SUMMARYThe phylogenetic and epidemic relationships of 104 clinical isolatesof Clostridium difficilefrom three hospitals of different geographical and population sources in China were investigated by multilocus sequence typing. Twenty-two sequence types (STs) were identified, four of which, ST117, ST118, ST119 and ST129, were novel. No geographically specific and host population-specific phylogenetic lineages were found and there was no correlation between geographical origin or host population and strain genotype. ST37 was the dominant type in our survey but the four novel STs underline the high genetic diversity and unique polymorphisms inC. difficilefrom China.

28Objective: Hospital environment has been implicated in enrichment and exchange of 29 pathogens and antibiotic resistances, but its potential in shaping the symbiotic microbial 30 community of the hospital staff is unclear. This study was designed to evaluate the 31 alteration of gut microbiome in medical workers compared to non-medical controls. 32 Design: Prospective cross-sectional cohort study. 33 Setting: Intensive care unit (ICU) and other departments from a center in northeast 34 China. 35 Subjects: 175 healthy medical workers (1-3 months short-term workers, n = 80; >1 year 36 long-term workers, n = 95) and 80 healthy normal controls. 37 Interventions: None. 38 Measurements and Main Results: Fecal samples of all subjects were analyzed using the 39 16S rRNA gene sequencing. Medical workers exhibited remarkable deviation in gut 40 microbial within-sample diversity and enterotypes stratification, and shift in overall 41 microbial structure. Short-term workers were significantly more abundant in taxa 42 including Lactobacillus, Butyrivibrio, Clostridiaceae_Clostridium, Ruminococcus, 43 Dialister, Bifidobacterium, Odoribacter and Desulfovibrio, and with lower abundances of 44 Bacteroides and Blautia compared with the controls. While long-term workers were 45 enriched in taxa including Dialister, Veillonella, Clostridiaceae_Clostridium, Bilophila, 46