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Disease and Defense class of 2019 > Pharmacology Unit 4 > Flashcards

Pharmacology Unit 4 Flashcards

1
Q

selective toxicity-define

A
  • feature of antibiotic therapy as effects of antimicrobial agents should be exerted on microbe and not host.
  • targets biochemical differences between pathogen target and host–>exploitation of these differences
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2
Q

selective toxicity-examples

A

-inhibition of metabolic pathway in bacteria but not humans–folate metabolism (metabolize intracellularly, mammals take up from environment)

-pathways that exist in both but are different in enzyme structure–protein synthesis (bacterial ribosomes that are 30 and 50S vs. 40 and 60S.
nucleic acid synthesis (DNA gyrase vs topoisomerase)

  • macromolecular structure doesn’t exist in humans (cell wall synthesis, peptidoglycan component)
  • macromolecular structure differs between humans and microbes (fungal cell membrane-ergosterol)
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3
Q

narrow vs. extended vs. broad antibacterial spectrum: basic definitions of the 3

A

narrow spectrum–most effective on susceptible organism, less disturbance of host flora. GRAM POSITIVE OR NEGATIVE

broad spectrum–sacrifice efficacy for greater scope of activity for initial empiric coverage, more likely to cause superinfections. GRAM POSITIVE AND NEGATIVE

extended spectrum–effective against gram positive and gram negative

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4
Q

narrow antibacterial examples (gram + or -)

A 
aminoglycosides
penicillinase-resistance penicillins
clindamycin
vancomycin
metronidazole
penicillin g, v
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5
Q

extended antibacterial examples (gram + and -)

A

extended-spectrum penicillins
cephalosporins
fluoroquinolones (cip, levo)
carbapenems

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6
Q

broad antibacterial examples (gram + and - and atypical)

A 
macrolides
chloramphenicol
fluroquinolones (moxi, gemi)
sulfonamides
tetracyclines
trimethoprim
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7
Q

resistance: chromosomal vs. plasmid mediated

A

mutational (chromosomal) resistance: effect varies, multiple generations must happen to see appreciable resistance. proper dosing prevents survival of slightly resistant strains

plasmid mediated resistance: extrachrosomal pieces of circular DNA, carrying genetic information that can confer resistance. source of multiple drug resistances that can emerge in 1 course of treatment

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8
Q

resistance: mechanisms

natural

A

natural (intrinsic) resistance: microbes lack susceptible target for drug action
-(fungal cell walls don’t have peptidoglycan and mycoplasma have no walls).

pseudomonas auerginosa is intrinsically resistant to many antibiotics (can’t cross the membrane)

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9
Q

resistance: mechanisms

escape

A

microbes are sensitive and antibiotic reaches target but organism “escapes” consequences due to availability of purines, thymidine, serine, methionine released from purulent infections (sulfonamide resistance)

failure to lyse due to lack of osmotic pressure difference (penicillin resistance)

importance drainage surgical procedures

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10
Q

resistance: mechanisms

acquired

A

selective pressure (antibiotic administration) produces generations of organisms with biochemical traits that minimize drug action

mutational
plasmid

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11
Q

resistance: implications for therapy

A

can be minimized by only using antibiotic when needed, select based on susceptibility tests, use adequate concentration and duration to prevent emergence of first and second step mutants.

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12
Q

classifications of antimicrobial mechanisms of action

A 
altered targets
enzymatic destruction
alternative resistant metabolic pathway
decreased entry 
increased efflux
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13
Q

bactericidal agents vs bacteriostatic agents definitions

A

bactericidal: organisms are killed
bacteriostatic: organisms are prevented from growing

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14
Q

bactericidal mechanisms

A

inhibition of cell wall synthesis
disruption of cell membrane function
interference with dan function/synthesis

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15
Q

bacteriostatic mechanisms

A

inhibition of protein synthesis (exception is aminoglycosides, -cidal)
inhibition of intermediary metabolic pathways

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16
Q

advantages of bactericidal agents

A
  • preferred in severe infections (assuming sensitive organism, drug distribution, drug safety)
  • act more quickly, action is often irreversible (sustained effect after drug is eliminated from blood)
  • compensate for patients with impaired host defense (diabetes, etc.)
  • required for treatment of infections in locations not accessible to host immune system responses (endocarditic vegetation, CSF)
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17
Q

importance of pharmacokinetic and host factors in selection of antimicrobial therapy

A

consider pharmacodynamics (antimicrobial activity against specific organism), pharmacokinetic properties (absorption from route of administration), distribution (to site of infection), elimination (hepatic or renal) as related to duration of antimicrobial activity

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18
Q

absorption (oral vs. parenteral vs. topical)

A

oral: advantage of ease, acceptance, lower cost. can cause GI upset/diarrhea, if NPO.

