Evaluation of IFN-γ Enzyme-linked Immunospot Assay (ELISPOT) as a First-line Test in the Diagnosis of Non-Immediate Hypersensitivity to Amoxicillin and Penicillin

Abstract

The current diagnostic algorithm for beta-lactam allergy is based on skin and provocation tests, both of which carry a certain risk of inducing hypersensitivity reactions. Thus, non-invasive in vitro tests reliable enough to replace skin and provocation tests at least in a portion of patients are desirable. We aimed to verify the utility of IFN-γ ELISPOT as a first-line test in patients with suspected non-immediate hypersensitivity reaction to amoxicillin (AMX) and penicillin (PNC). The prospective observational study included 24 patients with recent, suspected non-immediate hypersensitivity reaction to AMX or PNC and 6 recently-exposed healthy subjects. In vitro tests were performed in all patients and healthy subjects: a) IFN-γ ELISPOT with PNC, AMX and amoxicillin plus clavulanic acid (AMX-CL); b) penicillin specific IgE; c) basophil activation test (BAT). Skin and provocation tests followed only in certain patients. IFN-γ ELISPOT results with PNC and AMX stimulation did not differ from the unstimulated condition. The highest IFN-γ responses to AMX-CL were close to previously published criteria in three patients; one of which had true hypersensitivity according to drug provocation tests. Five patients with confirmed hypersensitivity by skin tests showed no response to the culprit antibiotic on IFN-γ ELISPOT assay. Our results did not support the utility of IFN-γ ELISPOT in the diagnosis of mild, non-immediate hypersensitivity to amoxicillin and penicillin.

Dose Dependent Antimicrobial Cellular Cytotoxicity—Implications for ex vivo Diagnostics

“…Various drug concentrations are described in the literature for ex vivo assays with varying units of measure including, millimoles (isoniazid, 1–4 mM; rifampicin, 0.1 mM) for tuberculosis related drugs ( Usui et al, 2017 ) or micromoles ( El-Ghaiesh et al, 2012 ) and mg/ml ( Rozieres et al, 2009 ; Tanvarasethee et al, 2013 ; Sedlackova et al, 2018 ) for beta-lactam drugs. Thus, a strength of this project is the use of the measured Cmax as a reference to ensure that these units are comparable across drugs and concentrations are optimised as being the point of maximal bacterial cytotoxicity with minimum tolerable cellular injury ( Supplementary Table S1 ).…”