Reduction of antibiotic use and antibiotic resistance in commercial poultry

Use of antibiotics for companion animals and livestock in the Netherlands has reduced by more than 60% over the last 10 years (SDa 2019; MARAN-2019). This reduction is the result of a change in policy towards the use of antibiotics in veterinary practice and is characterized by a series of coherent political decisions which changed the playing field for farmers and veterinarians considerably. In the years before 2009 the Netherlands was a high consumer of antibiotics in veterinary practice (Grave et al., 2010). The ban of antimicrobial growth promoters (AGPs) did not result in a reduction in total use since in the Netherlands the AGPs were fully replaced by antibiotics licensed for therapy. The total sales of all antibiotics remained stable at around 600 tons from 2000 to 2009.This use pattern resulted in high levels of antimicrobial resistance in bacteria from livestock and food thereof and high prevalence of Livestock Associated MRSA and ESBL-producing E. coli and Salmonella (MARAN, 2019; RIVM, 2009). Specifically, ESBL-producing isolates in the food chain were considered a risk for public health and their high prevalences, predominantly but not solely in poultry and poultry meat products were the direct reason to initiate the change in policy towards antibiotic use in animals.In this manuscript the trends in antibiotic use in poultry will be explored in the context of total use in livestock and its effect on the occurrence and trends in ESBL-producers and antimicrobial resistance in other bacterial species from poultry

Plasmid mediated quinolone resistance in Enterobacteriaceae

This thesis describes the occurrence of Plasmid Mediated Quinolone Resistance (PMQR) in Salmonella and E. coli from The Netherlands and other European countries. Furthermore, the genetic background of these genes was characterized. Fluoroquinolones are widely used antibiotics in both human and veterinary medicine. Resistance to fluoroquinolones is considered to be a risk for human health and is mainly caused by chromosomal mutations in topoisomerase genes. Since 1998, different types of PMQR emerged encoded by different resistant genes: qnrA, qnrS, qnrB, qnrC, qnrD, aac(6’)-1b-cr, oqxAB and qepA. PMQR in Enterobacteriaceae results in reduced susceptibility to (fluoro)quinolones to levels below clinical breakpoints. However, PMQR is considered clinically relevant because it facilitates the acquisition of full quinolone resistance. In a national study, the earliest identified PMQR-positive Salmonella isolate in The Netherlands was a human qnrS1-positive S. Corvallis isolate obtained in 2003. Furthermore, eight different Salmonella serovars were found harbouring different PMQR genes (qnrS1, qnrB2 and qnrB19). Almost all isolates were of human origin. Further study revealed the presence of PMQR genes on different plasmid families, including IncN plasmids carrying qnrS1, qnrB2 or qnrB19. But also qnrS1 on ColE, IncR or incHI2 plasmids. The majority of these plasmids were self-transferable by conjugation. However, PMQR-genes were also present on smaller non-conjugative plasmids.More recently, a continuous low prevalence of PMQR-suspected Salmonella isolates was observed in The Netherlands with a slight tendency to increase. The earliest identified PMQR-positive E. coli in animals from The Netherlands was a qnrS1-carrying E. coli obtained from a broiler obtained in 2009. To date, the prevalence of PMQR-suspected E. coli in food-producing animals in The Netherlands is low and only observed in broilers and veal calves. A European study demonstrated a low prevalence of PMQR-positive Salmonella isolates, with qnrS1, qnrB19 and qnrB2 as the predominant PMQR-determinants identified. The rare qnrD1 was identified in eight different serovars from three different countries. This study demonstrated a wide spread of PMQR genes in Europe among Salmonella from different sources despite the low prevalence and it suggest poultry to be the main source for PMQR-determinants in Salmonella. Similar to Salmonella, the prevalence of PMQR was low in E. coli with predominant variant qnrS1 in isolates from poultry (Gallus gallus and turkeys). Antibiotic resistant bacteria can spread over great distances via travel of people or transport of animals, but also by the worldwide trade in food and feed. In this thesis two examples of import of multidrug resistant Enterobacteriaceae are discussed: PMQR-positive, multidrug resistant Salmonella obtained in humans originated from or had a travel history to the African continent and PMQR-positive, multidrug resistant Enterobacteriaceae identified on culinary herbs from Southeast Asia. Despite the strong reduction of fluoroquinolone usage in animals in The Netherlands, resistance is still high in commensal E. coli and Campylobacter spp. in some food-producing animal species. Although fluoroquinolone resistance is mainly caused by chromosomal mutations, PMQR complicates the development and spread of fluoroquinolone resistance which makes it important to include this in the surveillance

