Carbapenem-Resistant Enterobacter hormaechei ST1103 with IMP-26 Carbapenemase and ESBL Gene bla SHV-178.

PURPOSE: To investigate the occurrence and genetic characteristics of the bla IMP-26-positive plasmid from a multidrug-resistant clinical isolate, Enterobacter hormaechei L51. METHODS: Species identification was determined by MALDI-TOF MS and Sanger sequencing. Antimicrobial susceptibility testing was performed by the agar dilution and broth microdilution. Whole-genome sequencing was conducted using Illumina HiSeq 4000-PE150 and PacBio Sequel platforms, and the genome was annotated by the RAST annotation server. The ANI analysis of genomes was performed using OAT. Phylogenetic reconstruction and analyses were performed using the Harvest suite based on the core-genome SNPs of 61 publicly available E. hormaechei genomes. RESULTS: The E. hormaechei L51 genome consists of a 5,018,729 bp circular chromosome and a 343,918 bp conjugative IncHI2/2A plasmid pEHZJ1 encoding bla IMP-26 which surrounding genetic context was intI1-bla IMP-26-ltrA-qacE∆1-sul1. A new sequence type (ST1103) was assigned for the isolate L51 which was resistant to cephalosporins, carbapenems, but sensitive to piperacillin-tazobactam, amikacin, tigecycline, trimethoprim-sulfamethoxazole and colistin. Phylogenetic analysis demonstrated that E. hormaechei L51 belonged to the same subspecies as the reference strain E. hormaechei SCEH020042, however 18,248 divergent SNP were identified. Resistance genes in pEHZJ1 including aac(3)-IIc, aac(6') -IIc, bla SHV-178, bla DHA-1, bla TEM-1, bla IMP-26, ereA2, catII, fosA5, qnrB4, tet(D), sul1 and dfrA19. CONCLUSION: In our study, we identified a conjugative IncHI2/2A plasmid carrying bla IMP-26 and bla SHV-178 in E. hormaechei ST1103, a novel multidrug-resistant strain isolated from China, and describe the underlying resistance mechanisms of the strain and detailed genetic context of mega plasmid pEHZJ1.

Biochemical and genetic characterization of a novel metallo-ß-lactamase from marine bacterium Erythrobacter litoralis HTCC 2594.

Metallo-ß-lactamases (MBLs) are a group of enzymes that can inactivate most commonly used ß-lactam-based antibiotics. Among MBLs, New Delhi metallo-ß-lactamase-1 (NDM-1) constitutes an urgent threat to public health as evidenced by its success in rapidly disseminating worldwide since its first discovery. Here we report the biochemical and genetic characteristics of a novel MBL, ElBla2, from the marine bacterium Erythrobacter litoralis HTCC 2594. This enzyme has a higher amino acid sequence similarity to NDM-1 (56%) than any previously reported MBL. Enzymatic assays and secondary structure alignment also confirmed the high similarity between these two enzymes. Whole genome comparison of four Erythrobacter species showed that genes located upstream and downstream of elbla2 were highly conserved, which may indicate that elbla2 was lost during evolution. Furthermore, we predicted two prophages, 13 genomic islands and 25 open reading frames related to insertion sequences in the genome of E. litoralis HTCC 2594. However, unlike NDM-1, the chromosome encoded ElBla2 did not locate in or near these mobile genetic elements, indicating that it cannot transfer between strains. Finally, following our phylogenetic analysis, we suggest a reclassification of E. litoralis HTCC 2594 as a novel species: Erythrobacter sp. HTCC 2594.

Comparative genomic study of three species within the genus Ornithinibacillus, reflecting the adaption to different habitats.

In the present study, we report the whole genome sequences of two species, Ornithinibacillus contaminans DSM22953(T) isolated from human blood and Ornithinibacillus californiensis DSM 16628(T) isolated from marine sediment, in genus Ornithinibacillus. Comparative genomic study of the two species was conducted together with their close relative Ornithinibacillus scapharcae TW25(T), a putative pathogenic bacteria isolated from dead ark clam. The comparisons showed O. contaminans DSM22953(T) had the smallest genome size of the three species indicating that it has a relatively more stable habitat. More stress response and heavy metal resistance genes were found in the genome of O. californiensis DSM 16628(T) reflecting its adaption to the complex marine environment. O. scapharcae TW25(T) contained more antibiotic resistance genes and virus factors in the genome than the other two species, which revealed its pathogen potential.

