ID 1 Flashcards
- P.E. is a 56-year-old man who comes to the clinic
with a 3-day history of fever, chills, pleuritic chest
pain, malaise, and productive cough. In the clinic,
his temperature is 102.1°F (38.9°C) (all other vital
signs are normal). His chest radiograph reveals
consolidation in the right lower lobe. His white
blood cell count (WBC) is 14,400 cells/mm3
, but
all other laboratory values are normal. He is given
a diagnosis of community-acquired pneumonia
(CAP). He has not received any antibiotics in 5
years and has no chronic disease states. Which is
the best empiric therapy for P.E.?
A. Doxycycline 100 mg orally twice daily.
B. Cefuroxime axetil 250 mg orally twice daily.
C. Levofloxacin 750 mg orally daily.
D. Trimethoprim/sulfamethoxazole double strength
orally twice daily.
- Answer: A
The patient has CAP that does not require hospitaliza-
tion (PSI score is 56, class II, which is low risk). Because
he has not received any antibiotics in the past 3 months
and has no comorbidities, he is at low risk of DRSP.
Therefore, the drug of choice is either a macrolide or
doxycycline (Answer A is correct). Cefuroxime is not
recommended for the treatment of CAP (Answer B is
incorrect). Fluoroquinolones are recommended only if
the patient has had recent antibiotics or has comorbid-
ities (Answer C is incorrect). Trimethoprim/sulfame-
thoxazole is not used for CAP (Answer D is incorrect)
- H.W. is a 38-year-old woman who presents with a
fever, malaise, dry cough, nasal congestion, and
severe headaches. Her symptoms began suddenly
3 days ago, and she has been in bed since then. She
reports no other illness in her family, but several
people have recently called in sick at work. It is
influenza season. Which is best for H.W.?
A. Azithromycin 500 mg, followed by 250 mg
daily orally for 4 more days.
B. Amoxicillin/clavulanic acid 875 mg orally
twice daily for 5 days.
C. Oseltamivir 75 mg twice daily orally for 5
days.
D. Symptomatic treatment only.
- Answer: D
The symptoms of this patient (high temperature, mal-
aise, dry cough, nasal congestion, and severe head-
aches) are most consistent with influenza; therefore, an
antibacterial agent would not affect recovery (Answers
A and B are incorrect). Oseltamivir should be initiated
within 48 hours of symptom onset, so because this
patient is more than 3 days out from symptom onset,
oseltamivir will not affect recovery (Answer C is incor-
rect). Because of the viral etiology and time since symp-
tom onset, symptomatic treatment is all that is indicated
(Answer D is correct).
- A study is designed to assess the risk of pneumo-
coccal pneumonia in older adults 10 years or more
after receiving their last pneumococcal vaccina-
tion, compared with older adults who have never
received any pneumococcal vaccinations. Which
study design is best?
A. Case series.
B. Case-control study.
C. Prospective cohort study.
D. Randomized controlled trial.
- Answer: B
A case-control study would be the most appropri-
ate study design because it is the most ethical, cost-
effective, timely method (Answer B is correct). A stron-
ger study design—for instance, a prospective cohort
study or a randomized controlled trial—has many dis-
advantages if used to answer this question. In a pro-
spective cohort study, too many patients would need
to be observed because of the low incidence of con-
firmed pneumococcal pneumonia. This study would
be too costly and take too long to complete (Answer
C is incorrect). Randomized controlled trials also have
many disadvantages in this situation. First, patients
would need to be vaccinated and then observed for at
least 10 years. Second, too many patients would need to
be observed because of the low incidence of confirmed
pneumococcal pneumonia. Third, it would be unethical
to randomly assign half of the patients to no vaccina-
tion. This study would therefore be too costly, uneth-
ical, and time-consuming (Answer D is incorrect).
A case series would evaluate only a few patients given
a diagnosis of pneumococcal pneumonia 10 years or
more after vaccination. It would not provide compar-
ative data, nor would it provide a strong study design
(Answer A is incorrect).
- A.B. is a 63-year-old woman who presents to the
emergency department with left leg pain and ery-
thema. The pain and erythema have worsened over
the past 24 hours. The left leg is significantly swol-
len with a large area of erythema and large bullae
extending from the thigh to the upper leg. There
is crepitus within the soft tissue. A.B. is found to
have rapidly progressing necrotizing fasciitis. A.B.
has normal renal function and no known drug
allergies. Which is the best empiric therapy for
A.B.?
A. Vancomycin 15 mg/kg intravenously every 12
hours.
B. Piperacillin/tazobactam 4.5 g intravenously
every 8 hours.
C. Vancomycin 15 mg/kg intravenously every
12 hours plus meropenem 1 g intravenously
every 8 hours plus clindamycin 900 mg intra-
venously every 8 hours.
D. Linezolid 600 mg intravenously every 12
hours plus ceftriaxone 1 g intravenously every
24 hours plus azithromycin 500 mg intrave-
nously daily.
