title: Reactivity of platelia Aspergillus galactomannan antigen with piperacillin-tazobactam: clinical implications based on achievable concentrations in serum.
abstract: The possible reactivities of commonly used antibiotics of fungal, nonfungal, and nonmicrobial or synthetic sources with the Platelia Aspergillus galactomannan assay were assessed. For drugs that tested positive, the minimal concentration of the antibiotic in serum that yielded a positive test (index, >0.5) was determined. At undiluted concentrations, piperacillin and multiple lots of piperacillin-tazobactam tested positive, whereas amoxicillin, ampicillin-sulbactam, nafcillin, cefazolin, ceftazidime, erythromycin, gentamicin, and levofloxacin tested negative. All three lots of piperacillin-tazobactam and all bags within each lot tested positive, with a mean index value of 5.168. At achievable concentrations in serum, however, only one of three lots of piperacillin-tazobactam yielded a positive test. Concentrations of 75, 150, and 300 microg/ml of serum tested positive with the Platelia Aspergillus enzyme immunoassay, whereas lower concentrations, mimicking the trough levels, tested negative. Thus, while achievable serum piperacillin-tazobactam concentrations may potentially result in a positive test for galactomannan, the timing of the collection of serum samples from patients may influence the test results, with reactivity being less likely in samples collected at trough levels or prior to the administration of a dose of the antibiotic.
authors.affiliation: Veterans Affairs Medical Center, Infectious Disease Section, University Dr. C, Pittsburgh, PA 15240, USA. nis5+@pitt.edu
authors.forename: Nina
authors.initials: N
authors.lastname: Singh
authors.forename: Asia
authors.initials: A
authors.lastname: Obman
authors.forename: Shahid
authors.initials: S
authors.lastname: Husain
authors.forename: Sherrie
authors.initials: S
authors.lastname: Aspinall
authors.forename: Sue
authors.initials: S
authors.lastname: Mietzner
authors.forename: Janet E
authors.initials: JE
authors.lastname: Stout
mesh_terms: D000946:Antigens, Fungal / Q000276:immunology*; D001230:Aspergillus / Q000187:drug effects / Q000276:immunology*; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000097:blood / Q000494:pharmacology*; D005690:Galactose / Q000031:analogs & derivatives; D008351:Mannans / Q000276:immunology*; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology*; D010406:Penicillins / Q000097:blood / Q000494:pharmacology*; D010878:Piperacillin / Q000097:blood / Q000494:pharmacology*; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors
chemical_list: D000946:Antigens, Fungal; D004791:Enzyme Inhibitors; D008351:Mannans; D010406:Penicillins; D065093:beta-Lactamase Inhibitors; C012990:galactomannan; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin; D005690:Galactose