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Patho & Pharmo > Antimicrobial Agents > Flashcards

Antimicrobial Agents Flashcards

1
Q

antibiotic

A

chemical produced by one microbe and has the ability to harm other microbes

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2
Q

antimicrobial drug

A

any agent, natural or synthetic, that has the ability to kill or suppress microorganisms

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3
Q

bacteriocidal

A

directly lethal to bacteria at clinically achievable concentrations

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4
Q

bacteriostatic drugs

A

slow bacterial growth but do not cause cell death

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5
Q

Selective toxicity

A

ability of a drug to injure a target cell or target organism without injuring other cells or organisms that are in the intimate contact with the target

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6
Q

narrow-spectrum antibiotics

A

active against only a few species of microorganisms

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7
Q

broad-spectrum antibiotics

A

active against a wide variety of microbes

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8
Q

Four basic mechanisms for drug resistance from microbes

A
  1. decrease concentration of a drug at its site location.
  2. alter the structure of drug target molecules.
  3. produce a drug antagonist.
  4. cause drug inactivation.
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9
Q

causes random changes in a microbe’s DNA

A

spontaneous mutations

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10
Q

process by which extrachromosomal DNA is transferred from one bacterium to another.

A

conjugation

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11
Q

R factor (resistance factor)

A
  1. code for mechanism of drug resistance.
  2. cod for sexual apparatus for DNA transfer.
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12
Q

Conjugation takes place in primarily what bacteria?

A

Gram-negative

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13
Q

multiple drug resistance

A

transferring DNA that codes for several different drug-metabolizing enzymes to a single bacterium

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14
Q

which antibiotic agents promore the emergence of resistance

A

broad-spectrum agents

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15
Q

Superinfection

A

new infection that appears during the course of treatment for a primary infection, ridding inhibitory nature of normal flora, allowing infectious agent to flourish

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16
Q

superinfections are more likely in which type of patients

A

those receiving broad-spectrum agents

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17
Q

therapeutic objective when treating an infection

A

produce maximal antimicrobial effects, while causing minimal harm to the host

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18
Q

factors considered when prescribing a new antibiotic

A
  1. identity of the infecting organism.
  2. drug sensitivity of the infecting organism.
  3. host factors, site of the infection and the status of host defenses.
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19
Q

why will one drug of first choice be chosen over another one

A

greater efficacy, lower toxicity, more narrow spectrum

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20
Q

conditions ruling out first choice drug of choice

A
  1. allergies to drug.
  2. inability of drug of choice to penetrate to the side of infection.
  3. heightened susceptibility of the patient to toxicity of the first-choice drug.
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21
Q

two host factors that influence the selection of antibiotics

A

host defense and infection site.
Also: age, pregnancy, previous drug reactions.

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22
Q

host defenses

A

primarily of the immune system and phagocytic cells - antimicrobial therapy would be rare without it (concert).

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23
Q

minimum inhibitory concentration (MIC)

A

amount of bacteriocide at the site of infection

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24
Q

Antimicrobial concerns in infants

A

vulnerable to drug toxicity. Eliminate drugs slowly. No sulfonamides, kernicterus.

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25
Q

Antimicrobial concerns in children/adolescents

A

tetracyclines bind to developing teeth, causing discoloration.A

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26
Q

Antimicrobial concerns in pregnant women.

A

Placental crossing. Gentamicin, irreversible hearing loss. Also risk to mother

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27
Q

Antimicrobial concerns in breastfeeding women

A

enter breast milk. Sulfas cause kernicterus in infants

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28
Q

Antimicrobial concerns in older adults

A

reduced metabolism and excretion can result in accumulation

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29
Q

desirable concentrations for antibiotics

A

4-8x the MIC

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30
Q

Antimicrobial effect of 2 drugs is equal to the sum f the effects of the two drugs alone

A

additive response

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31
Q

the effect of the combination is grater than the sum of the effects of the individual agents

A

potentiative interaction

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32
Q

less effective therapy with 2 drugs than the use of one by itself

A

antagonism

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33
Q

most common indication for using multiple antibiotics

A

initial therapy for severe infection of unknown etiology, especially in the neutropenic host.

