Cryptococcal antigen testing of lung tissue homogenate improves pulmonary cryptococcosis diagnosis:Two case reports

BACKGROUND Pulmonary cryptococcosis(PC)is an opportunistic infectious disease of the respiratory system.Lung tissue biopsies,culture of respiratory samples(e.g.,sputum,lung tissue,pleural fluid,and bronchoalveolar lavage fluid),and cryptococcal antigen(CrAg)testing are helpful for a definitive diagnosis.However,these tests are sometimes falsely negative.PC is often misdiagnosed or underdiagnosed owing to the absence of obvert symptoms,poor imaging specificity,and false-negative laboratory tests.CASE SUMMARY We report two female patients who underwent computed tomography-guided percutaneous needle pulmonary biopsy of a lung nodule for a confirmed diagnosis.In both patients,the CrAg test on the lung biopsy tissue homogenate was positive,while the serum CrAg test was negative.Combined with the lung tissue pathology,we made the diagnosis of PC.Antifungal therapy was effective in both patients.CONCLUSION Given the findings of our cases and the literature review,lung tissue homogenate CrAg testing can be helpful in improving the diagnosis of PC.

Cryptococcal Antigenaemia among Treatment-Naïve Adult HIV-Infected Nigerian Patients

Background: There is a high burden of HIV-related cryptococcal meningitis in Sub-Saharan Africa and it is a leading cause of morbidity and early mortality among severely immunocompromised patients. Objectives of the Study: This study was carried out to determine the prevalence of cryptococcal antigen (CrAg) and the relationship of positivity to CD4+ve T cell counts and WHO clinical stage among severely immunocompromised treatment naive adult HIV-infected Nigerian patients. Methods: This was a hospital based cross sectional and prospective study carried out among newly diagnosed and confirmed HIV infected patients. Bio data of consenting consecutive subjects was collected by the attending physician using structured questionnaire. Rapid point of care lateral flow assay kits (IMMY, USA) was used to screen plasma samples from subjects strictly following manufacturer’s instructions. Data were analysed with statistical package for social sciences (spss 15.0) software. Results were presented in simple tables with frequencies and percentages while statistical significance was taken to be p value ≤ 0.05. Results: Of 432 subjects, there were 184 (42.6%) males and 248 (57.4%) females in the study. The median CD4 count of the subjects was 74 (range 6 - 1264) cells/ul. Seven (1.6%) of the subjects were positive for cryptococcal antigen (CrAg) and all were females (100%). Six (85.7%) of CrAg positives had CD4+ T cell count less than 100 cells, while 1 (14.3%) had count above 200cells/ul. The WHO clinical stage of studied patients was;stage I 163 (37.7%), stage II 132 (30.6%) stage III 95 (22.0%) and stage IV 42 (9.7%). Among the CrAg positive subjects, 3 (42.9%) were in WHO clinical stage l while 4 (57.1%) were in stage II disease. Conclusion: The observed overall prevalence of CrAg positivity among studied patients was low but occurred most frequently among the severely immunocompromised subjects. Advancement in WHO clinical stage was not a predicting risk factor for cryptococcal antigenaemia in studied adult HIV infected patients.

Extent of Lung Involvement and Serum Cryptococcal Antigen Test in Non-Human Immunodeficiency Virus Adult Patients with Pulmonary Cryptococcosis

Background： Serum cryptococcal antigen （CrAg） test is the most used noninvasive method to detect cryptococcal infection. However, false-negative CrAg test is not uncommon in clinical practice. Then, the aim of this study was to investigate the factors associated with false-negative CrAg test among non-human immunodeficiency virus （HIV） adult patients with pulmonary cryptococcosis and its clinical features. Methods： One hundred and fourteen non-HIV adult patients with pulmonary cryptococcosis, proven by biopsy, were retrospectively reviewed. Finally, 85 patients were enrolled; 56 were CrAg positive （CrAg＋ group） and 29 were negative （CrAg- group）. It was a cross-sectional study. Then, baseline characteristics, underlying diseases, clinical symptoms, laboratory findings, and chest radiological findings were reviewed and analyzed. Chi-square test was used to analyze categorical variable. Odds ratio （OR） was used to measure correlation. Student＇s t-test was obtained to analyze continuous variable. Results： No difference in baseline characteristics, underlying diseases, clinical symptoms, and laboratory findings were found between two groups （P 〉 0.05 in all）. Nevertheless, diffuse extent lesion was 82.1% in CrAg＋ group and 10.3% in CrAg- group （χ2 = 40.34, P〈 0.001; OR = 39.87）. Conclusions： Among patients with limited pulmonary involvement, a negative serum CrAg does not preclude the diagnosis of pulmonary cryptococcosis. However, among patients with extensive pulmonary involvement, serum CrAg is a useful diagnostic tool for pulmonary cryptococcosis. Furthermore, we also noticed that the untypical and mild presentations with extensive pulmonary lesion might be the features of pulmonary cryptococcosis, which needs further investigation.