Virulence plasmids in clinical isolates of Rhodococcus equi from sick foals in the Netherlands.

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.

Monitoring of ticks and their pathogens from companion animals obtained by the "tekenscanner" application in The Netherlands.

Ticks are vectors for many pathogens of veterinary and medical interest. In order to monitor ticks and tick-borne pathogens, the "Tekenscanner" (Dutch for Tick scanner), a citizen science project, was launched in The Netherlands. It is a smartphone application for pet-owners to get ticks from their dog or cat, identified and checked for pathogens for free. At the same time, information about the pet and the geographic location of tick infestation becomes available for research. The application was launched in 2018, and the results of the first 6 months after launch of the app were reported. Ticks were identified based on morphology, and DNA was extracted and amplified by a panel of tick-borne pathogen-specific primers. Next, the amplicons were subjected to reverse line blot with specific probes for important pathogens to determine their presence or absence. The present paper describes the results of 2019 and 2020. There were 2260 ticks collected from 871 dogs and 255 cats (26 ticks were from an unknown host) and all pet owners were informed about the results. Four species of ticks were collected: Ixodes ricinus (90.0%), Ixodes hexagonus (7.3%), Dermacentor reticulatus (2.8%) and Rhipicephalus sanguineus (0.1%). Ixodes ricinus was the tick with the most divergent pathogens: Anaplasma sp. (1.3%), Babesia sp. (0.8%), Borrelia spp. (4.8%), Neoehrlichia sp. (3.7%) and Rickettsia helvetica (12.6%). In I. hexagonus, R. helvetica (1.8%) and Babesia sp. (0.6%) were detected and Rickettsia raoultii in D. reticulatus (16.2%). One of the two nymphs of R. sanguineus was co-infected with Borrelia and R. helvetica and the other one was uninfected. The high numbers of different pathogens found in this study suggest that companion animals, by definition synanthropic animals, and their ticks can serve as sentinels for emerging tick-borne pathogens.

Faecal carriage, risk factors, acquisition and persistence of ESBL-producing Enterobacteriaceae in dogs and cats and co-carriage with humans belonging to the same household.

BACKGROUND: ESBL-producing Enterobacteriaceae (ESBL-E) are observed in many reservoirs. Pets might play an important role in the dissemination of ESBL-E to humans since they live closely together. OBJECTIVES: To identify prevalence, risk factors, molecular characteristics, persistence and acquisition of ESBL-E in dogs and cats, and co-carriage in human-pet pairs belonging to the same household. METHODS: In a nationwide study, one person per household was randomly invited to complete a questionnaire and to submit a faecal sample. Dog and cat owners were invited to also submit a faecal sample from their pet. Repeated sampling after 1 and 6 months was performed in a subset. ESBL-E were obtained through selective culture and characterized by WGS. Logistic regression analyses and random forest models were performed to identify risk factors. RESULTS: The prevalence of ESBL-E carriage in these cohorts was 3.8% (95% CI: 2.7%-5.4%) for human participants (n=550), 10.7% (95% CI: 8.3%-13.7%) for dogs (n=555) and 1.4% (95% CI: 0.5%-3.8%) for cats (n=285). Among animals, blaCTX-M-1 was most abundant, followed by blaCTX-M-15. In dogs, persistence of carriage was 57.1% at 1 month and 42.9% at 6 months. Eating raw meat [OR: 8.8, 95% CI: 4.7-16.4; population attributable risk (PAR): 46.5%, 95% CI: 41.3%-49.3%] and dry food (OR: 0.2, 95% CI: 0.1-0.5; PAR: 56.5%, 95% CI: 33.2%-66.6%) were predictors for ESBL-E carriage in dogs. Human-dog co-carriage was demonstrated in five households. Human-cat co-carriage was not observed. CONCLUSIONS: ESBL-E prevalence was higher in dogs than in humans and lowest in cats. The main risk factor for ESBL-E carriage was eating raw meat. Co-carriage in dogs and household members was uncommon.

Plasmids carrying antimicrobial resistance genes in Enterobacteriaceae.

