Two Suspected Cases of Immunoglobulin-Mediated Interference Causing Falsely Low Vancomycin Concentrations with the Beckman PETINIA Method
Bibliographic record
Abstract
OBJECTIVE: To describe 2 recent cases of suspected immunoglobulin-mediated interference with the Beckman Coulter particle-enhanced turbidimetric inhibition immunoassay (PETINIA) used to measure vancomycin serum or plasma concentrations and to review the existing literature. CASE SUMMARY: A 64-year-old woman with a history of multiple immune-related comorbidities received vancomycin for treatment of a prosthetic joint infection growing coagulase-negative Staphylococcus spp. A 33-year-old man with a history of Felty syndrome received vancomycin for the treatment of methicillin-resistant Staphylococcus aureus pneumonia. Both patients had multiple vancomycin trough concentrations determined using the Beckman Coulter PETINIA method and had measured concentrations reported as less than 4 mg/L despite appropriate vancomycin dosing for their size, age, and organ function. The patients' serum was then tested by alternative methods, which reported vancomycin concentrations consistent with those expected with the patients' dosing regimens. DISCUSSION: Immunoglobulins are well known for interfering with chemistry assays. It is suspected that high levels of immunoglobulins in these 2 patients interfered with the accurate measurement of serum vancomycin concentrations. An objective causality assessment supported the interactions as being definite and probable, respectively. Two other cases of suspected immunoglobulin interference with vancomycin measurement have been reported in the literature when vancomycin concentrations were initially measured using the Beckman Coulter PETINIA method. In vitro studies support the hypothesis that immunoglobulin interference with vancomycin measurement by this method occurs and is a graded phenomenon. CONCLUSIONS: These cases suggest a high likelihood of immunoglobulin-mediated interference with the Beckman Coulter PETINIA method, which results in the reporting of falsely low vancomycin serum concentrations. When vancomycin concentrations do not correlate with what would be expected clinically, clinicians should have a high index of suspicion for potential assay interference.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.015 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.009 | 0.004 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".