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WOUNDCHEK Bacterial Status (WCBS) is an in vitro diagnostic chromatographic test for the qualitative detection of bacterial protease activity directly from wound fluid samples collected with a swab. The WCBS test is intended for use in adult patients as an aid in assessing the risk for non-healing of chronic venous, diabetic foot, and pressure ulcers associated with wounds where there are no signs of wound infection and where patients are asymptomatic for clinical signs of infection. The test is intended for use with chronic wounds that are between 21 days and 6 months of age that are

WOUNDCHEK Bacterial Status (WCBS) is a lateral flow assay that qualitatively detects bacterial protease activity in chronic wound fluid. Wound fluid is collected by rolling a swab over the cleansed wound surface until it is saturated. The swab is then incubated in the assay reagent which contains a substrate that can be cleaved by bacterial proteases and human neutrophil elastase (HNE) and an HNE inhibitor. The WCBS test card is used to detect cleavage products of the substrate. It consists of biotinylated bovine serum albumin (BSA) (Test Line (T)), and a control system protein, (Control line (C)), on a nitrocellulose membrane support. Neutravidin, which is conjugated to visualizing particles, binds the biotinylated end of a synthetic peptide and the biotinylated BSA test line. The test result is based on the presence or absence of a pink-to-purple colored Test Line (T) which means bacterial protease activity was detected. A negative test result is defined by the absence of a Test Line (T) which means bacterial protease activity was not detected. If the control line (C) is not present, then the test result is invalid. The device is intended for use on venous leg ulcers (VLU), diabetic foot ulcers (DFU) and pressure ulcers (PU).

A control kit, consisting of negative and positive swabs, is also available for WOUNDCHEK Bacterial Status.

Here's an analysis of the acceptance criteria and the study that proves the WOUNDCHEK Bacterial Status device meets these criteria, based on the provided text:

Acceptance Criteria and Device Performance

1. Table of Acceptance Criteria and Reported Device Performance

• Moderate Positive: 98.5% (133/135) agreement
• Low Positive: 95.6% (129/135) agreement
• True Negative: 97.8% (132/135) agreement
  The high negative panel member had 93.3% (126/135) agreement, acknowledged as variable but acceptable given its nature. No significant differences by site, operator, or day were reported. |
  | Sample Stability | Testing of all positive and negative swabs for various storage conditions (up to 9 hours at 2-8°C and 30°C) generated expected results. | Met.
  Ten positive and negative swabs were tested for each storage condition (0.5, 1, 1.5, 2, 4, 6, 9 hours at 2-8°C and 30°C). All generated expected results. Interpretations were made by two blinded operators, with a total of (b)(4) determinations per condition. Daily controls met expectations. |
  | Detection Limit (LOD) | LOD defined as the level of bacterial protease activity generating a positive result ~95% of the time (C95). C5 level also identified. | Met.
  Preliminary and confirmed LODs (C95, C5, C50) were established for individual proteases (V8, GelE, ZapA, LasB) and a pooled mix of these proteases, consistent with the objective of defining these detection levels. (Specific mU/test values are redacted but are reported as being established). |
  | Cross-reactivity - Human Proteases | Positive swabs must produce a positive result in the presence of any host protease. Negative swabs must produce a negative result in the presence of any host protease. | Met.
  The study identified specific concentrations of human proteases (e.g., MMP-13, MMP-9, HNE, Plasmin) at which no interference was observed with WCBS performance for both positive and negative samples. If initial levels showed interference, dilutions were tested until criteria were met. |
  | Interference - Microbial | Positive swabs (with analyte) must produce a positive result in the presence of tested microorganisms. Negative swabs must produce a negative result in the presence of tested microorganisms. | Met.
  The study determined specific levels of various fungi, mold, and viruses (e.g., Candida species, Aspergillus fumigatus, Herpes Simplex viruses) at which no interference was observed. If initial levels showed interference with stock solutions, log dilutions were tested until criteria were met. |
  | Interference - Healthy Skin Flora | Implied: Device should ideally not react to normal skin flora unless these flora are indicative of bacterial protease activity leading to non-healing. However, the study identified that performance is affected by normal skin flora. This led to a labeling mitigation. | Met (with mitigation).
  Out of (b)(4) apparently healthy skin swab samples, 20 were positive by both operators, and an additional 4 by one operator, totaling 44 false positives out of 102 readings. While the device is affected, this finding is acknowledged as expected due to skin flora secreting proteases. The mitigation is a prominent instruction in the IFU: "Do not swab intact skin." |
  | Interfering Substances | Positive swabs must produce a positive result in the presence of the interfering substance. Negative swabs must produce a negative result in the presence of the interfering substance. | Met.
  The study identified specific concentrations for a wide range of wound-related substances (e.g., acetic acid, silver dressings, Manuka honey, mupirocin, blood, various antibiotics, skin substitutes, iodine, antifungals) at which no interference was observed. If a substance failed at the initial level, it was diluted twofold until criteria were met. |
  | Clinical Performance (Risk Assessment for Non-Healing) | Provide Positive Likelihood Ratio (PLR) and Negative Likelihood Ratio (NLR) for indication. | Met (with caveats).
  For the intended use population (wounds

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