Abstract Background Since 2012, the incidence of vancomycin-resistant Enterococcus faecium (VREfm) has increased dramatically in Copenhagen and vanA E. faecium has become endemic and polyclonal. Objectives To examine whether a patient with a positive VRE clinical sample had the same VREfm in a preceding screening sample (within 60 days). Methods We performed a 30 month retrospective study. From our laboratory information system (LIS), we identified all patients with an invasive VREfm isolate and a VREfm rectal screening isolate within 60 days before infection. VREfm pairs (screening isolate and invasive isolate) were whole-genome sequenced. All isolates were analysed using SeqSphere and core-genome MLST (cgMLST) types were determined. We examined all isolates for the presence of the three most dominant vanA plasmids in the Capital Region of Denmark. Two novel vanA plasmids were closed by Nanopore/Illumina sequencing. Results We found a total of 19 VREfm pairs. Of these, 13 patients had pairs with matching cgMLST types and vanA plasmids and a median number of 6 days from identification of carriage to clinical infection. One patient had a pair with non-matching cgMLST types but matching vanA plasmids and 24 days between identification of carriage to clinical infection. Five patients had pairs with non-matching cgMLST types and non-matching vanA plasmids and a median number of 18 days from identification of carriage to clinical infection. Conclusions Of our 19 pairs, 13 were a match regarding cgMLST types (68%) and 1 more (5%) had matching vanA plasmids. Infection was thus preceded by colonization with the same isolates in 13 out of 19 patients. The five mismatches (26%) could be explained by the longer interval between colonization and infection.
In enterococci, resistance to linezolid is often mediated by mutations in the V domain of the 23S rRNA gene (G2576T or G2505A). Furthermore, four genes [optrA, cfr, cfr(B) and poxtA] encode linezolid resistance in enterococci. We aimed to develop a Web tool for detection of the two mutations and the four genes encoding linezolid resistance in enterococci from whole-genome sequence data. LRE-Finder (where LRE stands for linezolid-resistant enterococci) detected the fraction of Ts in position 2576 and the fraction of As in position 2505 of the 23S rRNA and the cfr, cfr(B), optrA and poxtA genes by aligning raw sequencing reads (fastq format) with k-mer alignment. For evaluation, fastq files from 21 LRE isolates were submitted to LRE-Finder. As negative controls, fastq files from 1473 non-LRE isolates were submitted to LRE-Finder. The MICs of linezolid were determined for the 21 LRE isolates. As LRE-negative controls, 26 VRE isolates were additionally selected for linezolid MIC determination. LRE-Finder was validated and showed 100% concordance with phenotypic susceptibility testing. A cut-off of 10% mutations in position 2576 and/or position 2505 was set in LRE-Finder for predicting a linezolid resistance phenotype. This cut-off allows for detection of a single mutated 23S allele in both Enterococcus faecalis and Enterococcus faecium, while ignoring low-level sequencing noise. A Web tool for detection of the 23S rRNA mutations (G2576T and G2505A) and the optrA, cfr, cfr(B) and poxtA genes from whole-genome sequences from enterococci is now available online.
We describe clonal shifts in vanA Enterococcus faecium isolates from clinical samples obtained from patients in Denmark from 2015 to the first quarter (Q1) of 2019. During Q1 2019, the vancomycin-variable enterococci (VVE) ST1421-CT1134 vanA E. faecium became the most dominant vanA E. faecium clone and has spread to all five regions in Denmark. Among 174 E. faecium isolates with vanA, vanB or vanA/vanB genes in Q1 2019, 44% belonged to this type.
Transmission of livestock-associated Staphylococcus aureus clonal complex 9 (LA-SA CC9) between pigs raised on industrial hog operations (IHOs) and humans in the United States is poorly understood. We analyzed whole-genome sequences from 32 international S. aureus CC9 isolates and 49 LA-SA CC9 isolates from IHO pigs and humans who work on or live near IHOs in 10 pig-producing counties in North Carolina, USA. Bioinformatic analysis of sequence data from the 81 isolates demonstrated 3 major LA-SA CC9 clades. North Carolina isolates all fell within a single clade (C3). High-resolution phylogenetic analysis of C3 revealed 2 subclades of intermingled IHO pig and human isolates differing by 0-34 single-nucleotide polymorphisms. Our findings suggest that LA-SA CC9 from pigs and humans share a common source and provide evidence of transmission of antimicrobial-resistant LA-SA CC9 between IHO pigs and humans who work on or live near IHOs in North Carolina.
