Biology subjects

Bernhoff, E.

Publications and source records attributed to Bernhoff, E..

4 recordsLinked to original sources

bioRxiv2025

A One Health study of Klebsiella pneumoniae species complex plasmids shows a highly diverse and ecologically adaptable plasmidome

Plasmids play a pivotal role in the horizontal gene transfer of antimicrobial resistance (AMR) and virulence determinants among bacteria. Members of the Klebsiella pneumoniae species complex (KpSC) can colonise humans, animals, and various environments, and frequently cause nosocomial and community-acquired infections in humans. While plasmid-borne AMR genes are prevalent in clinical strains, the diversity, distribution, and association of plasmids encoding AMR and virulence across ecological niches remain poorly characterised. Understanding the traits governing successful plasmid transmission within and between ecological niches is critical for developing effective AMR prevention strategies. Here, we characterise the diversity and distribution of KpSC plasmids and identify potential niche associations of AMR, heavy metal resistance, virulence factors, and plasmid clusters. We analysed the plasmidome (i.e. total genetic content attributable to plasmids) of 578 whole-genome sequenced KpSC isolates collected in Norway between 2001-2020 from human (n=453), terrestrial animal (n=102), and marine (n=23) sources. Plasmids from complete hybrid assemblies were annotated and clustered to evaluate the plasmid diversity and content across niches. Additionally, the representativeness of this plasmid collection was determined by clustering with a global collection of 8656 circularised KpSC plasmids. In total, 1415 circularised plasmids were identified and grouped according to rearrangement distance using Pling, resulting in 130 clusters (containing >1 plasmid), of which 36% (n=47) contained plasmids from >1 niche. The plasmids exhibited significant diversity, as 37% (n=524) remained singletons after clustering. AMR and virulence genes existed across diverse clusters and singletons, but predominantly resided on 120-250 kbp conjugative or mobilisable plasmids harbouring various transposable elements. The human niche exhibited a significantly higher prevalence of plasmids with AMR genes compared to animal or marine niches (p<0.001), whereas the animal niche displayed a significantly higher prevalence of virulence-encoding plasmids compared to human or marine niches (p<0.001), which was largely due to an enrichment of iuc3 plasmids in pigs. The high diversity of the KpSC plasmids underscores the dynamic nature of plasmid evolution, driven by horizontal gene transfer, and selective pressures. The presence of variable clusters, marked by high genetic diversity, indicates a dynamic plasmidome capable of rapid adaptation to environmental pressures through the acquisition and rearrangement of accessory genes.

microbiology↗

bioRxiv2024

A genome-wide One Health study of Klebsiella pneumoniae in Norway reveals overlapping populations but few recent transmission events across reservoirs

Members of the Klebsiella pneumoniae species complex (KpSC) are opportunistic pathogens that cause severe and difficult-to-treat infections. KpSC are common in non-human niches, but the clinical relevance of these populations is disputed. Utilising 3,255 whole-genome sequenced isolates from human, animal and marine sources collected during 2001-2020 in Norway, we showed the KpSC populations in different niches were distinct but overlapping. Notably, human infection isolates showed greatest connectivity with each other, followed by isolates from human carriage, pigs, and bivalves. Nearly 5% of human infection isolates had close relatives ([≤]22 substitutions) amongst animal and marine isolates, despite temporally and geographically distant sampling of these sources. Infection prevention measures are essential to limit transmission within human clinical settings and reduce disease burden. However, as colonisation often precedes infection, preventing transmission that leads to colonisation, e.g. transmission between animals and humans in the community, and in the food chain, could also be beneficial.

