Onychodystrophy Testing

Various nail disorders appear identical, which makes physical examination alone less reliable. Often, nail dystrophy can have more than one cause.

Causative infectious organisms are colorless and invisible to the eye. Diagnostic testing helps you determine the exact underlying causes of nail disease.


Onychodystrophy Test

Onychodystrophy + PCR Test

Onychodystrophy + PCR with Terbinafine Resistance

Collection Procedure

Clinical Education

Requisition Form

Histopathology Microscope


Microscopic evaluation of a specimen to determine infectious or non-infectious pathologies including traumatic, inflammatory or neoplastic processes.

Periodic Acid–Schiff (PAS): Identifies non-degenerated fungal elements

Grocott Methenamine Silver (GMS): Identifies degenerated fungal elements

Fontana-Masson (FM): Identifies pigmented saprophytes and melanin pigment which may be associated with a melanocytic neoplasm



Molecular analysis of a specimen to determine if DNA of an infectious organism is present.

Onychodystrophy PCR Test: Identifies genus and species of most common fungi (dermatophytes, saprophytes, and yeasts) as well as the bacteria, pseudomonas aeruginosa, that cause nail dystrophy

PCR with Terbinafine Resistance Reflex: When positive for T. rubrum or T. mentagrophytes, detects mutations associated with terbinafine resistance

The Complete Picture

  • Speciation for Targeted Treatment
  • Terbinafine Resistance for Treatment Efficacy
  • Identification of Non-Infectious and Infectious Causes
  • Highest Sensitivity and Specificity Testing Available*
  • Rapid results

*When used in combination; Bako Nail PCR Testing: 99.9% Analytical Specificity, 86% Clinical Sensitivity. Bako’s PCR testing highly correlates with histopathology. Histopathology: 93% Clinical Sensitivity, 96% Clinical Specificity. Fungal culture: 42% False Negative Rates

Test Comparison

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Advantages of the BakoDx Onychodystrophy PCR Test



Determine the genus and species of the infectious organism to provide the safest, most effective oral and topical treatments



Assess patient results with high confidence

99.9% analytical specificity 86% clinical sensitivity;¹ Correlates highly with histopathology

Cost Effective


Eliminate unnecessary additional testing, focus on the relevant agents of disease, and prevent treatment course changes



Document the genus and species information needed for pre-authorization of many anti-fungal prescriptions



Contracted  with all major insurance plans, and over 200 local insurance plans; Covered by Medicare



Begin appropriate treatment quickly with 1-2 day turnaround time

BakoDx Sample Report

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BakoDx’s Intelligent Onychodystrophy PCR Testing Report

Actionable reports with information to assist you in making treatment decisions.

  • Diagnosis

  • Treatment Recommendations

  • Relevant Clinical Images

  • Interpretations for All Tests Performed

  • Pathologists Available for Consult

Onychodystrophy Specimen Collection Procedure

Optimal Nail Specimen Collection for Onychodystrophy Testing

Nail Matrix Biopsy – Specimen Collection Techniques

Processing the specimen for ENFD submission is different from a routine punch biopsy. Punches taken for ENFD cannot be placed in formalin. The specimen requires fixation in Zamboni’s fixative for 8 hours, but not more than 24 hours. If left in contact with the specimen for more than 24 hours, the ENFD test may be compromised.

NOTE: Rinse is not required if shipped same day in Zamboni’s fixative. See processing steps below.

  • Place 3mm punch biopsy in Zamboni’s fixative for no less than 8 hours (it’s best to fix overnight), but no longer than 24 hours. Refrigerate, but do not freeze.

NOTE: Rinse is not required if shipped same day in Zamboni’s fixative.

