Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (495 page)

   
Pulmonary sporotrichosis
: Pulmonary sporotrichosis usually occurs in alcoholic men. Signs and symptoms may mimic TB. Chest radiography commonly shows upper lobe disease with cavitation, fibrosis, or nodular densities. Respiratory symptoms include cough, dyspnea, and sputum production (may be bloody).

   
Osteoarticular sporotrichosis
: Osteoarticular sporotrichosis is usually caused by hematogenous spread from a primary cutaneous infection in alcoholic men. Joint infection is usually seen in the extremities: the knee, elbow, ankle, and wrist are most commonly affected. Osteomyelitis may occur as a result of local invasion. Patients present with pain, swelling, and decreased range of motion.

   
CNS sporotrichosis
: CNS infection is rare and occurs mainly in patients with AIDS or other T-cell defects. CNS infection has a subacute presentation with fever and headache.

   Laboratory Findings

Direct detection
: Histopathologic examination of infected tissue shows a mixed pyogenic and granulomatous response. Typical “cigar-shaped” budding yeast may be seen. Detection is improved by use of fungal stains, like periodic acid–Schiff or methenamine silver stains. H&E staining may demonstrate “asteroid bodies”— basophilic yeast surrounded by eosinophilic material that probably represents antigen–antibody complex.

Culture
: Isolation of
S. schenckii
in culture provides definitive diagnosis of sporotrichosis. The organism is readily isolated from biopsy or aspirated material from infected sites. Growth usually appears during the first week of incubation, but cultures are usually incubated for 4 weeks before being signed out as negative.

Serology
: Does not play a significant role in the diagnosis of active infection.

CSF findings
: Patients with meningitis have a lymphocytic pleocytosis, low glucose, and increased protein.

Suggested Readings

Chapman SW, Dismukes WE, Proia LA, et al. Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America.
Clin Infect Dis.
2008;46:1801–1812.

Cuellar-Rodriguez J, Avery RK, Lard M, et al. Histoplasmosis in solid organ transplant recipients: 10 years of experience at a large transplant center in an endemic area.
Clin Infect Dis.
2009;49:710–716.

Dromer F, McGinnis MR. Chapter 12: Zygomycosis. In: Anaissie EJ, McGinnis MR, Pfaller MA, (eds).
Clinical Mycology
. Philadelphia, PA: Churchill Livingstone; 2003.

Galgiani JN, Ampel NM, Blair JE, et al. Coccidioidomycosis.
Clin Infect Dis.
2005;41:1217–1223.

Hage CA, Bowyer S, Tarvin SE, et al. Recognition, diagnosis, and treatment of histoplasmosis complicating tumor necrosis factor blocker therapy.
Clin Infect Dis.
2010;50:85–92.

Kauffman CA. Sporotrichosis.
Clin Infect Dis.
1999;29:231–237.

Kauffman CA, Bustamante B, Chapman SW, et al. Clinical Practice Guidelines for the Management of Sporotrichosis: 2007 Update by the Infectious Diseases Society of America.
Clin Infect Dis.
2007;45:1255–1265.

Koo S, Bryar JM, Page JH, et al. Diagnostic performance of the (1 → 3)-β-D-glucan assay for invasive fungal disease.
Clin Infect Dis.
2009;49:1650–1659.

Nucci M, Anaissie E.
Fusarium
infections in immunocompromised patients.
Clin Microbiol Rev.
2007;20:695–704.

Pera S, Patterson TF. Chapter 15 endemic mycoses. In: Anaissie EF, McGinnis MR, Pfaller MA, (eds).
Clinical Mycology
. Philadelphia, PA: Churchill Livingstone; 2003.

Perfect JR, Dismukes WE, Dromer F, et al. Clinical Practice Guidelines for the Management of Cryptococcal Disease: 2010 Update by the Infectious Diseases Society of America.
Clin Infect Dis.
2010;50:291–322.

Ribes JA, Vanover-Sams CL, Baker DJ. Zygomycetes in human disease.
Clin Microbiol Rev.
2000;13: 236–301.

Rex JH. Galactomannan and the diagnosis of invasive aspergillosis.
Clin Infect Dis.
2006;42:1428–1430.

Segal BH. Aspergillosis.
N Engl J Med.
2009;360:1870–1884.

Sun H-Y, Wagener MM, Singh N. Cryptococcosis in solid-organ, hematopoietic stem cell, and tissue transplant recipients: evidence-based evolving trends.
Clin Infect Dis.
2009;48:1566–1576.

Yozwiak ML, Lundergan LL, Kerrick SS, et al. Symptoms and routine laboratory abnormalities associated with coccidioidomycosis.
West J Med.
1988;149:419–421.

   
INFECTIOUS DISEASES CAUSED BY VIRAL PATHOGENS

This section reviews viral pathogens that are responsible for a very wide and diverse range of diseases. Viral pathogens are incapable of multiplication outside of host eukaryotic cells, but many do not require human cells for proliferation. Other mammals, arthropods, or other species may serve as intermediate or definitive hosts for pathogenic viruses. Most viral infections are mild, self-limited diseases and are presumptively diagnosed on the basis of clinical signs and symptoms. Serologic testing is most commonly used when definitive diagnosis is required and may be used for diagnosis of acute or past infection or to determine the immune status of a host. Viral infection may also be established presumptively by typical histopathologic findings; specific identification may be made by specific immunostaining. Isolation of virus in eukaryotic cell culture provides definitive diagnosis, but the sensitivity of culture for isolation usually falls significantly after acute symptoms resolve, and some viral pathogens cannot be isolated in culture. Molecular diagnostic procedures are playing an increasing role in the diagnosis of viral infections. Molecular methods may be used for diagnosis, predicting response to antiviral agents, monitoring disease activity or response to treatment, or other purposes.

CYTOMEGALOVIRUS INFECTION

   Definition

Human cytomegalovirus (CMV) is member of the
Herpesviridae
, subfamily
Betaherpesvirinae
. CMV is ubiquitous with a worldwide distribution. Although CMV infection can be demonstrated in a significant majority of individuals in developing and developed countries, clinical disease is uncommon in immunocompetent hosts. Acute infection with CMV, as characteristic of herpesviruses, results in longterm latent infection with periodic reactivation to a replicative phase of infection.

   Who Should Be Suspected?