Sulfonamides, Trimethoprim, Quinolones Flashcards
(83 cards)
1
Q
As structural analogs of PABA, sulfonamides
inhibit ______ and folate production.
A
dihydropteroate synthase
2
Q
Microorganisms stimulated by sulfonamides in their growth.
A
Rickettsiae
3
Q
Activity of sulfonamides is poor against?
A
Anaerobes
4
Q
intrinsically resistant to
sulfonamide antibiotics
A
Pseudomonas aeruginosa
5
Q
Relationship between sulfonamides and trimethoprim or pyrimethamine
A
synergism
6
Q
Forms of sulfonamide resistance
A
Mutations that
(1) cause overproduction of PABA
(2) cause production of a folic
acid-synthesizing enzyme that has low affinity for sulfonamides
(3) impair permeability to the sulfonamide
7
Q
Sulfonamides are absorbed in the CSF and CNS. True or false?
A
True
8
Q
Therapeutic concentrations of sulfonamides are
in the range of ?
A
40–100 mcg/mL of blood
9
Q
Long acting sulfonamide
A
Sulfadoxine (7 - 9 days)
10
Q
Intermediate acting sulfonamides
A
Sulfadiazine
Sulfamethoxazole
Sulfapyridine
11
Q
Trimethoprim half-Life
A
Intermediate (11 hours)
12
Q
Pyrimethamine half-Life
A
Long (4–6 days)
13
Q
drug of choice for infections such as Pneumocystis
jiroveci (formerly P carinii ) pneumonia, toxoplasmosis, nocardiosis,
and occasionally other bacterial infections
A
trimethoprim-sulfamethoxazole (bactrim)
14
Q
sulfonamides used almost exclusively to treat urinary tract infections
A
Sulfisoxazole and sulfamethoxazole
15
Q
first-line
therapy for treatment of acute toxoplasmosis
A
Sulfadiazine-pyrimethamine
16
Q
should also be administered
to minimize bone marrow suppression when taking Sulfadiazine-pyrimethamine
A
Folinic acid, 10 mg orally each day
17
Q
a second-line agent in the treatment of
malaria
A
pyrimethamine with sulfadoxine (Fansidar)
18
Q
widely used in ulcerative
colitis, enteritis, and other inflammatory bowel disease
A
Sulfasalazine (salicylazosulfapyridine)
19
Q
effective
in the treatment of bacterial conjunctivitis and as adjunctive
therapy for trachoma
A
Sodium sulfacetamide ophthalmic solution or ointment
20
Q
used topically but can be absorbed from burn sites
A
mafenide acetate
21
Q
AE of mafenide acetate
A
The drug and
its primary metabolite inhibit carbonic anhydrase and can cause
metabolic acidosis
22
Q
much less toxic topical sulfonamide and is preferred
to mafenide for prevention of infection of burn wounds
A
Silver
sulfadiazine
23
Q
particularly serious and
potentially fatal AE when taking sulfonamides
A
SJS
24
Q
The 7 most common adverse effects when taking sulfonamides
A
fever, skin
rashes, exfoliative dermatitis, photosensitivity, urticaria, nausea,
vomiting, diarrhea
25
Other unwanted effects when taking sulfonamides include?
stomatitis, conjunctivitis, arthritis, hematopoietic disturbances, hepatitis, and, rarely, polyarteritis nodosa and psych
26
when given in large doses, particularly
| if fluid intake is poor, can cause crystalluria
Sulfadiazine
27
Crystalluria is treated
| by administration?
sodium bicarbonate to alkalinize the urine
| and fluids to increase urine flow
28
Other renal AE of sulfonamides
nephrosis
| allergic nephritis
29
Sulfonamides can cause hemolytic or aplastic anemia, granulocytopenia,
thrombocytopenia, or leukemoid reactions. Sulfonamides
may provoke hemolytic reactions in patients with?
glucose-6-
| phosphate dehydrogenase deficiency
30
Trimethoprim, a trimethoxybenzylpyrimidine, selectively inhibits
bacterial _______ which converts dihydrofolic
acid to tetrahydrofolic acid
dihydrofolic acid reductase
31
Pyrimethamine, another benzylpyrimidine,
selectively inhibits dihydrofolic acid reductase of _____
compared with that of mammalian cells.
protozoa
32
Sulfonamides are bacteriostatic or bacteriocidal?