IV: needed for some drugs/patients has advantage of most rapid/predictable plasma levels (treating life-threatening infections). disadvantage needed with IV are greater training, expense, specific antiseptic conditions

switch to oral whenever and whenever possible

infections can be managed with local application of antibiotic (skin or mucus membranes)

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19
Q

distribution (CNS penetration, fetal exposure, selective accumulation-beneficial vs. harmful)

A

once antibiotic has been absorbed into systemic circulation must be distributed

CNS: most antibiotics distribute to tissue outside CNS, vary based in ability to cross BBB.

fetus: adverse effects may occur in the fetus that cross placenta. can be given orally, and have ability to cross gastric and placenta

selective-accumulation: certain antibiotics can result in harmful/beneficial response
beneficial: clindamycin into bone, treat osteomyelitis. concentrations of macrolides into pulmonary cells (upper respiratory infections). tetracyclines into gingival crevicular fluid. rapid excretion of nitrofurantoin

selective-increase toxicity: include amino glycoside binding to cells of inner ear, brush border. results increased ototoxicity, nephrotoxicity, tetracyclines-bind to developing bone and teeth to result in abnormal bone growth

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20
Q

elimination

A

renal: alerts to possibility of renal dosing if necessary in patients with kidney dysfunction. process where dose and frequency are adjusted based on renal function. measure SCr and CrCl
hepatic: possibility of drug-drug interactions or hepatotoxic antibiotics. no lab value to give estimate of liver function

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21
Q

drug classes eliminated by renal excretion

A 
require dosage adjustment if impaired
penicillins
cephalosporins
vancomycin
aminoglycosides
fluoroquinolones
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22
Q

drug classes eliminated by non renal mechanisms-use your mnemonic!!!

A

DQ CRIME
Doxycycline: non-regally eliminated tetracycline
(Q)uinolones: ciprofloxacin is really eliminated, but is non-substrate inhibitor of P450 (caffeine-theophylline)
Clindamycin: non-regally eliminated
Rifampin: inducer of P450, potential hepatotoxicity
Isoniazid: genetic polymorphism of n-acetyl transferase metabolism, potential hepatotoxicity
Metronidazole: drug-drug interaction with alcohol due to inhibition of aldehyde metabolism (Antabuse reaction)
Erythromycin-like: drug-drug interactions due to inhibition of P450 (Clar-Ery, not Azi)
Sulfonamides: n-acetylated to a more lipid-soluble metabolite-concern for renal crystalluria

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23
Q

strep pneumoniae

A

pneumonia, otitis media, sinusitis

cocci-gram +

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24
Q

strep pyogenes

A

pharyngitis

cocci-gram +

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25
Q

viridans streptococci

A

endocarditis

cocci-gram +

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26
Q

staph aureus

A

(MSSA, MRSA)
cutaneous infection, pneumonia, bacteremia, device associated infections
cocci-gram +

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27
Q

enterococcus faecium-faecalis

A

bacterimia, intraabdominal infections, UTI

cocci-gram +

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28
Q

neisseria gonorrheae

A

gonorrhea

cocci-gram -

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29
Q

neisseria meningitidis

A

meningitis

cocci-gram -

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30
Q

ecoli

A

utis, intra-abdominal infections, lower respiratory infections, bacteremias, traveler’s diarrhea
rods- gram -

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31
Q

pseudomonas aeruginosa

A

noncosomial infections at any site (UTI, pneumonia)

rods- gram -

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32
Q

clostridium difficile

A

pseudomembranous colitis

anerobes-gram + rod

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33
Q

clostridium perfringens-botulinim-tetani

A

anerobes-gram + rod

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34
Q

bacteriodes fragilis

A

intraabdominal and brain abcess

anerobes-gram - rod

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35
Q

clamydia

A

trachoma, community acquired pneumonia, urethitis

atypical

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36
Q

mycoplsma pneumoniae

A

community acquired pneumonia

atypical

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37
Q

side effects: direct toxicity

A

antibiotic effect on microbes affects host cellular processes (lack of selective toxicity)

