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Exam 3 > Prunuske- Antibacterial Drugs: Chemotherapy > Flashcards

Prunuske- Antibacterial Drugs: Chemotherapy Flashcards

1
Q

What does antimirobial therapy include?

A 
Anti: 
Bacterial
Fungal
Parasitic
Viral
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2
Q

What is selective toxicity?

A

Antibiotics INJURE invading organism while causing minimal ADVERSE EFFECTS to host.
It EXPLOITS DIFFERENCES in cell biology.
Harder to develop drugs that are toxic to eukaryotes (fungi/parasites) and EASIER to develop drugs for prokaryotes.

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3
Q

What are antibiotics?

A

Ligands

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4
Q

What are microbial targets?

A

Receptors

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5
Q

What is toxicity?

A
  1. An extension of normal mechanism of action of drug (trimethoprim can inhibit folate metabolism and result in bone marrow suppression)
  2. Unintended consequences
    (vanconmycin can stimulate histamine release resulting in red man syndrome)
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6
Q

What is the result of a high therapeutic index? What are examples of things with HTI?

A
  1. Fewer adverse side effects

2. Cell wall inhibitors, bc humans don’t have peptidoglycan

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7
Q

What are the three classifications for spectrum antibiotics?

A
  1. Narrow- Gram NEG COCCI
  2. Extended- Gram NEG RODS AND COCCI
  3. Broad- Gram POS and NEG organisms
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8
Q

What is prophylaxis?

A

NO INFECTION

Treat treat an infection that has not yet developed in individuals at a high risk of developing an infection.

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9
Q

What is a pre-emptive drug?

A

INFECTION NO SYMPTOMS

Have lab test indicating infection but no symptoms. Advantage decreases amount of antibiotics being used.

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10
Q

What is empiric therapy?

A

SYMPTOMS, INFECTION, NOT SURE OF SPECIFIC ORGANISM
Take cultures, patients have an infection with serious potential consequences but the organism has not been identified (broad spectrum). Severity of disease would increase if you waited to find out specific organism.

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11
Q

What is definitive therapy?

A 
PATHOGEN ISOLATION
Pathogen identified (monotherapy, narrow spectrum)
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12
Q

What is supressive therapy?

A

RESOLUTION
After initial disease is controlled therapy is continued at a lower does. Someone that is immunocompromised might have suprressive therapy.

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13
Q

What is an example of an empiric antibiotic therapy?

A

Beginning nitrofurantoin for a patient with signs and symptoms of a urinary tract infection with a positive urinalysis

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14
Q

What is pharmacokinetics?

A
  1. The body’s effect on the drug.
  2. Must treat individual with the RIGHT: drug, dose, route, and duration to kill enough bacteria to eliminate the infection
    * *EFFECTED BY ADME
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15
Q

What is absorption?

A

movement of drug into the vascular system

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16
Q

What is distribution?

A

Transfer of drug from intravascular to extravascular, blood brain barrier is TOUGH to get through

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17
Q

What is metabolism?

A
  1. Irreversible transformation of parent compound into daughter metabolites often in the liver.
  2. Drugs can become more or less active in the liver.
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18
Q

What is excretion?

A

Elimination of the drug from the body through URINE OR FECES

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19
Q

When does drug drug interaction occur?

A

when one drug inhibits or induces the uptake or

clearance of another drug.

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20
Q

What are ways to administer drugs?

A 
Oral
Intravenous
Intramuscular
subcutaneous
inhalant
sublingual
intrathecal
rectal
topical
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21
Q

What causes most pharyngitis?

A

Viruses and antibiotics DON’T DO ANYTHING for viral infections

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22
Q

Why don’t we want to overprescribe antibiotics?

A
  1. Need to minimize the development of antibiotic resistant microorganisms
  2. Minimize harm to the patient caused by toxicity due to the use of an
    unnecessary or inappropriate drug.
  3. Provide cost effective treatment. Hospital purchases of antibiotics usually
    represent 25-30% of the drug budget.
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23
Q

When are you instructed to do a rapid strep test?

A

When symptoms are consistent with bacterial infection: fever, age 5-15, nodes, etc.