- Answer: C
Although necrotizing fasciitis can be caused by
Streptococcus only, it is often a mixed infection that
includes gram-positive, gram-negative, and anaero-
bic bacteria. Therefore, in addition to urgent surgi-
cal debridement, it must be treated empirically with
broad-spectrum antibiotics. It is recommended that one
of those antibiotics have activity against P. aeruginosa.
Clindamycin therapy is also recommended initially
to decrease the production of toxin by Streptococcus.
Because vancomycin alone has no activity against
gram-negative organisms and does not decrease toxin
production, it is not the best empiric agent (Answer A is
incorrect). Moreover, piperacillin/tazobactam alone has
no activity against MRSA and does not decrease toxin
production (Answer B is incorrect). Although there are
some data that azithromycin may also decrease toxin
production and that linezolid has MRSA activity, ceftri-
axone has no activity against P. aeruginosa (Answer D
is incorrect). The best empiric option is vancomycin plus
meropenem plus clindamycin (Answer C is correct).
- N.R. is a 28-year-old woman who presents to the
clinic with a 2-day history of dysuria, frequency,
and urgency. She has no significant medical his-
tory, and the only drug she takes is an oral con-
traceptive. Which is the best empiric therapy for
N.R.?
A. Nitrofurantoin extended release (ER) 100 mg
orally twice daily for 3 days.
B. Ciprofloxacin 500 mg orally twice daily for
7 days.
C. Trimethoprim/sulfamethoxazole double strength
orally twice daily for 3 days.
D. Cephalexin 500 mg orally four times daily for
3 days.
- Answer: C
Although nitrofurantoin is a recommended first-
line agent, the therapy duration is too short for its
use (Answer A is incorrect). Because this patient
has no contraindications to the use of trimethoprim/
sulfamethoxazole or nitrofurantoin, and trimethoprim/
sulfamethoxazole resistance rates are not mentioned as
being high, fluoroquinolones would not be considered
appropriate as first-line therapy in this particular case
(Answer B is incorrect). In addition, 7 days of therapy
is not necessary. The best choice for this patient is tri-
methoprim/sulfamethoxazole double strength twice
daily orally for 3 days. The patient should be counseled
about the potential interaction between antibiotics and
oral contraceptives (Answer C is correct). β-Lactams
are not as effective as trimethoprim/sulfamethoxazole,
and data are limited on their use for 3 days (Answer D
is incorrect).
- B.Y. is an 85-year-old woman who is bedridden and
lives in a nursing home. She is chronically cathe-
terized, and her urinary catheter was last changed
3 weeks ago. Today, her urine is cloudy, and a uri-
nalysis reveals many bacteria. B.Y. is not noticing
any symptoms. A urine culture is obtained. Which
option is best for B.Y.?
A. No antibiotic therapy because she is chron-
ically catheterized and has no symptoms.
B. No antibiotic therapy, but the catheter should
be changed.
C. Ciprofloxacin 500 mg orally twice daily for
7 days and change the catheter.
D. Ciprofloxacin 500 mg orally twice daily for
14–21 days without a change in catheter.
- Answer: A
For the asymptomatic patient who is bedridden and
chronically catheterized, with cloudy urine and bac-
teria revealed by urinalysis, no therapy is indicated
(Answer A is correct). All patients with chronic urinary
catheters will be bacteriuric. Because this patient is
asymptomatic, the catheter does not need to be replaced
(Answer B is incorrect). If she were symptomatic, cath-
eter replacement might be indicated. Antibiotics are not
indicated; however, a 7-day course would be appropri-
ate if treatment were instituted (Answer C and D are
incorrect). A long course of treatment only increases
the risk of acquiring resistant organisms.
- V.E. is a 44-year-old man who presents to the
emergency department with a warm, erythema-
tous, and painful right lower extremity. There is
no raised border at the edge of the infection. Three
days ago, he scratched his leg on a barbed wire
fence on his property (no puncture wound associ-
ated with the fence). His temperature has been as
high as 101.8°F (38°C) with chills. Doppler studies
of his lower extremity are negative. Blood cultures
are negative. Which is the best empiric therapy
for V.E.?
A. Cefazolin 1 g intravenously every 8 hours.
B. Penicillin G 2 million units intravenously
every 4 hours.
C. Piperacillin/tazobactam 3.375 g intravenously
every 6 hours.
D. Apixaban 10 mg orally twice daily for 7 days,
followed by 5 mg orally twice daily.
- Answer: A
Because cellulitis (which the patient appears to have)
is usually caused by Streptococcus or Staphylococcus,
cefazolin is the drug of choice (vancomycin could be
initiated empirically if MRSA were a concern in this
patient) (Answer A is correct). Although penicillin is
the treatment of choice for erysipelas, the patient prob-
ably has acute cellulitis (there is no raised border at
the edge of the infection, which indicates erysipelas)
(Answer B is incorrect). Although piperacillin/tazo-
bactam has activity against both Streptococcus and
Staphylococcus, this treatment is too broad spectrum
for an acute cellulitis (Answer C is incorrect). Because
Doppler studies are negative, the likelihood of a deep
venous thrombosis is low (Answer D is incorrect).
- R.K. is a 36-year-old woman who presents to the
emergency department with a severe headache and
neck stiffness. Her temperature is 99.5°F (37.5°C).