Bacterial antimicrobial resistance (AMR) is constantly evolving and horizontal gene transfer through plasmids plays a major role. The identification of plasmid characteristics and their association with different bacterial hosts provides crucial knowledge that is essential to understand the contribution of plasmids to the transmission of AMR determinants. Molecular identification of plasmid and strain genotypes elicits a distinction between spread of AMR genes by plasmids and dissemination of these genes by spread of bacterial clones. For this reason several methods are used to type the plasmids, e.g. PCR-based replicon typing (PBRT) or relaxase typing. Currently, there are 28 known plasmid types in Enterobacteriaceae distinguished by PBRT. Frequently reported plasmids [IncF, IncI, IncA/C, IncL (previously designated IncL/M), IncN and IncH] are the ones that bear the greatest variety of resistance genes. The purpose of this review is to provide an overview of all known AMR-related plasmid families in Enterobacteriaceae, the resistance genes they carry and their geographical distribution.

Weather correlates of Campylobacter prevalence in broilers at slaughter under tropical conditions in Sri Lanka.

Campylobacter is the primary agent of human bacterial gastroenteritis worldwide. In contrast to temperate zones, weather effects on Campylobacter prevalence in broilers under tropical conditions are under-researched. We examined the association between weather and Campylobacter prevalence in slaughtered broilers in Sri Lanka, a tropical country with weather variations led by monsoons. Each month (October 2009-July 2011), 20-30 broiler batches referring to two semi-automated slaughterhouses from five Sri Lankan provinces were tested for Campylobacter contamination and analysed in relation to temperature, humidity and rainfall. Overall prevalence was 63.8% (95% CI 59.6-67.9%, n = 542), peaking in September-November. Each 1 °C increase in monthly mean temperature up to 26 °C increased Campylobacter-positive batches by 16.4% (95% CI 0.4-35.1%). For each 10 mm increase in monthly total rainfall up to 300 mm, Campylobacter-positive batches increased significantly by 0.8% (0.1-1.5%) at 1-month lag. For each 1% increase in relative humidity up to 80% at 1- and 2-month lags, Campylobacter-positive batches increased of respectively 4.2% (1.9-6.7%) and 4.0% (1.5-6.5), and decreased by 3.6% (2.6-4.6%) and 4.0% (2.6-5.4%) for unit increases above 80%. These results suggest that even in tropical countries without marked seasons, there are weather effects possibly reflecting Campylobacter potential to colonise its preferred host and/or survive in the environment.

Health and health-related quality of life in pig farmers carrying livestock-associated methicillin-resistant Staphylococcus aureus.

There is limited knowledge about the effect of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) carriage on health-related quality of life (QoL). With this study, we explored whether LA-MRSA causes infections or affects health-related QoL in pig farmers. This prospective cohort study surveyed persons working on 49 farrowing pig farms in The Netherlands for 1 year (2010-2011). On six sampling moments, nasal swabs, environmental samples and questionnaires on activities and infections were collected. At the end of the study year, persons were asked about their QoL using the validated SF-36 and EQ-5D questionnaires. Of 120 persons, 44 (37%) were persistent MRSA carriers. MRSA carriage was not associated with infections, use of antimicrobials, healthcare contact and health-related QoL items in univariate or multivariate analysis, most likely due to the 'healthy worker effect'. Despite high carriage rates, the impact of LA-MRSA carriage in this population of relatively healthy pig farmers on health and health-related QoL appears limited; more research is needed for confirmation.

Prevalence and risk factors for patent Toxocara infections in cats and cat owners' attitude towards deworming.

The prevalence of and risk factors for shedding Toxocara eggs in cats older than 6 months were determined by examining 670 faecal samples collected in 4 cross-sectional studies in the Netherlands. Additionally, cat owners provided information on their attitude towards routine deworming. Samples were examined using the centrifugal sedimentation flotation method. Overall Toxocara prevalence was 7.2 %. Multivariable logistic regression analysis revealed that young age and living in rural areas were significant risk factors for shedding Toxocara eggs. Moreover, the more time a cat was allowed to roam outdoors, the higher was its risk to shed Toxocara as compared to cats with no outdoor access at all. For 199 cats (81.6 % of cats subjected to a deworming regimen) owners provided the reason for treatment. The main reason for routine deworming (80.4 %) concerned the cat's health and only 10.6 % of the cats were treated for public health reasons. Moreover, the generally advocated four-times-a-year deworming advice was applied on only 24.5 % of cats. We concluded that free roaming is a key factor in the acquisition of patent Toxocara infections leading to the environmental contamination with Toxocara eggs. Additionally, the knowledge of cat owners is still insufficient to expect them to make sound decisions on routine deworming.

