. aminoglycosides and carbapenems
Bacillus polymyxa– Polymixin, Penicillium notatum– Penicillin
-Cephalosporium acremonium–> Cephalosporin
-Streptomyces venezuelae–> Chloramphenicol

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4
Q

Semi Synthetic

A

ampicillin, amoxicillin, methicillin

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5
Q

Synthetic

A

Sulphonamides, Quinolones

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6
Q

Selective Toxicity

A

Cause greater harm to microorganisms than to host
Chemotherapeutic index = lowest dose toxic to patient divided by dose typically used for therapy

-it selectively kills or inhibits the growth of microbial targets while causing minimal damage to host.

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7
Q

Classification - range of activity

A

Narrow spectrum - active towards fewer m.o.s (macrolides, polymyxin)

Narrow broad spectrum - active towards gram +ve and gram -ve (beta lactam)

Moderate spectrum - active towards Gram +ve bacteria and some systemic and UTI causing
Gram -ve bacteria. (Aminoglycosides, Sulfonamide)

Broad spectrum - active against Gram +ve and Gram -ve except Pseudomonas and Mycobacteria (Chloramphenicol, Tetracycline)

Anti-mycobacterial antibiotics: Ethambutol, Rifampicin, Isoniazid, Pyrazinamide-Treats TB

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8
Q

Broad spectrum is good first treatment of infection (T/F)

A

False; Can cause resistance to bacteria or destroy normal flora

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9
Q

Bacteriostatic vs Bactericidal

A

Bacteriostatic: Antibiotics that stops or inhibits the growth of bacteria i.e. no bacteria multiplication or
generation of new bacteria but they do not kill bacteria e.g. tetracycline, chloramphenicol – slow acting

• Bactericidal: Antibiotics that actually kill bacteria by any mechanism depending on the antibiotic used,
e.g. aminoglycosides – fast acting via killing

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10
Q

Lag, log, stationary, death phases

A

Lag+log phase - organism is maximally multiplying
Stationary - no deaths no new bacteria
Death- of bacteria

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11
Q

What phase do antimicrobials work at?

A

Log phase

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12
Q

Synergistic - Drug combinations

A

Action of one drug enhances the activity of another

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13
Q

Antagonistic - Drug combinations

A

Activity of one drug interferes with the action of another

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14
Q

Additive - Drug combinations

A

Neither synergistic or antagonistic

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15
Q

Indifference - Drug combinations

A

Each drug works no better or no worse alone or in combination

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16
Q

Prophylaxis therapy

A

– no organisms identified but used as a precautionary measure (used for prevention of infection)

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17
Q

Empirical therapy

A

– initial – infecting organism not identified – single broad spectrum agent (treat until you know what you are treating)

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18
Q

Definitive therapy

A

– microorganism identified – a narrow –spectrum low toxicity regiment to complete the course of treatment (definite diagnosis)

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19
Q

PK vs PD

A

Pharmacokinetics (PK) refers to the movement of drugs through the body, whereas pharmacodynamics (what body does to drug)
(PD) refers to the body’s biological response to drugs. (what drug does to body)

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20
Q

By graphing drug concentration versus time, you can get some ballpark estimates of the drug’s basic PK properties (T/F)

A

True

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21
Q

The maximum concentration the drug attains

A

Cmax

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22
Q

Time at which this maximum occurs

A

Tmax

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23
Q

Classification of Antimicrobial Agents against organisms

A 
Antibacterial 
•Antiviral
•Antifungal 
•Antiprotozoan 
•Anthelmintic
24
Q

β lactam antibiotics: chemical composition classification

A

Penicillin, cephalosporin, carbapenem, monbactam - -Beta lactam rings present with side chains

25
Q

Tetracycline group of antibiotics: chemical composition classification

A
  • Aminoglycosides: streptomycin, neomycin, kanamycin, amikacin, gentamicin
  • Polypeptide: polymixin, bacitracin
  • Glycopeptides: vancomycin, teicoplanin
26
Q

Beta lactam - no activity

A 
No activity against LAME
Listeria 
Atypicals (Mycoplasma/Chlamydia)
MRSA 
Enterococci
27
Q

The side structures determine what the beta lactam is active against (T/F)

A

True

28
Q

Another example of extending side chain antibiotic

A

Carabpanems - commonly used for the treatment of
severe or high-risk bacterial infections.
Clavanic acid - base of structure.
- reserved for known or
suspected multidrug-resistant (MDR) bacterial infections

29
Q

Antibiotic activity drugs

A

Macrolides - inhbits growth
Quinolones - inhibits/kills
Chloramphenicol - stops growth

30
Q

Antimicrobial agent

A

Streptogramins (treats VRSA)