After a negative computed tomographic scan of
the head, a lumbar puncture reveals the following:
glucose 54 mg/dL (peripheral, 104 mg/dL), protein
88 mg/dL, and WBC 220 cells/mm3
(100% lym-
phocytes). The Gram stain reveals no organisms.
Which option is best for R.K.?
A. This is aseptic meningitis, and no antibiotics
are necessary.
B. Administer ceftriaxone 2 g intravenously
every 12 hours until the cerebrospinal fluid
(CSF) cultures are negative for bacteria.
C. Administer ceftriaxone 2 g intravenously
every 12 hours and vancomycin 15 mg/kg
intravenously every 12 hours until the CSF
cultures are negative for bacteria.
D. Administer acyclovir 500 mg intravenously
every 8 hours until the CSF culture results are
negative for bacteria
- Answer: C
Even if a patient is believed to have aseptic meningi-
tis after analysis of the CSF, antibiotics must be given
until CSF cultures are negative (Answer A is incorrect).
In empiric therapy for bacterial meningitis in adults
(i.e., when the CSF Gram stain is negative), ceftriax-
one should be used in combination with vancomycin
(Answer B is incorrect). The vancomycin is necessary
for activity against resistant S. pneumoniae (Answer
C is correct). Although the symptoms and CSF results
are similar to what is expected for herpes simplex
encephalitis, the use of acyclovir alone in this patient
is inappropriate. Antibacterials must be used as well.
Viral meningitis is generally caused by coxsackievirus,
echovirus, and enterovirus, which are not treated with
acyclovir (Answer D is incorrect).
9.. L.G. is a 49-year-old woman with a history of
mitral valve prolapse. She presents to her physi-
cian’s office with malaise and a low-grade fever.
Her physician notes that her murmur is louder
than usual and orders blood cultures and an echo-
cardiogram. A large vegetation is observed on
L.G.’s mitral valve, and her blood cultures are
growing Enterococcus faecalis (susceptible to all
antibiotics). Which is the best therapy for L.G.?
A. Penicillin G plus gentamicin for 2 weeks.
B. Vancomycin plus ceftriaxone for 2 weeks.
C. Ampicillin plus ceftriaxone for 4–6 weeks.
D. Cefazolin plus gentamicin for 4–6 weeks.
- Answer: C
Enterococcal endocarditis should be treated for 4–6
weeks. The 2-week treatment regimen is indicated only
for streptococcal endocarditis (Answer A is incorrect).
There is also no indication that the patient is penicil-
lin allergic; thus, vancomycin should not be used as
first-line treatment (Answer B is incorrect). Ampicillin
plus ceftriaxone for 4–6 weeks is a regimen of choice
for penicillin-susceptible enterococcal endocarditis
(Answer C is correct). Cefazolin has no activity against
Enterococcus; therefore, the regimen with cefazolin is
inappropriate (Answer D is incorrect).
- N.L. is a 28-year-old woman with no significant
medical history. She reports to the emergency
department with fever and severe right lower
quadrant abdominal pain. The pain had been dull
for the past few days, but it suddenly became
severe during the past 8 hours. Her temperature is 103.5°F (39.7°C), and she has rebound tenderness
on abdominal examination. She is taken to surgery
immediately, where a perforated appendix is
diagnosed and repaired. Which is the best follow-up
antibiotic regimen?
A. Vancomycin 1000 mg intravenously every
12 hours plus metronidazole 500 mg intrave-
nously every 8 hours.
B. Cefazolin 1 g intravenously every 8 hours plus
ciprofloxacin 400 mg intravenously every 12
hours.
C. Ceftriaxone 1 g intravenously every 24 hours
plus metronidazole 500 mg intravenously
every 8 hours.
D. No antibiotics needed after surgical repair of
a perforated appendix.
- Answer: C
A perforated appendix requires antibiotics after surgery
for an intra-abdominal infection (Answer D is incor-
rect). The combination of vancomycin and metronida-
zole does not have adequate activity against aerobic,
gram-negative organisms (e.g., E. coli) (Answer A is
incorrect). The combination of cefazolin and ciproflox-
acin does not have adequate activity against anaerobic
organisms (e.g., B. fragilis group) (Answer B is incor-
rect). Ceftriaxone plus metronidazole is a good choice
for intra-abdominal infections, although it has limited
activity against Enterococcus (Answer C is correct).
- O.R. is a 73-year-old man who presents to the
emergency department with a 3-day history of
fever, chills, frequency, urgency, and perineal
pain. A urinalysis reveals many bacteria. A rectal
examination reveals a swollen, tender prostate. He
is given a diagnosis of acute bacterial prostatitis.
Which is the best regimen for this patient?
A. Amoxicillin/clavulanate 875 orally twice daily
for 7 days.
B. Trimethoprim/sulfamethoxazole double strength
orally twice daily for 14 days.
C. Cefprozil 500 mg orally twice daily for 21
days.
D. Ciprofloxacin 500 mg orally twice daily for
28 days.
- Answer: D
β-Lactam antibiotics are not recommended first-line
agents for patients with acute bacterial prostatitis.