What Is the Origin of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Clonal Complex 398 Isolates from Humans without Livestock Contact? An Epidemiological and Genetic Analysis.

Fifteen percent of all methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 398 (CC398) human carriers detected in The Netherlands had not been in direct contact with pigs or veal calves. To ensure low MRSA prevalence, it is important to investigate the likely origin of this MRSA of unknown origin (MUO). Recently, it was shown that CC398 strains originating from humans and animals differ in the presence of specific mobile genetic elements (MGEs). We hypothesized that determining these specific MGEs in MUO isolates and comparing them with a set of CC398 isolates of various known origin might provide clues to their origin. MUO CC398 isolates were compared to MRSA CC398 isolates obtained from humans with known risk factors, a MRSA CC398 outbreak isolate, livestock associated (LA) MRSA CC398 isolates from pigs, horses, chickens, and veal calves, and five methicillin-susceptible Staphylococcus aureus (MSSA) CC398 isolates of known human origin. All strains were spa typed, and the presence or absence of, scn, chp, φ3 int, φ6 int, φ7 int, rep7, rep27, and cadDX was determined by PCRs. The MRSA CC398 in humans, MUO, or MRSA of known origin (MKO) resembled MRSA CC398 as found in pigs and not MSSA CC398 as found in humans. The distinct human MSSA CC398 spa type, t571, was not present among our MRSA CC398 strains; MRSA CC398 was tetracycline resistant and carried no φ3 bacteriophage with scn and chp. We showed by simple PCR means that human MUO CC398 carriers carried MRSA from livestock origin, suggestive of indirect transmission. Although the exact transmission route remains unknown, direct human-to-human transmission remains a possibility as well.

Influence of applying different units of measurement on reporting antimicrobial consumption data for pig farms.

BACKGROUND: Antimicrobial use in livestock is one of the factors contributing to selection and spread of resistant microorganisms in the environment. National veterinary antimicrobial consumption monitoring programs are therefore in place in a number of countries in the European Union. However, due to differences in methodology, results on veterinary antimicrobial consumption from these national monitoring programs cannot be compared internationally. International comparison is highly needed to establish regulations on veterinary antimicrobial use and reducing antimicrobial resistance. The aim of this study was to assess differences in the outcomes on veterinary antimicrobial consumption by applying three different sets of nationally established animal defined daily dosages to the same antimicrobial drug delivery dataset of Dutch pigs in 2012. METHODS: Delivery information for the complete Dutch pig sector for the year 2012 reported to the Netherlands Veterinary Medicines Authority (SDa) was analysed with three differently and nationally established animal defined daily dosages from the Netherlands and Denmark: the Defined Daily Dosage AnimalNL (DDDANL), the Animal Daily DosageDK (ADDDK) and Defined Animal Daily DosageDK (DADDDK). For each applied Dutch product equivalent, Danish products were identified based on authorization for pigs, active substance (including form), administration route, concentration and dosage regimen. RESULTS: Consumption in number of ADDDK/Y was lower than in number of DDDANL/Y for sows/piglets and finisher pigs, with proportions of 83.3 % and 98.3 %. Use in number of DADDDK/Y was even lower, 79.7 % for sows/piglets and 88.1 % for finisher pigs compared to number of DDDANL/Y. At therapeutic group level proportions of number of DADDDK/Y to number of DDDANL/Y were 63.6-150.4 % (sows/piglets) and 55.6-171.0 % (finisher pigs). Proportions were > 100 % for the polymyxines (sows/piglets 150.4 % and finisher pigs 149.9 %) and the macrolides/lincosamides (finisher pigs 171.0 %). CONCLUSIONS: Differences between nationally established animal defined daily dosages caused by different correction factors for long-acting products and national differences in authorized dosages, have a substantial influence on the results of antimicrobial consumption in pigs. To enable international comparison of veterinary antimicrobial consumption data, harmonized units of measurement, animal weights and animal (sub) categories are needed.

