Patch testing with Indian standard series

Introduction

Until recently there was no standard patch test series for the Indian subcontinent. The Contact and Occupational Contact Dermatoses Forum of India has recommended the Indian Standard Series (ISS). The purpose of this study wss to find the frequency of sensitivity to its allergens and to recommend alterations if required.

Materials and Methods

Hundred patients (61 males, 39 females), between 1½ to 70 years with suspected allergic contact dermatitis were patch tested with ISS [Table - 1]. The allergens were obtained from Systopic Pharmaceuticals (P) Ltd., New Delhi. The standard patch testing technique using aluminium chambers was done and reactions were interpreted as recommended by ICDRG.

Results

Details of the 28 allergens and the number of patients with positive reactions are shown in [Table - 1]. The most frequent sensitizers observed were nickel sulphate-12 (15%), potassium dichromate-11(13.75%), neomycin sulphate-10 (12.5%), cobalt chloride and colophony-7(8.75%) each while benzocaine, formaldehyde, PEG-400, wool alcohol, ethylenediamine chloride, black rubber mix, 4TBPF resin and quarternium 15 showed reactions.

Discussion

Nickel was the most frequent sensitizer as reported by others.[1],[2],[3] Potassium dichromate was the next commonest sensitizer-11 (13.75%). Though its prevalence is decreasing, in developed countries,[4] it is still common in India as the construction industry is flourishing. Fragrance mix allergy formed a significant cause of contact dermatitis 6 (7.5%) in our study and may increase in the near future as more people are using perfumes and cosmetics.

Topical antibiotics and preservatives together accounted for 22 cases of contact dermatitis (27.5%) and is a major cause of iatrogenically induced dermatitis. In India many combination preparations such as a steroid with antibiotic, steroid with antifungal and even the combination of all the above three are available. These preparations are used for prolonged periods. A combination of antibiotic and steroid is used well after the infection has subsided or even on many an occasion when there is no bacterial infection to start with. This prolonged needless usage is possibly responsible for numerous cases of antibiotic sensitivity.[5],[6] Chlorocresol is included in ISS. This is the most commonest preservative used and we feel that it should be a part of any standard series.

Although parthenium sensitivity is quite rampant in India sesquiterpene lactone has not been included since

i) the diagnosis can most often be clinically made

ii) the reaction in the presence of sensitivity is at times severe enough to cause irritable back syndrome

iii) it must possible that the testing may precipitate the dermatitis in a person with subclinical sensitivity. ISS however can be extended with a plant series which is used whenever contact dermatitis to plants or parthenium is suspected.