Therefore, amoxicillin/clavulanate and cefprozil are
not the best options in this patient (Answers A and C
are incorrect). Although trimethoprim/sulfamethoxaz-
ole is an appropriate antibiotic, 14 days of treatment
is too short for prostatitis. Treatment duration should
be 4 weeks (Answer B is incorrect). Fluoroquinolones
are an appropriate antibiotic class for prostatitis, and
the 28-day duration is also appropriate (Answer D is
correct).
- J.M. is a 72-year-old woman with a history of atrial
fibrillation, hypertension, a right total hip replace-
ment 8 months earlier, and Crohn disease. She has
no drug allergies. She presents to the hospital with
increasing pain in her prosthetic hip over the past
month. There is concern about hip osteomyelitis.
Bone cultures are growing methicillin-sensitive
Staphylococcus aureus. J.M. has normal renal
function and no known drug allergies. Which is
the best antibiotic regimen for this patient?
A. Vancomycin 1000 mg intravenously every 12
hours plus rifampin 300 mg orally twice daily
for 2 weeks.
B. Cefazolin 2 g intravenously every 8 hours
plus rifampin 300 mg orally twice daily for
6 weeks followed by long-term oral antibiotics.
C. Nafcillin 1 g intravenously every 4 hours for
6 weeks.
D. Daptomycin 6 mg/kg intravenously daily for
6 weeks followed by long-term oral antibiotics.
- Answer: B
Because the organism causing the infection is known
to be MSSA, using vancomycin or daptomycin is
unnecessary. They both can potentially cause serious
toxicities, and daptomycin is expensive (Answers A
and D are incorrect). Both nafcillin and cefazolin are
appropriate choices for MSSA osteomyelitis; however,
because this infection involves a prosthetic joint rifam-
pin must be combined with the primary antibiotic, and this combination must continue for 2–6 weeks (Answer
C is incorrect). This must be followed with 3 months of
appropriate oral antibiotics. (Answer B is correct).
- B.K. is a 58-year-old woman (height 66 inches,
weight 82 kg) who is scheduled to undergo a total
knee replacement tomorrow. She has no significant
medical history and no drug allergies. Which is the
best surgical prophylaxis regimen for this patient?
A. Cefazolin 2 g within 1 hour of the incision and
no doses postoperatively.
B. Cefazolin 2 g within 4 hours of the incision
and three doses every 8 hours postoperatively.
C. Cefazolin 1 g within 1 hour of the incision and
three doses every 8 hours postoperatively.
D. Cefazolin 1 g within 4 hours of the incision
and no doses postoperatively.
- Answer: A
For any orthopedic surgical procedures in which pros-
thetic materials will be implanted, surgical prophylaxis
is necessary. The preferred agent is cefazolin, although
vancomycin may be used in patients with allergies. The
recommended dosage of cefazolin is at least 2 g (3 g
for those weighing more than 120 kg) (Answers C and
D are incorrect). Antibiotics must be present in the tis-
sues at the time of incision, and it is best to adminis-
ter the agent within 1 hour of the incision (Answer A
is correct). Because orthopedic procedures tend to be
shorter procedures, redosing is probably unnecessary.
Administering antibiotics beyond surgical closure is
unnecessary (Answer B is incorrect).
Patient Case
1. R.L. is a 68-year-old man who presents to the emergency department with coughing and shortness of
breath. His symptoms, which began 4 days ago, have worsened during the past 24 hours. He is coughing up
yellow-green sputum, and he has chills, with a temperature of 102.4°F (39°C). His medical history includes
coronary artery disease with a myocardial infarction 5 years ago, congestive heart failure, hypertension, and
osteoarthritis. He rarely drinks alcohol and has not smoked since his myocardial infarction. He lives at home
with his wife. His medications on admission include lisinopril 10 mg/day, hydrochlorothiazide 25 mg/day,
and acetaminophen 650 mg four times/day. On physical examination, he is alert and oriented, with the following
vital signs: temperature 101.8°F (38°C), heart rate 100 beats/minute, respiratory rate 32 breaths/minute,
and blood pressure 142/94 mm Hg. His laboratory results are normal except for blood urea nitrogen (BUN)
32 mg/dL (serum creatinine [SCr] 1.23 mg/dL). A chest radiograph reveals infiltrates in the right lower lobe.
A sputum specimen is not available. If R.L. were hospitalized, which would be the best empiric therapy for him?
A. Ampicillin/sulbactam 1.5 g intravenously every 6 hours.
B. Piperacillin/tazobactam 4.5 g intravenously every 6 hours plus gentamicin 180 mg intravenously every
12 hours.
C. Ceftriaxone 1 g intravenously every 24 hours plus azithromycin 500 mg intravenously every 24 hours.
D. Doxycycline 100 mg intravenously every 12 hours.
- Answer: C
Although ampicillin/sulbactam has good activity
against H. influenzae, Moraxella catarrhalis, and S.
pneumoniae (but not drug-resistant S. pneumoniae
[DRSP]), it has no activity against atypical organisms
(L. pneumophila, Mycoplasma pneumoniae,
Chlamydia pneumoniae). Current recommendations
are to include a macrolide with a β-lactam antibiotic for
hospitalized patients with CAP (Answer A is incorrect).