Toxocara canis in household dogs: prevalence, risk factors and owners' attitude towards deworming.

The prevalence of gastrointestinal parasites and risk factors for shedding of Toxocara eggs were determined for 916 Dutch household dogs older than 6 months. Additionally, the owners answered a questionnaire about their dogs and their attitude towards routine deworming was assessed. Faecal samples were examined using the centrifugal sedimentation flotation method. The overall prevalence of dogs shedding Toxocara eggs was 4.6 %. Multivariable logistic regression analysis revealed that the risk for 1-7-year-old dogs to shed Toxocara eggs was significantly lower (OR 0.38) than that of 6-12-month-old dogs. Compared to dogs walking ≤20 % of the time off-leash, those ranging freely 50-80 % and 80-100 % of the time had a significantly higher risk (OR 10.49 and 13.52, respectively) of shedding Toxocara eggs. Other risk factors were coprophagy (OR 2.44) and recently being kenneled (OR 2.76). Although the applied deworming frequency was not significantly associated with shedding Toxocara eggs, there was a trend towards no shedding in dogs under strict supervision that were dewormed 3-4 times a year. Most dog owners (68 %) recognized 'dog's health' as the main reason for deworming. Only 16 % of dogs were dewormed four times a year. It was concluded that the prevalence of Toxocara egg-shedding household dogs is almost unchanged over recent years and that the knowledge of owners is insufficient to expect sound decisions on routine deworming.

Comparative population structure analysis of Campylobacter jejuni from human and poultry origin in Bangladesh.

Campylobacter jejuni is the most important cause of antecedent infections leading to Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS). The objective of the present study was to define the genetic diversity, population structure, and potential role of poultry in the transmission of Campylobacter to humans in Bangladesh. We determined the population structure of C. jejuni isolated from poultry (n = 66) and patients with enteritis (n = 39) or GBS (n = 10). Lipooligosaccharide (LOS) typing showed that 50/66 (76 %) C. jejuni strains isolated from poultry could be assigned to one of five LOS locus classes (A-E). The distribution of neuropathy-associated LOS locus classes A, B, and C were 30/50 (60 %) among the typable strains isolated from poultry. The LOS locus classes A, B, and C were significantly associated with GBS and enteritis-related C. jejuni strains more than for the poultry strains [(31/38 (82 %) vs. 30/50 (60 %), p < 0.05]. Multilocus sequence typing (MLST) defined 15 sequence types (STs) and six clonal complexes (CCs) among poultry isolates, including one ST-3740 not previously documented. The most commonly identified type, ST-5 (13/66), in chicken was seen only once among human isolates (1/49) (p < 0.001). Amplified fragment length polymorphism (AFLP) revealed three major clusters (A, B, and C) among C. jejuni isolated from humans and poultry. There seems to be a lack of overlap between the major human and chicken clones, which suggests that there may be additional sources for campylobacteriosis other than poultry in Bangladesh.

Antimicrobial resistance in commensal Escherichia coli in veal calves is associated with antimicrobial drug use.

The aim of this study was to determine the association between farm management factors, including antimicrobial drug usage, and resistance in commensal Escherichia coli isolates from the faeces of white veal calves. Ninety E. coli isolates from one pooled sample per farm (n = 48) were tested for their phenotypical resistance against amoxicillin, tetracycline, cefotaxime, ciprofloxacin and trimethoprim/sulfamethoxazole (TMP/SMX). Logistic regression analysis revealed the following risk factors (P < 0·05); farmer wearing the same work clothes for several days [ciprofloxacin, odds ratio (OR) 2·6; tetracycline, OR 2·4], administration of trimethoprim-sulfonamide combinations (TMP/SMX, OR 3·0; amoxicillin, OR 3·1; tetracycline, OR 2·6), ⩾0·3 animal daily dosage per production cycle (ADD/pc), quinolones (ciprofloxacin, OR 2·8), ⩾1·3 ADD/pc, penicillins (ciprofloxacin, OR 3·3; tetracycline, OR 3·4), 20-40 ADD/pc, tetracyclines (tetracycline, OR 3·2) and >40 ADD/pc, tetracyclines (tetracycline, OR 13·1; amoxicillin, OR 6·5). In this study antimicrobial resistance in commensal E. coli was mainly associated with antimicrobial drug use.