Bacteriostatic when used solely
33
Resistance to trimethoprim can result from?
reduced cell permeability
overproduction of dihydrofolate reductase
production of
an altered reductase with reduced drug binding
34
Resistant enzymes against trimethoprim may be coded within _____ that exhibit a broad host range, accounting
for rapid and widespread dissemination of trimethoprim resistance?
transposons on
| conjugative plasmids
35
Trimethoprimsulfamethoxazole
| can also be given intravenously. True or False?
True
36
trimethoprim is more lipid-soluble than sulfamethoxazole,
| it has a larger volume of distribution than the latter drug. True or false?
True
37
Ratio of trimethoprim-sulfamethoxazole in formulation
1T:5S
38
Ratio of trimethoprim-sulfamethoxazole in peak plasma concentrations
1T:20S
39
The
dose of trimethoprim-sulfamethoxazole should be reduced by half for patients with creatinine clearances
of?
15–30 mL/min
40
concentrates in prostatic fluid and
in vaginal fluid, therefore, it
has more antibacterial activity in prostatic and vaginal fluids than
many other antimicrobial drugs.
Trimethoprim (a weak base)
41
Trimethoprim can be given alone in what dosage in acute
| urinary tract infections?
100 mg twice daily
42
A combination of trimethoprim-sulfamethoxazole is effective
| treatment for a wide variety of infections including?
```
P. jiroveci
pneumonia shigellosis
systemic salmonella infections
urinary
tract infections prostatitis
some nontuberculous mycobacterial
infections
most Staphylococcus aureus
strains, both methicillin-susceptible and methicillin-resistant, respiratory tract pathogens such as pneumococcus,
Haemophilus sp, Moraxella catarrhalis, and K pneumoniae (
Mycoplasma pneumoniae ).
```
43
Respiratory tract pathogen that is resistant to trimethoprim-sulfamethoxazole
Mycoplasma pneumoniae
44
One double strength tablet of trimethoprim-sulfamethoxazole contains?
each tablet contains trimethoprim
| 160 mg plus sulfamethoxazole 800 mg
45
DS tablet of trimethoprim-sulfamethoxazole given every 12 hours is effective for?
treatment for urinary tract infections and prostatitis
treatment for infections caused by susceptible
strains of shigella and salmonella
46
It is the agent of choice for moderately severe
| to severe pneumocystis pneumonia
80 mg trimethoprim plus
400 mg sulfamethoxazole per 5 mL diluted in 125 mL of 5%
dextrose in water IV for 60 - 90 minutes
47
used for treatment of
| leishmaniasis and toxoplasmosis
oral Pyrimethamine and sulfadiazine
48
Patients highly at risk for AE of trimethoprim-sulfamethoxazole
Patients
| with AIDS and pneumocystis pneumonia
49
The important quinolones are?
synthetic fluorinated analogs of
| nalidixic acid
50
Quinolones are classified as?
DNA gyrase inhibitors
51
Quinolones block bacterial DNA synthesis by inhibiting?
```
bacterial
topoisomerase II (DNA gyrase) and topoisomerase IV
```
52
Inhibition of
| DNA gyrase prevents?
prevents the relaxation of positively supercoiled DNA
| that is required for normal transcription and replication
53
Inhibition
| of topoisomerase IV interferes with?
separation of replicated chromosomal
| DNA into the respective daughter cells during cell division
54
Earlier quinolones such as nalidixic acid did not achieve systemic
antibacterial levels and were useful only in the treatment of?
lower
| urinary tract infections
55
the least
active of the fluoroquinolones against both gram-negative and
gram-positive organisms, with minimum inhibitory concentrations
(MICs) fourfold to eightfold higher than those of ciprofloxacin
Norfloxacin
56
comprise a second group of quinolones possessing
excellent gram-negative activity and moderate to good activity
against gram-positive bacteria
Ciprofloxacin, enoxacin, lomefloxacin, levofloxacin, ofloxacin, and
pefloxacin
57
MICs of second group of quinolones for gram-negative cocci and bacilli, including Enterobacter sp, P aeruginosa , Neisseria meningitidis, H aemophilus sp, and Campylobacter jejuni?
