Question 31
A 38-year-old previously healthy woman has had a worsening non-productive cough for the past 4 days. On physical examination her temperature is 38.3 C. A chest radiograph shows patchy infiltrates and diffuse interstitial markings. Laboratory studies show a sputum gram stain with mixed flora. Her Hgb is 12.9 g/dL, platelet count 229,450/microliter, and WBC count 5815/microliter. Her cold agglutinin titer is elevated. Following a course of erythromycin therapy, she improves, with no complications. Which of the following infectious agents is most likely to cause the pulmonary disease seen in this woman?
A Nocardia asteroides
B Mycoplasma pneumoniae
C Mycobacterium kansasii
D Respiratory syncytial virus
E Chlamydia psittici
F Adenovirus
G Klebsiella pneumoniae
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(B) CORRECT. Mycoplasma affects the interstitium more, and is not an alveolar filling process. It is a cause for a 'primary atypical pneumonia' which is difficult to diagnose because this organism is not cultured by routine methods for bacterial organisms. The cold agglutinin titer is elevated in about half of cases and is a characteristic finding.
(A) Incorrect. Nocardia braziliensisInfections occur in immunocompromised hosts and produce a chronic abscessing process.
(C) Incorrect. M. kansasii produces a granulomatous disease similar to tuberculosis.
(D) Incorrect. RSV infections are more likely to occur in children. They do not respond to erythromycin therapy.
(E) Incorrect. Psitticosis is rare and can lead to a severe pneumonia known as ornithosis. It does not respond to erythromycin therapy.
(F) Incorrect. Adenovirus can produce interstitial infiltrates, but does not respond to erythromycin.
(G) Incorrect. Klebsiella is a gram negative bacterium that most often produces a bronchopneumonia with productive cough and neutrophilia.
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Question 32
A 23-year-old primigravida is found on prenatal testing to have an elevated hemoglobin A1C level. Her pregnancy is uncomplicated until the 29th week of gestation, when she has the onset of premature labor and delivers a male infant 24 hours later. The infant initially has Apgar scores of 4 and 6 at 1 and 5 minutes, but within an hour is in severe respiratory distress and requires intubation with mechanical ventilation. Which of the following pharmacologic therapies administered to the mother prior to birth could have helped to prevent this infant's neonatal respiratory distress?
A Hydrocortisone
B Nafcillin
C Ibuprofen
D Lecithin
E Vitamin A
F Surfactant
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(A) CORRECT. She has diabetes mellitus, which inhibits fetal lung development. At 29 weeks, the baby's lungs do not make sufficient surfactant. Corticosteroids administered to the mother help to speed up type II pneumonocyte production of surfactant in the baby. At birth, exogenous surfactant can be given to the neonate.
(B) Incorrect. Antibiotic therapy will not help to prevent hyaline membrane disease. It is unlikely that there is a congenital pneumonia in this emergent setting.
(C) Incorrect. Non-steroidal anti-inflammatory drugs will not help to improve fetal lung maturity.
(D) Incorrect. The lecithin-sphingomyelin (L/S) ratio is used as a measure of fetal lung maturity.
(E) Incorrect. Vitamin A helps to maintain epithelia, but it is not going to play a major role in surfactant production.
(F) Incorrect. Exogenous surfactant administered to the infant soon after birth can help prevent respiratory distress syndrome with hyaline membrane disease.
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Question 33
For the past 5 months, a 51-year-old woman has noted increased swelling of her lower legs as the day progresses. She has no fever and no cough. On physical examination, she has pitting edema to the knees. A chest radiograph reveals bilateral pleural effusions, and the right heart border is prominent. Laboratory studies show a serum AST of 238 U/L, ALT 263 U/L, LDH 710 U/L, and CK 127 U/L. Which of the following underlying diseases is most likely to cause these findings?
