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Although the Netherlands is a country with a low endemic level of methicillin-resistant Staphylococcus aureus (MRSA), a national MRSA surveillance has been in place since 1989. In 2003 livestock emerged as a major reservoir of MRSA and currently livestock-associated MRSA (clonal complex CC398) make up 25% of all surveillance isolates. To assess possible transfer of resistant strains or resistance genes, MRSA obtained from humans and animals were characterized in detail.

Clinical samples from 123 foals with suspected rhodococcosis submitted to the Veterinary Microbiological Diagnostic Centre of the Faculty of Veterinary Medicine between 1993 and 2006 were tested for the presence of the virulence gene vapA. Of the 123 samples, 120 were vapA-positive and 3 vapA-negative Rhodococcus equi were isolated. The 120 vapA-positive R. equi were isolated from 70 tracheal wash, 19 lung tissues, 7 lymph nodes, 6 synovial fluids, 13 abscesses or pus and single isolates from the uterus, gut, cerebrospinal fluid, abdomen fluid and faeces. Of the 120 isolates, 46 were from Dutch warmblood horses, 23 from Friesian horses, 14 from Trotters, 4 from Holsteiners, 3 from Arab breed, 2 from ponies, 1 from a Welsh pony and 27 from undefined breed horses. Using plasmid profile analysis of the 120 isolates, 117 isolates contained the 85-kb type I plasmid, 2 contained the 87-kb type I plasmid and 1 contained the novel 52-kb non-mobilizable virulence plasmid reported recently. These results showed that the virulent R. equi strains harbouring a virulence plasmid of 85-kb type I or 87-kb type I, which have been detected in clinical isolates from five European countries, are widespread in the Netherlands. This is the first report of plasmid types of clinical R. equi isolates in the Netherlands.

The relatedness of the equine-associated Escherichia coli ST1250 and its single- and double-locus variants (ST1250-SLV/DLV), obtained from horses in Europe, was studied by comparative genome analysis. A total of 54 isolates of E. coli ST1250 and ST1250-SLV/DLV from healthy and hospitalized horses across Europe [Czech Republic (n=23), the Netherlands (n=18), Germany (n=9), Denmark (n=3) and France (n=1)] from 2008-2017 were subjected to whole-genome sequencing. An additional 25 draft genome assemblies of E. coli ST1250 and ST1250-SLV/DLV were obtained from the public databases. The isolates were compared for genomic features, virulence genes, clade structure and plasmid content. The complete nucleotide sequences of eight IncHI1/ST9 and one IncHI1/ST2 plasmids were obtained using long-read sequencing by PacBio or MinION. In the collection of 79 isolates, only 10 were phylogenetically close (98% similarity) regardless of country of origin and varied only in the structure and integration site of MDR region. E. coli ST1250 and ST1250-SLV/DLV are phylogenetically-diverse strains associated with horses. A strong linkage of E. coli ST1250 with epidemic multi-drug resistance plasmid lineage IncHI1/ST9 carrying blaCTX-M-1 and the fos operon was identified.

The relatedness of the equine-associated Escherichia coli strain ST1250 and its single- and double-locus variants (ST1250-SLV/DLV), obtained from horses in Europe, was studied by comparative genome analysis. A total of 54 isolates of E. coli ST1250 and ST1250-SLV/DLV from healthy and hospitalized horses across Europe (Czech Republic [n = 23], The Netherlands [n = 18], Germany [n = 9], Denmark [n = 3], and France [n = 1]) from 2008 to 2017 were subjected to whole-genome sequencing. An additional 25 draft genome assemblies of E. coli ST1250 and ST1250- SLV/DLV were obtained from the public databases. The isolates were compared for genomic features, virulence genes, clade structure, and plasmid content. The complete nucleotide sequences of eight IncHI1/ST9 plasmids and one IncHI1/ST2 plasmid were obtained using long-read sequencing by PacBio or MinION. In the collection of 79 isolates, only 10 were phylogenetically close (,8 single nucleotide polymorphisms [SNP]). The majority of isolates belonged to phylogroup B1 (73/79 [92.4%]) and carried blaCTX-M-1 (58/79 [73.4%]). The plasmid content of the isolates was dominated by IncHI1 of ST9 (56/62 [90.3%]) and ST2 (6/62 [9.7%]), while 84.5% (49/58) of the blaCTX-M-1 genes were associated with the presence of the IncHI1 replicon of ST9 and 6.9% (4/58) with the IncHI1 replicon of ST2 within the corresponding isolates. The operon for the utilization of short-chain fructooligosaccharides (the fos operon) was present in 55 of 79 (69.6%) isolates, and all of these carried IncHI1/ST9 plasmids. The eight complete IncHI1/ST9 plasmid sequences showed the presence of blaCTX-M-1 and the fos operon within the same molecule. Sequences of IncHI1/ST9 plasmids were highly conserved (.98% similarity) regardless of country of origin and differed only in the structure and integration site of the multidrug resistance (MDR) region. E. coli ST1250 and ST1250-SLV/DLV are phylogenetically diverse strains associated with horses. A strong linkage of E. coli ST1250 with the epidemic multidrug resistance plasmid lineage IncHI1/ST9 carrying blaCTX-M-1 and the fos operon was identified.

