Infectious Disease
A 65-year-old woman is evaluated for a 1-day history of fever, headache, and altered
mental status. Medical history includes type 2 diabetes mellitus and hypertension
treated with glipizide and hydrochlorothiazide. She has no allergies.
On physical examination, the patient appears confused. Temperature is 38.9 °C (102.0
°F), blood pressure is 104/66 mm Hg, pulse rate is 100/min, and respiration rate is
20/min. Her neck is supple, and she has no rashes.
Laboratory studies indicate a leukocyte count of 19,000/µL (19 × 109/L) with 30% band
forms and a platelet count of 90,000/µL (90 × 109/L). A non-contrast– enhanced CT
scan of the head is normal. Cerebrospinal fluid (CSF) analysis shows a leukocyte count
of 1300/µL (1300 × 106/L) with 98% neutrophils, glucose concentration of 20 mg/dL
(1.1 mmol/L) (plasma glucose, 120 mg/dL [6.7 mmol/L]), and protein level of 200
mg/dL (2000 mg/L). CSF Gram stain results are negative.
After providing adjunctive dexamethasone, which of the following empiric
antimicrobial regimens should be initiated in this patient?
1.
2.
3.
4.
5.
Ceftriaxone
Penicillin G
Vancomycin, ampicillin and ceftriaxone
Vancomycin plus ceftriaxone
0%
0%
Vancomycin plus trimethoprim- sulfamethoxazole
1
2
0%
3
0%
0%
4
5
Meningitis
• Most common bacterial
causes:
–
–
–
–
–
S. pneumonia (61%)
Neisseria meningitidis
GBS
Haemophilus influenza
Listeria monocytogenes
Meningitis Diagnosis
Meningitis Treatment
• Repeat LP if pt not improving at
48hrs on appropriate abx
• Dex given with or just before first
dose abx
Brain
Abscess
Subdural
Empyema
Epidural
Abscess
• Most commonly from contiguous spread (middle ear, mastoid
cells, paranasal sinus)
• Symptoms: severe ipsilateral headache
• Diagnosis: MRI more sensitive than CT
• Treatment: emergent surgery and empiric abx
•
•
•
•
Most commonly from otorhinologic infections (paranasal sinus)
Symptoms: meningeal signs and focal neurologic deficit
Diagnosis: MRI more sensitive than CT
Treatment: emergent surgery and empiric abx
•
•
•
•
Most commonly from hematogenous spread
Symptoms: fever, spinal pain, neurologic deficits
Diagnosis: MRI can better visualize spinal cord and epidural space
Treatment: surgical decompression, abscess drainage and long
term abx
Viral CNS Infections
Herpes Simplex:
• Symptoms: Fever, headache, behavior abnormalities, seizures
• Diagnosis:
• MRI: Edema and hemorrhage of temporal lobe
• LP: HSV PCR (false- negative when hemoglobin in CSF; repeat testing
if strong suspicion)
• Treatment: Acyclovir
West Nile virus:
• Symptoms: Tremors, myoclonus, parkinsonism, flaccid paralysis
• Diagnosis:
• MRI: mixed intensity (hypodense lesions on T1, hyperintense on T2)
• LP: IgM antibodies
• Treatment: None
An 18-year-old woman undergoes evaluation in the emergency department for
increasing muscle pain in the left biceps area, nausea, light-headedness, and fever of 3
days’ duration. She was recently diagnosed with varicella virus infection. She admits to
having vigorously scratched a lesion in that area and in other areas several days earlier.
Vaccinations except for the varicella vaccine are up-to-date. Her only medication has
been ibuprofen as needed.
On physical examination, temperature is 38.7 °C (101.8 °F), blood pressure is 85/55
mm Hg, pulse rate is 120/min, and respiration rate is 20/min. Skin examination reveals
healing varicella lesions. The left biceps area is notable for tenderness, warmth, and
“woody” induration to palpation.
Hemoglobin 11.0, WBC 20,000; Platelet 75,000; Creatinine 2.0; AST 95; ALT 100
Urinalysis is normal. MRI shows evidence of superficial fascial necrosis between the
skin and the biceps muscle.
The patient had a single dose of vancomycin and piperacillin-tazobactam before
undergoing emergency surgical debridement. Gram stain of the surgically obtained
tissue and fluid reveals only gram-positive cocci in short chains.