24
Q

What are methods that can be used to confirm the identity of an organism calling infection?

A

Bacterial culture

25
Q

What is a rapid strep test?

A
  1. Positive rapid antigen detection test
  2. Specific but not very sensitive
  3. Detects antigens: proteins or polysaccharides detected with antibodies (serologic test)
  4. May have a false negative or infection could be due to another bacterial organism
26
Q

How do serology tests work?

A

slide 20

27
Q

What is a back up culture?

A

A backup culture of a throat swab for all children with a negative result takes 24-48 hours Gram stain and morphologic analysis (cocci vs. bacilli)

  1. Used for negative rapid strep test
  2. Takes 24-48 hours.
  3. Gram stain and morphologic analysis
  4. POSITIVE IS PURPLE, NEGATIVE IS PINK
28
Q

What is a biochemical test?

A
  1. Catalase test- monitors degradation of H2O2; differentiates between staphylococci (present) and streptococci (absent)
  2. Coagulase test–clumping, differentiates Staphylococcus strains
  3. Hemolysis–clearing around colonies on a blood agar plate differentiates between streptococci
  4. Glucose/lactose fermentation–metabolism will differentiate between bacteria
29
Q

What are the characteristics of bacteria for strep A?

A
  1. PURPLE STAIN IS GRAM POSITIVE
  2. Streptococcus in long chains
  3. Beta hemolysis–clearing around colony on agar plate
30
Q

What is alpha hemolysis?

A

α-hemolytic form green ring–some lysis

31
Q

What is beta hemolysis?

A

β-hemolytic clearing around colonies on agar plates–complete yellow clearing

32
Q

What is gama hemolysis?

A

γ-hemolysis no hemolysis

33
Q

What is alpha hemolysis?

A

α-hemolytic form green ring–some lysis

34
Q

What is beta hemolysis?

A

β-hemolytic clearing around colonies on agar plates–complete yellow clearing

35
Q

What is gama hemolysis?

A

γ-hemolysis no hemolysis

36
Q

What do you do if there is a history of drug reaction/allergy?

A
  1. Beta-lactams (penicillin) and sulfonamides
  2. In some cases, allergy to a particular drug will predict allergies to other drugs in the class–penicillan/amoxicillan
  3. Must be careful about labeling a patient as allergic since this can result in treatment with inferior drugs
  4. Can do a skin test to confirm and try penicillin desensitization
37
Q

How does age affect dosing?

A
  1. In the elderly, kidney function is reduced. With DECREASED INCRETION INCREASES HALF LIFE, the half life of beta-lactams, aminoglycosides and fluoroquinolones increasing likelihood of adverse effects.
  2. Does the pt. have other diseases? Chloramphenicol is inactivated by liver metabolism.
    With impaired liver function, dose should be reduced
38
Q

Why is it important to know the status of the pt’s immune system?

A
  1. Bacteriostatic- LIMITS GROWTH and if removed the organism can grow again. Usually successful because allows immune system to catch up. (ribosome inhibitors)
  2. Bactericidal- KILLS BACTERIA 99.9% reduction in bacterial inoculums within 24 hr period of exposure. (cell wall inhibitors)—do not work well if the cells are not actively dividing!

**Drug may be bacteriostatic against one organism and bactericidal against another. Many bactericidal drugs

39
Q

If your patient was undergoing cancer chemotherapy and had a suppressed immune system, would you choose a bacteriocidal drug or a bacteriostatic to treat the infecting organism? Why?

A

Bactericidal–Kill bacteria

40
Q

What genetic factors make the patient more susceptible to toxic side effects?

A

SULFONAMIDES: May cause hemolysis of red blood cells in individuals with glucose-6-phosphate dehydrogenase deficiency.

41
Q

Why is it important to know if the patient is pregnant?

A

Look at pregnancy category definitions. B is passable. First trimester is when you’re most concerned about using safe drugs.

42
Q

Why is it important to know if the patient has recently been on an antibiotic?

A
  1. Drug resistance

2. Super infection

43
Q

What factors effect which antibiotic you’ll use?