Piperacillin/tazobactam has good activity against H.
influenzae, M. catarrhalis, and S. pneumoniae (but not
DRSP) and, with gentamicin, is excellent for pneumonia
caused by most gram-negative organisms. However,
this increased activity is not necessary for CAP, and the
combination has no activity against atypical organisms
(Answer B is incorrect). Ceftriaxone plus azithromycin
is the best initial choice. It has excellent activity
against atypical organisms (because of azithromycin),
H. influenzae, M. catarrhalis, and S. pneumoniae (even
intermediate DRSP) (Answer C is correct). Although
doxycycline has activity against atypical organisms and
most of the typical organisms that cause CAP, it is not
recommended as monotherapy in hospitalized patients.
In addition, its activity against S. pneumoniae may be
limited (if the patient lives in an area with extensive
DRSP). Doxycycline would not be the best initial choice
(Answer D is incorrect).
Patient Case
2. B.P. is a 66-year-old woman who underwent a two-vessel coronary artery bypass graft 8 days ago and has
been on a ventilator in the surgical intensive care unit since then. Her temperature is now rising and her chest
radiograph reveals a new infiltrate in the right lower lobe. Her medical history includes coronary artery disease
with a myocardial infarction 2 years ago, COPD, and hypertension. All antipseudomonal antibiotics in
the institution are active against at least 90% of strains. B.P. has no known drug allergies. Which is the best
empiric therapy for B.P.?
A. Ceftriaxone 1 g intravenously every 24 hours plus gentamicin 7 mg/kg intravenously every 24 hours plus
linezolid 600 mg intravenously every 12 hours.
B. Piperacillin/tazobactam 4.5 g intravenously every 6 hours.
C. Levofloxacin 750 mg intravenously every 24 hours plus linezolid 600 mg intravenously every 12 hours.
D. Cefepime 2 g intravenously every 8 hours plus tobramycin 7 mg/kg intravenously every 24 hours plus
vancomycin 15 mg/kg intravenously every 12 hours.
- Answer: D
Ceftriaxone plus gentamicin plus linezolid is not good
empiric therapy because ceftriaxone has no activity
against P. aeruginosa. Because the patient has been in a
hospital for 5 days or more (8 days at this point), she is at
increased risk of MDR organisms, specifically P. aeruginosa
and MRSA (Answer A is incorrect). Although
piperacillin/tazobactam has good activity against most
common causes of nosocomial pneumonia (including
P. aeruginosa), the most recent guidelines recommend
two antibiotics with activity against P. aeruginosa for
patients with risk factors for MDR organisms She also
needs an antibiotic with MRSA activity (Answer B is
incorrect). Levofloxacin has activity against P. aeruginosa,
but two drugs should be used (Answer C is incorrect).
Cefepime plus tobramycin plus vancomycin is the
best empiric therapy because it includes two antibiotics
with activity against P. aeruginosa and another agent
for MRSA (Answer D is correct).
Patient Case
3. S.C. is a 46-year-old woman who presents to the clinic with purulent nasal discharge, nasal and facial congestion,
headaches, fever, and dental pain. Her symptoms began about 10 days ago, improved after about 4 days,
and then worsened again a few days later. Which is the best empiric therapy for S.C.?
A. Cefpodoxime proxetil 200 mg orally twice daily.
B. Clindamycin 300 mg orally four times daily.
C. Amoxicillin/clavulanate 875 mg/125 mg orally twice daily.
D. No antibiotic therapy needed.
- Answer: C
This patient has symptoms suggestive of bacterial sinusitis,
including two major symptoms and a few minor
symptoms. That the symptoms improved and then
worsened suggests a bacterial sinusitis that followed a
viral infection (Answer D is incorrect). Although the
combination of cefpodoxime and clindamycin is an
option for sinusitis in penicillin-allergic patients, it is
not recommended to give either of these alone for treatment
(Answers A and B are incorrect). The best option
is amoxicillin/clavulanate, which has activity against
organisms commonly seen in bacterial sinusitis and is
considered a first-line agent (Answer C is correct).
Patient Case
4. G.N. is a 62-year-old woman who presents to the emergency department with a 3-day history of urinary frequency
and dysuria. During the past 24 hours, she has had nausea, vomiting, and flank pain. G.N. has a history
of type 2 diabetes, which is poorly controlled, with some diabetes-related complications. G.N. also has
hypertension and a history of several episodes of deep venous thrombosis. Her medications include glyburide
5 mg orally daily, enalapril 10 mg orally twice daily, warfarin 3 mg orally daily, and metoclopramide 10 mg
orally four times daily. On physical examination, she is alert and oriented, with the following vital signs:
temperature 102.8°F (39°C), heart rate 120 beats/minute, respiratory rate 16 breaths/minute, supine blood
pressure 140/75 mm Hg, and standing blood pressure 110/60 mm Hg. Her laboratory values are within normal
limits except for elevated international normalized ratio 2.7, BUN 26 mg/dL, SCr 1.88 mg/dL, and WBC
12,000 cells/mm3 (78 polymorphonuclear leukocytes, 7 band neutrophils, 10 lymphocytes, and 5 monocytes).
