• Competition between Escherichia coli Populations with and without Plasmids Carrying a Gene Encoding Extended-Spectrum Beta-Lactamase in the Broiler Chicken Gut.

      Fischer, Egil A J; Dierikx, Cindy M; van Essen-Zandbergen, Alieda; Mevius, Dik; Stegeman, Arjan; Velkers, Francisca C; Klinkenberg, Don (2019-09-01)
      Extended-spectrum-beta-lactamase (ESBL)/AmpC-producing Escherichia coli strains are widely found in E. coli isolates from broiler feces, largely due to the presence of the blaCTX-M-1 gene on IncI1 plasmids. Plasmid carriage is theorized to cause fitness loss and thus should decrease under conditions of reduced antibiotic use. However, in vitro studies showed plasmid carriage to increase in the absence of antimicrobials, due to plasmid conjugation. We investigated whether this translates to increased levels of plasmid in the gastrointestinal tracts of chickens, where conjugation rates may be different and subtle differences in growth rates may have a larger impact on colonization. Eight groups of five chickens were orally inoculated at 4 days of age with a 0.5-ml volume containing 106 CFU/ml E. coli cells, of which 0%, 0.1%, 10%, or 100% carried the IncI1 plasmid with the gene blaCTX-M-1 At 13 time points during 41 days, fecal samples were taken from each chicken. E. coli strains with and without plasmids were quantified. Trends in E. coli subpopulations were analyzed using generalized linear mixed models, and population dynamics were studied by fitting to a mechanistic model. Trends in E. coli subpopulations were different between groups rather than between individual chickens, suggesting substantial levels of E. coli exchange between chickens in a group. The IncI1 plasmid carrying blaCTX-M-1 was transferred with conjugation coefficients at levels higher than those observed in vitro Across groups, the plasmids disappeared or were established independently of the initial fraction of plasmid-carrying E. coli, but no major increase occurred as observed in vitro Differences in growth rates were observed, but competitive exclusion of plasmid-carrying variants was counteracted by conjugation.IMPORTANCE Bacteria that produce extended-spectrum beta-lactamases are resistant to an important class of antimicrobials in human and veterinary medicine. Reduction in antibiotic use is expected to decrease the prevalence of resistance. However, resistance genes often lie on plasmids which can be copied and transferred to other bacteria by conjugation, so in vitro resistance was observed to increase in the absence of antimicrobials. We sought to determine whether this also occurs in the chicken gut and if competitive exclusion by similar E. coli variants without the resistance occurred. We studied the excretion of E. coli carrying IncI1 plasmids with the blaCTX-M-1 resistance gene in small groups of broiler chickens, after inoculating the chickens with E. coli suspensions containing different fractions of plasmid-carrying cells. Our results showed little variation between chickens within groups but large differences between groups that were independent of the ratio of variants with and without the plasmid and with persistence or extinction of the plasmid. However, there was no major plasmid increase as observed in vitro We conclude that in vivo studies with sufficient independent replications are important for intervention studies on plasmid-mediated antimicrobial resistance.
    • The extent of carbapenemase encoding genes in public genome sequences

      I Janse; A Swart; M Visser; R Beeloo; L Schouls; E van Duijkeren; MWJ van Passel (2019-10-03)
    • The public uptake of information about antibiotic resistance in the Netherlands.

      van Rijn, Michiel; Haverkate, Manon; Achterberg, Peter; Timen, Aura (2019-02-12)
      In this study, we test to what extent an educational video on the intricacies of antibiotic resistance affects public attitudes towards antibiotic resistance and how such information is absorbed by the most likely targets of public health campaigns. We use a representative sample of 2037 individuals (from 2016) to test how people respond to a video educating them about antibiotic resistance. Our results show that receiving information does increase the general awareness of antibiotic resistance among our respondents. Yet, these effects are most profound for those who are the most likely targets of such information: the least knowledgeable group and those who have a more apathetic worldview. Our results are in line with suggestions made by the knowledge deficit model and show that the influence of cultural predispositions on the uptake of information about antibiotic resistance should not be ignored in future campaigns.
    • Strong correlation between the rates of intrinsically antibiotic-resistant species and the rates of acquired resistance in Gram-negative species causing bacteraemia, EU/EEA, 2016.

      Jarlier, Vincent; Diaz Högberg, Liselotte; Heuer, Ole E; Campos, José; Eckmanns, Tim; Giske, Christian G; Grundmann, Hajo; Johnson, Alan P; Kahlmeter, Gunnar; Monen, Jos; et al. (2019-01-01)
      BackgroundAntibiotic resistance, either intrinsic or acquired, is a major obstacle for treating bacterial infections.AimOur objective was to compare the country-specific species distribution of the four Gram-negative species Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter species and the proportions of selected acquired resistance traits within these species.MethodWe used data reported for 2016 to the European Antimicrobial Resistance Surveillance Network (EARS-Net) by 30 countries in the European Union and European Economic Area.ResultsThe country-specific species distribution varied considerably. While E. coli accounted for 31.9% to 81.0% (median: 69.0%) of all reported isolates, the two most common intrinsically resistant species P. aeruginosa and Acinetobacter spp. combined (PSEACI) accounted for 5.5% to 39.2% of isolates (median: 10.1%). Similarly, large national differences were noted for the percentages of acquired non-susceptibility to third-generation cephalosporins, carbapenems and fluoroquinolones. There was a strong positive rank correlation between the country-specific percentages of PSEACI and the percentages of non-susceptibility to the above antibiotics in all four species (rho > 0.75 for 10 of the 11 pairs of variables tested).ConclusionCountries with the highest proportion of P. aeruginosa and Acinetobacter spp. were also those where the rates of acquired non-susceptibility in all four studied species were highest. The differences are probably related to national differences in antibiotic consumption and infection prevention and control routines.