Lymphocyte subpopulations of blood and alveolar lavage in blastomycosis

Diagnostic Methods and Risk Factors for Severe Disease and Mortality in Blastomycosis: A Retrospective Cohort Study

Background: Blastomycosis can cause severe disease with progressive respiratory failure and dissemination even in immunocompetent individuals. We sought to evaluate risk factors for severe disease and mortality using clinical and laboratory data within a large health system in an endemic area. Methods: We performed a retrospective cohort study of patients diagnosed with blastomycosis at all Mayo Clinic sites from 1 January 2004 through 31 March 2020. Diagnosis was established by culture, histopathology/cytopathology, serology, antigen testing, or PCR. Disease was categorized as mild for patients treated in the outpatient setting, moderate for hospitalized patients who did not require intensive care, and severe for patients admitted to the intensive care unit. Logistic regression was used to evaluate risk factors for severe disease. A Cox proportional hazards model was constructed to evaluate mortality. Findings: We identified 210 patients diagnosed with blastomycosis. Mean age was 51 years (range, 6–84). Most subjects were male (71.0%). Extrapulmonary disease was confirmed in 24.8%. In this cohort, 40.5% of patients had mild disease, 37.6% had moderate disease, and 21.9% had severe disease. Independent risk factors for severe disease were neutrophilia (odds ratio (OR) 3.35 (95% CI 1.53–7.35), p = 0.002) and lymphopenia (OR 3.34 (95% CI 1.59–7.03), p = 0.001). Mortality at 90 days was 11.9%. Median time from diagnosis to death was 23 days (interquartile range 8–31 days). Independent risk factors for mortality were age (OR 1.04 (95% CI 1.01–1.08), p = 0.009), neutrophilia (OR 2.84 (95% CI 1.04–7.76), p = 0.041), and lymphopenia (OR 4.50 (95% CI 1.67–12.11), p = 0.003). Blastomyces immunodiffusion had an overall sensitivity of 39.6% (95% CI 30.1–49.8). Sensitivity was higher among those who were tested 4 weeks or longer after the onset of symptoms. Urine Blastomyces antigen had a significantly higher sensitivity of 80.8% (95% CI 68.1–89.2) compared to serology. There was a trend towards higher antigen concentration in patients with severe disease. The sensitivity of PCR from respiratory specimens was 67.6% (95% CI 50.1–85.5). Conclusion: In this cohort, we did not find an association between pharmacologic immunosuppression and disease severity. Lymphopenia at diagnosis was an independent risk factor for mortality. This simple marker may aid clinicians in determining disease prognosis.

Bronchoscopy with bronchoalveolar lavage in tuberculosis and fungal infections

STUDY OBJECTIVE

To determine the utility of bronchoscopy with bronchoalveolar lavage for diagnosing M tuberculosis and fungal infections.

DESIGN

Retrospective review of patients over a six-year period.

SETTING

In- and outpatients of one University hospital and affiliated Veterans Administration Medical Center.

PATIENTS

Those who were subsequently found to have either M tuberculosis or fungal infections.

INTERVENTIONS

Bronchoscopy with bronchoalveolar lavage specimens were compared to prebronchoscopy sputum, when available. Specimens were sent for smear and culture for both acid-fast bacilli and fungi. In the case of lavage, an aliquot also was studied for cellular differential.

MEASUREMENTS AND RESULTS

For TB, sputum was smear-positive in 6/47 (34 percent) and culture positive in 24/47 (51 percent), while bronchoscopy was smear positive in 34/50 (68 percent) and culture positive in 46/50 (92 percent). For fungal infections, no sputum was smear-positive and only 1/22 (5 percent) was sputum culture-positive, while bronchoscopy was smear-positive in 14/41 (34 percent) and culture positive in 35/41 (85 percent). Bronchoscopy washings and BAL provided complementary specimens. Eighty-three patients had adequate lavages and the cellularity was significantly different from controls (lymphocytes: TB 18 +/- 11.2 percent [mean +/- SD]; fungal: 13 +/- 11.1 percent; controls 6 +/- 3.1 percent; p less than 0.001; neutrophils: TB 9 +/- 11.5 percent; fungal: 6 +/- 9.1 percent controls: 2 +/- 1.5 percent, p less than 0.01); however, there was overlap and no pattern was characteristic for TB or fungal infections.

CONCLUSION

Bronchoscopy with BAL is useful in diagnosing tuberculosis and fungal infections.

Analysis of T cell subsets in normal adults. Comparison of whole blood lysis technique to Ficoll-Hypaque separation by flow cytometry

Analysis of peripheral blood T cells and T cell subsets by immunofluorescence and flow cytometry is employed commonly in studies of normal individuals and in certain disease states. Methods for separating T cells from granulocytes and erythrocytes vary. We have sought to determine whether or not such procedures alter the composition of cells being analyzed. In this communication, we report that, in normal individuals, Ficoll-Hypaque separation of lymphocytes selectively decreases the OKT8+ subset compared to the whole blood lysis technique (P less than 0.01). The decrease in the OKT8+ subset results in a significant increase (P less than 0.01) in the OKT4/OKT8 ratio. This disparity appears to be due to a selective loss of OKT8+ cells during centrifugation over Ficoll-Hypaque. With the Ficoll-Hypaque method, we have also found that the fixation of lymphocytes reacted with monoclonal antibodies is less stable than cells prepared by the whole blood lysis method. The interpretation of measurements of T cell subsets is influenced by the method by which these cells are isolated.