Nosocomial outbreak of vanD-carrying vancomycin-resistant Enterococcus faecium

Development of an investigation form for hemodialysis infection outbreak: Identifying sources in the early stage

BACKGROUND

There are many infectious factors causing the outbreak of hemodialysis infection, which may easily lead to the delay of investigation and treatment. This study aimed to develop an investigation form for hemodialysis infection outbreak (HIO), and to identify sources of outbreak in early stage.

METHODS

After an exhaustive literature review, we used the Delphi method to determine the indicators and relative risk scores of the assessment tools through 2 rounds of specialist consultation and overall consideration of the opinions and suggestions of 18 specialists.

RESULTS

A total of 87 studies of HIOs were eligible for inclusion. The mean authority coefficient (Cr) was 0.89. Kendall's W coefficient of the specialist consultation was 0.359 after 2 rounds of consultation (P < .005), suggesting that the specialists had similar opinions. Based on 4 primary items and 13 secondary items of the source of HIO, and tripartite distribution characteristics of infected patients, we constructed the investigation form.

CONCLUSIONS

The investigation form may be implemented during the initial phase of an outbreak investigation, it is a prerequisite for taking effective control measures, avoiding HIO occurrence. However, the efficacy of the investigation form needs to be further evaluated.

Antibacterial, Antibiofilm, and Antioxidant Activities of Aqueous Crude Gymnema inodorum Leaf Extract against Vancomycin-Resistant Enterococcus faecium

Vancomycin-resistant Enterococcus faecium (VREF) causes nosocomial infections with high mortality and morbidity rates. This study aimed to evaluate the antibacterial and antibiofilm activities of aqueous crude Gymnema inodorum leaf extract (GIE) against the VREF ATCC 700221 strain. The antimicrobial activity of GIE against VREF was performed using disk diffusion and broth microdilution. The antibiofilm activities were evaluated using the crystal violet staining assay. The antioxidant potential was evaluated. Preliminary screening of the antimicrobial activity of 50 and 100 µg/disk of GIE against VREF revealed inhibition zones of 8.33 ± 0.58 mm and 8.67 ± 0.29 mm, respectively. Additionally, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against VREF were 125 and ≥ 250 mg/mL, respectively. SEM analysis showed that treatment with GIE caused morphological changes, including incomplete cell division, damaged cell walls, and cell content leakage, suggesting a disruption of bacterial cells. GIE also inhibited and eradicated biofilms formed by VREF. The extract exhibited antioxidant activities in the DPPH and ABTS assays. While GIE shows potential as an antibacterial and antibiofilm agent, further studies are necessary to fully understand the underlying mechanisms and optimize its use for therapeutic applications.

Enterococcus faecium Bacteriophage vB_EfaH_163, a New Member of the Herelleviridae Family, Reduces the Mortality Associated with an E. faecium vanR Clinical Isolate in a Galleria mellonella Animal Model

The rise of antimicrobial resistant (AMR) bacteria is a major health concern, especially with regard to members of the ESKAPE group, to which vancomycin-resistant (VRE) Enterococcus faecium belongs. Phage therapy has emerged as a novel alternative for the treatment of AMR infections. This, however, relies on the isolation and characterisation of a large collection of phages. This work describes the exploration of human faeces as a source of new E. faecium-infecting phages. Phage vB_EfaH_163 was isolated and characterised at the microbiological, genomic, and functional levels. vB_EfaH_163 phage, a new member of Herelleviridae, subfamily Brockvirinae, has a dsDNA genome of 150,836 bp that does not harbour any virulence factors or antibiotic resistance genes. It infects a wide range of E. faecium strains of different origins, including VRE strains. Interestingly, it can also infect Enterococcus faecalis strains, even some that are linezolid-resistant. Its capacity to control the growth of a clinical VRE isolate was shown in broth culture and in a Galleria mellonella animal model. The discovery and characterisation of vB_EfaH_163 increases the number of phages that might be used therapeutically against AMR bacteria.

Novel genomic islands and a new vanD-subtype in the first sporadic VanD-type vancomycin resistant enterococci in Norway

Background

Vancomycin-resistant enterococci (VRE) represent several types of transferable vancomycin resistance gene clusters. The vanD type, associated with moderate to high level vancomycin resistance, has only sporadically been described in clinical isolates. The aim of this study was to perform a genetic characterization of the first VanD-type VRE strains detected in Norway.

