Objective To determine whether erythromycin-resistant propionibacteria isolated from patients with acne in Wuhan city harbor 23S rRNA gene mutations as well as the transposon Tn5432 carrying ermX genes.Methods Twenty-nine Propionibacterium strains isolated from outpatients with acne in Wuhan city were included in this study.The E-test method was used to determine the susceptibility of these strains to erythromycin and clindamycin.PCR was performed to amplify the 23S rRNA,ermX,ermX (cj),IS1249a and IS1249b genes from resistant strains followed by DNA sequencing and nucleotide alignment.Results Among the 29 Propionibacterium strains,19 were identified as P.acnes and 10 as P.avidum.All of these Propionibacterium strains were resistant to erythromycin (MIC ＞ 256 μg/ml) and clindamycin (MIC ＞ 256 μg/ml),except for 3 P.acnes strains sensitive to clindamycin.Seven P.acnes strains resistant to both antibiotics exhibited an A→G transition at a position cognate with Escherichia coli 23S rRNA 2058.An A→G transition at a position cognate with E.coli 23S rRNA 2059 was identified in one clindamycin-resitant and three clindamycin-sensitive P.acnes isolates.The ermX gene was found in the remaining 8 P.acnes isolates and 2 P.avidum isolates,with the sequence 100％ identical to the reference sequence of the ermX gene of P.acnes in Genbank.Meanwhile,the ermX (cj) gene was successfully amplified from the other 8 P.avidum isolates,which showed 99％ sequence homology with the ermX (cj) gene of Corynebacterium jeikeium,but 94％ homology with the ermX gene of P.acnes in Genbank.Both IS1249a and IS1249b genes were amplified in the 10 ermX gene-positive Propionibacterium strains,but not in the other ermX gene-negative strains.Conclusions The erythromycin resistance in Propionibacterium isolates from Wuhan city may be associated with the A→G transition at the E.coli equivalent bases 2058 and 2059 of the 23S rRNA gene,as well as the presence of the erm X (transferred through the transposon Tn5432) and ermX (c j) genes.

Objective:To investigate the effect of different delivery and feeding modes on intestinal microflora in infants with atopic dermatitis (AD) .Methods:A total of 33 infants with AD were enrolled from Department of Dermatology, Wuhan NO.1 Hospital from July 2019 to December 2020, and 30 healthy infants were selected as control group. Then, all infants were grouped according to different delivery and feeding modes: cesarean-delivery AD group (22 cases) , cesarean-delivery control group (19 cases) , spontaneous-delivery AD group (11 cases) , and spontaneous-delivery control group (11 cases) ; mixed-feeding AD group (13 cases) , mixed-feeding control group (11 cases) , formula milk powder-feeding AD group (12 cases) , formula milk powder-feeding control group (11 cases) , breastfeeding AD group (8 cases) , and breastfeeding control group (12 cases) . The total DNA was extracted from the infant feces, PCR was performed to amplify the V1 - V9 regions of bacterial 16S rRNA gene, and PacBio Sequel sequencer was used for high-throughput sequencing. Wilcoxon rank sum test was used to compare the bacterial community composition at genus and species levels, and correlations of relative abundance of differentially abundant bacterial taxa with eosinophil counts and SCORing Atopic Dermatitis (SCORAD) scores were analyzed.Results:In the spontaneous-delivery control group, cesarean-delivery control group, spontaneous-delivery AD group, and cesarean-delivery AD group, the top 5 bacterial genera with high relative abundance were Bifidobacterium, Bacteroides, Veillonella, Streptococcus, and Escherichia. In the formula milk powder-feeding control group, breastfeeding control group, mixed-feeding control group, formula milk powder-feeding AD group, breastfeeding AD group, and mixed-feeding AD group, the top 5 abundant bacterial genera were Bifidobacterium, Bacteroides, Clostridium, Veillonella, and Escherichia. Linear discriminant analysis of effect size (LEfSe) showed no significant difference in the relative abundance of bacterial taxa among different delivery mode groups; among different feeding mode groups, Akkermansia and Akkermansiamuciniphila were the most differentially abundant microbes in the formula milk powder-feeding AD group at genus (LDA = 4.78) and species (LDA = 4.91) levels, respectively. The relative abundance of Akkermansia and Akkermansiamuciniphila (both 9.6% ± 0.72%) was significantly higher in the formula milk powder-feeding AD group than in the formula milk powder-feeding control group (both 2.50% ± 0.83%, Z = 1.66, P = 0.048) , the mixed-feeding AD group (both 0, Z = 2.26, P = 0.012) and the breastfeeding AD group (both 0, Z = 1.85, P = 0.032) . Additionally, the relative abundance of Akkermansia and Akkermansia- muciniphila was positively correlated with SCORAD scores in AD patients ( ρ = 0.384, 0.387, respectively, both P < 0.05) . Conclusion:Different delivery modes did not significantly affect the intestinal flora of AD or healthy infants, and the relative abundance of Akkermansia and Akkermansiamuciniphila increased in the formula milk powder-feeding infants with AD, which may be involved in the occurrence of AD.