Table 3.
Summary of number of in vivo, ex vivo and combined testing results in patients with a history of antibiotic-associated SCAR
| Patient study No. | Skin test results (in vivo) | IFN-γ ELISpot results (ex vivo)b | Combined results | ||||
|---|---|---|---|---|---|---|---|
| Modality positive: Antibiotic(s)a | Concentration (mg/ml) | Interpretation | Antibiotics positive | Concentrations (μg/ml)c | Interpretation | In vivo or ex vivo | |
| S1 | PT/IDT: CEF | 10%/2.5 | Positive (CEF) | CEF | 20,200,2000 | Positive (CEF) | Positive |
| S2 | Nil | Negative | TEIC | 25, 50, 100 | Positive (TEIC) | Positive | |
| S3 | NP | NP | Nil | - | Negative | Negative | |
| S4 | Nil | Negative | Nil | - | Negative | Negative | |
| S5 | Nil | Negative | Nild | - | Indeterminate | Negative | |
| S6 | IDT: AMP, PIP-TAZ | 25, 4.5 | Positive (PIP-TAZ, AMP) |
PIP-TAZ | 37.5/300, 375/3000 | Positive (PIP-TAZ) | Positive |
| S7 | IDT: CEFZ, MERO | 1, 2.5 | Positive (CEFZ, MERO) | CEFZ MERO |
20, 200, 200 20, 200 |
Positive (CEFZ, MERO) | Positive |
| S8 | IDT: AMP, FLU, PENG, PIP-TAZ | 25, 2, 10, 4.5 | Positive (AMP, FLU, PENG, PIP-TAZ) |
AMP FLUC PENG PIP-TAZ |
200, 2000 200 20, 200, 2000 18.75/150, 187.5/1500 |
Positive (PENICILLINS) | Positive |
| S9 | Nil | Negative | VAN | 5, 50, 500 | Positive (VAN) | Positive | |
| S10 | Nil | Negative | VAN | 5, 50, 500 | Positive (VAN) | Positive | |
| S11 | IDT: AMP | 25 | Positive (AMP) | Nil | - | Negative | Positive |
| S12 | Nil | Negative | VAN | 5, 50, 500 | Positive (VAN) | Positive | |
| S13 | PT/IDT: MET | 3 | Positive (MET) | Nil | - | Negative | Positive |
| S14 | Nil | Negative | Nil | - | Negative | Negative | |
| S15 | NP | NP | VAN | 5, 50, 250 | Positive | Positive | |
| S16 | IDT: PIP-TAZ | 4.5 | Positive (PIP-TAZ) | Nil | - | Negative | Positive |
| S17 | PT: TMP | 5% | Positive (TMP) | Nil | - | Negative | Positive |
| S18 | IDT: PIP-TAZ | 4.5 | Positive (PIP-TAZ) | Nil | - | Negative | Positive |
| S19 | Nil | Negative | VAN | 5, 50, 500 | Positive | Positive | |
Abbreviations: IDT, delayed intradermal testing; PT, patch testing; NP, not performed; Nil, nil positive. AMP, ampicillin; CEF, ceftriaxone; CEFZ, cefazolin; FLU, flucloxacillin; MER, meropenem; MET, metronidazole; PIP-TAZ, piperacillin-tazobactam; TEIC, teicoplanin; VAN, vancomycin; TMP, trimethoprim.
In patients beta-lactam implicated in SCAR causality a standard panel employed for IDT (DAP-major, DAP -minor, PENG, FLU, AMP, PIP-TAZ, CEFX, CEF) in addition to implicated beta-lactam at recommended concentrations1. For all other drugs the implicated antibiotic was tested via either patch testing (PT) or delayed intradermal testing (IDT). For PT, expressed as %. In patient S3 ELISpot testing was also performed to ibuprofen and for S18 PT was also performed to allopurinol.
A SFU/million cells of > 50 was interpreted as positive result by subtracting the spot count in the negative control (no drug) from the spot count in the wells with drugs.
Performed in triplicate (or duplicate if thawed PBMC numbers low).
Negative CD3 control.