The mutation of COL7A1 gene encoding type VII collagen resul
The mutation of COL7A1 gene encoding type VII collagen results in dystrophic epidermolysis bullosa (DEB). Severe recessive DEB (RDEB) is the classic form, and RDEB infants are typically born with widespread bulla and erosion and often caused by rubbing and scratching during birth. Severe atopic dermatitis (AD) patients also show scratching behavior causing erosion. In AD, the increasingly dominant species of skin bacteria is Staphylococcus aureus (S. aureus), accompanied by a decrease in filaggrin and natural moisturizing factor. RDEB and AD show similarities in skin condition and previous studies reported S. aureus as dominant species. The growth of S. aureus is known as a cause of exacerbation in AD patients; therefore, we considered that it is important to understand the distribution of superficial skin bacteria in patients with RDEB in Japan as a possible link to skin exacerbation.

A male infant delivered naturally presented with bulla and erosion on the whole body including the mouth at the time of his birth. The infant had nonconsanguineous parents with no family history of DEB. The bulla and erosion were managed using a soft fitting gauze with petrolatum ointment; he sometimes received intravenous antibiotics for frequent remission and exacerbation of the infection. His toes fused gradually owing to repeated inflammatory changes. The author performed a skin biopsy of the bulla and immunofluorescence mapping revealed an absence of type VII collagen. Based on these findings, the author made a diagnosis of severe RDEB. The mutation in the COL7A1 gene was not checked by the hope of parents. The infant grew to the age of two with the repeated occurrence of bulla, erosion, and scars accompanied by a secondary skin infection. Methicillin-resistant Staphylococcus aureus was always detected at any skin whether erosion or not since 37 days after birth. The author analyzed his skin microbiome using a wet swab from intact skin of the arm without bulla and erosion after obtaining informed consent from his parents. The author performed 16SrRNA analysis using the next-generation sequencer and identified 371 species in the investigated 2,200 species. S. aureus comprised approximately 33% of all bacterial species.