Plasmid mediated quinolone resistance in Enterobacteriaceae

This thesis describes the occurrence of Plasmid Mediated Quinolone Resistance (PMQR) in Salmonella and E. coli from The Netherlands and other European countries. Furthermore, the genetic background of these genes was characterized. Fluoroquinolones are widely used antibiotics in both human and veterinary medicine. Resistance to fluoroquinolones is considered to be a risk for human health and is mainly caused by chromosomal mutations in topoisomerase genes. Since 1998, different types of PMQR emerged encoded by different resistant genes: qnrA, qnrS, qnrB, qnrC, qnrD, aac(6’)-1b-cr, oqxAB and qepA. PMQR in Enterobacteriaceae results in reduced susceptibility to (fluoro)quinolones to levels below clinical breakpoints. However, PMQR is considered clinically relevant because it facilitates the acquisition of full quinolone resistance. In a national study, the earliest identified PMQR-positive Salmonella isolate in The Netherlands was a human qnrS1-positive S. Corvallis isolate obtained in 2003. Furthermore, eight different Salmonella serovars were found harbouring different PMQR genes (qnrS1, qnrB2 and qnrB19). Almost all isolates were of human origin. Further study revealed the presence of PMQR genes on different plasmid families, including IncN plasmids carrying qnrS1, qnrB2 or qnrB19. But also qnrS1 on ColE, IncR or incHI2 plasmids. The majority of these plasmids were self-transferable by conjugation. However, PMQR-genes were also present on smaller non-conjugative plasmids.More recently, a continuous low prevalence of PMQR-suspected Salmonella isolates was observed in The Netherlands with a slight tendency to increase. The earliest identified PMQR-positive E. coli in animals from The Netherlands was a qnrS1-carrying E. coli obtained from a broiler obtained in 2009. To date, the prevalence of PMQR-suspected E. coli in food-producing animals in The Netherlands is low and only observed in broilers and veal calves. A European study demonstrated a low prevalence of PMQR-positive Salmonella isolates, with qnrS1, qnrB19 and qnrB2 as the predominant PMQR-determinants identified. The rare qnrD1 was identified in eight different serovars from three different countries. This study demonstrated a wide spread of PMQR genes in Europe among Salmonella from different sources despite the low prevalence and it suggest poultry to be the main source for PMQR-determinants in Salmonella. Similar to Salmonella, the prevalence of PMQR was low in E. coli with predominant variant qnrS1 in isolates from poultry (Gallus gallus and turkeys). Antibiotic resistant bacteria can spread over great distances via travel of people or transport of animals, but also by the worldwide trade in food and feed. In this thesis two examples of import of multidrug resistant Enterobacteriaceae are discussed: PMQR-positive, multidrug resistant Salmonella obtained in humans originated from or had a travel history to the African continent and PMQR-positive, multidrug resistant Enterobacteriaceae identified on culinary herbs from Southeast Asia. Despite the strong reduction of fluoroquinolone usage in animals in The Netherlands, resistance is still high in commensal E. coli and Campylobacter spp. in some food-producing animal species. Although fluoroquinolone resistance is mainly caused by chromosomal mutations, PMQR complicates the development and spread of fluoroquinolone resistance which makes it important to include this in the surveillance

Evaluation of Eight Different Cephalosporins for Detection of Cephalosporin Resistance in Salmonella enterica and Escherichia coli

This study evaluates the efficacy of eight different cephalosporins for detection of cephalosporin resistance mediated by extended spectrum beta-lactamases (ESBL) and plasmidic AmpC beta-lactamases in Salmonella and Escherichia coli. A total of 138 E. coli and 86 Salmonella isolates with known beta-lactamase genes were tested for susceptibility toward cefoperazone, cefotaxime, cefpodoxime, cefquinome, ceftazidime, ceftiofur, ceftriaxone, and cefuroxime using minimum inhibitory concentration determinations and disc diffusion. The collection consisted of 84 ampicillin-susceptible, 57 ampicillin-resistant but cephalosporin-susceptible, 56 ESBL isolates and 19 isolates with plasmidic AmpC, as well as 10 ampC hyper-producing E. coli. The minimum inhibitory concentration distributions and zone inhibitions varied with the tested compound. Ampicillin-resistant isolates showed reduced susceptibility to the cephalosporins compared to ampicillin-susceptible isolates. Cefoperazone, cefquinome, and cefuroxime were not useful in detecting isolates with ESBL or plasmidic AmpC. The best substances for detection were cefotaxime, cefpodoxime, and ceftriaxone, whereas ceftazidime and ceftiofur were not as efficient. Ceftriaxone may be the recommended substance for monitoring because of some ability in separating ampC hyper-producing E. coli from ESBL and plasmidic AmpC isolate

