Background Coronary artery disease (CAD) is associated with gut microbiota alterations in different populations. Gut microbe-derived metabolites have been proposed as markers of major adverse cardiac events. However, the relationship between the gut microbiome and the different stages of CAD pathophysiology remains to be established by a systematic study. Results Based on multi-omic analyses (sequencing of the V3-V4 regions of the 16S rRNA gene and metabolomics) of 161 CAD patients and 40 healthy controls, we found that the composition of both the gut microbiota and metabolites changed significantly with CAD severity. We identified 29 metabolite modules that were separately classified as being positively or negatively correlated with CAD phenotypes, and the bacterial co-abundance group (CAG) with characteristic changes at different stages of CAD was represented by Roseburia , Klebsiella , Clostridium IV and Ruminococcaceae . The result revealed that certain bacteria might affect atherosclerosis by modulating the metabolic pathways of the host, such as taurine, sphingolipid and ceramide, and benzene metabolism. Moreover, a disease classifier based on differential levels of microbes and metabolites was constructed to discriminate cases from controls and was even able to distinguish stable coronary artery disease from acute coronary syndrome accurately. Conclusion Overall, the composition and functions of the gut microbial community differed from healthy controls to diverse coronary artery disease subtypes. Our study identified the relationships between the features of the gut microbiota and circulating metabolites, providing a new direction for future studies aiming to understand the host–gut microbiota interplay in atherosclerotic pathogenesis. Electronic supplementary material The online version of this article (10.1186/s40168-019-0683-9) contains supplementary material, which is available to authorized users.

The genetic basis for fluoroquinolone resistance was examined in 30 high-level fluoroquinolone-resistant Escherichia coli clinical isolates from Beijing, China. Each strain also demonstrated resistance to a variety of other antibiotics. PCR sequence analysis of the quinolone resistance-determining region of the topoisomerase genes (gyrA/B, parC) revealed three to five mutations known to be associated with fluoroquinolone resistance. Western blot analysis failed to demonstrate overexpression of MarA, and Northern blot analysis did not detect overexpression of soxS RNA in any of the clinical strains. The AcrA protein of the AcrAB multidrug efflux pump was overexpressed in 19 of 30 strains of E. coli tested, and all 19 strains were tolerant to organic solvents. PCR amplification of the complete acrR (regulator/repressor) gene of eight isolates revealed amino acid changes in four isolates, a 9-bp deletion in another, and a 22-bp duplication in a sixth strain. Complementation with a plasmid-borne wild-type acrR gene reduced the level of AcrA in the mutants and partially restored antibiotic susceptibility 1.5-to 6-fold. This study shows that mutations in acrR are an additional genetic basis for fluoroquinolone resistance.Fluoroquinolones are powerful broad-spectrum antimicrobial agents used for the treatment of a wide variety of community-acquired and nosocomial infections (35,45). However, resistance to fluoroquinolones has increased markedly since their introduction in the late 1980s (1,7,26,32,39,44,49). In Beijing from 1997 to 1999, approximately 60% of Escherichia coli strains isolated from hospital-acquired infections and 50% of the E. coli strains isolated from the community were resistant to ciprofloxacin. Of those fluoroquinolone-resistant strains, 80% exhibited ciprofloxacin MICs of Ͼ32 g/ml (references 54 and 61 and unpublished data). These findings contrast with much lower frequencies in other parts of the world.Mechanisms of fluoroquinolone resistance fall into two principal categories: alterations in drug targets (e.g., DNA gyrase or topoisomerase IV) (12,19,34,52) and decreased cellular accumulation of quinolones involving the major multidrug efflux pump, AcrAB (23, 37). Mutations causing quinolone resistance occur primarily in a highly conserved region (the quinolone resistance-determining region [QRDR]) of DNA gyrase and topoisomerase IV (9,19,25,37,52,55,59,60). Other secondary mechanisms, such as those that affect the regulatory gene marA (multiple antibiotic resistance) (9, 10) or soxS (superoxide) (2), generally cause decreased expression of the OmpF porin (11) and overexpression of the AcrAB efflux pump (40). These porin and pump changes lead to resistance not only to the quinolones but also to a number of structurally unrelated compounds (2,10,40).In this study, we sought to determine whether the regulatory genes (marA, soxS, acrR), in addition to the structural genes (gyrA/B, parC), contained mutations which contribute to the high-level fluoroquinolone resistance of clinical E. coli isolates fr...

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) has been increasing yearly at Peking Union Medical College Hospital (PUMCH). In order to understand the molecular evolution of MRSA at PUMCH, a total of 466 nonduplicate S. aureus isolates, including 302 MRSA and 164 methicillin-susceptible (MSSA) isolates recovered from 1994 to 2008 were characterized by staphylococcal cassette chromosome mec (SCCmec) typing, spa typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). The 302 MRSA isolates were classified into 12 spa types and 9 sequence types (STs). During the years from 1994 to 2000, the most predominant MRSA clone was ST239-MRSA-III-spa t037. Since 2000, ST239-MRSA-III-spa t030 has rapidly replaced t037 and become the major clone. Another clone, ST5-MRSA-II-spa t002 emerged in 2002 and constantly existed at a low prevalence rate. The 164 MSSA isolates were classified into 62 spa types and 40 STs. ST398 was the most common MLST type for MSSA, followed by ST59, ST7, ST15, and ST1. Several MSSA genotypes, including ST398, ST1, ST121, and ST59, were identical to well-known epidemic community-acquired MRSA (CA-MRSA) isolates. MLST eBURST analysis revealed that the ST5, ST59, and ST965 clones coexisted in both MRSA and MSSA, which suggested that these MRSA clones might have evolved from MSSA by the acquisition of SCCmec. Two pvl-positive ST59-MRSA-IV isolates were identified as CA-MRSA according to the clinical data. Overall, our data showed that the ST239-MRSA-III-spa t037 clone was replaced by the emerging ST239-MRSA-III-spa t030 clone, indicating a rapid change of MRSA at a tertiary care hospital in China over a 15-year period.