  • varies with drugs and concentrations
  • can be mild/life threatening
  • usually involves GI tract, liver, kidney, nervous system, blood and blood forming system
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38
Q

side effects: indirect toxicity

A 
allergic reactions, hypersensitivity
salt effects (salt administered with antibiotic not antibiotic)
drug-drug interactions, may alter CYP450 drug metabolizing enzymes
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39
Q

side effects: superinfections

A

disturbances in ecological balance of microbial community
allows for overgrowth of normally suppressed pathogenic organism
pseudomembranous colitis due to clostridium difficile overgrowth
more commonly associated with broad spectrum antibiotics
increased if 50, pulmonary disease, prolonged duration

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40
Q

cell wall synthesis inhibitors: penicillins-prototype

A

penicilin G

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41
Q

cell wall synthesis inhibitors: penicillins- acid stable

A

penicillin V

42
Q

cell wall synthesis inhibitors: penicillins- penicillinase resistant

A

dicloxacillin

43
Q

cell wall synthesis inhibitors: penicillins- extended spectrum

A

amoxicillin +/- clavulanate

ampicillin +/- sulbactam

44
Q

cell wall synthesis inhibitors: penicillins- anti-pseudomonal

A

peperacillin-tazobactam

45
Q

cell wall synthesis inhibitors: penicillins- beta-lactamase inhibitor

A

clavulanic acid

tazobactam

46
Q

cell wall synthesis inhibitors: cephalosporins- 1st

A

cefazolin

cephalexin

47
Q

cell wall synthesis inhibitors: cephalosporins-2nd

A

cefuroxime

48
Q

cell wall synthesis inhibitors: cephalosporins- 3rd

A

cefriaxone

ceftazidime

49
Q

cell wall synthesis inhibitors: cephalosporins- 4th

A

cefepime

50
Q

cell wall synthesis inhibitors: cephalosporins- 5th

A

ceftaroline

51
Q

cell wall synthesis inhibitors: cephalosporins- carbapenems

A 
ertrapenem
imipenem-cilastin
meropenem
doripenem
VANCOMYCIN
52
Q

protein synthesis inhibitors- macrolydes

A

erythromycin
clarithromycin
azithromycin

53
Q

protein synthesis inhibitors-tetracyclines

A

tetracycline

doxycycline

54
Q

protein synthesis inhibitors-others

A

clindamycin

chloramphenicol

55
Q

protein synthesis inhibitors-aminoglycosides

A

know characteristics of class-not individual agents

56
Q

inhibitors of DNA function- fluoroquinolones

A

ciprofloxacin
levofloxacin
moxifloxacin

57
Q

inhibitors of DNA function-other

A

nitrofurantoin
metronidazole
trimethoprim-sulfamethoxazole

58
Q

Bacteria develop resistance to tetracyclines by which primary mechanism?

Altered ribosomal target
Bypass pathway in folic acid metabolism
Enzymatic inactivation
Increased drug efflux
Mutations of DNA gyrase
A

Increased drug efflux == MDR gene

59
Q

Which of the following is the primary mechanism of β-lactam antibiotic resistance with Streptococcus pneumoniae?

Modification of drug target
Decreased intracellular drug levels due to changes in permeability
Decreased intracellular drug levels due to an efflux pump
Enzymatic inactivation of drug

A

Modification of drug target

60
Q

Which of the following antibiotics are considered to exert bactericidal actions against most organisms in their spectrum at readily attained clinical levels?

Tobramycin - AG
Vancomycin - GP
Ceftriaxone 3rd C
Clindamycin
Azithromycin - MAC
Levofloxacin - urFQ
A

Tobramycin - AG
Vancomycin - GP
Ceftriaxone 3rd C
Levofloxacin - urFQ

61
Q

All of the following influence the penetration and concentration of an antibacterial agent in the cerebrospinal fluid EXCEPT:

Lipid solubility of the drug
Minimum inhibitory concentration of the drug
Protein binding of the drug
Molecular weight of the drug

A

Minimum inhibitory concentration of the drug

62
Q

A 58-year-old male with a history of hepatitis C, cirrhosis, and ascites presents with spontaneous bacterial peritonitis. Which of the following antibiotics may require close monitoring and possible dosage adjustment in this patient given his liver disease?

