Introduction: DH, is a major opportunistic infection in patients with AIDS, especially in the Mississippi River basin. Early diagnosis may lead to decreased morbidity/mortality. Detection of Histoplasma (H) antigen (Ag) is widely used for early diagnosis of DH, with a reported sensitivity of 95%. We report our data of sensitivity of H Ag among AIDS patients in a city hospital in an area endemic for H. Methodology: Retrospective review of 124 episodes of DH among 80 AIDS patients with a diagnosis of DH admitted to the Regional Medical Center at Memphis between 1/1/99 to 12/30/03. The present study is restricted to those 50 patients in whom diagnosis of DH was based on culture from a sterile site and /or pathology and in whom H Ag testing was also done. Logistic regression was used to compare the group of patients with a false + test with true +. Results: Among the 50 patients who met the above criteria, the H Ag was + [standard definitions] in 35 cases with a sensitivity of 70%. In the 15 cases with negative H Ag results, the diagnosis was made in 13 by a + blood culture, in 1 by positive pathology, and 1 by bone marrow culture. Of the patients in whom the test was negative, the value was 10 in 22 patients. No statistically significant correlation was seen when comparing the groups with false positive to true + in terms of severity of disease, blood counts, absolute CD4 count, or prior OI. No statistically significant difference was found when comparing patients with a + test and levels of H Ag 10. No change in sensitivity was found when categorized yearly. Conclusion: The sensitivity of H Ag testing for the diagnosis of DH among patients with AIDS was found to be 70% in our series. No correlation was detected in the different parameters between the false and true positive groups, or among those patients with a positive test with Ag level more or less than 10. The sensitivity of the test did not correlate with year of testing.
Full conference title:
15th Annual Focus on Fungal Infections
- FFI 15th (2005)