Campylobacteriosis in returning travellers and potential secondary transmission of exotic strains.

SUMMARY: Multilocus sequence types (STs) were determined for 232 and 737 Campylobacter jejuni/coli isolates from Dutch travellers and domestically acquired cases, respectively. Putative risk factors for travel-related campylobacteriosis, and for domestically acquired campylobacteriosis caused by exotic STs (putatively carried by returning travellers), were investigated. Travelling to Asia, Africa, Latin America and the Caribbean, and Southern Europe significantly increased the risk of acquiring campylobacteriosis compared to travelling within Western Europe. Besides eating chicken, using antacids, and having chronic enteropathies, we identified eating vegetable salad outside Europe, drinking bottled water in high-risk destinations, and handling/eating undercooked pork as possible risk factors for travel-related campylobacteriosis. Factors associated with domestically acquired campylobacteriosis caused by exotic STs involved predominantly person-to-person contacts around popular holiday periods. We concluded that putative determinants of travel-related campylobacteriosis differ from those of domestically acquired infections and that returning travellers may carry several exotic strains that might subsequently spread to domestic populations even through limited person-to-person transmission.

Multilocus sequence typing for characterization of Staphylococcus pseudintermedius.

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs. Four housekeeping genes with allelic polymorphisms were identified and used to develop an expanded multilocus sequence typing (MLST) scheme. The new seven-locus technique shows S. pseudintermedius to have greater genetic diversity than previous methods and discriminates more isolates based upon host origin.

Brachyspira species and gastroenteritis in humans.

Brachyspira species have been implicated as a potential cause of gastroenteritis in humans; this is, however, controversial. In 733 gastroenteritis cases and 464 controls, we found 29 samples positive for Brachyspira species (2.3% of cases and 2.6% of controls; P = 0.77). Brachyspira species were not associated with gastroenteritis in humans.

Colonization of Campylobacter spp. in broiler chickens and laying hens reared in tropical climates with low-biosecurity housing.

The onset and prevalence of Campylobacter colonization in broilers and layers at commercial farms with low biosecurity in tropical climates were tested. Despite the presence of positive animals at the same farms, the broiler flocks tested negative until, on average, 21 days. Prelaying flocks showed a higher prevalence than laying flocks.

A novel link between Campylobacter jejuni bacteriophage defence, virulence and Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is a post-infectious disease in which the human peripheral nervous system is affected after infection by specific pathogenic bacteria, including Campylobacter jejuni. GBS is suggested to be provoked by molecular mimicry between sialylated lipooligosaccharide (LOS) structures on the cell envelope of these bacteria and ganglioside epitopes on the human peripheral nerves, resulting in autoimmune-driven nerve destruction. Earlier, the C. jejuni sialyltransferase (Cst-II) was found to be linked to GBS and demonstrated to be involved in the biosynthesis of the ganglioside-like LOS structures. Apart from a role in pathogenicity, we report here that Cst-II-generated ganglioside-like LOS structures confer efficient bacteriophage resistance in C. jejuni. By bioinformatic analysis, it is revealed that the presence of sialyltransferases in C. jejuni and other potential GBS-related pathogens correlated significantly with the apparent degeneration of an alternative anti-virus system: type II Clusters of Regularly Interspaced Short Palindromic Repeat and associated genes (CRISPR-Cas). Molecular analysis of the C. jejuni CRISPR-Cas system confirmed the bioinformatic investigation. CRISPR degeneration and mutations in the cas genes cas2, cas1 and csn1 were found to correlate with Cst-II sialyltransferase presence (p < 0.0001). Remarkably, type II CRISPR-Cas systems are mainly found in mammalian pathogens. To study the potential involvement of this system in pathogenicity, we inactivated the type II CRISPR-Cas marker gene csn1, which effectively reduced virulence in primarily cst-II-positive C. jejuni isolates. Our findings indicate a novel link between viral defence, virulence and GBS in a pathogenic bacterium.