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34
Q

indications for antibiotic combinations

A
  1. initial therapy of severe infection.
  2. mixed infections.
  3. preventing resistance.
  4. decreased toxicity.
  5. enhanced antibacterial action.
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35
Q

locations susceptible to mixed infections

A

brain abscesses, pelvic infections, abd perf organs

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36
Q

infectious disease treated by multiple antibiotic combination

A

tuberculosis

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37
Q

combining amphotericin B with flucytosine does what

A

decreases toxicity - decreases risk of amphotericin-induced damage to kidneys

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38
Q

antibiotic treatment for enterococcal endocarditis

A

penicillin (weakens wall) and aminoglycoside (supress protein synthesis) - enhanced bacterial action

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39
Q

percentage of antibiotics used for prophylaxis

A

30-50%

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40
Q

surgical cases considered 100% infection risk, for which antibiotics is a treatment

A

contaminated surgery - perforated abdominal organs, compound fractures, lacerations from animal bites

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41
Q

most operations antibiotic choice

A

first-generation cephalosporin

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42
Q

bacterial endocarditis

A

congenital or valvular heart disease with prosthetic heart valves - unusually susceptible. Dislodge bacteria into bloodstream. AHA - much less often than previously prescribed.

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43
Q

much smaller number of neutrophils, which indicates for prophylactic antibiotic use

A

neutropenia

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44
Q

neutropenia prophylactic antibiotic use increases risk for

A

fungal infections - killing normal flora that suppresses fungal growth

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45
Q

prophylaxis for recurrent UTI

A

trimethoprim/sulfamethoxazole

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46
Q

prophylaxis against influenza

A

oseltamivir

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47
Q

bactericidal that disrupt the bacterial cell wall

A

beta-lactam

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48
Q

rigid, permeable, mesh-like structure that lies outside the cytoplasmic membrane

A

bacterial cell wall

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49
Q

penicillin mechanism of action

A

weakens bacterial cell wall, cell takes up water and bursts

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50
Q

penicillin is only effective against bacteria

A

undergoing growth and division

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51
Q

how does penicillin weaken the cell wall

A
  1. inhibition of transpeptidases
  2. disinhibition (activation) of autolysins
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52
Q

factors to determine bacterial resistance to penicillins

A
  1. inability of penicillins to reach their targets (PBPs)
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53
Q

beta-lactamases

A

enzymes that cleave the beta-lactam ring rendering beta-lactam antibiotics inactive

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54
Q

beta-lactamases that act selectively on penicillins

A

penicillinases

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55
Q

produce large amounts of penicillinases and export them into the surrounding medium

A

gram-positive bacteria

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56
Q

produce small amounts of penicillinases and secrete them into the periplasmic space

A

gram-negative bacteria

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57
Q

penicillin derivative resistant to actions of beta-lactamases

A

methicillin

58
Q

mechanism of resistance for methicillin resistant staph. aureus

A

production of PBPs with low affinity for penicillins and almost all other beta-lactam antibiotics

59
Q

PBPs

A

Penicillin-binding proteins - high affinity to penicillin, constituent in many bacteria

60
Q

Four major groups of penicillins

A
  1. narrow-spectrum, penicillinase sensitive
  2. narrow-spectrum, penicillinase resistant (antistaphylococcal penicillins)
  3. broad-spectrum penicillins (aminopenicillins)
  4. extended-spectrum penicillins (antipseudomonal penicillins)
61
Q

Examples of narrow-spectrum, penicillinase sensitive penicillins

A

Penicillin G, Penicillin V.
Streptococcus species, Neisseria species, many anaerobes, spirochetes.

62
Q

Examples of narrow-spectrum, penicillinase resistant (antistaphylococcal) penicillins

A

Nafcillin, Oxacillin, Dicloxacillin.
Staphylococcus aureus.

63
Q

Examples of broad-sprectrum penicillins (aminopenicillins)

A

Ampicillin, Amoxicillin.
Haemophilum influenzae, E. coli, Proteus mirabilis, enterococci, Neisseria gonorrhoeae

64
Q

Examples of extended-spectrum penicillin (antipseudomonal) penicillin

A

Piperacillin.
Same as aminopenicillins plus more.

65
Q

First penicillin available

A

Penicillin G (benzylpenicillin)

66
Q

Penicillin G is first drug of choice for

A

pharyngitis and infectious endocarditis, also staph. aureus that don’t produce penicillinase.

