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Pharm block 2 > Anti-microbials > Flashcards

Anti-microbials Flashcards

1
Q

What are the 4 ways microbes achieve resistance to anti-biotics?

A
  1. alterations in receptor target
  2. decreased entry or effleux of drug out of microbes
  3. alterations in metabolic pathways
  4. drug is inactive
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2
Q

When considering an anti-infective drug, what are the microbe factors to consider?

A
  • identificaiton of organism
  • susceptibility to concentration levels
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3
Q

What are the host factors to consider when selecting an anti-infective?

A
  • drug allergies
  • pharmacokinetic variables
  • effect of food on drug absorption
  • diseases affecting drug absorption
  • effect of other drugs that alter biotransformation
  • renal/hepatic function
  • pregnancy/lactation
  • site of infection
  • signs and symptoms
  • fever, malaise, leukocytosis, purulent drainage
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4
Q

Antibacterial agents work by 4 distinct major mechanism of action. name them

A
  1. inhibition of cell wall synthesis
  2. inhibition of protein synthesis
  3. inhibition of folic acid biosynthetic pathways
  4. inhibition of DNA/RNA synthesis
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5
Q

What are the drug classes that are cell wall synthesis inhibitors?

A
  • penicillins
  • cephalosporins
  • carbapenems
  • monobactams
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6
Q

WRT specificity and spectrum, what is the best use and why?

A

most specific narrow spectrum drug applicable

often more reactive and less alteration of normal GI microflora

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7
Q

What are the bactericidal antibiotics?

A
  • penicillins
  • cephalosporins
  • imipenem
  • vancomycin
  • aminoglycosides
  • bacitracin
  • polymixins
  • metronidazole
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8
Q

What are the bacteriostatic antibiotics?

A
  • erythromycin
  • tetracycline
  • sulfonamides
  • chloramphenicol
  • clindamycin
  • trimethoprim
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9
Q

Why are bactericidal antibiotics preferred?

A
  • reduces number of microbes
  • may be more rapid acting
  • produce irreversible damage
  • complete killing required in some cases
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10
Q

When choosing the correct antimicrobial therapy, the concentration of antibiotic at the site of infection is key. what are the 5 perameters associated with this?

A
  • dosage and duration of therapy
  • route of administration
  • distribution, metabolism, excretion
  • compliance
  • protected sites (blood brain barrier, prostate)
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11
Q

What are some factors at the site of infection that can alter the microbial therapy?

A
  • presence of pus
  • presence of hemoglobin
  • pH
  • anaerobic conditions
  • presence of foreign body
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12
Q

What are the 2 principles for antimicrobial development?

A

drugs can be found or developed that will specifically target site of action on parasites

sites of action should not be present in the organs and tissues of the host

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13
Q

What indications do you review for combination therapy of antibiotics?

A
  • Treatment of mixed bacterial infections
  • Treatment of severe infections of unknown etiology
  • Enhancement of activity (drug synergy)
  • Prevent emergence of resistant organisms
  • Permit lower dose of one of the antibiotics
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14
Q

What are the 4 disadvantages of combination therapy?

A
  • ** NOT usually necessary**=> Exceptions - more often treated with a combination of drugs – TB – Malaria – HIV
  • Antagonism of therapy • Wrong combination of drugs, i.e. static plus cidal
  • Increased toxicity • Avoid combining drugs with same site toxicity
  • Increased cost
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15
Q

What are the 3 main adverse side effects?

A

Organ tissue toxicity

drug allergies

superinfections

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16
Q

Name the specific organ/tissue toxicity you would expect with different parts of ADME

A

GI => oral administration

Hepatotoxicity => primary site of drug metabolism

Nephrotoxicity => primary site of drug excretion

17
Q

What are superinfections? How do they arise?

A

– Appearance of bacteriological and clinical evidence of a new infection during the chemotherapy of a primary infection.

Antibiotic-induced alterations of the normal GI flora

Incidence is greater with broad spectrum agents

18
Q

What 2 general ways can antimicrobials demonstrate resistance?

A

intrinsic or natural resistance

acquired resistance

19
Q

How does an organism get acquired resistance?

A

Occurs as a result of stable alterations in the genetic composition of the bacterial cell

Consequence of antibiotic therapy through selection of resistant organisms

NOT necessarily caused by the antibiotic

20
Q

What are the mechanisms of drug resistance (antibiotic resistance?

A

– Alteration in receptors for drug

– Decreased transport of drug across cell wall

– Increased export of drug from cell

– Inactivation of drug

– Alternative and salvage metabolic pathways

– Defect in drug metabolism or activation

21
Q

What are 5 failures of antibiotics?

A
  • Inability to penetrate to site of infection
  • Resistant organism
  • Superinfections
  • Drug reactions
  • Competing treatment modalities
22
Q

What are the indications of prophylactic use of antibiotics?

A

prevent infection by specific organism

prevent bacterial endocarditis or recurrence of rhematic fever

prevent infection resulting from rupture of viscus or a surgical procedure

patients with compromised host defense mechanisms

23
Q

What are the inappropriate uses of prophylactic antibiotics?

A

prevent all potential secondary infections in patients ill with other diseases

24
Q

What are the misuses of antibiotics?

A

• Treatment of insensitive infections
– viral infections

• Treatment of fever of undetermined
origin

  • Treatment without adequate bacteriological data
  • Un- or mis-diagnosed etiologic agent
  • Improper dosage
25
Q

What is the ideal antibiotic?

A
  • Bactericidal
  • Good antibacterial activity against usual organisms of infections
  • Narrowest antibacterial spectrum possible
  • No bacterial resistance
  • Acid stable
26
Q

WRT to ADME, what is the ideal antibiotic?

A
  • Well absorbed orally
  • No effect of food on absorption
  • Good distribution to bones as well as soft tissues
  • High tissue concentration – above MLC
  • MLC achieved at reasonable dose
  • Long half-life for optimal dosing
27
Q

Considering the adverse reactions, what are other ideal characteristics of the right antibiotic?

A
  • Nontoxic to mammalian cells
  • Exhibits no side effects
  • Creates no adverse drug interactions
  • Readily excreted
  • Ameliorates the infections in at least 5 to 7 days

Pharm block 2 (12 decks)

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