Infectious Disease

Answers

1.  The answer is c. (Gorbach, 2/e, pp 542-544.) This patient, with the
development of hoarseness, breathing difficulty, and stridor, is likely to
have acute epiglottitis. Because of the possibility of impending airway
obstruction, the patient should be admitted to an intensive care unit for
close monitoring. The diagnosis can be confirmed by indirect laryngoscopy
or soft tissue x-rays of the neck, which may show an enlarged epiglottis.
Otolaryngology consult should be obtained. The most likely organism
causing this infection is Haemophilus influenzae. Many of these organisms
are β-lactamase-producing and would be resistant to ampicillin. The clini-
cal  findings  are  not  consistent  with  the  presentation  of  streptococcal
pharyngitis. Lateral neck films would be more useful than a chest x-ray.

2.  The answer is a. (Braunwald, 15/e, p 190.) Ear pain and drainage in an elderly diabetic patient must raise concern about malignant external otitis. The swelling and inflammation of the external auditory meatus strongly suggest this diagnosis. This infection usually occurs in older diabetics and is almost always caused by P. aeruginosa. H. influenzae and M. catarrhalis frequently cause otitis media, but not external otitis.

3-4. The answers are 3-b, 4-a. (Braunwald, 15/e, pp 1046-1047.) The dif-
fuse rash involving palms and soles would in itself suggest the possibility of
secondary syphilis. The hypertrophic, wartlike lesions around the anal area,
called condylomata lata, are specific for secondary syphilis. The VDRL slide
test will be positive in all patients with secondary syphilis. The Weil-Felix
titer has been used as a screening test for rickettsial infection. In this patient,
who has condylomata and no systemic symptoms, Rocky Mountain spotted
fever would be unlikely. No chlamydial infection would present in this way.
Blood cultures might be drawn to rule out bacterial infection such as chronic
meningococcemia; however, the clinical picture is not consistent with a sys-
temic bacterial infection. Penicillin is the drug of choice for secondary
syphilis. Ceftriaxone and tetracycline are usually considered to be alternative
therapies. Interferon α has been used in the treatment of condyloma acumi-
nata, a lesion that can be mistaken for syphilitic condyloma.

5-7.  The answers are 5-c, 6-b, 7-a. (Braunwald, 15/e, pp 1073-1074.)
This young woman presents with symptoms of both upper and lower res-
piratory infection. The combination of sore throat, bullous myringitis, and
infiltrates on chest x-ray is consistent with infection due to M. pneumoniae.
This minute organism is not seen on Gram stain. Neither S. pneumoniae nor
H. influenzae would produce this combination of upper and lower respira-
tory tract symptoms. The patient is likely to have high titers of IgM cold
agglutinins. The low hematocrit and elevated reticulocyte count reflect a
hemolytic anemia that can occur from mycoplasma infection. These IgM-
class antibodies are directed to the I antigen on the erythrocyte membrane.
The treatment of choice for mycoplasma infection is erythromycin.

8-10.  The answers are 8-c, 9-a, 10-c. (Braunwald, 15/e, pp 1109-1111.)
This young man presents with classic signs and symptoms of infectious
mononucleosis. In a young patient with fever, pharyngitis, lymphadenopa-
thy, and lymphocytosis, the peripheral blood smear should be evaluated for
atypical lymphocytes. A heterophile antibody test should be performed.
The symptoms described in association with atypical lymphocytes and a
positive heterophile test are virtually always due to Epstein-Barr virus. Nei-
ther liver biopsy nor lymph node biopsy is necessary. Workup for toxo-
plasmosis or cytomegalovirus infection or hepatitis B and C would be
considered in heterophile-negative patients, Hepatitis does not occur in the
setting of rheumatic fever, and an antistreptolysin O titer is not indicated.
Corticosteroids are indicated in the treatment of infectious mononucleosis
when severe hemolytic anemia is demonstrated or when airway obstruc-
tion occurs. Neither fatigue nor the complication of hepatitis is an indica-
tion for corticosteroid therapy.

11-14. The answers are 11-c, 12-d, 13-e, 14-a. (Braunwald, 15/e, pp
809-814, 882-885, 959, 1009, 1620.) The 30-year-old-female with mitral
valve prolapse has developed subacute bacterial endocarditis. The likely eti-
ologic agent is a viridans streptococci. Viridans streptococci cause most
cases of subacute bacterial endocarditis. No other agent listed is likely to
cause this infection. The 80-year-old-male with a Foley catheter in place has
developed a nosocomial infection likely secondary to urosepsis. Providencia
species frequently cause urinary tract infection in the hospitalized patient.
The young man with a fluctuant lesion and fistula over the mandible pre-
sents a classic picture of cervicofacial actinomycosis. The sickle cell anemia

patient who presents with concomitant pneumonia and meningitis has
overwhelming infection with S. pneumoniae due to functional asplenia.
S. pneumoniae causes a particularly severe infection associated with sickle cell disease.
15-18.  The answers are 15-f, 16-a, 17-c, 18-e. (Braunwald, 15/e, pp 1092-1100.) Amantadine has been shown to alter the course of influenza A favorably, particularly when begun within 48 h of the start of symptoms. The HIV-positive patient with a low CD4 count and visual blurring has developed cytomegalovirus retinitis. Gancyclovir is the drug of choice (foscarnet has also been used effectively). Interferon α has been approved for intralesional therapy of condyloma acuminatum (venereal warts caused by papillomavirus). Ribavirin improves mortality in mechanically ventilated infants with RSV infection.

19-21. The  answers  are    19-b,    20-g,    21-f.    (Braunwald,    15/e,  pp
1173-1179.) Blastomycosis presents with signs and symptoms of chronic
respiratory infection. The organism has a tendency to produce skin lesions
in exposed areas that become crusted, ulcerated, or verrucous. Bone pain is
caused by osteolytic lesions. Mucormycosis is a zygomycosis that originates
in the nose and paranasal sinuses. Sinus tenderness, bloody nasal discharge,
and  obtundation  occur  usually  in  the  setting  of  diabetic  ketoacidosis.
Aspergillus can result in several different infectious processes, including
aspergilloma, disseminated Aspergillus in the immunocompromised patient,
or allergic bronchopulmonary aspergillosis. Bronchopulmonary aspergillo-
sis is the most likely diagnosis in the young woman with asthma and
eosinophilia. Bronchial plugs, often filled with hyphal forms, result in
repeated infiltrates and exacerbation of wheezing.

22-24.  The  answers  are    22-c,    23-b,    24-a.    (Braunwald,    15/e,  pp
1061-1065.) This patient presents with a symptom complex that includes
facial nerve palsies, arthralgia, and first-degree AV block. Facial nerve palsy
has been increasingly recognized as a first manifestation of Lyme disease.
Within several weeks of the onset of illness, about 8% of patients develop
cardiac involvement, with heart block being the most common manifesta-
tion. During this stage of early disseminated infection, musculoskeletal
pain is common. The diagnosis of Lyme disease is based on careful history
and physical exam with serologic confirmation by detection of antibody to

Borrelia burgdorferi. Neither CT or MRI of head would be indicated as the lesion is a peripheral facial palsy. Sarcoidosis can also cause both facial nerve palsy and AV block, but it is much less likely, and the Kveim test is rarely used to pursue this diagnosis. The treatment of choice for Lyme disease at this stage would be penicillin or ceftriaxone.

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