67
Q

Penicillin is preferred agent

A

for several gram-positive bacilli - gas gangrene and anthrax

68
Q

pharmacokinetics of penicillin

A

available in 4 salts, all absorb to release penicillin G.

69
Q

intramuscular administration of penicillin

A

all 4 salts may be administered, but different absorption rates

70
Q

intravenous administration of penicillin

A

when high blood levels are needed rapidly. only potassium or sodium salts.

71
Q

distribution of penicillin

A

distributes well to most tissues and fluids. varies in inflammation for penetration to cerebrospinal fluid, joints, and eyes.

72
Q

metabolism of penicillin

A

minimal metabolism, eliminated by kidneys unchanged.

73
Q

least toxic of all antibiotics

A

penicillin G

74
Q

effective and safe alternatives for patients with penicillin allergies

A

vancomycin, erythromycin, clindamycin

75
Q

examples of beta-lactamase resistant penicillin

A

nafcillin, oxacillin, dicloxacilin

76
Q

what do beta-lactamase resistant penicillins treat

A

penicillinase-producing staph aureus and staph epidermidis

77
Q

treatment of choice for MRSA

A

vancomycin

78
Q

therapeutic goal of penicillins

A

treatment of infections caused by sensitive bacteria

79
Q

baseline data of penicillin administration

A

tests to identify infection organisms and its drug sensitivity. microscopic culture before starting treatment. skin allergy test for hx of penicillin allergy.

80
Q

high-risk patients for penicillin administration

A

hx of severe allergic reaction to penicillins, cephalosporins, or carbapenems

81
Q

PO administration of penicillins with meals

A

one hour before or two hours after

82
Q

evaluating therapeutic effects of penicillins

A

monitor for indications of antimicrobial effects

83
Q

monitoring kidney function

A

measuring intake and output in kidney disease, acutely ill patients, and very old and young

84
Q

minimizing adverse effects of penicillin

A

allergy skin test.
monitor sodium levels in sodium loaded.
monitor potassium levels and cardiac status in K loaded.

85
Q

drug that is bactericidal, often resistant to beta-lactamases, active against broad spectrum of pathogens, low toxicity,

A

cephalosporin

86
Q

mechanism of action of cephalosporin

A
  1. disrupt cell wall synthesis
  2. activate autolysins (cleave bonds in cell walls)
87
Q

cephalosporin is most effective against cells

A

undergoing active growth and division

88
Q

main form of resistance for cephalosporin

A

beta-lactamases

89
Q

how many generations of cephalosporin are there

A

5

90
Q

absorption of cephalosporin

A

most are parenterally

91
Q

distribution of cephalosporin

A

well in pleural, pericardial, peritoneal fluids

92
Q

metabolism of cephalosporin

A

kidney elimination

93
Q

adverse reaction of cephalosporin

A

bleeding - cefotetan and ceftriaxone - interference with vitamin K metabolism.
thrombophlebitis - rotating infusion site and dilute med.
immune mediated hemolytic anemia- d/c.

94
Q

differences when choosing which of the many cephalosporin to employ

A

antimicrobial spectrum and phamacokinetics

95
Q

antimicrobial spectrum for cephalosporin

A

no broader than required

96
Q

pharmacokinetic properties of interest in cephalosporin

A
  1. route of admin.
  2. duration of action.
  3. distribution of the CSF.
  4. route of elimination.
97
Q

beta-lactam antibiotics with very broad antimicrobial spectra - none active against MRSA

A

cabapenems

98
Q

four available cabapenems

A

imipenem, meropenem, ertapenem, doripenem

99
Q

most widely used antibiotic in US hospitals

A

vancomycin

100
Q

primary indications for vancomycin

A

C. diff, MRSA, serious infections with allergies to penicillin. only gram-positive

101
Q

major toxicity of vancomycin use

A

renal failure

102
Q

mechanism of action of vancomycin

A

inhibits cell wall synthesis - binding to molecules that serve as precursors for cell wall biosynthesis

103
Q

high-risk patients for cephalosporins

A

history of allergic reactions to cephalosporins or other penicillins. Ceftriaxone for neonates reaching IV calcium.

