Solubilization in vitro of tea tree oil and first results of antifungal effect in onychomycosis

INTRODUCTION

Onychomycosis is the main cause of nail alteration. Hepatotoxicity, interference and low adherence to pharmacological treatment are associated. Therefore, our objective was to assess the in vitro effectiveness of tea tree essential oil (less harmful) against main causative agents of these infections.

MATERIAL AND METHODS

Thrichophyton rubrum and Thrichophyton mentagrophytes were isolated and inoculated at a concentration of 3 × 10⁵ CFU/mL in potato agar dextrose and tea tree essential oil at different concentrations to assess its effect by counting colony forming units and radial growth.

RESULTS

Trichophyton rubrum growth inhibition was obtained at concentrations higher than 0.04% of the essential tea tree oil (p = 0.004). In the case of Thrichophyton mentagrophytes, inhibition was obtained at 0.02% (p = 0.017), and even complete inhibition at a final concentration of the oil at 0.07%.

CONCLUSIONS

Tea tree essential oil inhibits the in vitro growth of the fungus and may be a less harmful alternative to the onychomycosis treatment.

Commercial real time PCR implementation for rapid diagnosis of onychomycosis: A new workflow in a clinical laboratory

INTRODUCTION

Onychomycosis is a frequent and underdiagnosed condition. Approximately 90% of toenail onychomycosis infections are caused by dermatophytes, but classical diagnosis based on culture and microscopy observation is slow and has low sensitivity. Both limitations can be solved incorporating molecular techniques to routine diagnosis of onychomycosis.

OBJECTIVE

Prospective evaluation of the utility of incorporating in the clinical laboratory workflow a commercial real time PCR (qPCR) for dermatophytes detection in nails after potassium hydroxide direct observation screening.

MATERIALS AND METHODS

152 nail samples were included (34 KOH negative and 118 KOH positive) and processed by culture and qPCR.

RESULTS

In the negative KOH group, only one dermatophyte grew in culture and three were detected by qPCR. In the group of positive KOH, 57 dermatophytes grew in culture and 81 were detected by qPCR. In this group, 25% of diagnosed dermatophytes were detected only by qPCR. The sensitivity of qPCR compared to culture is 92.8% and time of response decreases from days to hours.

CONCLUSION

Based in our results, we propose a workflow algorithm for a clinical laboratory that eliminates culture for qPCR positive samples.

Solubilization in vitro of tea tree oil and first results of antifungal effect in onychomycosis

INTRODUCTION

Onychomycosis is the main cause of nail alteration. Hepatotoxicity, interference and low adherence to pharmacological treatment are associated. Therefore, our objective was to assess the in vitro effectiveness of tea tree essential oil (less harmful) against main causative agents of these infections.

MATERIAL AND METHODS

Trichophyton rubrum and Trichophyton mentagrophytes were isolated and inoculated at a concentration of 3x105 CFU / mL in potato agar dextrose and tea tree essential oil at different concentrations to assess its effect by counting colony forming units and radial growth.

RESULTS

Trichophyton rubrum growth inhibition was obtained at concentrations higher than 0.04% of the essential tea tree oil (p = 0.004). In the case of Trichophyton mentagrophytes, inhibition was obtained at 0.02% (p = 0.017), and even complete inhibition at a final concentration of the oil at 0.07%.

CONCLUSIONS

Tea tree essential oil inhibits the in vitro growth of the fungus and may be a less harmful alternative to the onychomycosis treatment.

Commercial real time PCR implementation for rapid diagnosis of onychomycosis: A new workflow in a clinical laboratory

INTRODUCTION

Onychomycosis is a frequent and underdiagnosed condition. Approximately 90% of toenail onychomycosis infections are caused by dermatophytes, but classical diagnosis based on culture and microscopy observation is slow and has low sensitivity. Both limitations can be solved incorporating molecular techniques to routine diagnosis of onychomycosis.

OBJECTIVE

Prospective evaluation of the utility of incorporating in the clinical laboratory workflow a commercial real time PCR (qPCR) for dermatophytes detection in nails after potassium hydroxide direct observation screening.

MATERIALS AND METHODS

152 nail samples were included (34 KOH negative and 118 KOH positive) and processed by culture and qPCR.

RESULTS

In the negative KOH group, only one dermatophyte grew in culture and three were detected by qPCR. In the group of positive KOH, 57 dermatophytes grew in culture and 81 were detected by qPCR. In this group, 25% of diagnosed dermatophytes were detected only by qPCR. The sensitivity of qPCR compared to culture is 92.8% and time of response decreases from days to hours.

