Etiology, Infections and Laboratory characteristics of Pemphigus Vulgaris: beyond the dermatopathology

Introduction: Pemphigus vulgaris, a dermatological affliction is an organ-specific autoimmune bullous disease. Infections are important complications in these patients due to the disease itself and immunosuppression. Staphylococcus aureus is an important etiology carrying large repertoire of virulence factors, to establish and maintain infections. Methods: This prospective study was performed on 47 in-patients from February to August 2018. The clinical specimens sent were subjected to bacteriological culture, gram staining, and isolation of the pathogen followed by antibiotic susceptibility test. S aureus was detected phenotypically, confirmed by PCR and subjected to the presence of virulence factors. The organisms were divided into 2 groups according to corresponding WBC count determined as per Low power field (LPF) for each lesion.Results: The clinical presentation comprised of pemphigus vulgaris (PV) (n= 35), bullous pemphigoid (n= 5), and one case each of erythema multiforme and mycosis fungoides with septicemia. Among PV patients, urinary tract (n=3), bacteremia/septicemia (n=2) and skin infections (n=30) were disclosed as chief infections. The bacterial etiology composed of S.aureus (n= 26) followed by P. aeruginosa (n=2), E.coli (n=3), Enterobacter spp. (n=1), A.baumannii (n=1) and K.pneumoniae (n=2). Nineteen S.aureus isolates (non-repetitive) were methicillin sensitive (MSSA) while, 3 were MRSA. Five isolates were found resistant to erythromycin and clindamycin, with 2 D test positive. All were sensitive to vancomycin. S.aureus capable of producing exfoliative toxin A (ETA) and exfoliative toxin B (ETB) were associated with infections with low WBC counts, while Panton-Valentine leukocidin (PVL) positive allied with high WBC counts. Conclusion: Pemphigus vulgaris, leading autoimmune skin disorder had S.aureus as chief etiology. Though S.aureus have the potential to express a number of immunomodulating factors, however, low WBCs count in the lesions requires further analysis with large group of bacterial isolates.