Which of the following treatment regimens should be given now?
1.
2.
3.
4.
Intravenous immune globulin
Metronidazole and ciprofloxacin
0%
Penicillin and clindamycin
1
Vancomycin plus cefepime and metronidazole
0%
2
0%
3
0%
4
Skin and Soft Tissue Infections
Infection
Treatment
Notes
Cellulitis
Dicloxacillin, Cephalexin
S. Aureus, GABHS
CA- MRSA
TMP-SMX, Tetracycline,
Clinda
Purulent drainage, abscess
Animal Bite Wounds
Amoxicillin/Clavulanate
Perform tetanus, rabies
assessment
Human Bite Wounds
Amoxicillin/Clavulanate
Perform tetanus assessment
A 21-year-old man is evaluated in August for a 2-day history of fever, diffuse myalgia,
and a mild frontal headache. Recent travel history includes a 2-month hike on the
Appalachian Trail completed 10 days prior to presentation.
On physical examination, the patient is not ill appearing. Vital signs are normal except
for a temperature of 37.9 °C (100.2 °F). Skin examination findings of the lower
extremity are shown .
A 21-day course of oral doxycycline is initiated, and after100%
2 days, the rash resolves and
the patient is asymptomatic.
One week after completing therapy, the patient undergoes follow-up evaluation for
generalized malaise, diffuse aching, and a mild sore throat. The rash and the fever
have not returned.
Physical examination is normal.
WBC 7600, Hemoglobin 16.4, ESR 14, AST 34,
Serologic test for Borrelia Positive
Which of the following is the most appropriate next step in treatment?
1.
2.
3.
4.
5.
IV ceftriaxone for 4 weeks
Oral amoxicillin for 4 weeks
Oral atavoquone for 4 weeks
0%
Oral azithromycin for 4 weeks
1 therapy
2
No additional antibiotic or antimicrobial
0%
3
0%
0%
4
5
Tick Borne Illnesses
• Lyme Disease (Borrelia burgdorferi)
– Vector: Ixodes scapularis (deer tick)
– Reservoirs: deer, mice
– Infection occurs after ticks have fed for at least 36
hours
– Treatment: doxycycline
Early: Erythema
Migrans at 5-14d
Serologic Tests
are negative
Early
Disseminated:
neurologic and
cardiac
Late: rheum,
neuro or
cutaneous at
months- years
Tick Borne Illnesses
•
Babesiosis (Babesia microti)
–
–
–
–
–
•
Ehrichiosis (Ehrlichia chaffeensis)–
–
–
–
–
•
Vector: Ixodes scapularis (deer tick)
Reservoirs: rodents, cattle
Symptoms: nonspecific febrile illness
Diagnosis: peripheral smear
Treatment: quinine + clinda or atovaquone + azithro
Vector: Lone star tick
Reservoirs: deer, dogs, goats
Symptoms: fever, headache and myalgias
Diagnosis: peripheral smear
Treatment: doxycycline
Anaplasmosis (Anaplasma phagocytophilum)
–
–
–
–
–
Vector: Ixodes scapularis (deer tick)
Reservoirs: deer, rodents
Symptoms: fever, headache and myalgias
Diagnosis: peripheral smear
Treatment: doxycycline
Tick Borne Illnesses
• Rocky Mountain Spotted Fever (Rickettsia
rickettsii)
– Vector: dog and wood ticks
– Reservoir: Humans
– Symptoms: fever, headache and myalgias; rash at
wrist/ankles and centripetally spread
– Treatment: doxycyline
A 32-year-old female physician is beginning a postgraduate
fellowship at a university hospital and must undergo tuberculin
skin testing. This is the first time she will have undergone such
testing. She is healthy. She grew up in Africa and completed
medical school and residency training in London. She received
the bacille Calmette-Guérin (BCG) vaccine as 100%
a child.
Tuberculin skin testing results indicate a 16-mm area of
induration at the tuberculin skin testing site.
Physical examination is normal.
Which of the following is the most appropriate next step in the
management of this patient?
1.
2.
3.
4.
Chest radiograph
Isoniazid, rifampin, pyrazinamide, and ethambutol
Repeat tuberculin skin testing in 2 weeks
No additional therapy or evaluation
0%
1
2
0%
3
0%
4
Tuberculosis
• A history of BCG vaccine
should NOT influence
interpretation TST.