Her urinalysis reveals turbidity, 2+ glucose, pH 7.0, protein 100 mg/dL, 50–100 WBCs, positive nitrites, 3–5
red blood cells, and many bacteria and positive for casts. Which is the best empiric therapy for G.N.?
A. Trimethoprim/sulfamethoxazole double strength orally twice daily for 7 days. Monitor INR carefully.
B. Ciprofloxacin 400 mg intravenously twice daily and then 500 mg orally twice daily for a total of 7 days.
Monitor INR carefully.
C. Gentamicin 140 mg intravenously every 24 hours for 3 days.
D. Tigecycline 100 mg once, then 50 mg intravenously every 12 hours and then doxycycline 100 mg orally
twice daily for a total of 10 days.
- Answer: B
Although the treatment duration is correct for this
patient’s diagnosis (7 days), oral trimethoprim/sulfamethoxazole
is inappropriate for complicated pyelonephritis.
It will also interact with warfarin, increasing the
risk of bleeding. (Answer A is incorrect). Ciprofloxacin
400 mg intravenously twice daily and then 500 mg
orally twice daily for 7 days is an appropriate choice
and duration (7–14 days) for this complicated pyelonephritis
(it may also interact with warfarin but to a
lesser extent than trimethoprim/sulfamethoxazole). It
would be expected to have activity against the common
organisms causing complicated pyelonephritis (Answer
B is correct). Gentamicin for 3 days is too short a treatment
duration (Answer C is incorrect). Tigecycline,
followed by doxycycline, is not recommended for complicated
pyelonephritis (although tigecycline is found
unchanged in the urine) (Answer D is incorrect).
Patient Case
5. G.N. returns to the clinic in 6 months with no urinary symptoms, but her chief concern is now an ulcer on her
right foot. She recently returned from a vacation in Florida and thinks she might have stepped on something
while walking barefoot on the beach. Her foot is not sore but is red and swollen around the deep ulcer. Her
medications are the same as in Patient Case 4. Vital signs are stable, and there is nothing significant on physical
examination except for the right foot ulcer. Laboratory values are within normal limits (SCr 0.86 mg/dL).
Which is the best empiric therapy for G.N.?
A. Nafcillin 2 g intravenously every 6 hours for 6–12 weeks.
B. Tobramycin 120 mg intravenously every 12 hours plus levofloxacin 750 mg intravenously every 24 hours
for 1–2 weeks.
C. Ampicillin/sulbactam 3 g intravenously every 6 hours for 2–3 weeks.
D. Below-the-knee amputation followed by ceftriaxone 1 g intravenously every 24 hours for 1 week.
- Answer: C
Nafcillin has excellent activity against gram-positive
organisms, but it would miss the gram-negative organisms
and anaerobes often involved in moderate to
severe diabetic foot infections (Answer A is incorrect).
Tobramycin and levofloxacin would be good against
aerobic organisms, but levofloxacin has only limited
activity against anaerobes. Tobramycin may also not
be a good choice for a patient with diabetes mellitus
with long-term complications (because of the increased
risk of nephrotoxicity) (Answer B is incorrect).
β-Lactamase inhibitor combinations are good agents
because they have activity against the organisms that
are often involved. At this time, a regimen active against P. aeruginosa is probably not necessary.
Treatment duration may need to be extended if the bone
is involved (Answer C is correct). Aggressive antibiotic
treatment often prevents the need for an amputation
(Answer D is incorrect).
Patient Case
6. W.A. is a 55-year-old man who is admitted with weight loss, malaise, and severe back pain and spasms that
have progressed during the past 2 months. He has also experienced loss of sensation in his lower extremities.
Four months before this admission, he had surgery for a fractured tibia, followed by an infection treated with
unknown antibiotics. W.A. has hypertension and a history of diverticulitis. On physical examination, he is
alert and oriented, with the following vital signs: temperature 99.4°F (37.4°C), heart rate 88 beats/minute,
respiratory rate 14 breaths/minute, and blood pressure 130/85 mm Hg. His laboratory values are within normal
limits, except for WBC 14,300 cells/mm3, erythrocyte sedimentation rate 89 mm/hour, and C-reactive
protein 12 mg/dL. Magnetic resonance imaging reveals bony destruction of lumbar vertebrae 1 and 2, which
is confirmed by a bone scan. A computed tomography–guided bone biopsy reveals gram-positive cocci in
clusters. Which is the best therapy for W.A.?
A. Vancomycin 15 mg/kg intravenously every 12 hours for 6 weeks.
B. Nafcillin 2 g intravenously every 6 hours for 2 weeks.
C. Levofloxacin 750 mg orally every 24 hours for 6 weeks.
D. Ampicillin/sulbactam 3 g intravenously every 6 hours for 2 weeks.
- Answer: A
Because sensitivities of the gram-positive organism are
still unknown, vancomycin is the best choice. In addition,
the therapy duration for osteomyelitis is 4–6 weeks
(Answer A is correct). Therefore, the 2-week duration
with nafcillin is too short (Answer B is incorrect).
