A Novel Contrast Stain for the Rapid Diagnosis of Pityriasis Versicolor: A Comparison of Chicago Sky Blue 6B Stain, Potassium Hydroxide Mount and Culture

Chicago sky blue gel for better visualization of Demodex in patients with Demodex blepharitis

Background

Demodex blepharitis is a common chronic disease. The number of mites is associated with ocular discomfort. The accurate number derived from well-stained specimens is, hence, in favor of diagnosing, monitoring, and determining treatment responses.

Methods

A cross-sectional study was conducted between April and July 2022 at the dermatology and ophthalmology clinic, Walailak University, Thailand. Adult participants with clinical suspicion of Demodex blepharitis were recruited. We examined eyelashes under light microscopy to quantify the number of Demodex mites before and after adding CSB gel. The mite counts, evaluated by an untrained investigator and an experienced investigator, were recorded and compared.

Results

A total of 30 participants were included for final analysis, among which 25 (83.3%) were female. The median age was 64.0 years (IQR, 61.0-68.0). The median Demodex counts evaluated by the experienced investigator before and after adding CSB gel were 1.0 (IQR, 0.0-1.0) and 2.5 (IQR, 2.0-3.0), respectively (p < 0.001). Moreover, the median Demodex counts evaluated by the untrained investigator before and after adding CSB gel were 1.0 (IQR, 0.0-1.0) and 2.0 (IQR, 1.0-3.0), respectively (p < 0.001). The correlation coefficient between Demodex counts after the addition of CSB counted by the experienced investigator and those counted by the untrained investigator was 0.92 (p < 0.001). CSB gel is a promising product to identify and quantify the number of Demodex mites. The findings supported the consideration of CSB gel as one of the diagnostic stains.

Use of Potassium Hydroxide in Dermatology Daily Practice: A Local Study From Saudi Arabia

Introduction

Potassium hydroxide (KOH) is an inorganic keratolytic test. It is considered one of the most worldwide methods used in the dermatological field with reasonable reliability and sensitivity. One of its major uses is in identifying fungal elements in the skin, hair, nails, and different body secretions. In this study, we aimed to identify the prevalence of KOH usage in different hospitals in the Al-Ahsa region, Saudi Arabia. Additionally, we aimed to identify the dermatological conditions in which KOH is being used and practiced by physicians.

Methods

This was an anonymous questionnaire-based cross-sectional study that was distributed and carried out among dermatologists in Al-Ahsa city in the Eastern province of Saudi Arabia.

Results

A total of 30 dermatologists completed the study questionnaire. Participants’ ages ranged from 29 to 59 years old with a mean age of 39.5 ± 11.4 years old. 14 (46.7%) dermatologists reported that the KOH test is available in their clinic. Using KOH once a day was reported among 14.3% while 21.4% used it once a week. The most reported condition for KOH use was hair dermatophytes (100%).

Conclusion

There is a clear lack of usage and availability of KOH in clinics. The shortage of availability of diagnostic tools, including KOH might affect the diagnosis of several diseases and may cause a waste of resources, wrong prescriptions, and patient’s burden.

Evaluation Of The Efficacy Of Fluorescent Staining And Chicago Sky Blue Staining As Methods For Diagnosis Of Dermatophytosis In Hair And Nails

Purpose

Dermatophytes are fungi that cause infections affecting hair, nail, and skin; in nails they cause onychomycosis, while in hair they lead to tinea capitis. Detection of dermatophytes using traditional methods, including potassium hydroxide (KOH) and culture on agar-based media leads to high rates of false-negative results. Here, we investigated more accurate diagnostic techniques, including Chicago sky blue staining and Calcofluor white fluorescent staining and compared them with traditional KOH and culture methods for the diagnosis of fungi causing onychomycosis and tinea capitis.

Patients and methods

This study was conducted using samples from 50 patients with dermatophytosis of the hair or nail. Samples were subjected to all the following laboratory investigations: KOH wet mount, culture on Sabouraud's dextrose agar, Chicago sky blue staining, and Calcofluor white staining. The results of the new diagnostic techniques were compared with those of the traditional methods.

Results

Calcofluor white stain and Chicago sky blue stain for dermatophytosis of hair and nail are more specific and sensitive as compared to traditional diagnostic methods. KOH wet mount is simple, rapid, and inexpensive test but lacks color contrast and gave more false positive (artifacts) and false-negative results as compared to these new stain methods.

Conclusion

Chicago sky blue and Calcofluor white staining are excellent methods for diagnosis of fungal infections, including those that cannot be confirmed using conventional methods.

A Novel Contrast Stain for the Rapid Diagnosis of Dermatophytoses: A Cross-Sectional Comparative Study of Chicago Sky Blue 6B Stain, Potassium Hydroxide Mount and Culture

Background

The current upsurge of complicated dermatophytosis in India and other parts of the world has necessitated the development of rapid and accurate diagnostic techniques. Conventional methods such as potassium hydroxide (KOH) mount lack color contrast and require a trained eye, whereas fungal culture is laborious and costly. Chicago sky blue 6B (CSB) a new contrast stain promises to be a reliable and rapid diagnostic method. It contains 1% CSB stain and is used with 10% KOH as clearing agent.

Aims and Objectives

The objective of this study is to compare the efficacy of a novel contrast stain (CSB) and KOH mount in the diagnosis of dermatophytoses with culture as the reference method.

Methods

The infected skin scrapings, nail clippings, and hair specimens from 100 patients, with clinically diagnosed dermatophytoses, were subjected to KOH mount, CSB stain, and culture on Sabouraud's dextrose agar. Using fungal culture as the reference standard, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CSB stain and KOH mount were determined. An inter-rater reliability analysis was performed using the Cohen's κ statistic to determine agreement amongst the different diagnostic modalities.

Results

Of the 100 cases, the CSB stain and KOH mount were positive in 85 (85%) and 70 (70%) cases, respectively. Cultures on Sabouraud's agar yielded growth in 59 (59%) cases. The sensitivity, specificity, PPV, NPV, and accuracy of CSB stain were 98%, 34%, 68%, 93%, and 72%, respectively. The same for KOH mount were 71%, 32%, 60%, 43%, and 55%, respectively.

Conclusion

CSB stain is a simple, rapid, sensitive, accurate, and inexpensive office-based method with qualitatively superior demonstration of dermatophytes compared to KOH mount.

A comparison of conventional rapid methods in diagnosis of superficial and cutaneous mycoses based on KOH, Chicago sky blue 6B and calcofluor white stains

BACKGROUND AND OBJECTIVES

Rapid confirmation of dermatomycoses is desirable, as it allows the clinicians to initiate appropriate therapy immediately. In this study, the utility of a novel contrast stain, Chicago sky blue stain, was compared with potassium hydroxide mount and calcofluor white stain to determine the causative fungal elements in the rapid detection method.

MATERIALS AND METHODS

In this survey, 189 samples of suspected dermatomycosis infections were assessed in 3 incubation times of 30 minutes, 2 hours, and > 6 hours.

RESULTS

Positive cases were shown in Chicago sky blue 6B (55%), calcofluor white (53.4%), and potassium hydroxide (36%), with 30-minute incubation. Positive results increased in other incubation times. Sensitivity, specificity, PPV, NPV and accuracy of Chicago sky blue 6B were 97%, 100%, 100%, 96% and 98% and, for potassium hydroxide, they were 66%, 98%, 97%, 98%, 80% versus CFW, respectively.

CONCLUSION

This study provides evidence that the Chicago sky blue 6B stain is a simple, fast and cost-effective method.