Additional file 3: Comparison of veterinary healthcare workers with the general population. Results of the comparison of veterinary healthcare workers (AREND study) with the general population (ESBLAT study, Nov 2014–Nov 2016) using a multivariable logistic regression model (Table S4).

Additional file 2: Tables S2. ESBL/pAmpC gene types and E. coli sequence types in veterinary healthcare workers that were tested ESBL-E/K positive at both sampling moments (T0 and T1); Table S3. Characteristics of household members of ESBL-E/K positive veterinary healthcare workers.

Additional file 1: Table S1. Primers and PCR conditions used in this study. Overview of primers and conditions used in PCR screening and sequencing.

Background In the Netherlands, the prevalence of intestinal extended-spectrum beta-lactamase–producing Enterobacteriaceae (ESBL-E) carriage in community-dwelling subjects is ~5%. Little is known about the dynamics of ESBL-E carriage. Methods In a nationwide, population-based study (2014–2016) with 4177 community-dwelling subjects, fecal samples from 656 subjects were collected after 1 (time point [T] = 1) and 6 (T = 2) months. The growth of ESBL-E was quantified and a whole-genome sequence analysis was performed. Subjects were categorized as either an incidental, short-term, or long-term carrier or as a noncarrier. Risk factors were determined by random forest models and logistic regression. The transmissibility and duration of ESBL-E carriage was quantified using a transmission model, which also incorporated previous study data. Results Out of 656 participants, 96 were ESBL-E carriers at T = 0. Of these, 66 (10.1%) subjects were incidental carriers, 22 (3.3%) were short-term carriers, and 38 (5.8%) were long-term carriers; the remaining 530 (80.8%) were noncarriers. The risk factors for long-term carriage were travelling to Asia, swimming in a sea/ocean, and not changing the kitchen towel daily. The log-transformed colony forming units ratio at T = 0 was predictive for ESBL-E carriage at T = 1 (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.2–1.6) and T = 2 (OR, 1.2; 95% CI, 1.1–1.4). Model simulations revealed a median decolonization rate of 2.83/year, an average duration of carriage of 0.35 years, and an acquisition rate of 0.34/year. The trend of the acquisition rate during the study period was close to 0. Conclusions The risk factors for long-term ESBL-E carriage were travel- and hygiene-related. The dynamics of ESBL-E carriage in the general Dutch population are characterized by balancing decolonization and acquisition rates.

Background: In recent years, ESBL/AmpC-producing Escherichia coli (ESBL/AmpC-EC) have been isolated with increasing frequency from animals, food, environmental sources and humans. With incomplete and scattered evidence, the contribution to the human carriage burden from these reservoirs remains unclear. Objectives: To quantify molecular similarities between different reservoirs as a first step towards risk attribution. Methods: Pooled data on ESBL/AmpC-EC isolates were recovered from 35 studies in the Netherlands comprising >27 000 samples, mostly obtained between 2005 and 2015. Frequency distributions of ESBL/AmpC genes from 5808 isolates and replicons of ESBL/AmpC-carrying plasmids from 812 isolates were compared across 22 reservoirs through proportional similarity indices (PSIs) and principal component analyses (PCAs). Results: Predominant ESBL/AmpC genes were identified in each reservoir. PCAs and PSIs revealed close human-animal ESBL/AmpC gene similarity between human farming communities and their animals (broilers and pigs) (PSIs from 0.8 to 0.9). Isolates from people in the general population had higher similarities to those from human clinical settings, surface and sewage water and wild birds (0.7-0.8), while similarities to livestock or food reservoirs were lower (0.3-0.6). Based on rarefaction curves, people in the general population had more diversity in ESBL/AmpC genes and plasmid replicon types than those in other reservoirs. Conclusions: Our 'One Health' approach provides an integrated evaluation of the molecular relatedness of ESBL/AmpC-EC from numerous sources. The analysis showed distinguishable ESBL/AmpC-EC transmission cycles in different hosts and failed to demonstrate a close epidemiological linkage of ESBL/AmpC genes and plasmid replicon types between livestock farms and people in the general population.