Molecular epidemiology of unilateral amyloid arthropathy in broiler breeders associated with Enterococcus faecalis

Although symmetrical polyarticular amyloidosis has been described extensively in brown layers, spontaneous unilateral amyloid arthropathy has not been described previously in chickens. Birds from nine flocks of broiler parent stock (PS) had unilateral lameness associated with severe swelling of the left hock joint and the caudal aspect of the metatarsus. Gross pathology was restricted to the left hock joint and the left digital flexor tendons in almost all cases, suggesting an association with administration of Marek's disease vaccine. Amyloid deposits were found in 83% (25/30) of affected joints by histological examination of Congo red stained sections. Systemic amyloidosis, involving mainly the liver and spleen, was found in 59% (10/17) of birds. Enterococcus faecalis was isolated from joints in 77% (23/30) of cases and Staphylococcus aureus was isolated from the joint in one case (1/30). Thirty-five E. faecalis isolates from joints, tendons and blood samples from birds in five affected PS flocks were compared using pulsed-field gel electrophoresis (PFGE) to separate genomic fragments after digestion with Sma I. All but one isolate had identical or closely related restriction endonuclease digestion (RED) patterns that were very similar to a known arthropathic and amyloidogenic E. faecalis isolate. A further 30 E. faecalis isolates from seven grandparent stock (GPS) flocks and two isolates from two unaffected PS flocks of the same genetic background were analysed by PFGE. Among these isolates, 11 originating from four GPS flocks had RED patterns identical to or closely related to the reference amyloid-inducing strain. Moreover, one E. faecalis isolate from amyloidotic joints of brown layers housed in California, USA was included in the analysis and appeared to be identical to the reference strain. This study showed that the E. faecalis isolates involved in these outbreaks of unilateral amyloid arthropathy in broiler breeders belonged to the same clone as that responsible for outbreaks in brown layers

Kwaliteitscontrole van de nieuwe Europese gevoeligheidstest in 2013

Dit artikel beschrijft de resultaten van twee rondzendoefeningen voor antibioticumgevoeligheidstesten uitgevoerd in 2014 door veterinaire laboratoria en dierartsenpraktijken met de door hun gehanteerde standaardmethode. Het artikel bevat tevens een vergelijking van de kwaliteit van de resultaten van 2014 met de rondzendingen van 2013 (eerder gepubliceerd in dit tijdschrift: deel 138, aflevering 2). De methodes voor en uitvoering van gevoeligheidstesten in veterinaire laboratoria en dierenartsenpraktijken zijn in 2014 verder geharmoniseerd. Bovendien is er meer uniformiteit ontstaan in de keuze van de antibiotica in de testpanels. De verbeterde harmonisatie is het resultaat van de implementatie van adviezen van CVI en de GD en heeft geleid tot een verbetering van de testkwaliteit

In vitro antibiotic susceptibility of Dutch Mycoplasma synoviae field isolates originating from joint lesions and the respiratory tract of commercial poultry

The in vitro susceptibility of 17 Dutch Mycoplasma synoviae isolates from commercial poultry to enrofloxacin, difloxacin, doxycycline, tylosin and tilmicosin was examined. Three isolates originated from joint lesions and 14 were from the respiratory tract. The type strain M. synoviae WVU 1853 was included as a control strain. Antibiotic susceptibility was tested quantitatively using the broth microdilution test. Based on initial and final minimum inhibitory concentration values, all tested isolates were susceptible to doxycycline, tylosin and tilmicosin. Two isolates from the respiratory tract were resistant to enrofloxacin and showed intermediate resistance to difloxacin

Quantitative susceptibility of Streptococcus suis strains isolated from diseased pigs in seven European countries to antimicrobial agents licenced in veterinary medicine

The susceptibility of Streptococcus suis strains (n = 384) isolated from diseased pigs in seven European countries to 10 antimicrobial agents was determined. For that purpose a microbroth dilution method was used according to CLSI recommendations. The following antimicrobial agents were tested: ceftiofur, cefquinome, enrofloxacin, florfenicol, gentamicin, penicillin, spectinomycin, tetracycline, tilmicosin and trimethoprim/sulphamethoxazole. Using breakpoints established by CLSI for veterinary pathogens, all strains were susceptible to ceftiofur, florfenicol, enrofloxacin and penicillin. MIC-90 values of these antibiotics wer