  • Immediately place specimen in yellow Zamboni’s fixative (provided in kit). Verify sample is floating in prior to sealing securely. Note: After this step, if specimen is sent same-day, proceed to label vials with appropriate patient and body site stickers from provided BakoDx Requisition form.
  • If same-day shipping is unavailable, in-office rinse is necessary. After a minimum of 8 hours in refrigerator (but no more than 24 hours), pour out Zamboni’s into secondary tray, keep specimen in vial. Refill with buffer rinse.
  • Pour out buffer rinse (into dish), again, leaving skin biopsy in its original tube.
  • Repeat buffer, using the remaining buffer rinse and pour out.
  • Refill the vial containing the biopsy specimen with cryoprotectant and screw the cap on tightly.
  • Label vials with appropriate patient and body site stickers from provided BakoDx Requisition form.
  • Ship to BakoDx in Styrofoam cooler with cool-pack (provided) using FedEx or UPS prepaid overnight shipping (prepaid shipping labels provided with kit).
  • Biopsies left in Zamboni’s fixative must be shipped Mon-Fri. Tissue sent over weekends or holidays require rinse and cryoprotection steps.
  • For help, call BakoDx at 855-422-5628.


New insights, only from BakoDx

Onychodystrophy PCR Test with Terbinafine Resistance

Know before you treat

  • Eliminate terbinafine “watchful waiting” period

  • Avoid unnecessary medications & potential side effects

  • Increase treatment efficacy & patient satisfaction

While terbinafine is most often prescribed for onychomycosis caused by dermatophytic fungi, an increasing rate of cases with terbinafine resistance may be impeding treatment success.

To date, 12 specific genetic mutations have been identified in Trichophyton genera, primarily T. rubrum and T. mentagrophytes complex, which confer terbinafine resistance.

The new BakoDx Onychodystrophy PCR test with terbinafine resistance enables you to understand the likelihood of treatment effectiveness in days, instead of months.

How does BakoDx lab testing impact therapy outcomes, especially if a patient’s fungus is terbinafine-resistant?

Drag the slider right to see the Bako difference:

BakoDx Definitive Diagnosis

(1) Sigurgeirsson B, Olafsson JH, Steinsson JB, Paul C, Billstein S, Evans EG. Long-term Effectiveness of Treatment With Terbinafine vs Itraconazole in Onychomycosis: a 5-year blinded prospective follow-up study. Arch Dermatology 2002; 138:353–357.

Compare Fungal Nail Tests for Terbinafine Resistance

BakoDx Terbinafine Test Comparison

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While superficial onychomycosis caused by Trichophyton rubrum and T. mentagrophytes can often be treated with terbinafine, an increasing rate of cases with antifungal resistance mutations is impeding treatment success.

There is a serious global public health concern that antifungal treatment, traditionally oral and/or topical terbinafine, may be ineffective against 12 resistant mutation strains found in members of the Trichophyton genera.

BakoDx’s highly experienced molecular analysis team developed an advanced real-time PCR terbinafine resistance reflex to seamlessly integrate with our Onychodystrophy PCR test to accurately detect when 12 terbinafine resistant mutations are present in T. rubrum and T. mentagrophytes.

  • At initial presentation of nail dystrophy
  • When considering terbinafine therapy
  • Cases of treatment failure


Just as the current onychodystrophy test provides cost effectiveness through a proprietary reflex algorithm, this new addition will only reflex to terbinafine resistance when it identifies T. rubrum and/or T. mentagrophytes. Furthermore, our test is able to detect 12 current mutations in just four reactions. BakoDx is contracted with most insurance plans throughout the United States, providing clients and their patients with a superior level of access to testing services.

Terbinafine treatment failure may occur in patients with terbinafine resistant strains of dermatophytic fungi. Many times, despite having a positive T. rubrum or T. mentagrophytes diagnosis, patients do not improve. In these cases, where there is a poor response or non-responsiveness to the recommended antifungal, patients may grow frustrated, lose valuable time with unnecessary treatment and incur added Rx costs. In addition, there are secondary bacterial infections, which are potentially the most significant complication leading to adverse outcomes.

Clinical Resources for Onychodystrophy

Nail Collection Guide

Optimal Nail Specimen Procedure Guide. Download this easy-to-follow training tool for your staff.

BakoDx Clinical White Paper

DNA-based detection for onychomycosis correlates better to histopathology than does fungal culture.

Nail Collection Guide

Reference this hands-on, procedural video created by BakoDx clinical consultants.

Additional BakoDx Testing Services