1–2 mcg/mL and often less
58
Ciprofloxacin is the
| most active agent of this group against gram-negative organisms, ____ in particular.
P aeruginosa
59
the L-isomer of ofloxacin,
has superior activity against gram-positive organisms, including
Streptococcus pneumoniae
levofloxacin
60
make up a third
group of fluoroquinolones with improved activity against grampositive
organisms, particularly S pneumoniae and some staphylococci
Gatifloxacin, gemifloxacin, and moxifloxacin
61
During fluoroquinolone therapy, resistant organisms emerge in
about one of every ____, especially among staphylococci,
P aeruginosa , and Serratia marcescens
10^7 –10^9 organisms
62
Resistance is due to one
or more point mutations in the quinolone binding region of the
target enzyme or to a change in the permeability of the organism. More recently
two types of plasmid-mediated resistance have been described. These are?
The
first type utilizes Qnr proteins, which protect DNA gyrase from the
fluoroquinolones. The second is a variant of an aminoglycoside
acetyltransferase capable of modifying ciprofloxacin
63
Resistance to one
fluoroquinolone, particularly if it is of high level, generally confers
cross-resistance to all other members of this class. True or false?
True
64
After oral administration, the fluoroquinolones are well absorbed
(bioavailability of?)
80 - 90%
65
Oral absorption of quinolones is impaired by
divalent and trivalent cations, including those
in antacids
oral fluoroquinolones should be taken 2
hours before or 4 hours after any products containing these cations
66
Dosage adjustment
| for renal failure is not necessary for which quinolone?
moxifloxacin
67
Nonrenally cleared fluoroquinolones are relatively contraindicated in patients with?
hepatic failure
68
Quinolone not effective against UTIs?
Moxifloxacin
69
Fluoroquinolones (except _____, which does not achieve adequate systemic concentrations)
have been used in infections of soft tissues, bones, and joints
and in intra-abdominal and respiratory tract infections, including
those caused by multidrug-resistant organisms such as Pseudomonas
and Enterobacter .
norfloxacin
70
drug of choice for prophylaxis
| and treatment of anthrax
Ciprofloxacin
71
Quinolones effective in treating
| chlamydial urethritis or cervicitis
Ciprofloxacin and levofloxacin
72
occasionally used for treatment of tuberculosis and atypical mycobacterial infections
Ciprofloxacin, levofloxacin,
| or moxifloxacin
73
agents that may be suitable
for eradication of meningococci from carriers or for prophylaxis
of infection in neutropenic cancer patient
Ciprofloxacin, levofloxacin,
| or moxifloxacin
74
so-called respiratory fluoroquinolones effective and used
increasingly for treatment of upper and lower respiratory tract
infections
levofloxacin, gatifloxacin, gemifloxacin, and moxifloxacin
75
With enhanced gram-positive activity and activity against
| atypical pneumonia agents (chlamydiae, Mycoplasma , and Legionella
levofloxacin, gatifloxacin, gemifloxacin, and moxifloxacin
76
Fluoroquinolones are generally well tolerated. The most common
effects are?
nausea, vomiting, and diarrhea
77
Photosensitivity has been reported with which quinolones?
lomefloxacin and
| pefloxacin
78
ECG change that occurs with gatifloxacin, levofloxacin,
| gemifloxacin, and moxifloxacin
QTc prolongation
79
gatifloxacin, levofloxacin,
| gemifloxacin, and moxifloxacin, should be avoided or used with caution in patients with which cardiac conditions?
```
QT c interval prolongation
uncorrected hypokalemia
those receiving class IA (eg,
quinidine or procainamide) or class III antiarrhythmic agents
(sotalol, ibutilide, amiodarone)
patients receiving other
agents known to increase the QT c interval (eg, erythromycin, tricyclic
antidepressants)
```
80
Quinolone associated with hyperglycemia
in diabetic patients and with hypoglycemia in patients
also receiving oral hypoglycemic agents
Gatifloxacin
81
Fluoroquinolones may damage growing cartilage and cause an
| arthropathy. Thus, these drugs are not routinely recommended for?
patients under 18 years of age.
82
a rare complication
| that has been reported in adults using quinolones
tendonitis
83
Fluoroquinolones are considered safe for pregnancy. True or false?
False
