Introduction: DH, an infection causing high mortality unless treated early, is a major opportunistic infection in patients with AIDS, especially in the Mississippi River basin. Early diagnosis is important for decreasing morbidity/mortality and for avoiding empiric treatment with potentially harmful drugs. Diagnosis by positive fungal culture or Histoplasma (H) antigen may take 10 or more days to return. Detection of H in PBS leads to an earlier diagnosis. We examined several factors that may affect the probability of detection of H on PBS. Methodology: Retrospective review of 80 AIDS patients admitted to the Regional Medical Center at Memphis between January/99 to 12/2003 with diagnosis of ADH. Diagnosis was based on positive blood culture, H antigen and/or pathology for Histoplasma capsulatum. Logistic regression was done on various routine blood chemistry and peripheral blood counts to study the relation of the probability of a positive blood smear. Results: Of the 80 patients reviewed, 22 patients had a positive blood smear [27.5%]. The mean time to diagnosis in patients with a positive smear was 4 days as compared to 17 days in whom the diagnosis was based on culture or other definitive tests. The probability of positive smear was significantly higher in patients with high levels of serum LDH, AST, decreased platelet count and increased Creatinine. In 79 % of the patients with positive smear, the serum LDH was more than 1000, as compared to 41 % of patients with negative smears. Similarly the Serum AST levels were > 200 in 60% of the patients with a positive smear as compared to 8% of patients with a negative smear. Conclusion Diagnosis of H can be expedited by screening of LDH and AST among other parameters in AIDS patients presenting with fever. PBS of patients with Serum LDH of > 1000 and AST levels of >200 should be carefully screened for presence of H. Other clues to positive PBS are thrombocytopenia and abnormal renal function tests. Although leukopenia is a common occurrence in patients with ADH, the probability of positive smear did not correlate with this finding. The above findings also indicate that presence of H on PBS may correlate to the severity of disease.
Full conference title:
15th Annual Focus on Fungal Infections
- FFI 15th (2005)