Penicillin G - nPCN
Tobramycin - AG
Metronidazole 
Clindamycin
Levofloxacin - urFQ
Cephalexin - 1st C
A

Metronidazole

Clindamycin

63
Q

Which drug increases the hepatic metabolism of other drugs?

Azithromycin - MAC
Erythromycin - MAC
Ketoconazole - AF
Tobramycin - AG
Rifampin - TB
Metronidazole
A

Rifampin - TB

64
Q

The persistent suppression of bacterial growth that may occur after limited exposure to some antibacterial drugs is called:

Clinical synergy
Concentration-dependent killing
Post antibiotic effect
Sequential blockade
Time-dependent killing
A

Post antibiotic effect

65
Q

Which of the following antibiotics exhibits concentration-dependent killing?

Tobramycin - AG
Vancomycin - GP
Ceftriaxone 3rd C
Clindamycin
Azithromycin - MAC
Levofloxacin - urFQ
A

Tobramycin - AG

Levofloxacin - urFQ

66
Q

Which of the following agents is considered a narrow-spectrum agent?

Ceftriaxone - 3rd C
Levofloxacin - urFQ
Amoxicillin - ePCN
Tobramycin - AG
Doripenem - CARB
Penicillin V - nPCN
A

Tobramycin - AG

Penicillin V - nPCN

67
Q

Antimicrobial prophylaxis has been used in which of the following clinical situations?

Tuberculin skin test converters
Recurrent urinary tract infections
Recurrent genital herpes simplex infections
Gastrointestinal surgical procedures
Healthcare workers exposed to blood after needlestick injury
Dental patients with artificial heart valves undergoing extractions

A

Tuberculin skin test converters
Recurrent urinary tract infections
Recurrent genital herpes simplex infections
Gastrointestinal surgical procedures
Healthcare workers exposed to blood after needlestick injury
Dental patients with artificial heart valves undergoing extractions

68
Q

Antibiotics are commonly administered before surgical procedures. Which of the following statements best describes an appropriate use for perioperative antimicrobial prophylaxis?

Begin antibiotic prophylaxis at least 24 hours before surgery
Include an antifungal in the regimen
Select the broadest spectrum antibiotic for complete coverage
Use antibiotic combinations as opposed to monotherapy
Administer the antibiotic just prior to the procedure

A

Administer the antibiotic just prior to the procedure

69
Q

When using combination antibiotic therapy, it is important to administer drugs that work synergistically if possible. Which of the following represents a combination with known synergism?

A penicillin and a cephalosporin
Two drugs that work on the same step
Two drugs in which the second drug will displace the first from plasma protein-binding sites
A beta-lactam and an aminoglycoside
Two drugs that are eliminated by different routes
A sulfonamide with a dihydrofolate reductase inhibitor

A

A beta-lactam and an aminoglycoside

A sulfonamide with a dihydrofolate reductase inhibitor

70
Q

A 24-year-old pregnant woman presents to the urgent care clinic with fever, urinary frequency and urgency. She is diagnosed with a urinary tract infection (UTI). Based on potential harm to the fetus, which of the following medications should be avoided in treating her UTI?

Nitrofurantoin
Amoxicillin - ePCN
Cephalexin - 1st C
Gentamicin - AG
Trimethoprim-sulfamethoxazole
A

Gentamicin - AG

Trimethoprim-sulfamethoxazole

71
Q

Which of the following antibiotics is considered safe to use in neonates?

Chloramphenicol
Sulfamethoxazole-Trimethoprim
Doxycycline TCN
Ampicillin - ePCN
Ceftriaxone - 3rd C
A

Ampicillin - ePCN

Ceftriaxone - 3rd C

72
Q

In a patient suffering from pseudomembranous colitis due to C. difficile with established hypersensitivity to metronidazole, the drug most likely to be of clinical value is:

Ampicillin - ePCN
Clindamycin 
Doxycycline - TCN
Levofloxacin - urFQ
Vancomycin
A

Vancomycin

73
Q

The primary mechanism of antibacterial action of the penicillins involves inhibition of:

Beta-lactamases
Cell membrane synthesis
N-acetylmuramic acid synthesis
Reactions involving transpeptidation
Porin insertion into membranes
A

Reactions involving transpeptidation

74
Q

Methicillin-resistant Staphylococcus aureus is a common nosocomial pathogen that is increasing in frequency in community settings. Which of the following best describes the most common mechanism of resistance to methicillin by S. aureus?

