Eclipsed phenomenon: the relationship between nail and foot infections in patients presenting with nondermatophyte infections after dermatophyte infections in onychomycosis

Developing diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes

Background

The predisposing factors and clinical presentations of fungal foot infections caused by non-dermatophytes and dermatophytes are challenging to differentiate. Definite diagnoses of non-dermatophyte infections at first visits facilitate their treatment.

Objectives

This study aimed to develop diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes.

Methods

Diagnostic prediction research based on a retrospective, observational, cross-sectional study. The reviewed patients were aged ≥18 and underwent a mycological examination for fungal foot infections. A fungal culture at the initial visit was the gold standard for determining causative organisms.

Results

Analyses were carried out on the data from 371 patients. N. dimidiatum accounted for 184 (49.6%) infections, and dermatophytes caused the remaining 187 (50.4%) cases. Five significant predefined predictors were used to develop the diagnostic criteria and score. They were immunocompetence status, no family history of fungal infections, the absence of pruritus, the absence of other concurrent fungal skin infections, and agricultural work. The lower score cutoff was <8 (sensitivity 97.8% and specificity 25.7%). The higher cutoff was >11 (sensitivity 83.7% and specificity 57.8%). The score showed an area under the receiver operating characteristic curve of 0.755 and was well calibrated.

Conclusions

The criteria and score show promise for clinical use, with acceptable discriminative performance and good calibration. They will help physicians differentiate the causative organisms in patients with fungal foot infections at the first visit, enabling the determination of appropriate antifungal treatment.

Prognostic factors for mycological cure in patients with onychomycosis caused by Neoscytalidium dimidiatum: A retrospective cohort study

BACKGROUND

The prognostic factors for cure have been derived from cases of dermatophyte onychomycosis. However, there are limited studies in non-dermatophyte onychomycosis. Neoscytalidium dimidiatum is the common causative agents of non-dermatophyte onychomycosis which has proven to be recalcitrant to treatment.

OBJECTIVE

This retrospective cohort study investigated mycological cure and prognostic factors in Neoscytalidium onychomycosis patients.

METHODS

Patients aged 18 or older with newly diagnosed Neoscytalidium onychomycosis were enrolled. All patients were treated and followed up for at least 1 year. Mycological cure was analysed with Cox proportional hazard regression. The hazard ratios (HRs) of previously reported potential prognostic factors were included in univariable and multivariable stratified Cox regression analyses.

RESULTS

From total 198 patients, mycological cure was achieved in 108 (54.6%) patients with a median of 490 (± SD 62.2) days. The poor prognostic factors for mycological cure were age ≥ 70 years (HR, 0.63; 95% CI, 0.41-0.97; p = .034); nail thickness ≥2 mm (HR, 0.20; 95% CI, 0.11-0.35; p < .001); and peripheral vascular disease (HR, 0.46; 95% CI, 0.28-0.77; p = .003). Combination therapy was associated with achieving a mycological cure (HR, 2.55; 95% CI, 1.49-4.38; p < .001).

CONCLUSIONS

Approximately half of the patients with onychomycosis caused by Neoscytalidium dimidiatum achieved a mycological cure, with a median time to cure exceeding 1 year. Combined topical and systemic antifungal treatments yield a higher chance of mycological cure than monotherapies. Advanced age, nail thickness and peripheral vascular disease are obstacle factors to cure.

Clinical Clues to Differentiate between Dermatophyte Onychomycosis (DP-OM) and Dermatophytoma-Like Traumatic Onychodystrophy (DP-TO)

Background

Dermatophytoma is a recalcitrant condition of onychomycosis (OM). It presents as a white- or yellow-colored fungal mass that appears linear/triangular or round on a nail plate. Traumatic onychodystrophy (TO) can present with dermatophytoma-like lesions. Typically, OM and TO are not clinically distinguishable. Mycological testing is the gold standard for differentiating these disorders.

Objectives

This study is aimed at differentiating between the clinical and dermoscopic factors related to dermatophytoma onychomycosis (DP-OM) and dermatophytoma-like traumatic onychodystrophy (DP-TO).

