Dataset Information

Determination of a Tentative Epidemiological Cut-Off Value (ECOFF) for Dalbavancin and Enterococcus faecium.

ABSTRACT: Dalbavancin is a lipoglycopeptide antibiotic that shows potent activity against Gram-positive bacteria. It circumvents vanB-type glycopeptide resistance mechanisms; however, data on the in vitro activity of dalbavancin for Enterococcus faecium (E. faecium) are scarce, and thus, no breakpoints are provided. In recent years, there has been a continuing shift from vanA-type to vanB-type vancomycin-resistance in enterococci in Central Europe. Therefore, we aimed to investigate the in vitro activity of dalbavancin against different van-genotypes, with particular focus on vanB-type E. faecium. Dalbavancin susceptibility was determined for 25 van-negative, 50 vanA-positive, and 101 vanB-positive clinical E. faecium isolates (typed by cgMLST). Epidemiological Cut-Off Values (ECOFFs) were determined using ECOFFinder. For vanB-type E. faecium isolates, dalbavancin MICs were similar to those of vancomycin-susceptible isolates reaching values no higher than 0.125 mg/L. ECOFFs for van-negative and vanB-positive isolates were 0.5 mg/l and 0.25 mg/L respectively. In contrast, E. faecium possessing vanA predominantly showed dalbavancin MICs >8 mg/L, therefore preventing the determination of an ECOFF. We demonstrated the potent in vitro activity of dalbavancin against vancomycin-susceptible and vanB-type E. faecium. On the basis of the observed wildtype distribution, a dalbavancin MIC of 0.25 mg/L can be suggested as a tentative ECOFF for E. faecium.

SUBMITTER: Weber RE

PROVIDER: S-EPMC8388697 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Determination of a Tentative Epidemiological Cut-Off Value (ECOFF) for Dalbavancin and Enterococcus faecium.

Weber Robert E RE Fleige Carola C Layer Franziska F Neumann Bernd B Kresken Michael M Werner Guido G

Antibiotics (Basel, Switzerland) 20210727 8

Dalbavancin is a lipoglycopeptide antibiotic that shows potent activity against Gram-positive bacteria. It circumvents vanB-type glycopeptide resistance mechanisms; however, data on the in vitro activity of dalbavancin for Enterococcus faecium (E. faecium) are scarce, and thus, no breakpoints are provided. In recent years, there has been a continuing shift from vanA-type to vanB-type vancomycin-resistance in enterococci in Central Europe. Therefore, we aimed to ...[more]

PMID: 34438965

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Project description:From 2015 onwards, the number of vancomycin-resistant Enterococcus faecium (VREfm) isolates increased in Tasmania. Previously, we examined the transmission of VREfm at the Royal Hobart Hospital (RHH). In this study, we performed a state-wide analysis of VREfm from Tasmania's four public acute hospitals. Whole-genome analysis was performed on 331 isolates collected from screening and clinical specimens of VREfm. In silico multi-locus sequence typing (MLST) was used to determine the relative abundance of broad sequence types (ST) across the state. Core genome MLST (cgMLST) was then applied to identify potential clades within the ST groupings followed by single-nucleotide polymorphic (SNP) analysis. This work revealed that differences in VREfm profiles are evident between the state's two largest hospitals with the dominant vanA types being ST80 at the RHH and ST1421 at Launceston General Hospital (LGH). A higher number of VREfm cases were recorded at LGH (n = 54 clinical, n = 122 colonization) compared to the RHH (n = 14 clinical, n = 67 colonization) during the same time period, 2014-2016. Eleven of the clinical isolates from LGH were vanA and belonged to ST1421 (n = 8), ST1489 (n = 1), ST233 (n = 1), and ST80 (n = 1) whereas none of the clinical isolates from the RHH were vanA. For the recently described ST1421, cgMLST established the presence of individual clusters within this sequence type that were common to more than one hospital and that included isolates with a low amount of SNP variance (≤16 SNPs). A spatio-temporal analysis revealed that VREfm vanA ST1421 was first detected at the RHH in 2014 and an isolate belonging to the same cgMLST cluster was later collected at LGH in 2016. Inclusion of isolates from two smaller hospitals, the North West Regional Hospital (NRH) and the Mersey Community Hospital (MCH) found that ST1421 was present in both of these institutions in 2017. These findings illustrate the spread of a recently described sequence type of VREfm, ST1421, to multiple hospitals in an Australian state within a relatively short time span.

Project description:Enterococcus faecium clinical isolates A902 and BM4538, which were resistant to relatively high levels of vancomycin (128 and 64 microg/ml, respectively) and to low levels of teicoplanin (4 microg/ml), and Enterococcus faecalis clinical isolates BM4539 and BM4540, which were resistant to moderate levels of vancomycin (16 microg/ml) and susceptible to teicoplanin (0.25 microg/ml), were studied. They were constitutively resistant by synthesis of peptidoglycan precursors ending with d-alanyl-d-lactate and harbored a chromosomal vanD gene cluster which was not transferable by conjugation to other enterococci. VanX(D) activity, which is not required in the absence of d-Ala-d-Ala, was low in the four strains, although none of the conserved residues was mutated; and the constitutive VanY(D) activity in the membrane fractions was inhibited by penicillin G. The mutations E(13)G in the region of d-alanine:d-alanine ligase (which is implicated in d-Ala1 binding in A902) and S(319)N of the serine involved in ATP binding in BM4538 and a 7-bp insertion at different locations in BM4539 and BM4540 (which led to putative truncated proteins) led to the production of an impaired enzyme and accounted for the lack of d-Ala-d-Ala-containing peptidoglycan precursors. The same 7-bp insertion in vanS(D) of BM4539 and BM4540 and a 1-bp deletion in vanS(D) of A902, which in each case led to a putative truncated and presumably nonfunctional protein, could account for the constitutive resistance. Strain BM4538, with a functional VanS(D), had a G(140)E mutation in VanR(D) that could be responsible for constitutive glycopeptide resistance. This would represent the first example of constitutive van gene expression due to a mutation in the structural gene for a VanR transcriptional activator. Study of these four additional strains that could be distinguished on the basis of their various assortments of mutations confirmed that all VanD-type strains isolated so far have mutations in the ddl housekeeping gene and in the acquired vanS(D) or vanR(D) gene that lead to constitutive resistance to vancomycin.