Increased synthesis of metabolic factors
Reduced permeability to beta-lactams
Acquisition of the novel protein PBP2a
Increased cell wall repair
Increased efflux of beta-lactams
A

Acquisition of the novel protein PBP2a

75
Q

Select the FALSE statement concerning use of ampicillin:

Antibacterial activity is enhanced by sulbactam
Causes maculopapular rashes
Drug of choice for Listeria monocytogenes infections
Eradicates most strains of methicillin-resistant Staphylococcus aureus
May cause pseudomembranous colitis with extended use

A

Eradicates most strains of methicillin-resistant Staphylococcus aureus

76
Q

A 23-year-old male presents with acute appendicitis that ruptures shortly after admission. He is taken the OR for surgery, and post surgical cultures reveal E. coli and Bacteroides fragilis. Which of the following provides adequate empiric coverage of these two pathogens?

Tobramycin - AG
Vancomycin
Ceftriaxone - 3rd C
Piperacillin-tazobactam - apPCN
Clindamycin
A

Piperacillin-tazobactam - apPCN

77
Q

Select the FALSE statement concerning penicillin G:

It is eliminated from the body primarily by renal excretion.
It has reliable antimicrobial activity against most gram positive cocci.
It is less reliably absorbed following oral administration than penicillin VK.
It is effective in treating infections caused by penicillinase-producing organisms.
It is more effective in killing rapidly growing bacteria than bacteria in the stationary phase.

A

It is effective in treating infections caused by penicillinase-producing organisms.

78
Q

A 20-year-old female presents to the emergency department with headache, stiff neck, and fever of 2 days duration and is diagnosed with bacterial meningitis. Which of the following agents is the best choice for treatment of meningitis?

Acyclovir
Piperacillin-tazobactam - apPCN
Ceftriaxone - 3rd C
Cefotaxime - 3rd C
Tobramycin - AG
Cefazolin - 1st C
A

Ceftriaxone - 3rd C

Cefotaxime - 3rd C

79
Q

A 21-year-old man was seen in a clinic with a complaint of dysuria and urethral discharge of yellow pus. Gram stain of the urethral exudate showed gram-negative diplococci. The most appropriate treatment of gonorrhea in this patient is:

Amoxicillin (ePCN) orally for 7 days
Ceftriaxone (3rd C) intramuscularly as a single dose
Tetracycline (TCN) orally for 7 days
Benzathine penicillin G (nPCN) as a single intramuscular dose
Vancomycin intramuscularly as a single dose

A

Ceftriaxone (3rd C) intramuscularly as a single dose

80
Q

A major distinction between 1st and 3rd generation cephalosporins is:

3rd generation agents have less activity against Pseudomonas
3rd generation agents have increased activity against chlamydia
1st generation agents have increased penetration into the CNS
3rd generation agents have increased activity against resistant gram-negative organisms
1st generation agents have greater activity against methicillin-resistant Staphylococcus aureus

A

3rd generation agents have increased activity against resistant gram-negative organisms

81
Q

A 45-year-old male presented to the hospital ED with severe cellulitis and a large abscess on his left leg. Incision and drainage were performed on the abscess, and cultures revealed methicillin-resistant Staphylococcus aureus. Which of the following antibiotics would be appropriate for this infection?

Ceftaroline - 5th C
Piperacillin-tazobactam - apPCN
Vancomycin
Ceftriaxone - 3rd C
Doxycycline - TCN
Clindamycin
A

Ceftaroline - 5th C
Vancomycin
Doxycycline - TCN
Clindamycin

82
Q

Amoxicillin (ePCN) shares all of the following properties with cephalexin (1st C ) EXCEPT:

Inhibition of  cell wall synthesis
Bactericidal action
Elimination primarily by the kidneys
Beta-lactam ring in structure
High susceptibility to bacterial beta-lactamases
A

High susceptibility to bacterial beta-lactamases

83
Q

Select the FALSE statement concerning inhibitors of cell wall synthesis:

Second generation cephalosporins have good-to-excellent activity against anaerobic organisms.
The concentration of penicillin G in the CSF is higher when administered to patients with meningococcal meningitis than it is when given to normal, uninfected patients.
First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins.
First generation cephalosporins (e.g., cefazolin) should not be given to patients with a Type I anaphylactic reaction to amoxicillin.