104
Q

how long do you bolus a cephalosporin injection to a continuous IV infusion

A

3 to 5 minutes

105
Q

Vancomycin therapeutic goal

A

CDI, infection with MRSA, allergies to penicillin

106
Q

red man syndrome

A

rapid infusion of vancomycin - flushing, rash, pruritus, urticaria, tachycardia, and hypotension.

107
Q

second line agents used to treat infections resistant to first-line agents

A

bacteriostatic inhibitors

108
Q

bacteriostatic inhibitors

A

tetracycline, macrolines, clindamycin

109
Q

Four tetracyclines available for systemic therapy

A

tetracycline, demeclocycline, doxycycline, minocycline

110
Q

mechanism of action for tetracyclines

A

suppress bacterial growth by inhibiting protein synthesis

111
Q

Tetracyclines are first-line therapy for what infectious disorders

A
  1. rickettsial diseases.
  2. Chlamydia trachomatis.
  3. brucellosis.
  4. cholera.
  5. pneumonia by Mycoplasma pneumonia.
  6. Lyme disease.
  7. Anthrax.
  8. Gastic infection by H. pylori.
112
Q

how are tetracyclines eliminated

A

liver and kidneys - liver bilee

113
Q

tetracyclines bind to what in the teeth

A

calcium - yellow discoloration. darker is longer

114
Q

clinical manifestations of hepatoxicity

A

lethargy and jaundice

115
Q

vestibular toxicity has occurred with what tetracycline

A

minocycline

116
Q

photosensitivity occurs with what antibiotic

A

tetracyclines

117
Q

least expensive and most widely used member of the tetracycline family

A

tetracycline hydrochloride

118
Q

Oldest member of the macrolides family

A

erythromycin

119
Q

broad-spectrum antibiotics that inhibit protein synthesis and are big

A

macrolides

120
Q

macrolides mechanism of action

A

bacteriostatic protein synthesis

121
Q

erythromycin is first-choice drug for what

A

whooping cough, acute diphtheria, certain chlamydial infections, and pneumonia

122
Q

erythromycin adverse effects

A

cardiac death from QT prolongation

123
Q

clindamycin can promote what?

A

severe CDAD

124
Q

clindamycin mechanism of action

A

binds to the 50S subunit of bacterial ribosomes and inhibits protein synthesis

125
Q

therapeutic goal of tetracyclines

A

treatment of tetracycline-sensitive infections, acne, and periodontal disease

126
Q

high risk patients for tetracyclines

A

pregnant women and children under 8, renal impairment

127
Q

wait two hours after taking tetracycline to eat what

A

chelators (milk, calcium, iron, magnesium, antiacids)

128
Q

high-risk patients of erythomycin

A

QT prolongation, inhibitors of CYP3A4

129
Q

Therapeutic goal of clyndamicin

A

treatment of anaerobic infections outside the CNS

130
Q

aminoglycosides

A

natural and semisynthetic antibiotics, bactericidal, potent, serious toxicities

131
Q

ahminoglycosides are composed of

A

two or more amino sugars connected by a glycoside linkage

132
Q

poqtantibiotid effect

A

bactericidal effect several hours after serum levels have dropped below the minimal bacterial concentration

133
Q

antibiotic that cannot kill anaerobes

A

aminoglycosides - must be transported with oxygen

134
Q

adverse side effects of aminoglycosides

A

ototoxicity and nephrotoxicity

134
Q

gentamicin oral therapy indication

A

suppression of bowel flora before elective colorectal surgery

135
Q

gentamicin topical therapy indication

A

local infections of the eyes, ears, and skin

136
Q

mechanism of action of sulfonamides

A

bacteriostatic - suppress bacterial growth by inhibiting synthesis of tetrahydrofolate

137
Q

principal indication for sulfonamides

A

UTI

138
Q

most severe hypersensitivity response to sulfonamides

A

stevens-johnson syndrome - widespread lesions of the skin and mucous membrane, fever, malaise, toxemia.

139
Q

antibacterial agent specifically for protozoal infections caused by anaerobic bacteria

A

metronidazole

140
Q

fluorinated analogs of nalidixic acid

A

fluoroquinolones

141
Q
A

Patho & Pharmo (6 decks)

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