Methods

The VanD-type VRE-strains (n = 6) from two patient cases were examined by antimicrobial susceptibility testing and whole genome sequencing (WGS) to uncover Van-phenotype, strain phylogeny, the vanD gene clusters, and their genetic surroundings. The putative transferability of vanD was examined by circularization PCR and filter mating.

Results

The VanD-type Enterococcus faecium (n = 4) and Enterococcus casseliflavus (n = 2) strains recovered from two cases (A and B), expressed moderate to high level vancomycin resistance (MIC 64—>256 mg/L) and various levels of teicoplanin susceptibility (MIC 2—>256 mg/L). WGS analyses revealed phylogenetically different E. faecium strains (A1, A2, and A3 of case A and B1 from case B) as well as vanD gene clusters located on different novel genomic islands (GIs). The E. casseliflavus strains (B2 and B3 of case B) were not clonally related, but harbored nearly identical novel GIs. The vanD cluster of case B strains represents a novel vanD-subtype. All the vanD-GIs were integrated at the same chromosomal site and contained genes consistent with a Clostridiales origin. Circular forms of the vanD-GIs were detected in all strains except B1. Transfer of vanD to an E. faecium recipient was unsuccessful.

Conclusions

We describe the first VanD-type E. casseliflavus strains, a novel vanD-subtype, and three novel vanD-GIs with a genetic content consistent with a Clostridiales order origin. Despite temporal occurrence, case A and B E. faecium strains were phylogenetically diverse and harbored different vanD subtypes and vanD-GIs.

Emergence of vancomycin- and teicoplanin-resistant Enterococcus faecium via vanD5-harbouring large genomic island

BACKGROUND

Treatment of VRE is of clinical concern. While certain numbers of vanD-type VRE have been isolated, only two vanD5-harbouring Enterococcus faecium isolates have been reported in Canada and Japan.

METHODS

We report the isolation of vanD5-type E. faecium and the first ever determination of the whole-genome sequence to investigate the possible mechanisms of the acquisition of the vanD5 gene cluster in E. faecium.

RESULTS

Two vanD5-harbouring vancomycin-resistant E. faecium were isolated from the skin (SMVRE19) and faeces (SMVRE20) of a patient with a skin ulcer in Japan. The isolates exhibited vancomycin and teicoplanin MIC values of 128 mg/L, whilst the previous isolates of vanD5-harbouring E. faecium were only resistant to vancomycin. SMVRE19 and SMVRE20 were clones related to ST18, which is also seen in vanA- and vanB-type VRE. These isolates harboured an insertion element, ISEfm1, in the ddl gene, similar to a previously described teicoplanin-resistant vanD3-type E. faecium. The vanD5 gene cluster was integrated into the SMVRE20 chromosome as a part of a large genomic island (approximately 127 kb), similar to other recently spreading vanD variants in the Netherlands. The genomic island shared the greatest similarity with a part of the Blautia coccoides genome sequence, except for the region surrounding the vanD gene cluster.

CONCLUSIONS

This study reports that emergence of vancomycin- and teicoplanin-resistant vanD5-type E. faecium occurred via acquisition of the vanD5 cluster and ISEfm1 insertion into ddl. Considering the genetic similarity between the various VRE strains, the current study should serve as a warning against the spread of vanD5-type VRE.

First isolation and characterization of vancomycin-resistant Enterococcus faecium harboring vanD5 gene cluster recovered from a 79-year-old female inpatient in Japan

This study reports the first isolation and characterization of a vanD5 genotype vancomycin-resistant Enterococcus faecium strain (E. faecium IPHb306) recovered from a 79-year-old Japanese female inpatient. Species identification was determined by biochemical testing, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and species-specific PCR. Susceptibility tests indicated that E. faecium IPHb306 was resistant to vancomycin but susceptible to teicoplanin. Southern hybridization analyses indicated that E. faecium IPHb306 harbored a vanD5 gene cluster on chromosomal DNA. Growth curve analyses showed that a vancomycin resistance phenotype could be inducible. Sequencing analyses of the vanD5 gene cluster and the ddl_{E. faecium} gene demonstrated several point mutations were present. Because this strain belongs to ST203, a major hospital-adapted lineage, spread of the vanD5 genotype E. faecium ST203 is considered a clinical threat in Japan.