Objectives: False positive results in Aspergillus galactomannan antigen detection by ELISA method from patients receiving piperacillin-tazobactam have been reported. In this study, we aimed to investigate A. galactomannan antigen levels for piperacillin-tazobactam and other various antimicrobial agents that are often used for the treatment of infections in immunocompromised patients. Methods: The level of galactomannan antigen was investigated for piperacillin-tazobactam, ampicillinsulbactam, ampicillin, penicillin G, ceftriaxone, cefepime, imipenem, clarithromycin, ciprofloxacin, vancomycin, gentamicin, trimethoprim-sulfamethoxazole, ornidazole, fluconazole and amphotericin B. Antigen levels were determined by using the Platelia Aspergillus ELISA (Bio-Rad, France) according to the manufacturer's instructions. Samples were run in triplicate and the entire experiment was repeated. Results: Among the 15 antibiotics, ampicillin expressed highest level of galactomannan with a galactomannan index (GI) of 0.540. Although this index value is not a positive result for the presence of galactomannan according to the manufacturer's instructions, it can be accepted as positive according to the test products with FDA approval. Piperacillin-tazobactam expressed the second high level of galactomannan (GI = 0.235), however this value is below the both cutoff limits. Galactomannan levels for the other antibiotics ranged from 0.011 to 0.188. Conclusion: It can be concluded that among the antibiotics that was investigated in this study, ampicillin might cause a false positive result in galactomannan antigen test by ELISA because it showed significant level of galactomannan antigen and piperacillin-tazobactam can also cause cross reactivity in the sera of patients due to its relatively high galactomannan level in the test.
Full conference title:
16th European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 16th (2006)