31
Q

Slow spread of mycobacteria

A

Rifabutin

32
Q

Antifungal

A 
- Treats and prevents myosis
Imidazoles belong to the class of azole antifungals, which includes ketoconazole, miconazole, and clotrimazole
33
Q

Classification based on Mechanisms of Action Antimicrobials

A
  1. Inhibition of bacterial cell wall synthesis
  2. Inhibition of protein synthesis
  3. Inhibition of nucleic acid synthesis
  4. Inhibition of metabolic pathways
  5. Disruption of cell membrane permeability
  6. Inhibition of viral enzymes
34
Q

Inhibition of bacterial cell wall synthesis

A 
Cycloserine
Vancomycin
Bacitracin
Penicillin
Cephalosporin
Monobactams
Carapenems
35
Q

Inhibition of protein synthesis

A

Chloramphenicol (binds to 50s portion; inhibits peptide bond formation)
Erythromycin
Tetracyclines (interferes with tRNA to rRNA attachment)
Streptomycin (changes shape of 30s; mRNA read incorrectly)

36
Q

Disruption of cell membrane permeability

A

Polymyxin B

Azoles - antifungal agents

37
Q

Inhibition of viral enzymes (producing metabolites)

A

Sulfanilamide

Trimethroprim

38
Q

PBP - cell wall (Cephalosporin)

A

PBP produces folate which is responsible for the production of RNA and DNA
Result: Deformed cell wall
- Cephalosporins (Cephalexin, cefotaxime andvceftazidime)

39
Q

Abx

A

Antibiotics

40
Q

Antifungal agents (Polyenes)

A

Polyene (macrocyclic ring) consists of:
- Amphotericin B - polyene macrolide antibiotic produced by Streptomyces nodosus
- blocks microtubule that transports
nutrients
- Nystatin - obtained from Streptomyces noursei
- similar mechanism as Amp B

41
Q

Echinocandins

A
  • binds to fungal cell membrane (Ergosterol) and forms pores. This alters permeability & transport and
    as a result, cell death occurs. Inhibits glucan biosynthesis
42
Q

Heterocyclic benzofuran

A
  • Early antifungal (Griseofulvin)
  • Active against Dermatophytes: epidermophyt
    on, trichophyton , microsporum
  • Interferes with mitosis
43
Q

Antimetabolite

A
  • Flucytosine
  • Converted by fungal enzyme through steps and incorporated into fungal RNA leading to miscoding during mRNA,dna and protein synthesis
44
Q

Allylamine

A
  • Terbinafine
  • Synthetic; orally active
  • inhibits squalene (ergosterol biosynthesis); build up causes cell death
45
Q

Azoles

A
  • Disrupts synthesis of ergosterol

- Disrupts membrane structure and cell growth

46
Q

Azoles - groups

A

Imidazoles - Clotrimazole, Econazole, Miconazole, Ketoconazole
Triazoles - Fluconazole, Itraconazole, Posaconazole, Voriconazole

47
Q

Topical antifungal - Cicloporix

A

-Cicloporix
-active against Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum, Microsporum canis, Candida albicans, and Malassezia
furfur.
-Inhibits element transport in cells -> disrupting rna,dna,protein synthesis

48
Q

Topical antifungal - Tolnaftate

A
  • Distorts hypae; stunts mycelia growth

- active against Epidermophyton, Microsporum, and Malassezia furfur

49
Q

Antiparasitic Agents - Antiprotozoal

A

Metronidazole; Nifurtimox, Atovaquone, Pentamidine, Benznidazole, Quinacrine, Dehydroemetine, Sodium
stibogluconate

50
Q

Antihelmintic - Niclosamide

A

Niclosamide blocks glucose uptake by

intestinal tapeworms.

51
Q

Antihelmintic - Mebendazole

A

• Mebendazole blocks glucose uptake by
nematodes. Albendazole is similar to
mebendazole.

52
Q

Antihelmintic - Levamisole

A

• Levamisole paralyses the musculature of nematodes which lose anchorage and are expelled

53
Q

Antihelmintic - Praziquantel

A

• Praziquantel paralyses both adult worms and larvae.

54
Q

Antihelmintic - Thiabendazole

A

Thiabendazole inhibits cellular enzymes

55
Q

Antihelmintic - Pyrantel

A

Pyrantel depolarises neuromuscular
junctions of susceptible nematodes
expelled in faeces.

56
Q

Antihelmintic - Diethylcarbamazine

A

•Diethylcarbamazine kills microfilariae and adult worms.

57
Q

Antihelmintic - Ivermectin

A

•Ivermectin kills microfilaria (early stage in the life cycle of certain parasitic nematodes)

Bacteriology (9 decks)

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