CONCLUSION

Based in our results, we propose a workflow algorithm for a clinical laboratory that eliminates culture for qPCR positive samples.

[Evaluation of the usefulness of nail biopsy in the diagnosis of onychomycosis]

BACKGROUND

Onychomycosis affects between 2% to 30% of the world population. Nail biopsy may help in making a diagnosis and can distinguish between invasion and colonisation.

AIMS

To evaluate the diagnostic usefulness of nail biopsy with Periodic acid-Schiff (PAS) staining for onychomycosis, compared to direct KOH examination, culture and its combination in a reference laboratory in Colombia.

METHODS

The study included 66 patients in whom a blind and independent reading of the three tests was performed. The usefulness was defined based on the validity (sensitivity, specificity, Youden's index, likelihood ratios), performance (predictive values) efficiency (proportion of correctly diagnosed patients), and reproducibility (kappa coefficient).

RESULTS

The mean age of the patients was 55±16 years, and included 76% women. The direct tests with KOH were positive in 66.7% (n=44), 62.1% (n=41) were positive with culture, and 56.1% (n=37) with the biopsy. The main causal agents were non-dermatophytes moulds in 36.4% (n=24). The most frequent species were Neoscytalidium dimidiatum (n=11), Trichophyton rubrum (n=11), and Candida parapsilosis (n=13). The sensitivity of nail biopsy, when compared to the standard (KOH and/or culture), was 71%, specificity 83%, Youden's index 0.54, positive likelihood ratio 4.25, negative likelihood ratio 0.35, positive predictive value 92%, negative predictive value 52%, efficiency 74% and kappa coefficient 0.45. When biopsy was evaluated only in patients with onycholysis of the nail plate greater than 50%, all the parameters of diagnostic usefulness increased.

CONCLUSIONS

The overall usefulness of the biopsy was moderate for patients with more severe symptomatology, which makes its use advisable in cases of extensive onycholysis, and when discriminating colonisation from invasion is required.

[Onychomycosis by yeast not common in diabetics of a health center]

BACKGROUND

Mexican diabetic population frequently presents mycosis under foot hyperkeratosis; however, in another type of onychomycosis as the ones that is assumed Candida albicans is the causal agent, it is unknown the frequency, the prevalence and if another Candida species or other yeasts are found.

OBJECTIVE

Evaluate the frequency of yeasts causing onychomycosis in diabetic patients looked after in public institutions of health of the State of Hidalgo, Mexico, and its association with clinical epidemiological variables.

MATERIALS AND METHODS

An observational, descriptive and transversal study was made on 261 patients, from which one nail sample of each one was obtained, used to isolate and identify dermatophytes and yeasts; the results were statistically correlated with 24 epidemiological parameters. The clinical study was done through interrogation and by medical exploration in order to evaluate Tinea pedis and onychomycosis.

RESULTS

Onychomycosis were caused by Candida guilliermondii, Candida parapsilosis, Candida glabrata, Candida krusei, Candida spp., Kodamaea ohmeri, Prototheca wickerhamii and unidentified yeasts. The prevalence for general onychomycosis, by dermatophytes, mixed onychomycosis and by yeasts were: 24.1, 19.5, 2.3 and 14.6%, respectively. Patients with significant probability to be diagnosed as having onychomycosis by yeasts are those wearing open shoes (2.59%); technicians and professionals (10.49%) and alcohol drinkers (3.72%).

CONCLUSION

The fact that Candida albicans is not present in this study as causal agent of onychomycosis, and emerging and non-common yeasts were indeed isolated, creates new challenges. It is remarked the clinical criterion that when onychomycosis is suspected in diabetics, the diagnosis for culturing dermatophytes and yeasts should be included.

[Isolation of Sporothrix pallida complex in clinical and environmental samples from Chile]

The isolation of S. pallida complex from medical samples and home garden soil of a patient in Chile is here in reported. Fungi of the Sporothrix schenckii complex can cause various infections. In Chile, the medical and environmental isolates of these this complex are rare. The aim of this study was to identify an unusual agent in a case of onychomycosis and to detect its presence in the patient's home garden. For this purpose, clinical samples were obtained by scraping the patient's subungueal first right toe nail as well as by taking soil samples from different areas of her home garden. Species identification was performed by morphophysiology and one of the strains isolated from the patient's toe nail was sent to CBS for molecular confirmation (14.062). S. pallida complex was identified both from the patient's toe nail and samples taken from her home garden.