• Treatment:
– Active: Rifampin,
Isoniazid, pyrazinamide,
ethambutol x 2months,
then rifampin &
Isoniazid x 7 months
– Latent: Isoniazid x
9months
A 31-year-old man is evaluated for a 12-day history of low-grade fever, pleuritic chest
pain, and a nonproductive cough. Two weeks ago, the patient traveled to Phoenix,
Arizona, for 3 days to play in a golf tournament. He lives in central Pennsylvania.
Medical history is noncontributory, and he takes no medications.
On physical examination, temperature is 37.7 °C (100.0 °F). The remaining vital signs
are normal. Chest examination reveals occasional bibasilar crackles.
100%
The leukocyte count is 7400/µL (7.4 × 109/L) with 52% neutrophils,
32% lymphocytes,
10% monocytes, and 6% eosinophils. Chest radiographs show bilateral small, scattered
infiltrates and bilateral pleural effusions.
Thoracentesis is performed and yields 300 mL of amber-colored turbid fluid with a
leukocyte count of 1200/µL (1.2 × 109/L) with 88% lymphocytes and 12% neutrophils.
Gram stain and acid-fast bacilli stain show no organisms.
Which of the following is the most likely cause of this patient’s illness?
1.
2.
3.
4.
5.
Blastomyces dermatitidis
Coccidioides immitis
Cryptococcus neoformans
Fusarium oxysporum
Histoplama capsulatum
0%
1
0%
2
3
0%
0%
4
5
Fungi Infections
Fungus
Symptom
Diagnosis
Treatment
Cryptococcosis
Pulm and CNS
Antigen, PCR
Fluconazole,
Itraconazole,
Ampho B
Histoplasmosis
Pulm
Urine Antigen
Itraconazole
(moderate),
Ampho B
(severe)
Bird, Bat
droppings;
Great River
Vallies
Blastomycosis
Pulm and Skin
Tissue path
Itraconazole
(moderate),
Ampho B
(severe)
Southeastern
US & around
Great Lakes &
Ohio, MS River
Culture,
Antibodies
Ampho B,
Itraconazole,
Ketoconazole,
Fluconazole
Arizona, Cali,
New Mexico
Coccidioidomyc Pulm
osis
Notes
A 25-year-old man is evaluated in the emergency department for a 3-day
history of scrotal pain without fever. Medical history is unremarkable, and he
takes no medications. The patient is frequently sexually active with women
and never has sex with men.
On physical examination, vital signs, including temperature, are normal.
Genitourinary examination discloses a purulent urethral
discharge and right100%
sided scrotal swelling and tenderness, especially superior to the right testis.
Duplex Doppler ultrasonography of the scrotum shows normal-sized testes
and a swollen right epididymis with normal blood flow.
Which of the following is the most appropriate treatment?
1.
2.
3.
4.
Ampicillin and gentamicin
Azithromycin
Ceftriaxone and doxycyline
Ofloxacin
0%
1
0%
2
3
0%
4
Azithro
or Doxy
Ceftriaxone
Penicillin G
Acyclovir
A 29-year-old woman is evaluated in the emergency department for blurred vision,
diplopia, slurred speech, nasal regurgitation of fluids, and bilateral upper extremity
weakness. The vision disturbances developed yesterday, and the slurred speech and
upper extremity weakness began earlier today. Two other patients with similar
symptoms are also being evaluated in the emergency department.
On physical examination, the patient is alert, awake, and fully oriented. Speech is fluid
but slurred. Temperature is 37.0 °C (98.6 °F), blood pressure
is 90/60 mm Hg, pulse
100%
rate is 50/min, and respiration rate is 12/min. The pupils are dilated, and extraocular
movements show bilateral deficits in cranial nerve IV. She cannot abduct her arms
against resistance.
Complete blood count and routine blood chemistry studies are normal. CT scan of the
head is normal. Lumbar puncture is performed; cerebrospinal fluid examination is
unremarkable.
Which of the following is the most likely diagnosis?
1.
2.
3.
4.