Methods

A retrospective study was conducted of patients with dermatophytoma-like nail lesions who visited the Siriraj Nail Clinic between January 2010 and July 2020. The diagnosis of DP-OM was made by direct microscopy, fungal cultures, and histopathology of nail clippings.

Results

A total of 36 nails were included in the study. Thirteen nails were DP-OM, and 23 nails were DP-TO. The demographic data and risk factors for the 2 groups were not significantly different. Dermatophytoma lesions were found on the lateral side of nails in 12 cases of DP-OM (92.3%) and 11 cases of DP-TO (47.8%; P = 0.008). DP-OM was associated with longitudinal striae adjacent to dermatophytoma (69.2% vs. 30.4%; P = 0.024), sulfur-nugget-like subungual debris (23.1% vs. 0%; P = 0.040), and scale on the ipsilateral foot (69.2% vs. 8.7%; P < 0.001). DP-TO was associated with a homogenous, whitish discoloration (47.8% vs. 7.7%; P = 0.014) and a sharp edge of the onycholytic area (43.5% vs. 0%; P = 0.005).

Conclusions

The lateral location of dermatophytoma, adjacent striae, sulfur-nugget-like debris, and scale on the ipsilateral foot were significantly associated with DP-OM. Dermoscopic examination (dorsal and hyponychium views) and foot examination are beneficial for distinguishing between DP-OM and DP-TO.

Efficacy of a Newly Developed Inward Airflow Safety Cabinet to Prevent the Spread of Infected Nail Dust Particles During Mechanical Nail Reduction in Onychomycosis

BACKGROUND

Nail thickening is a poor prognostic factor in onychomycosis. Mechanical reduction by micromotor nail grinding is an alternative treatment for onychomycosis. However, this treatment introduces a large amount of infected nail dust particles into the air and can adversely affect other patients and health-care providers. The innovative recirculating airflow safety cabinet (ASC) was developed to prevent the spread of these generated infected nail dust particles. The aim of this study was to determine the efficacy of the ASC in patients with onychomycosis or traumatic onychodystrophy.

METHODS

The ASC was used during the nail-grinding process in 50 patients, including 36 onychomycosis patients and 14 traumatic onychodystrophy patients. For each patient, five Sabouraud dextrose agar plates with chloramphenicol were positioned within the working space of the ASC, and the other five plates were positioned near the area of air exit after the carbon filters within the cabinet. A total of 500 plates were incubated at 25°C and evaluated every 7 days. The results of fungal cultures were analyzed.

RESULTS

In the traumatic onychodystrophy group, all fungal cultures of nail dust particles from both before and after filtration from the ASC were negative in all 14 patients. In the onychomycosis group, 52 fungal cultures (28.9%) from nail particles within the ASC working area tested positive; however, the results of fungal cultures of nail dust particles after filtration were all negative.

CONCLUSIONS

The newly developed ASC was found to be effective for preventing the spread of infected nail dust particles generated by micromotor nail grinding to mechanically reduce nail thickness in patients with onychomycosis.

Effectiveness and safety of topical amphotericin B in 30% dimethyl sulfoxide cream versus 30% dimethyl sulfoxide cream for nondermatophyte onychomycosis treatment: A pilot study

BACKGROUND

Although topical amphotericin B cream is effective for the treatment of nondermatophyte mold onychomycosis in vitro, studies of its effectiveness and safety in vivo are limited.

OBJECTIVES

We studied the effectiveness and safety of topical 0.3% amphotericin B in 30% dimethyl sulfoxide cream (amphotericin B cream) in nondermatophyte mold onychomycosis using the vehicle cream 30% dimethyl sulfoxide cream as control.

METHODS

This randomized controlled study was conducted between January 2019 and November 2020. Patients diagnosed with nondermatophyte mold onychomycosis were randomly divided into two groups of ten patients each: one treated with amphotericin B cream and the other with the vehicle cream. Clinical and mycological cure as well as safety were evaluated.

