The skin microbiome of wound scars and unaffected skin in patients with moderate to severe burns in the subacute phase.

Although studies on skin microbiome of acute and chronic wounds abound, evidence on newly built microbial communities of subacute wounds remains scant. To characterize the skin microbiome of recently healed (scarred) burn wounds in relation to unaffected skin surfaces, we collected weekly swabs from patients with moderate to severe burns in the 3rd postburn month for 4 weeks in 2015. We performed skin type (moist, dry, and oily)-matched comparisons within six burn patients (43 pairs of swabs) and with 13 skin-healthy, control patients (22 pairs of samples) using 16S ribosomal RNA gene sequencing results. Results of comparative microbiome analysis showed that, there were no substantial variations in the microbial abundance (all p > 0.05) or composition (all p > 0.01, adjusted for multiple comparisons) between samples obtained from wound scars and those from unaffected surfaces of burn patients. Nor did we find significant temporal dynamics in microbial richness or diversity in burn samples (all p ≥ 0.05). However, samples from burn patients harbored more Firmicutes (median: 25.6%, interquartile range [IQR]: 14.3%-52.8%) than those of control patients (14.9%, IQR: 6.7%-27.0%; p: 0.016), even after adjusting for host age, sex, and skin type-matching (p: 0.026). The number of observed bacterial operational taxonomic units at the genus level was reduced in burn patients (median: 62, IRQ: 32-85) as compared to control patients (median: 128, IQR: 112-136; age-, skin type-adjusted p < 0.01). Meanwhile, estimates of community diversity and evenness for surveyed body sites of burn patients were higher than those of control patients (all adjusted p ≤ 0.05). With a much-reduced bacterial burden and a relative overgrowth of Staphylococcus spp., the skin microbiota of burn patients remained dysbiotic in the subacute phase as compared to that of skin-normal patients.