A

k

44
Q

What are mechanisms associated with bacterial resistance to antibiotics?

A
  1. A cell is susceptible if a drug can go in and bind with target
  2. Resistant if drug can’t get in to begin with, eflux pumps get rid of drug so never get high enough concentrations, enzymes that modify or change drug, drugs that effect ligands
45
Q

What is intrinsic resistance?

A
  1. An absence or inaccessibility of the target for the drug action.
    For example, MYCOPLASMA lack cell walls so they are intrinsically resistant to cell wall inhibitors
  2. No change in the genetics of the bacteria occurs.
46
Q

What is acquired drug resistance?

A

The bacteria CHANGE their DNA (mutation) or ACQUIRE new DNA resulting in resistance to a drug.

**DRUG does not cause resistance, variability in population of bacteria

47
Q

What is DNA mediated transformation?

A
  1. Process of taking up DNA resistance gene
  2. incorporating it into bacterial genome through homologous recombination (only gets incorporated on one strand)
  3. One strand is resistant, one is sensitive
  4. Grow bacteria in streptomyacin, one’s with resistant DNA will increase more rapidly in populatoin
48
Q

What are bacteriophages?

A
  1. Introduce new DNA through transduction

2. Pick up DNA from other bacteria they’ve infected

49
Q

What is conjugation?

A

Transfer of R plasmid may contain several resistance determinant genes common amongst Gram Neg.

50
Q

WHat contributes to our growing antibiotic resistance problem?

A
  1. Fewer antibiotics are being developed
51
Q

What is transposition?

A
  1. It causes the movement of the genetic material within the genome.
  2. Ex. resistant MRSA strains comes form interspecies conjugation. Enterococcus plasmid is picked up, but won’t be replicated unless it jumps over to more stable plasmid. Resistance allele is integrated.
52
Q

What are the ways that bacteria can acquire resistance?

A

Transformation
Bacteriophages
Conjugation
Transposition

53
Q

WHat contributes to our growing antibiotic resistance problem?

A
  1. Fewer antibiotics are being developed
54
Q

What is an antibiotic susceptibility test?

A
  1. Test that tells you how effective an antibiotic will be
  2. Results can be at least as important as determining the etiologic agent
  3. Some organisms have predictable susceptibility to antimicrobial agents (ie, Streptococcus pyogenes to penicillin). Therefore, antibiotic susceptibility testing for such pathogens is seldom required or performed
55
Q

What are the steps in the antibiotic susceptibility test?

A
  1. Minimum Inhibitory concentration (MIC) lowest concentration of antibiotic that prevents visible growths in culture, usually reported as ug/mL
  2. IF MIC is lower than the breakpoint then the bacterium is considered susceptible. The breakpoint is determined by looking at the pharmacokinetics, achievable antibiotic concentration, and clinical efficacy.
  3. Advantage of agar testing over broth testing- contamination and heterogenous populations are more obvious–>Using a phenotypic assay gives you a clearer result

Will treating the patient with that antibiotic kill enough bacteria?

56
Q

What are the 12 steps to prevent antimicrobial resistance?

A
  1. Vaccinate
  2. Remove catheters
  3. Target specific pathogen
  4. Access the experts
  5. Practice antimicrobial control
  6. Use local data
  7. Treat infection not contamination
  8. Treat infection not colonization
  9. Know when to say no to vano (used for MRSA)
  10. Stop treatment when infection is cured or unlikely
  11. Isolate pathogen
  12. Stop the spread!
57
Q

What are the consequences of overly broad antibiotic treatment?

A

SUPERINFECTION!!

  1. The balance of the normal residents of the bowel, skin, etc. is maintained by competition for nutrients and the production by bacteria of compounds that inhibit the growth of other bacteria. When an antibiotic kills an important resident bacterium, other harmful bacteria may be able to multiply and cause a secondary infection or superinfection.
  2. The broader the spectrum of activity and the longer time period of antibiotic treatment, the more likely that treatment with the antibiotic will cause superinfection.
  3. Symptoms range from mild diarrhea to acute enteritis.

Exam 3 (12 decks)

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