QUESTION: 61

A 34-year-old amateur spelunker develops cough, dyspnea, and fever 2 weeks after a caving expedition to caves in Kentucky. On physical examination, the patient's temperature is 102°F and respiratory rate is 24. On pulmonary examination, there are diffuse crackles bilaterally. A CXR is shown in Figure .

What diagnostic test would be most appropriate?

serum cryptococcal antigen
fungal serologies
a PPD skin test
an HIV enzyme-linked immunosorbent assay (ELISA) test
arterial blood gas determination

Answer(s): E

Explanation:

The patient has diffuse interstitial infiltrates on CXR that correspond in time and presentation to acute inhalation histoplasmosis. This would be seen in a patient, such as an amateur spelunker, who has been in a cave with bats. It is the act of crawling through the cave that disturbs the spores of histoplasmosis that grow in the bat guano. The incubation period for influenza is 12 days. It is passed primarily by secretions from the nose spread by hands. The other members of the expedition were not sick, as they might be with influenza. Disseminated aspergillosis occurs in immunocompromised patients who have defects in both cell-mediated and humoral immunity. This patient does not have this. While the CXR could mimic military tuberculosis, the association with caving 14 days before would make tuberculosis less likely and histoplasmosis more likely. There is no history that the patient is immunocompromised with HIV and would be at risk for P. jiroveci pneumonia. Fungal serologies would establish the diagnosis, but acute and convalescent serologies would take 3 weeks for results. These are only useful in outbreak investigations. The other choices do not fit due to the reasons above. Treatment of acute respiratory histoplasmosis is based on severe hypoxia and would require arterial blood gases to establish the need for therapy. None of the fungal infections mentioned are transmissible person to person, therefore respiratory isolation would not be necessary. Histoplasmosis is a dimorphic fungus that grows as a yeast at body temperature and a mold at room temperature. The mold produces the spores that are infectious. A similar situation occurs for Cryptococcus neoformans. C. immitis and aspergillosis are not transmitted from person to person.

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QUESTION: 62

A 34-year-old amateur spelunker develops cough, dyspnea, and fever 2 weeks after a caving expedition to caves in Kentucky. On physical examination, the patient's temperature is 102°F and respiratory rate is 24. On pulmonary examination, there are diffuse crackles bilaterally. A CXR is shown in Figure .

Which of these is the most appropriate statement about infection control of this patient if the patient is hospitalized?

The patient is not likely to need respiratory isolation.
The patient should be placed in respiratory isolation if histoplasmosis is suspected.
The patient should be placed in respiratory isolation if P. jiroveci is suspected.
The patient should be placed in respiratory isolation if pulmonary aspergillosis is suspected.
The patient should be placed in respiratory isolation if cryptococcal pneumonia is suspected.

Answer(s): A

Explanation:

The patient has diffuse interstitial infiltrates on CXR that correspond in time and presentation to acute inhalation histoplasmosis. This would be seen in a patient, such as an amateur spelunker, who has been in a cave with bats. It is the act of crawling through the cave that disturbs the spores of histoplasmosis that grow in the bat guano. The incubation period for influenza is 12 days. It is passed primarily by secretions from the nose spread by hands. The other members of the expedition were not sick, as they might be with influenza. Disseminated aspergillosis occurs in immunocompromised patients who have defects in both cell-mediated and humoral immunity. This patient does not have this. While the CXR could mimic military tuberculosis, the association with caving 14 days before would make tuberculosis less likely and histoplasmosis more likely. There is no history that the patient is immunocompromised with HIV and would be at risk for P. jiroveci pneumonia. Fungal serologies would establish the diagnosis, but acute and convalescent serologies would take 3 weeks for results. These are only useful in outbreak investigations. The other choices do not fit due to the reasons above. Treatment of acute respiratory histoplasmosis is based on severe hypoxia and would require arterial blood gases to establish the need for therapy. None of the fungal infections mentioned are transmissible person to person, therefore respiratory isolation would not be necessary. Histoplasmosis is a dimorphic fungus that grows as a yeast at body temperature and a mold at room temperature. The mold produces the spores that are infectious. A similar situation occurs for Cryptococcus neoformans. C. immitis and aspergillosis are not transmitted from person to person.

