DOI: http://dx.doi.org/10.18203/issn.2455-4529.IntJResDermatol20221635

Diagnostic utility of Chicago sky blue stain in superficial dermatophytosis

Agni Kumar Bose, Vidya Kharkar, Shashir Wanjare, Gita Nataraj, Apama Thirumalaiswamy

Abstract


Background: Dermatophyte infections are one of the commonest presentations to a dermatology OPD. The clinical lesions are highly variable and closely resemble other skin diseases, thus it is important to confirm one’s diagnosis using rapid, cheap methods.

Methods: Skin scrapings from the lesions of 352 suspected cases of dermatophytosis were subjected to KOH mount and KOH with Chicago sky blue (CSB) stain for direct microscopic examination and culture using Sabouraud’s dextrose agar (SDA). Taking the culture as the gold standard method for diagnosis, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of KOH mount and CSB staining method was calculated. Kappa statistics were used to determine the degree of congruence between the various diagnostic methods.

Results: Direct microscopy with CSB stain, KOH mount and mycological culture showed positive results in 251 (71.3%), 227 (64.5%) and 292 (82.9%) patients, respectively. Cohen’s Kappa was used to see the agreement between KOH mount and culture (Kappa=0.09) which was statistically significant (p<0.05) at 95% CI. CSB staining and Culture (Kappa=0.09) also showed negligible agreement (Kappa=0.09) which was statistically significant (p<0.05). CSB staining and KOH mount showed substantial agreement (Kappa=0.8) which statistically significant (p<0.05).

Conclusions: The addition of CSB stain to KOH provides a colour contrast that highlights the fungal elements well, making interpretation easy which increases the overall diagnostic accuracy. CSB stain is inexpensive, easily available and provides a rapid method to diagnose dermatophytosis.


Keywords


CSB, Culture, Dermatophytosis, Potassium hydroxide mount

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References


Superficial Mycoses: Dermatophytosis. Infectious Disease Advisor. 2019. Available at: https://www.infectiousdiseaseadvisor.com/home/decision-support-in-medicine/infectious-diseases/superficial-mycoses-dermatophytosis/. Accessed on 2021 Nov 26.

Kalita J, Goyal G, Kumar P, Misra UK. Intracerebral hemorrhage in young patients from a tertiary neurology center in North India. J Neurol Sci. 2014;336(1-2):42-7.

Kalita JM, Sharma A, Bhardwaj A, Nag VL. Dermatophytoses and spectrum of dermatophytes in patients attending a teaching hospital in Western Rajasthan, India. J Fam Med Prim Care. 2019;8(4):1418-21.

Poojary S, Lodha N. A novel contrast stain for the rapid diagnosis of pityriasis versicolor: A comparison of Chicago Sky Blue 6B stain, potassium hydroxide mount and culture. Indian J Dermatol. 2015;60(4):340.

Sentamilselvi G, Kamalam A, Ajithadas K, Janaki C, Thambiah AS. Scenario of chronic dermatophytosis: an Indian study. Mycopathologia. 1998;140(3):129-35.

Verma SB, Panda S, Nenoff P, Singal A, Rudramurthy SM, Uhrlass S, et al. The unprecedented epidemic-like scenario of dermatophytosis in India: I. Epidemiology, risk factors and clinical features. Indian J Dermatol Venereol Leprol. 2021;87(2):154-75.

Hanumanthappa H, Sarojini K, Shilpashree P, Muddapur SB. Clinicomycological study of 150 cases of dermatophytosis in a tertiary care hospital in South India. Indian J Dermatol. 2012;57(4):322-3.

Gandhi S, Patil S, Patil S, Badad A. Clinicoepidemiological study of dermatophyte infections in pediatric age group at a tertiary hospital in Karnataka. Indian J Paediatr Dermatol. 2019;20(1):52.

Nenoff P, Verma SB, Vasani R, Burmester A, Hipler U-C, Wittig F, et al. The current Indian epidemic of superficial dermatophytosis due to Trichophyton mentagrophytes-A molecular study. Mycoses. 2019;62(4):336-56.

Lim S-L, Lim CS-H. New contrast stain for the rapid diagnosis of pityriasis versicolor. Arch Dermatol. 2008;144(8):1058-9.

Tambosis E, Lim C. A comparison of the contrast stains, Chicago blue, chlorazole black, and Parker ink, for the rapid diagnosis of skin and nail infections. Int J Dermatol. 2012;51(8):935-8.