Isolation and characterization of a crude oil degrading bacteria from formation water: comparative genomic analysis of environmental Ochrobactrum intermedium isolate versus clinical strains.

In this study, we isolated an environmental clone of Ochrobactrum intermedium, strain 2745-2, from the formation water of Changqing oilfield in Shanxi, China, which can degrade crude oil. Strain 2745-2 is aerobic and rod-shaped with optimum growth at 42 °C and pH 5.5. We sequenced the genome and found a single chromosome of 4 800 175 bp, with a G+C content of 57.63%. Sixty RNAs and 4737 protein-coding genes were identified: many of the genes are responsible for the degradation, emulsification, and metabolizing of crude oil. A comparative genomic analysis with related clinical strains (M86, 229E, and LMG3301(T)) showed that genes involved in virulence, disease, defense, phages, prophages, transposable elements, plasmids, and antibiotic resistance are also present in strain 2745-2.

Nontuberculous mycobacterial osteomyelitis.

Osteomyelitis caused by nontuberculous mycobacteria (NTM) can have severe consequences and a poor prognosis. Physicians therefore need to be alert to this condition, especially in immunocompromised patients. Although the pathogenesis of NTM osteomyelitis is still unclear, studies in immunodeficient individuals have revealed close relationships between NTM osteomyelitis and defects associated with the interleukin-12-interferon-γ-tumor necrosis factor-α axis, as well as human immunodeficiency virus infection, various immunosuppressive conditions, and diabetes mellitus. Culture and species identification from tissue biopsies or surgical debridement tissue play crucial roles in diagnosing NTM osteomyelitis. Suitable imaging examinations are also important. Adequate surgical debridement and the choice of appropriate, combined antibiotics for long-term anti-mycobacterial chemotherapy, based on in vitro drug susceptibility tests, are the main therapies for these bone infections. Bacillus Calmette-Guerin vaccination might have limited prophylactic value. The use of multiple drugs and long duration of treatment mean that the therapeutic process needs to be monitored closely to detect potential side effects. Adequate duration of anti-mycobacterial chemotherapy together with regular monitoring with blood and imaging tests are key factors determining the recovery outcome in patients with NTM osteomyelitis.

Administration of Lactobacillus salivarius LI01 or Pediococcus pentosaceus LI05 improves acute liver injury induced by D-galactosamine in rats.

This work investigated the effect of the intragastric administration of five lactic acid bacteria from healthy people on acute liver failure in rats. Sprague-Dawley rats were given intragastric supplements of Lactobacillus salivarius LI01, Lactobacillus salivarius LI02, Lactobacillus paracasei LI03, Lactobacillus plantarum LI04, or Pediococcus pentosaceus LI05 for 8 days. Acute liver injury was induced on the eighth day by intraperitoneal injection of 1.1 g/kg body weight D-galactosamine (D-GalN). After 24 h, samples were collected to determine the level of liver enzymes, liver function, histology of the terminal ileum and liver, serum levels of inflammatory cytokines, bacterial translocation, and composition of the gut microbiome. The results indicated that pretreatment with L. salivarius LI01 or P. pentosaceus LI05 significantly reduced elevated alanine aminotransferase and aspartate aminotransferase levels, prevented the increase in total bilirubin, reduced the histological abnormalities of both the liver and the terminal ileum, decreased bacterial translocation, increased the serum level of interleukin 10 and/or interferon-γ, and resulted in a cecal microbiome that differed from that of the liver injury control. Pretreatment with L. plantarum LI04 or L. salivarius LI02 demonstrated no significant effects during this process, and pretreatment with L. paracasei LI03 aggravated liver injury. To the best of our knowledge, the effects of the three species-L. paracasei, L. salivarius, and P. pentosaceus-on D-GalN-induced liver injury have not been previously studied. The excellent characteristics of L. salivarius LI01 and P. pentosaceus LI05 enable them to serve as potential probiotics in the prevention or treatment of acute liver failure.