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QUESTION: 63

A 53-year-old insulin-dependent diabetic, who underwent a cadaveric renal transplant 1 year prior to admission, presents with fever and cough of 3 weeks duration. He works as a long-haul trucker, carting fruit from McAllen, Texas (on the Texas- Mexico border) to Fresno, California. He does not smoke. His PPD skin test prior to admission was positive. On physical examination, his respiratory rate is 25, his oral temperature is 101°F, his lungs have rhonchi and de creased breath sounds on the left. His CXR is shown in Figure.

What organism besides Mycobacterium tuberculosis leads your differential as a cause of pneumonia in this case?

Haemophilus influenzae
CMV
P. jiroveci
C. immitis
Histoplasma capsulatum

Answer(s): D

Explanation:

The clinical picture is most consistent with disease caused by C. immitis. This is due both to the nature of the cavitary lesion on CXR and the endemic area. Figure 1-4 shows a peripheral, thinwalled cavitary lesion on CXR as well as a right lower lobe infiltrate. As a renal transplant recipient 1 year out, this patient is likely to have infections with tuberculosis and disseminated fungal infections. It is interesting that the route that he travels is through the lower Sonoran life zone where coccidiomycosis is endemic. CMV produces a diffuse interstitial infiltrate pattern on CXR, as does Pneumocystis and H. capsulatum. Fiberoptic bronchoscopy with bronchial alveolar lavage should be performed in any patient with this clinical presentation who is immunocompromised because of the lack of ability to produce a good sputum specimen. We know that the patient is PPD positive, so skin testing is not useful. The patient is not mentioned to be in the endemic area for histoplasmosis. Serum cryptococcal antigen testing is a remote possibility. While Cryptococcus can produce a pulmonary disease with cavitary lesions, in immunocompromised hosts such as this, the patient more likely would present with meningitis.

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QUESTION: 64

A 53-year-old insulin-dependent diabetic, who underwent a cadaveric renal transplant 1 year prior to admission, presents with fever and cough of 3 weeks duration. He works as a long-haul trucker, carting fruit from McAllen, Texas (on the Texas- Mexico border) to Fresno, California. He does not smoke. His PPD skin test prior to admission was positive. On physical examination, his respiratory rate is 25, his oral temperature is 101°F, his lungs have rhonchi and de creased breath sounds on the left. His CXR is shown in Figure.

What is the best diagnostic approach?

PPD skin testing
urine histoplasma antigen testing
serum cryptococcal antigen testing
sputum for silver staining for P. jiroveci
fiberoptic bronchoscopy with bronchial alveolar lavage

Answer(s): E

Explanation:

The clinical picture is most consistent with disease caused by C. immitis. This is due both to the nature of the cavitary lesion on CXR and the endemic area. Figure 1-4 shows a peripheral, thinwalled cavitary lesion on CXR as well as a right lower lobe infiltrate. As a renal transplant recipient 1 year out, this patient is likely to have infections with tuberculosis and disseminated fungal infections. It is interesting that the route that he travels is through the lower Sonoran life zone where coccidiomycosis is endemic. CMV produces a diffuse interstitial infiltrate pattern on CXR, as does Pneumocystis and H. capsulatum. Fiberoptic bronchoscopy with bronchial alveolar lavage should be performed in any patient with this clinical presentation who is immunocompromised because of the lack of ability to produce a good sputum specimen. We know that the patient is PPD positive, so skin testing is not useful. The patient is not mentioned to be in the endemic area for histoplasmosis. Serum cryptococcal antigen testing is a remote possibility. While Cryptococcus can produce a pulmonary disease with cavitary lesions, in immunocompromised hosts such as this, the patient more likely would present with meningitis.

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