A Goodpasture syndrome
B Recurrent thromboembolism
C Renovascular hypertension
D Bronchial asthma
E Rheumatoid arthritis
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(B) CORRECT. Pulmonary hypertension and right heart failure can occur in the small number of cases in which recurrent thromboembolism takes place. The right heart failure that occurs then leads to hepatic passive congestion with centrilobular necrosis that is the cause for the increased transaminases.
(A) Incorrect. In Goodpasture syndrome there is antibody directed at vascular basement membrane, leading to acute hemorrhage.
(C) Incorrect. Hypertension in the systemic circulation is not accompanied by pulmonary arterial hypertension with predominantly right-sided heart failure with cor pulmonale.
(D) Incorrect. The episodes of bronchial asthma are short and typically do not lead to significant alteration to the pulmonary vasculature.
(E) Incorrect. Rheumatoid arthritis may be accompanied by formation of rheumatoid nodules in various tissues, including lung, but they are usually peripheral and not numerous.
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Question 34
A 51-year-old man received an orthotopic cardiac transplant a month ago. He has developed a fever with cough over the past 5 days. On physical examination his temperature is 37.5 C. A chest CT scan shows consolidation with abscess formation involving the left lower lobe. A sputum gram stain reveals normal upper respiratory tract flora. He does not respond to antibiotic therapy over the next 6 months. His mental status deteriorates and MR imaging of the brain shows multiple abscesses. He is most likely to have an infection with which of the following organisms?
A Mycoplasma pneumoniae
B Aspergillus fumigatus
C Mycobacterium avium-intracellulare
D Nocardia braziliensis
E Cytomegalovirus
F Pneumocystis carinii (jiroveci)
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(D) CORRECT. Nocardia braziliensis infection can persist and lead to chronic abscesses. It can complicate the course of immunocompromised patients.
(A) Incorrect. This produces a primary atypical pneumonia without abscess or alveolar filling.
(B) Incorrect. Aspergillus does not typically produce abscesses.
(C) Incorrect. MAI typically affects AIDS patients, and lung involvement is minimal.
(E) Incorrect. CMV does not produce abscesses.
(F) Incorrect. Pneumocystis pneumonia is rarely disseminated and most often produces a diffuse pneumonic consolidation with minimal inflammatory cell infiltration and no abscess formation.
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Question 35
Three weeks after visiting her grandmother dying from a respiratory tract infection, a healthy 5-year-old girl develops a fever along with wheezing. On physical examination her temperature is 37.9 C. Her lung fields are clear to auscultation but there are expiratory wheezes. A chest radiograph reveals a solitary 2 cm peripheral mid-lung nodule and marked hilar lymphadenopathy. Laboratory studies show Hgb 13.6 g/dL, platelet count 183,600/microliter, and WBC count 5480/microliter. These findings are most consistent with infection by which of the following organisms?
A Mycobacterium tuberculosis
B Candida albicans
C Coccidioides immitis
D Aspergillus flavus
E Bacteroides fragilis
F Streptococcus pneumoniae
G Respiratory syncytial virus
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(A) CORRECT. The pattern of lung involvement is the classical 'Ghon complex' of primary tuberculosis, which is seen more commonly in children, though only about 5% of cases are symptomatic. The enlarged hilar nodes can impinge upon central airways to produce obstruction.
(B) Incorrect. Candidiasis is seen in persons who are immunocompromised. A true Candida pneumonia is rare. Candida is more likely to colonize the upper respiratory tract.
(C) Incorrect. Fungal granulomatous disease can mimic tuberculosis but is less common overall and is more typically seen in adults.
(D) Incorrect. This is most likely to be seen in immunocompromised adults.
(E) Incorrect. Lung abscesses from B. fragilis are not common in healthy children. Abscesses usually complicate a previous pulmonary infection or occur with aspiration.
(F) Incorrect. Pneumococcal infections can produce a lobar pneumonia or bronchopneumonia.
(G) Incorrect. RSV can produce childhood pneumonias, but they are typically interstitial pneumonias.
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