Background Carbapenemase-producing Escherichia coli are increasing worldwide. In recent years, an increase in OXA-244-producing E. coli isolates has been seen in the national surveillance of carbapenemase-producing organisms in Denmark. Aim Molecular characterisation and epidemiological investigation of OXA-244-producing E. coli isolates from January 2016 to August 2019. Methods For the epidemiological investigation, data from the Danish National Patient Registry and the Danish register of civil registration were used together with data from phone interviews with patients. Isolates were characterised by analysing whole genome sequences for resistance genes, MLST and core genome MLST (cgMLST). Results In total, 24 OXA-244-producing E. coli isolates were obtained from 23 patients. Among the 23 patients, 13 reported travelling before detection of the E. coli isolates, with seven having visited countries in Northern Africa. Fifteen isolates also carried an extended-spectrum beta-lactamase gene and one had a plasmid-encoded AmpC gene. The most common detected sequence type (ST) was ST38, followed by ST69, ST167, ST10, ST361 and ST3268. Three clonal clusters were detected by cgMLST, but none of these clusters seemed to reflect nosocomial transmission in Denmark. Conclusion Import of OXA-244 E. coli isolates from travelling abroad seems likely for the majority of cases. Community sources were also possible, as many of the patients had no history of hospitalisation and many of the E. coli isolates belonged to STs that are present in the community. It was not possible to point at a single country or a community source as risk factor for acquiring OXA-244-producing E. coli .
The aim of the study was to molecularly characterize third-generation cephalosporin-resistant Klebsiella pneumoniae isolated from bloodstream infections in Denmark in 2018 using whole-genome sequencing (WGS) data, and to compare these isolates to the most common clones detected in 2006 and 2008. Sixty-two extended-spectrum beta-lactamase (ESBL)/AmpC-producing K. pneumoniae isolates from Danish blood cultures from 2018 were analysed using WGS to obtain multilocus sequence typing (MLST), core genome MLST (cgMLST), resistance profile and phylogeny. These were compared to the most common ESBL K. pneumoniae clones detected in 2006 and 2008. The most common ESBL clone was ST15 CTX-M-15, the DHA-1 enzyme was the most common in AmpC isolates, and the OXA-48-like group was the most common carbapenemase. Thirty-nine different sequence types (STs) were found, with the most frequent being ST14, ST15 and ST37, accounting for 24% of the isolates. The isolates were subdivided into 55 complex types (CTs) of which 49 were singletons, with the most frequent being ST14-CT2080. Two of the CTX-M-15-producing isolates from 2018 belonged to the ST15-CT105/CT3078 clone, which was first detected in 2006. The ESBL/AmpC K. pneumoniae isolates detected in Danish blood cultures belonged to many different types. No dominant clones were circulating in Danish hospitals, but the ST15-CT105/CT3078 CTX-M-15 K. pneumoniae clone was seen 13 years after its first detection.
We unexpectedly identified MRSA isolates carrying mecC (mecC-MRSA) from a Danish swine farm located in eastern Zealand. The objective of the present study was to investigate the origin of these isolates and their genetic relatedness to other mecC-MRSA isolates from Zealand. WGS was used to infer the phylogenetic relationship between 19 identified mecC-MRSA isolates from the swine farm and 34 additional epidemiologically unrelated human isolates from the same geographical region of Denmark. Variations in the accessory genome were investigated by bioinformatics tools, and antibiotic susceptibility profiles were assessed by MIC determination. mecC-MRSA was isolated from a domestic swine farm, but not from cattle reared at the same farm. Phylogenetic analysis revealed that all mecC-MRSA isolates from both farm animals and workers formed a separate cluster, whereas human isolates from the same municipality belonged to a closely related cluster. Analysis of the accessory genome supported this relationship. To the best of our knowledge, this is the first report of mecC-MRSA isolated from domestic swine. The investigation strongly indicates that transmission of mecC-MRSA has taken place on the swine farm between the farmers and swine. The close clustering of farm isolates and isolates from the same municipality suggests a local transmission of mecC-MRSA.