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Project description:Enterococci are among the leading causes of hospital-acquired infections in the United States and Europe, with Enterococcus faecalis and Enterococcus faecium being the two most common species isolated from enterococcal infections. In the last decade, the proportion of enterococcal infections caused by E. faecium has steadily increased compared to other Enterococcus species. Although the underlying mechanism for the gradual replacement of E. faecalis by E. faecium in the hospital environment is not yet understood, many studies using genotyping and phylogenetic analysis have shown the emergence of a globally dispersed polyclonal subcluster of E. faecium strains in clinical environments. Systematic study of the molecular epidemiology and pathogenesis of E. faecium has been hindered by the lack of closed, complete E. faecium genomes that can be used as references.In this study, we report the complete genome sequence of the E. faecium strain TX16, also known as DO, which belongs to multilocus sequence type (ST) 18, and was the first E. faecium strain ever sequenced. Whole genome comparison of the TX16 genome with 21 E. faecium draft genomes confirmed that most clinical, outbreak, and hospital-associated (HA) strains (including STs 16, 17, 18, and 78), in addition to strains of non-hospital origin, group in the same clade (referred to as the HA clade) and are evolutionally considerably more closely related to each other by phylogenetic and gene content similarity analyses than to isolates in the community-associated (CA) clade with approximately a 3-4% average nucleotide sequence difference between the two clades at the core genome level. Our study also revealed that many genomic loci in the TX16 genome are unique to the HA clade. 380 ORFs in TX16 are HA-clade specific and antibiotic resistance genes are enriched in HA-clade strains. Mobile elements such as IS16 and transposons were also found almost exclusively in HA strains, as previously reported.Our findings along with other studies show that HA clonal lineages harbor specific genetic elements as well as sequence differences in the core genome which may confer selection advantages over the more heterogeneous CA E. faecium isolates. Which of these differences are important for the success of specific E. faecium lineages in the hospital environment remain(s) to be determined.

Project description:Enterococcus faecium has become a major opportunistic pathogen with the emergence of multidrug-resistant clones that are well-adapted to the hospital environment. As part of the vast diversity of gut microbiota, they are faced with different environmental stress, including antimicrobial pressure. By contrast, little is known about the effect of non-antibiotic molecules on bacterial physiology while numerous drugs are used in inpatients, especially those hospitalized in intensive care units (ICUs). The aim of this study was to investigate the impact of the most prescribed xenobiotics in ICUs on fitness, pathogenicity and antimicrobial resistance of E. faecium. Several phenotypic analysis was carried out and we rapidly brought to light that caspofungin, an antifungal agent belonging to the echinocandin family, seemed to have an important impact on E. faecium growth. Since the fungal target of caspofungin [beta-(1,3)-glucan synthase] is absent in enterococci, the mechanism of caspofungin action was investigated by several approaches. First, we decided to confirm this result by electronic microscopy and a peptidoglycan analysis by Ultra Performance Liquid Chromatography coupled with mass spectrometry (UPLC-MS/MS). Again, we highlighted that caspofungin even at subinhibitory concentrations (SICs) seemed to have an impact on cell wall organization especially in muropeptide precursors abundance. Then, a transcriptomic analysis was performed by RNA-seq (HiSeq 2500, Illumina) using the vanB-positive reference strain E. faecium Aus0004 in the presence or absence of caspofungin SIC (8 mg/L i.e., ¼ of the MIC). Transcriptomic analysis showed that the expression of 568 genes (19.9% of the genome) was significantly altered in the presence of caspofungin SIC, with 323 genes induced (fold change >2, p-value <0.1) and 245 genes repressed (fold change <-2, p-value <0.1). Regarding the repressed genes, the pdhABCD operon is largely downregulated (fold changes -4.3, -9.7, -6.9 and -6.4, respectively). This operon encoded components of the pyruvate deshydrogenase multienzyme complex involved in bacterial energetic pathway by the citrate cycle (i.e., TCA cycle). Moreover, it seemed that the glycerol metabolism pathway and in particular the glpOKF operon is downregulated too. The dramatic alteration of TCA seemed to have an drastic impact on bacterial cells viability indeed decrease of glycerol metabolism could explain the conformational modifications of peptidoglycan.

Dataset Information

Determination of a Tentative Epidemiological Cut-Off Value (ECOFF) for Dalbavancin and Enterococcus faecium.

Publications

Determination of a Tentative Epidemiological Cut-Off Value (ECOFF) for Dalbavancin and <i>Enterococcus faecium</i>.

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