RESULTS

Ten patients each treated with amphotericin B cream and the vehicle cream were included in the study, but only nine patients in the vehicle cream group were available for follow up. All the 19 evaluable patients had distal lateral subungual onychomycosis and the great toenails were affected in 18 (94.7%) of these. Mycological cure was achieved in 8 (80%) patients treated with amphotericin B cream and in 4 (44.4%) patients using the control (vehicle) cream. Clinical cure was achieved in 7 (70%) patients treated with amphotericin B cream, but only in 2 (22.2%) patients on the control cream. No adverse events were observed.

LIMITATIONS

The small sample size and the fact that PCR fungal identification that provides accurate identification of fungal species was not performed are limitations of our study.

CONCLUSION

Topical amphotericin B cream was both very effective and safe in the treatment nondermatophyte mold onychomycosis. The control (vehicle) cream containing 30% dimethyl sulfoxide also demonstrated some antifungal activity.

Onychomycosis in older adults: The age and associated factors affecting the complete cure rate

BACKGROUND

Limited studies exist on the factors associated with a complete cure of onychomycosis in older adults.

OBJECTIVES

To determine the age and factors associated with a complete cure among older adults diagnosed with toenail onychomycosis.

METHODS

A retrospective cohort study was conducted of 95 older adult patients (aged ≥ 60 years) diagnosed with toenail onychomycosis between January 2016 and December 2017. Demographic data, mycological findings, treatments and durations to a complete cure were reviewed.

RESULTS

The complete cure rates of the patients aged < 70 years and ≥70 years were 67.4% and 44.9%, respectively (P = 0.027). Patients aged ≥ 70 years were significantly higher in male gender, had higher history of smoking, peripheral arterial disease, impaired renal function, antihypertensive drug and amorolfine nail lacquer usage, and polypharmacy. A multivariate analysis revealed that being aged ≥70 years and having a nail thickness >2 mm were associated with failure to achieve a complete cure. The median times to a complete cure for older adults aged <70 years and ≥70 years were 20 months and 47 months, respectively (P = 0.007).

CONCLUSIONS

An age ≥ 70 years was related to a lower cure rate and delays in achieving a complete cure. A nail thickness > 2 mm was a poor prognostic factor for a complete cure. Moreover, very old adults were more likely to suffer side effects arising from the use of systemic antifungal medications.

Predisposing factors, clinical features and treatment outcomes of Fusarium onychomycosis and comparison of its characteristics with Neoscytalidium onychomycosis

BACKGROUND

Fusarium spp. are common organisms causing onychomycosis. Research on the clinical presentations and treatment of this condition is limited.

OBJECTIVE

This study evaluated the demographic data, clinical characteristics, and treatment outcomes of Fusarium onychomycosis.

METHODS

A retrospective study was conducted at Siriraj Hospital, Thailand. Patients with onychomycosis, at least 2 repeated positive mycological cultures for Fusarium spp., and a photo at diagnosis (January 2014-December 2019) were included. Demographic data and clinical characteristics of Fusarium onychomycosis were analyzed and compared with those of Neoscytalidium onychomycosis, the other common nondermatophytes onychomycosis in tropical countries.

RESULTS

Seventeen patients with twenty-four nails were analyzed. Fusarium onychomycosis was significantly related to a history of pedicure (p = 0.04). Predominant lateral involvements of subungual hyperkeratosis onychomycosis, but without concurrent foot infections, were significantly found in Fusarium onychomycosis (p < 0.001 for each). Among the treatments, urea was 80% effective. Topical amphotericin B was 75% effective. Both amorolfine 5% nail lacquer and long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser were 66.7% effective. Lastly a combination of long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser and amorolfine 5% nail lacquer was 50% effective.

CONCLUSIONS

Important predisposing factors and clinical manifestations of Fusarium onychomycosis were a history of pedicure and predominant lateral-nail involvement, but no concomitant fungal foot infections. Topical treatment (urea cream, amphotericin B, or amorolfine nail lacquer) showed excellent outcomes.