Fig. 1

Characteristics of the oral microbiome in patients with CCA. a The Shannon index [(3.61 ± 0.05) vs. (2.86 ± 0.05), P < 0.001] and Simpson index [(0.06 ± 0.003) vs. (0.14 ± 0.01), P < 0.001] showed that the α-diversity of the oral microbial community was significantly increased in CCA group compared with HC group. b The PCoA showed that the samples of the CCA and HC groups were obviously separated in the direction of the PC2 axis and PC3 axis, showing that the overall oral microbial composition was different between the CCA and HC groups. c A Venn diagram based on microbial OTUs illustrated that 469 of the 540 OTUs were shared between the CCA group and HC group, and it is worth noting that 34 OTUs were exclusive to the CCA group. d At the phylum level, 8 phyla including Firmicutes, Fusobacteriota, Campilobacterota, Spirochaetota, Cyanobacteria, Synergistota, Desulfobacterota and Chloroflexi were significantly increased in CCA group, and 3 phyla covering Bacteroidota, Actinobacteriota and unclassified Bacteria were enriched in the HC group (P < 0.05). e At the genus level, 36 genera were identified as the genera with significant differences between the two groups (P < 0.05), the top 10 with the highest abundance were displayed, among which Streptococcus, Veillonella, Haemophilus, Leptotrichia, Granulicatella, Capnocytophaga and Alloprevotella were enriched in the CCA group, and Rothia, Actinomyces and Peptostreptococcus were enriched in the HC group. PCoA principal co-ordinates analysis, OTUs operational taxonomy units, CCA cholangiocarcinoma, HC healthy control