Immunization and Bacterial Pathogens in the Oropharynx as Risk Factors for Alopecia Areata

Abstract Introduction Alopecia areata is an autoimmune inflammatory disease affecting the hair follicles. Researchers are currently interested in whether the presence of bacterial pathogens and/or a history of immunization can trigger an autoimmune response in patients who are genetically predisposed. Objective This study aimed to determine whether there is an association between the development of alopecia areata and throat carriage of bacterial pathogens or a history of immunization. Material and methods Sixty-five men and women with alopecia areata and 65 control patients with other skin diseases were studied at the Dr Ladislao de la Pascua Dermatology Clinic between September 2008 and February 2009. The patients ranged in age from 18 to 59 years. Patients with scalp diseases were excluded from the control group. In all cases, the patient was questioned about immunizations received in the previous 6 months, and a throat swab was cultured. Results A history of immunization (odds ratio [OR], 3.3; 1.6% confidence interval [CI], 1.6-6.7; P =.001), the presence of bacterial pathogens in the oropharynx (OR, 2.6; 95% CI, 1.1-6.2; P =.033), and being a carrier of Streptococcus pyogenes (OR, 2.1; 95% CI, 1.7-2.5; P =.042) were risk factors for alopecia areata. Klebsiella pneumoniae, S pyogenes, Pseudomonas aeruginosa, Streptococcus pneumoniae, Serratia marcescens and Escherichia coli were isolated from cultures. Conclusions This is the first study to show an association between alopecia areata and throat carriage of bacterial pathogens or history of immunization, as risk factors for development of the disease. Given the characteristics of our study population, the association appears valid for patients with less than 25% hair loss and a course of disease under 1 year.