Project description:Investigation of whole genome gene expression level changes in a Gluconacetobacter xylinus NBRC 3288 delta-fnrG mutant, compared to the wild-type strain.
Project description:Atlantibacter hermannii, previously known as Escherichia hermannii, is a rare causative agent of human infections. Several reports testify that the most frequently infected patients are immunosuppressed, especially those undergoing hemodialysis. A 34-year-old man with an end-stage renal disease complained of chills, fever, and general fatigue at the end of a regular hemodialysis session. The echocardiographic examination showed vegetation located on the dialysis catheter in the right atrium. Empirical therapy was initiated with intravenous gentamicin, and after the isolation of the agent, the treatment was continued with intravenous imipenem/cilastatin. The blood cultures and the tip of the replaced catheter were positive for A. hermannii, identified by Vitek 2 Compact. Verification of the automated identification was performed using 16S sequencing. The 16S sequence product was used to query the NCBI bacterial database and revealed 99.75% identity to that of A. hermannii strain CIP 103176 16S ribosomal RNA in the NCBI GenBank database. The antimicrobial susceptibility results revealed resistance to aminopenicillins and susceptibility to all other tested antimicrobials. To our knowledge, this is the first report of catheter-related vegetation with echocardiographic confirmation and the successful eradication of A. hermannii infection in a patient undergoing hemodialysis with imipenem/cilastatin.
Project description:The differential expression of VIM-1 in Atlantibacter hermannii WEB-2 and Enterobacter hormaechei ssp. hoffmannii WEB-1 clinical isolates from a rectal swab of a hospitalized patient in France was investigated. A. hermannii WEB-2 was resistant to all β-lactams except carbapenems. It produced ESBL SHV-12, but the Carba NP test failed to detect any carbapenemase activity despite the production of VIM-1. Conversely, E. hormaechei WEB-1, previously recovered from the same patient, was positive for the detection of carbapenemase activity. The bla VIM-1 gene was located on a plasmid and embedded within class 1 integron. Both plasmids were of the same IncA incompatibility group and conferred the same resistance pattern when electroporated in Escherichia coli TOP10 or Enterobacter cloacae CIP7933. Quantitative RT-PCR experiments indicated a weaker replication of pWEB-2 in A. hermannii as compared to E. hormaechei. An isogenic mutant of A. hermannii WEB-2 selected after sequential passages with increased concentrations of imipenem possessed higher MICs for carbapenems and cephalosporins including cefiderocol, higher levels of the bla VIM-1 gene transcripts, and detectable carbapenemase activity using the Carba NP test. Assessment of read coverage demonstrated that a duplication of the region surrounding bla VIM-1 gene occurred in the A. hermannii mutant with detectable carbapenemase activity. The lack of detection of the VIM-1 carbapenemase activity in A. hermannii WEB-2 isolate was likely due to a weak replication of the IncA plasmid harboring the bla VIM-1 gene. Imipenem as selective pressure led to a duplication of this gene on the plasmid and to the restoration of a significant carbapenem-hydrolyzing phenotype.