A

First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins.

84
Q

Which of the following adverse reactions is associated with vancomycin?

Teratogenic effects
Red man syndrome
Ototoxicity
QT prolongation
Severe GI upset
Nephrotoxicity
A

Red man syndrome
Ototoxicity
Nephrotoxicity

85
Q

Vancomycin:

Is bacteriostatic
Binds to penicillin-binding proteins
Is active against MRSA
Has advantage of oral bioavailability
Requires dosage reduction in renal impairment
Is inactivated by beta-lactamases
A

Is active against MRSA

Requires dosage reduction in renal impairment

86
Q

Select the FALSE statement concerning the bio-disposition of beta-lactam antibiotics:

1st generation cephalosporins cause the blood-brain barrier poorly even when the meninges are inflamed
Lability of some penicillins in gastric acid can limit their oral absorption
Ceftriaxone (3rd C) is eliminated by both renal and biliary-fecal excretion
Benzathine penicillin G (nPCN) is used via intramuscular injection
The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid

A

The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid

87
Q

A 25-year-old male, otherwise healthy, comes to your office with symptoms of nasal congestion, clear rhinorrhea, and headache of 4 days duration. He reports that he was treated with penicillin V for strep throat as a 10 year-old with no adverse responses. Six weeks ago he received a single IM dose of ceftriaxone for a gonococcal infection. Current clinical guidelines suggest that a reasonable initial course of action should be treatment with:

Azithromycin
High dose amoxicillin
Amoxicillin plus clavulanate
Oral 3rd generation cephalosporin (Cefdinir-Omnicef)
Ibuprofen as needed for pain and saline nasal lavage

A

Ibuprofen as needed for pain and saline nasal lavage

88
Q

The primary mechanism of resistance of gram-positive organisms to macrolide antibiotics is:

Decreased activity of uptake mechanisms
Decreased permeability of drug through cytoplasmic membrane
Synthesis of drug-inactivating acetyltransferases
Synthesis of esterases that hydrolyze the lactone ring
Methylation of drug binding sites on the 50S ribosomal subunit

A

Methylation of drug binding sites on the 50S ribosomal subunit

89
Q

Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. Advantages of clarithromycin include:

Does not inhibit drug metabolizing enzymes
Eradicates mycoplasmal infections in a single dose
Has greater activity against H. pylori
Is active against methicillin-resistant strains of staphylococci
Is active against strains of Streptococci that are resistant to erythromycin
Greater duration of activity

A

Has greater activity against H. pylori

Greater duration of activity

90
Q

A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise for 3-4 days. She appears to have some respiratory difficulty and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of sputum does not show any bacterial pathogens. Patient has no history of serious medical problems. The patient is taking loratadine for allergies, multivitamins, and iron supplements. She is an avid consumer of coffee and caffeinated beverages. The initial diagnosis is community-acquired pneumonia and a suitable drug choice would be:

Amoxicillin
Azithromycin
Erythromycin
Clindamycin
Doxycycline
A

Azithromycin
Erythromycin
Doxycycline

91
Q

If the patient with CAP were prescribed erythromycin you should advise her to:

Avoid exposure to sunlight
Avoid taking supplemental iron tablets
Decrease her intake of caffeinated beverages
Have her serum creatinine checked before starting therapy
Temporarily stop the antihistamine

A

Decrease her intake of caffeinated beverages

92
Q

Select the TRUE statement regarding the pharmacologic actions of macrolide antibiotics:

Erythromycin use is associated with less GI upset than clarithromycin.
Possess bactericidal action via irreversible inhibition of protein synthesis.
Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450.
Erythromycin has a longer half-life and requires less frequent administration than clarithromycin.
Macrolides are more effective than metronidazole against anaerobic infections.

A

Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450.

