Rapid Noninvasive Diagnosis of Pneumocystis carinii from Induced Liquefied Sputum

Abstract

Pneumocystis carinii organisms cluster in alveolar casts. A method for concentrating alveolar casts in sputum specimens might improve the diagnostic usefulness of sputum studies in possible cases of pulmonary infection with Pneumocystis carinii. The use of sputum induction to detect Pneumocystis carinii was studied in 40 consecutive patients with known or suspected human immunodeficiency virus infection having bronchoscopy for evaluation of pulmonary disease. Sputum produced by deep coughing induced by 3% saline via a jet nebulizer was liquefied with dithiothreitol, and cells were sedimented and stained. Liquefaction of mucus allowed concentration of alveolar casts where P. carinii cysts were readily identified. A total of 28 patients were found to have P. carinii, which was detected in concentrated sputum in 21 of 38 patients, unconcentrated sputum in 10 of 38 patients, and by bronchoscopy in 25 of 37 patients. Sensitivity of concentrated sputum compared with bronchoscopy was 78% (95% CI, 58 to 90), with a negative predictive value of 71% (95% CI, 47 to 87). Values for unconcentrated sputum were 43% (95% CI, 25 to 63) and 48% (95% CI, 30 to 67), respectively. Liquefaction of adequately induced sputum facilitates processing and interpretation and increases yield for P. carinii, eliminating the need for invasive procedures in most patients.

Meta-analysis of diagnostic procedures forPneumocystis cariniipneumonia in HIV-1-infected patients

“…The remaining 36 articles were reviewed in detail, and 29 of these were excluded (see Appendix). Overall, data retrieved from seven publications were included in the meta-analysis [38][39][40][41][42][43][44]. Table 1 summarises the characteristics of the seven studies included in the meta-analysis.…”

Pneumocystis jiroveci pneumonia in patients with rheumatoid arthritis treated with infliximab: A retrospective review and case–control study of 21 patients

“…Studies have shown that the organism is detectable on microscopic examination of induced sputum in 55-92% of PCP patients with HIV infection (39,40). In patients with PCP but without HIV infection, detectability is Ͻ10%; thus, bronchoalveolar lavage fluid examination is often required (38).…”

Recent advances in the diagnosis, treatment, and prevention of Pneumocystis carinii pneumonia

“…While colorimetric staining (e.g., Gomori methenamine silver nitrate, toluidine blue 0, and Giemsa stains) of expectorated sputum alone has a comparatively poor yield, several groups have found that the sensitivity of this procedure can be markedly increased when sputum specimens are obtained by hypertonic saline nebulization (2,33). Estimates of up to 55% sensitivity have been described using sputum induced by the nebulization technique, which can be further improved to 78% by addition of a sputum liquefication step using reducing agents such as dithiothreitol (47). Immunofluorescence staining of sputum specimens using monoclonal antibodies against surface antigens ofP.…”