Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Apr 2004
Pulmonary histoplasmosis syndromes: recognition, diagnosis, and management.
Pulmonary manifestations are the hallmark of histoplasmosis. Clinical syndromes range from asymptomatic infection to diffuse alveolar disease causing respiratory difficulty and even death. Serologic tests for antibodies and antigen detection are especially helpful in the diagnosis of histoplasmosis but are frequently overlooked. ⋯ Although histoplasmosis is mild and self-limited in most healthy individuals, antifungal therapy is indicated in those with acute diffuse pulmonary infection, chronic pulmonary histoplasmosis, progressive disseminated disease, and perhaps mediastinal adenitis accompanied by obstructive symptoms. Antifungal therapy to prevent reactivation of histoplasmosis during immunosuppressive therapy, or transition of mediastinal adenitis to fibrosing mediastinitis, although controversial, is not recommended. Several new drugs active against H. capsulatum offer alternatives in patients failing or intolerant of current therapies.
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Persons with cystic fibrosis (CF) are susceptible to respiratory tract infection with a variety of bacterial species. Among these are several species in the genus Burkholderia (including members of the B. cepacia complex, B. gladioli, and B. pseudomallei), Stenotrophomonas maltophilia, Achromobacter ( Alcaligenes) xylosoxidans, certain Ralstonia species, and species within the new genus Pandoraea. Enterobacteriaceae and several other rather unusual or novel species also can be found. ⋯ Although their role in contributing to pulmonary disease in CF is not clear, the incidence of infection by some of these species appears to be increasing. The broad-spectrum antimicrobial resistance typically exhibited by these species severely limits treatment options. Newly developed genotypic methods of identification will enable studies to better assess the epidemiology and natural history of these emerging pathogens in CF.
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Patients with cystic fibrosis (CF) have an abnormal propensity for recurrent and chronic infections of the lower respiratory tract (LRT), and the most common cause of a shortened lifespan is chronic infection with Pseudomonas aeruginosa. A few other gram-negative organisms, primarily Burkholderia cepacia complex have, however, emerged as serious pathogens capable of establishing chronic LRT infection. Details of these and other CF pathogens can be found in the article by Dr. ⋯ Other more rare pathogens such as Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and nontuberculous mycobacteria (NTM) appear less capable of causing patient-to-patient transmission. Both the physical proximity and the duration of exposure of noninfected patients to patients chronically infected with P. aeruginosa and B. cepacia complex are important determinants of the risk of cross-infection. Cohorting of patients according to presence or absence of specific pathogens coupled with conventional hygienic precautions can, however, lead to a decrease in incidence and prevalence of chronic infections with these two species, wherefore patient cohorting is now an integral component of infection control in patients with CF.
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Organizing pneumonia is defined by the presence of buds of granulation tissue (fibroblastic cells and connective matrix) within the alveolar lumen, usually associated with proliferative bronchiolitis obliterans. It may result from several causes, but cryptogenic organizing pneumonia is a distinct clinicopathologic entity with characteristic clinical and imaging features. Typical COP is thus easily recognized by the clinician, and the diagnosis is made by the finding of organizing pneumonia on lung biopsy specimen. The response to corticosteroids is rapid and complete usually without sequelae, but relapses occur frequently and prolonged corticosteroid treatment is often necessary.
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Inflammatory and fibrotic processes can involve the small airways (i.e., respiratory and terminal bronchioles) in several connective tissue disorders (CTDs). Obliterative (constrictive) bronchiolitis (OB) as well cryptogenic organizing pneumonia (COP), previously termed bronchiolitis obliterans with organizing pneumonia (BOOP), are well-recognized, albeit rare, complications of rheumatoid arthritis and other CTDs. Bronchiectasis has also been described in patients with CTDs. ⋯ Surgical (open or thoracoscopic) lung biopsies can substantiate the diagnosis, but in some cases, the diagnosis can be affirmed less aggressively by appropriate imaging studies (e.g., HRCT) and transbronchial lung biopsies. Corticosteroids are highly efficacious for COP, but therapeutic options for OB are disappointing. Prophylactic antibiotics and good pulmonary hygiene remain the mainstay of therapy for patients with bronchiectasis.