Botulism
Guillain-Barre syndrome
Myasthenia gravis
0%
Poliomyelitis
1
0%
2
3
0%
4
Disease
Incubation
Anthrax
1-60d
Smallpox
S/Sx
Treatment
Bioterrorism
Ppx
Inhalation:
Cipro or Doxy
febrile flu illness
Cutaneous:
necrotic lesion
Cipro
7-17d
High fevers and
dense rash
Supportive
Vaccine if
exposed in
last 7d
Plague
(Yersinia)
1-6d
Fulminating
pneumonia and
sepsis
Streptomycin,
Cipro or doxy
Cipro or
doxy
Botulism
1-8d
Descending
flaccid paralysis
Antibotulinum
IG
Antitoxin
Tularemia
3-5d
Febrile, flu-like
illness
Streptomycin,
Cipro or doxy
Cipro or
doxy
A 35-year-old man seeks disease-prevention advice prior to taking a 6-week
African safari trip to Tanzania and Kenya, where he will spend time camping in
tents. He is generally healthy and takes no medications. All of his basic
immunizations are up-to-date.
Immunizations for hepatitis A, typhoid, and yellow fever are recommended;
prescriptions for traveler’s diarrhea treatment and malaria prophylaxis are
provided; risks of travel-related automobile injury100%
are discussed; and
information about careful contact with dogs is provided.
In addition to the steps taken above, which of the following is the most
appropriate advice to provide to this patient for his upcoming travel?
1.
2.
3.
4.
5.
Avoid carbonated water (soda)
Avoid locally made hot tea
Sleep under bed netting
Use citronella-based insect repellents
0%
0%
0%
Wear a facemask on the airplane
1
2
3
4
0%
5
Travel Medicine
• Malaria: cyclic fevers, splenomegaly, GI sx
–
–
–
–
Screened areas from dusk to dawn
Sleeping with bed netting (permethrin treated)
Insect repellants
Chemoprophylaxis with chloroquine when in endemic areas
• Typhoid fever: fever and constitutional sx
– Treat with fluoroquinolone, 3rd cephalosporin
• Traveler’s diarrhea:
– Avoid unpeeled fresh fruits and vegetables
– Avoid ice from local water
– Add sodium hypochlorite or tinture of iodine to water and waiting 30min to consume
water
– Chemoprophylaxis for high-risk settings with TMP-SMX, doxy, Fluoroquinolones
– Can treat severe cases with FQ, azithro but mild cases resolve in 3-5d
• Dengue Virus Infection: fever, myalgia, retro-orbital pain; dengue shock syndrome
and hemorrhagic fever occur in second infections
– Insect repellents
– Use of screens during day (no bed netting bc Aedes mosquito active during day only)
• Hepatitis A
– Vaccinated 2-4 weeks before traveling to an endemic area
HIV Opportunistic Infection
Infection
Symptoms/Diseas
e
Treatment
CD4
Ppx
CMV
Disseminated or
End organ (GI,
retina, CNS)
Ganciclovir
< 50
MAC
Disseminated
Macrolide and Ethambutol
< 50
Cryptococcus
Meningitis
Ampho B and Fluconazole
< 100
Toxoplasmosis
CNS
Sulfadiazine +
Pyrimethamine
< 100
TMX-SMP
PJP
Pulmonary
TMX-SMP + steroids
< 200
TMX-SMP
Azithromy
cin
HIV Treatment
• Goal of therapy to lower HIV RNA viral load to
<50 copies
• Guidelines recommend initiating HARRT
– CD4 < 350
– patient with an AIDS defining illness
– HIV nephropathy
– Hep B co-infection
– Pregnant patients
HIV Treatment
HIV HAART Complications
Metabolic
• Lipohypertrophy of abdomen
• Lipoatrophy of face, extremities
Cardiovascular
• Increased risk of CV events; aggressively modify risk factors
Immune Reconstitution Inflammatory Syndrome
• Clinical deterioration despite immunologic and viral control
• Unmasking: in pts with an occult infection
• Paradoxical: in pts with previously successfully treated infections
Repeated Infections
• Congenital IgA Deficiency: multiple
sinopulmonary bacterial infections; multiple
GI infections (Giardia)
• Common Variable Immunodeficiency:
repeated episodes of bronchitis and sinusitis,
repeated pneumonias, GI infections (Giardia)
• Terminal Complement (C5-C9): recurrent
Neisseria infections
– Check CH50 levels