93
Q

A 26-year-old woman was treated for gonorrhea at a neighborhood clinic. She was treated with a single IM dose of ceftriaxone and given a prescription for oral doxycycline (100 mg bid x 7d). Two weeks later she returned to the clinic with a mucopurulent cervicitis. On questioning she admitted not having the prescription filled. The best course of action at this point would be to:

Delay drug treatment until the infecting organism is identified
Rewrite the original prescription for oral doxycycline
Treat her in the clinic with a single oral dose of amoxicillin
Treat her in the clinic with a single oral dose of azithromycin
Write a prescription for oral erythromycin for 7 days

A

Treat her in the clinic with a single oral dose of azithromycin

94
Q

A 5-year-old kindergarten student presents with headache, fever, and cough of 2 days duration. Sputum is scant and nonpurulent and a Gram stain reveals many white cells but no organisms. Since this patient appears to have atypical (mycoplasmal) pneumonia, you should initiate treatment with:

Azithromycin (Zithromax)
Doxycycline
Cephalexin (Keflex, a 1st generation cephalosporin)
Chloramphenicol
Either A or B
A

Azithromycin (Zithromax)

95
Q

A 19-year-old woman with recurring sinusitis has been treated with different antibiotics on several occasions. During the course of one such treatment she developed a severe diarrhea and was hospitalized. Sigmoidoscopy revealed colitis and pseudomembranes were confirmed histologically. Which of the following drugs is mostly to have caused this superinfection?

Clindamycin (Cleocin)
Clarithromycin (Biaxin)
Metronidazole (Flagyl)
Penicillin V K
Vancomycin
A

Clindamycin (Cleocin)

96
Q

Doxycycline is:

Bactericidal
Excreted mainly in the urine
Eliminated rapidly and is dosed 4 times a day
More effective than tetracycline against H. pylori
Recommended therapy for community-acquired pneumonia

A

Recommended therapy for community-acquired pneumonia

97
Q

A patient is being discharged from the hospital on a 3-week course of clindamycin. Which of the following potential adverse effects should be discussed with her?

Nephrotoxicity
Drug interactions due to enzyme induction
C. difficile diarrhea
Skin rash
Ototoxicity
A

C. difficile diarrhea

98
Q

Regarding the mechanism of action of aminoglycosides, the drugs:

Are bacteriostatic
Bind irreversibly to the 30S ribosomal subunit
Cause misreading of the code on the mRNA template
Inhibit peptidyl transferase
Cause breakup of polysomes

A

Bind irreversibly to the 30S ribosomal subunit
Cause misreading of the code on the mRNA template
Cause breakup of polysomes

99
Q

An aspirate from a peritoneal abscess grows two organisms. One is Escherichia coli while the other has the following characteristics: Gram-negative bacillus, obligate anaerobe, catalase-positive, and possesses a polysaccharide capsule. From your recommended training in microbiology you recognize this organism is most likely Bacteroides fragilis. From your required training in pharmacology you know that antibiotics with activity against such an anaerobe include all of the following EXCEPT:

Cefoxitin (2nd generation cephalosporin)
Clindamycin (Cleocin)
Metronidazole (Flagyl)
Gentamicin, an aminoglycoside
Piperacillin-Tazobactam
A

Gentamicin, an aminoglycoside

100
Q

All of the following statements about the clinical uses of the aminoglycosides are accurate EXCEPT:

They are effective in the treatment of Pseudomonal infections
Owing to their polar nature, aminoglycosides are not absorbed after oral administration
MRSA are usually sensitive to aminoglycosides
Antibacterial action is concentration-dependent
Ototoxicity due to aminoglycosides includes vestibular function and is often irreversible
The earliest sign of aminoglycoside-induced nephrotoxicity is an increased blood creatinine

A

MRSA are usually sensitive to aminoglycosides

101
Q

A 30-year-old pregnant female has cellulitis caused by MRSA. Which of the following would be the most appropriate option for outpatient therapy?

Amoxicillin-clavulanate
Ceftaroline
Clindamycin
Doxycycline
Minocycline
Vancomycin
A

Clindamycin

102
Q

You notice that an otherwise healthy patient has developed a mild case of oral candidiasis (thrush) while receiving antibiotic treatment for a respiratory infection. Which of these drugs is a broad-spectrum antibacterial agent that would most likely have caused this fungal superinfection?

Penicillin V
Dicloxacillin
Doxycycline
Clindamycin (Cleocin)
Clarithromycin
A

Doxycycline

Disease and Defense class of 2019 (9 decks)

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