Although levofloxacin is advantageous because it can be
given orally, it will probably not achieve adequate bone
concentrations to eradicate S. aureus (the most likely
organism) (Answer C is incorrect). Ampicillin/sulbactam
is effective against S. aureus (except for MRSA); its
broad spectrum of activity is not necessary in this situation,
and the duration is too short (Answer D is incorrect).
Patient Case
7. D.M. is a 21-year-old university student who presents to the emergency department with the worst headache
of his life. During the past few days, he has felt slightly ill but has been able to go to class regularly and eat and
drink adequately. This morning, he awoke with a terrible headache and pain whenever he moved his neck. He
has no significant medical history and takes no medications. He cannot remember the last time he received a
vaccination. On physical examination, he is in extreme pain (10/10) with the following vital signs: temperature
102.4°F (39.1°C), heart rate 110 beats/minute, respiratory rate 18 breaths/minute, and blood pressure
130/75 mm Hg. His laboratory values are within normal limits, except for WBC 22,500 cells/mm3 (82 polymorphonuclear
leukocytes, 11 band neutrophils, 5 lymphocytes, and 2 monocytes). A computed tomography
scan of the head is normal, so a lumbar puncture is performed with the following results: glucose 44 mg/dL
(peripheral, 110), protein 220 mg/dL, and WBC 800 cells/mm3 (85% neutrophils, 15% lymphocytes). Which
is the best empiric therapy for D.M.?
A. Penicillin G 4 million units intravenously every 4 hours.
B. Ceftriaxone 2 g intravenously every 12 hours.
C. Ceftriaxone 2 g intravenously every 12 hours plus dexamethasone 10 mg intravenously every 6 hours.
D. Ceftriaxone 2 g intravenously every 12 hours plus vancomycin 1000 mg intravenously every 8 hours plus
dexamethasone 10 mg intravenously every 6 hours.
- Answer: D
From his presentation and laboratory values, this
patient has bacterial meningitis. Penicillin is effective
against N. meningitidis and S. pneumoniae; however,
some strains are resistant, and until culture results are
received, it is unwise to use this agent alone (Answer A
is incorrect). Ceftriaxone alone is effective for meningococcal
and pneumococcal meningitis; however,
vancomycin should be started empirically with ceftriaxone
in case the patient has a highly penicillin-resistant
S. pneumoniae (Answers B and C are incorrect).
Ceftriaxone is the appropriate empiric antibiotic therapy
in this situation and vancomycin is generally used
empirically because of its activity against highly penicillin-
resistant S. pneumoniae (Answer D is correct).
The vancomycin can be discontinued when highly penicillin-
resistant pneumococcal meningitis is ruled out.
Patient Case
8. D.M.’s CSF cultures grew N. meningitidis. Which is the best recommendation for meningitis prophylaxis?
A. The health care providers in close contact with D.M. should receive rifampin 600 mg orally every
12 hours for four doses.
B. Everyone in D.M.’s dormitory and in all of his classes should receive rifampin 600 mg orally every
24 hours for 4 days.
C. Everyone in the emergency department at the time of D.M.’s presentation should receive the meningococcal
conjugate vaccine.
D. Everyone in the emergency department at the time of D.M.’s presentation should receive rifampin
600 mg orally every 12 hours for four doses.
- Answer: A
Only people in close contact to a patient with meningococcal
meningitis need prophylaxis (primarily those
who live closely with the patient and those who are
exposed to oral secretions) (Answer B and D are incorrect).
The correct regimen is rifampin 600 mg every 12
hours for four doses (Answer A is correct). Although
the vaccine is a good idea for those at future risk of
acquiring this infection (e.g., college students living in
dormitories), its use during an outbreak is very limited
(Answer C is incorrect).
- T.S. is a 48-year-old man who presents to the emergency department with fever, chills, nausea and vomiting,
anorexia, lymphangitis in his right hand, and lower back pain. He has no significant medical history except
for kidney stones 4 years ago. He has no known drug allergies. He is homeless and was a person with substance
use disorder (intravenous heroin) for the past year but quit 2 weeks ago. On physical examination, he
is alert and oriented, with the following vital signs: temperature 100.8°F (38°C), heart rate 114 beats/minute,
respiratory rate 12 breaths/minute, and blood pressure 127/78 mm Hg. He has a faint systolic ejection murmur,
and his right hand is erythematous and swollen. His laboratory values are all within normal limits. He had an
HIV test 1 year ago, which was negative. One blood culture was obtained in the emergency department that
later grew MSSA. Two more cultures were obtained 24 hours after the first culture and are now both growing
gram-positive cocci in clusters. A transesophageal echocardiogram reveals vegetation on the mitral valve.
Which is the best therapeutic regimen for T.S.?
A. Nafcillin therapy for 7–10 days.
B. Nafcillin plus rifampin plus gentamicin therapy for 6 weeks or longer.
C. Nafcillin plus gentamicin therapy for 2 weeks of both antibiotics.
D. Nafcillin therapy for 6 weeks.
- Answer: D
A treatment duration of 7-10 days is too short for S.
aureus endocarditis in the mitral position (Answer A
is incorrect). Only streptococcal endocarditis can be
treated for 2 weeks. Although nafcillin intravenously
plus rifampin plus gentamicin therapy for 6 weeks or
longer is an appropriate duration for MSSA, the rifampin
and gentamicin need not be added in patients with
native valve endocarditis (Answer B is incorrect).