Increased risk for Campylobacter jejuni and C. coli infection of pet origin in dog owners and evidence for genetic association between strains causing infection in humans and their pets.

We compared Campylobacter jejuni/coli multilocus sequence types (STs) from pets (dogs/cats) and their owners and investigated risk factors for pet-associated human campylobacteriosis using a combined source-attribution and case-control analysis. In total, 132/687 pet stools were Campylobacter-positive, resulting in 499 strains isolated (320 C. upsaliensis/helveticus, 100 C. jejuni, 33 C. hyointestinalis/fetus, 10 C. lari, 4 C. coli, 32 unidentified). There were 737 human and 104 pet C. jejuni/coli strains assigned to 154 and 49 STs, respectively. Dog, particularly puppy, owners were at increased risk of infection with pet-associated STs. In 2/68 cases vs. 0.134/68 expected by chance, a pet and its owner were infected with an identical ST (ST45, ST658). Although common sources of infection and directionality of transmission between pets and humans were unknown, dog ownership significantly increased the risk for pet-associated human C. jejuni/coli infection and isolation of identical strains in humans and their pets occurred significantly more often than expected.

Practical considerations of surveillance of Salmonella serovars other than Enteritidis and Typhimurium.

Non-typhoid Salmonella serovars other than Salmonella enterica serovars S. Enteritidis (SE) and S.Typhimurium (ST) are isolated throughout the world with huge variations in prevalence. Besides the more generally occurring serovars, such as S. Infantis and S. Hadar, there are many examples of serovars that are principally reported from the regions and are most probably associated with local reservoirs. In most countries of the world, no formal surveillance systems for human salmonellosis are in place and data are limited to ad hoc studies. Data on animals, food and animal feed are even more scarce. The identification of non-SE/ST serovars may be hampered by a lack of experience in serotyping and the availability of quality-assured antisera. Subtyping Salmonella remains important to identify sources of human infections and to target interventions and control measurements. However, in the future, there will be an increasing use of culture-independent diagnostic assays, with the consequence that epidemiological subtyping and antimicrobial susceptibility data will no longer be generated. The validation of these assays for all serovars, particularly the rare ones, needs attention. Although current subtyping based on the Kauffmann-White scheme is well established, and has been shown to be robust, a new generation of subtyping methods will replace it in the near future.

Occurrence and characteristics of extended-spectrum-ß-lactamase- and AmpC-producing clinical isolates derived from companion animals and horses.

OBJECTIVES: To investigate the occurrence and characteristics of extended-spectrum ß-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae isolates in clinical samples of companion animals and horses and compare the results with ESBL/AmpC-producing isolates described in humans. METHODS: Between October 2007 and August 2009, 2700 Enterobacteriaceae derived from clinical infections in companion animals and horses were collected. Isolates displaying inhibition zones of ≤ 25 mm for ceftiofur and/or cefquinome by disc diffusion were included. ESBL/AmpC production was confirmed by combination disc tests. The presence of resistance genes was identified by microarray, PCR and sequencing, Escherichia coli genotypes by multilocus sequence typing and antimicrobial susceptibility by broth microdilution. RESULTS: Sixty-five isolates from dogs (n = 38), cats (n = 14), horses (n = 12) and a turtle were included. Six Enterobacteriaceae species were observed, mostly derived from urinary tract infections (n = 32). All except 10 isolates tested resistant to cefotaxime and ceftazidime by broth microdilution using clinical breakpoints. ESBL/AmpC genes observed were bla(CTX-M-1, -2, -9, -14, -15,) bla(TEM-52), bla(CMY-2) and bla(CMY-)(39). bla(CTX-M-1) was predominant (n = 17). bla(CTX-M-9) occurred in combination with qnrA1 in 3 of the 11 Enterobacter cloacae isolates. Twenty-eight different E. coli sequence types (STs) were found. E. coli carrying bla(CTX-M-1) belonged to 13 STs of which 3 were previously described in Dutch poultry and patients. CONCLUSIONS: This is the first study among a large collection of Dutch companion animals and horses characterizing ESBL/AmpC-producing isolates. A similarity in resistance genes and E. coli STs among these isolates and isolates from Dutch poultry and humans may suggest exchange of resistance between different reservoirs.