microbiology↗

bioRxiv2022

Within-patient and global evolutionary dynamics of Klebsiella pneumoniae ST17

Klebsiella pneumoniae sequence type (ST) 17 is a global problem clone that causes multidrug-resistant (MDR) hospital infections worldwide. In 2008-2009, an outbreak of MDR ST17 occurred at a neonatal intensive care unit (NICU) in Stavanger, Norway. Fifty-seven children were colonised. We observed intestinal persistence of ST17 in all of the children for up to two years after hospital discharge. Here, we investigated the within-host evolution of ST17 in 45 of those children during long-term colonisation and compared the outbreak with 254 global strains. Ninety-two outbreak-related isolates were whole-genome sequenced. They had capsule locus KL25, O locus O5 and carried yersiniabactin. During within-host colonisation ST17 remained stable with few single nucleotide polymorphisms, no acquisition of antimicrobial resistance (AMR) or virulence determinants, and persistent carriage of a blaCTX-M-15-encoding IncFII(K) IncFIB(K) plasmid (pKp2177_1). The global collection included ST17 from 1993-2020 from 34 countries, that were from human infection (41.3%), colonisation (39.3%) and respiratory specimens (7.3%), from animals (9.3%), and from the environment (2.7%). We estimate that ST17 emerged mid-to-late 19th century (1859, 95% HPD 1763-1939) and diversified through recombinations of the K and O loci to form several sublineages, with various AMR genes, virulence loci and plasmids. There was limited evidence of persistence of AMR genes in any of these lineages. A globally disseminated sublineage with KL25/O5 accounted for 52.7% of the genomes. It included a monophyletic subclade that emerged in the mid-1980s, which comprised the Stavanger NICU outbreak and 10 genomes from three other countries, which all carried pKp2177_1. The plasmid was also observed in a KL155/OL101 subclade from the 2000s. Three clonal expansions of ST17 were identified, all were healthcare-associated and carried either yersiniabactin and/or pKp2177_1. To conclude, ST17 is globally disseminated and associated with opportunistic hospital-acquired infections. It contributes to the burden of global MDR infections, but many diverse lineages persist without acquired AMR. We hypothesise that non-human sources and human colonisation may play a crucial role for severe infections in vulnerable patients, such as preterm neonates. Impact statementKlebsiella pneumoniae is an opportunistic pathogen that frequently causes hospital-associated multidrug-resistant (MDR) infections. Infections with K. pneumoniae strains that are resistant to third generation cephalosporins and/or carbapenems are considered a major public health threat, as there are limited treatment options available. Some MDR K. pneumoniae clones, including ST307 and ST258, are global problem clones because they disproportionately contribute to the burden of MDR infections and are common causes of such infections and/or outbreaks in hospitals around the world. Here we describe another such clone, ST17, which caused an MDR outbreak in our neonatal intensive care unit, affecting 57 children. We found that this clone underwent minor within-host evolution during two years of long-term gastrointestinal colonisation after hospital discharge. We then investigated the evolutionary history of ST17 globally, as it had not previously been studied. When we compared ST17 isolates from around the world with the isolates from our hospital, we discovered that whilst ST17 with antimicrobial resistance has contributed to outbreaks in other neonatal care units, it also frequently causes infections or colonises humans and non-human sources without any antimicrobial resistance. Data summaryThe genome sequences generated in this study have been deposited at the European Nucleotide Archive under BioProject PRJEB36392. The BioSample accession numbers and associated metadata for the genomes are available in Table S1. The completed annotated genome assembly of Kp2177 is available in GenBank under accession numbers CP075591 (chromosome), CP075592 (pKp2177_1), CP075593 (pKp2177_2) and CP075594 (pKp2177_3). The global dataset of 300 ST17 genomes is available for interactive viewing in Microreact at https://microreact.org/project/kpst17.

microbiology↗

bioRxiv2021

A nationwide genomic study of clinical Klebsiella pneumoniae in Norway 2001-2015: Introduction and spread of ESBL facilitated by CG15 and CG307

SynopsisO_ST_ABSObjectiveC_ST_ABSWe have used the nationwide Norwegian surveillance program on resistant microbes in humans (NORM) to address longitudinal changes in the population structure K. pneumoniae isolates during 2001-15, encompassing the emergence and spread of ESBL-producing Enterobacterales (ESBL-E) in Norway. Material and methodsAmong blood (n= 6124) and urinary tract (n=5496) surveillance isolates from 2001-15, we used Illumina technology to whole genome sequence 201 ESBL-producing isolates from blood (n=130) and urine (n=71), and 667 non-ESBL isolates from blood. Complete genomes for four isolates were resolved with Oxford Nanopore sequencing. ResultsIn a highly diverse collection, Klebsiella variicola ssp. variicola caused a quarter of Klebsiella pneumoniae species complex bacteraemias. ESBL-production was limited to K. pneumoniae sensu stricto (98.5 %). A diverse ESBL population of 57 clonal groups (CGs) were dominated by multidrug resistant CG307 (17%), CG15 (12%), CG70 (6%), CG258 (5%) and CG45 (5%) carrying blaCTX-M-15. Yersiniabactin was significantly more common in ESBL-positive (37.8%) compared to non-ESBL K. pneumoniae sensu stricto isolates (12.7%), indicating convergence of virulence and resistance determinants Moreover, we found a significant lower prevalence of yersinabactin (3.0 %, 37.8 % and 17.3 %), IncFIB (58.7 %, 87.9 % and 79.4 %) and IncFII plasmid replicons (40.5 %, 82.8 % and 54.2%) in K. variicola ssp. variicola compared to ESBL- and non-ESBL K. pneumoniae sensu stricto, respectively. ConclusionThe increase in Norwegian KpSC ESBLs during 2010-15 was driven by blaCTX-M-15 carrying CG307 and CG15. K. variicola ssp. variicola was a frequent cause of invasive KpSC infection, but rarely carried ESBL.

microbiology↗