Nafcillin intravenously plus gentamicin intravenously
for 2 weeks is too short for S. aureus endocarditis
(Answer C is incorrect). Nafcillin intravenously for 6
weeks is the recommended treatment for MSSA endocarditis
(Answer D is correct).
Patient Case
10. Six months after treatment of his endocarditis, T.S. is visiting his dentist for a tooth extraction. Which antibiotic
is best for prophylaxis?
A. Tooth extractions do not warrant endocarditis prophylaxis.
B. Administer amoxicillin 2 g 1 hour before the extraction.
C. Administer amoxicillin 3 g 1 hour before the extraction and 1.5 g 6 hours for four doses after the extraction.
D. T.S. is not at increased risk of endocarditis and does not need prophylactic antibiotics.
- Answer: B
This patient is at increased risk of endocarditis because
of his history of the disease (Answer D is incorrect).
Tooth extractions warrant prophylaxis for those at risk
(Answer A is incorrect) Amoxicillin 2 g, 1 hour before
the tooth extraction, is the current recommended dose
(Answer B is correct). The 2-g dose is adequate for protection,
and a follow-up dose is not needed. Amoxicillin
3 g 1 hour before the extraction and 1.5 g 6 hours for
four doses after the extraction is the older recommended
dose. A follow-up dose is not needed (Answer
C is incorrect).
Patient Case
11. R.K. is a 72-year-old man who presents to the emergency department with a 2-day history of redness and
swelling of his upper right extremity. He scraped his arm while clearing some brush in his yard. Although
the scratch was initially healing, the area around the injury has become red and warm to the touch over the
past few days, and the redness appears to be spreading. His medical history includes gastroesophageal reflux
disease, hypertension, hyperlipidemia, and osteoarthritis. R.K. is taking pantoprazole 40 mg orally daily, lisinopril
20 mg orally daily, atorvastatin 40 mg orally daily, and acetaminophen 500 mg orally as needed. R.K.
has no known drug allergies. R.K. is hospitalized and sent home after a few days with a prescription for oral
clindamycin for his cellulitis. Two weeks after completing therapy for his cellulitis, R.K. has watery diarrhea.
R.K. goes to the emergency department, and his C. difficile toxin is positive. His WBC is 24,500 cells/mm3,
albumin is 2.8 g/dL, and SCr is 1.74 mg/dL (normally around 0.90 mg/dL). Which is the best therapeutic
regimen for R.K.?
A. Metronidazole 500 mg orally three times daily for 7 days.
B. Vancomycin 125 mg orally four times daily for 10 days.
C. Fidaxomicin 200 mg orally twice daily for 14 days.
D. Rifaximin 400 mg orally twice daily for 7 days.
- Answer: B
This patient is having a severe episode of C. difficile
diarrhea, as demonstrated by his low albumin, high
WBC, and elevated SCr. Therefore, metronidazole is
not the optimal choice (and the duration is too short)
(Answer A is incorrect). Fidaxomicin and rifaximin are
not first-line agents (Answers C and D are incorrect).
Fidaxomicin could be used first line in patients who are
at high risk of recurrence, but the duration of 14 days is
too long. The best therapy for this patient is vancomycin
for 10 days (Answer B is correct).
Patient Case
12. You are a pharmacist who works closely with the surgery department to optimize therapy for patients undergoing
surgical procedures at your institution. The surgeons provide you with principles of surgical prophylaxis
that they believe are appropriate. Which is the best practice for optimizing surgical prophylaxis?
A. Antibiotics should be redosed for extended surgical procedures; redose if the surgery lasts longer than
4 hours or involves considerable blood loss.
B. All patients should be given antibiotics for 24 hours after the procedure; this will optimize prophylaxis.
C. Preoperative antibiotics can be given up to 4 hours before the incision; this will make giving the antibiotics
logistically easier.
D. Vancomycin is the antibiotic of choice for surgical wound prophylaxis because of its long half-life and
activity against MRSA.
- Answer: A
Redosing antibiotics for surgical prophylaxis is very
important, especially for antibiotics with short halflives,
for extended surgical procedures, or for when
there is extensive blood loss (Answer A is correct).
Antibiotics given beyond the surgical procedure are generally
unnecessary and only increase the potential for
adverse drug reactions and resistant bacteria (Answer
B is incorrect). Although preoperative antibiotics given up to 4 hours before the incision may improve the logistics
of administering surgical prophylaxis, study results
show that antibiotics must be given as close to the time
of the incision as possible (definitely within 2 hours)
(Answer C is incorrect). Vancomycin should not be
used routinely for surgical prophylaxis. The Centers for
Disease Control and Prevention does not recommend
the use of vancomycin for “routine surgical prophylaxis
other than in a patient with life-threatening allergy to
β-lactam antibiotics.”(Answer D is incorrect).
