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Antimicrobial resistance in animals, food and beyond

High-level AmpC beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in Dutch hospitals and livestock farms: results from the i-4-1-Health project

April 20 • P2376

E. den Drijver1/2, M. Kluytmans1/3, B. Diederen4, S. Pas1, J. Stohr1/2, F. Velkers5, C. Verhulst1, J. Verweij2, A. Stegeman5, J. Kluytmans1/3, i-4-1-Health Study Group

1) Department of Infection Control, Amphia Hospital, Breda, The Netherlands
2) Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
3) Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, The Netherlands
4) ZorgSaam Hospital, Terneuzen, The Netherlands
5) University Utrecht, Utrecht, The Netherlands

Introduction: High-level AmpC beta-lactamase-production in Escherichia coli and Klebsiella pneumoniae (HL-AmpC-Ec/Kp) is emerging as antimicrobial resistance mechanism and is based on mutations in the promoter/attenuator of the chromosomal AmpC gene (cAmpC) or plasmid-located AmpC genes (pAmpC). This study aimed to determine the prevalence of HL-AmpC-Ec/Kp among patients in Dutch hospitals and in livestock farms.

Methods: Between September 2017 and April 2018, HL-AmpC-Ec/Kp prevalence surveys were performed in 2 hospitals, 16 pig farms and 14 broiler farms in the South of the Netherlands. Perianal or gastrointestinal stoma swabs (human) or fecal swabs (livestock) (FecalSwab, Copan Italy) were pre-enriched in a non-selective tryptic soy broth (Copan Italy) and subsequently cultured on an AmpC screening agar plate (McC, cefoxitin 8mg/L, cefotaxime or ceftazidime 1mg/L, Mediaproducts). MastDiscs (D68C, Mast Group) were used to confirm AmpC-production. Whole-genome sequencing of all phenotypic AmpC-producing Ec/Kp was performed on a MiSeq (Illumina), followed by de novo assembly with SPAdes v3.9.1 and whole-genome multilocus sequence typing (wgMLST) with Ridom SeqSphere (Ridom). ResFinder v3.1 (CGE) was used to detect acquired resistance genes and chromosomal mutations.

Results: A total number of 370 patients were cultured. Of those, 12 (3%) were rectal carrier of HL-AmpC-Ec/Kp. Mutations in the cAmpC promoter were identified in 7 Ec isolates and pAmpC (blaCMY-4,blaDHA-1) in 3 Ec and 2 Kp isolates. All HL-AmpC-Ec/Kp isolates from patients were clonally unrelated. For pig and broiler farms, 128 and 119 cultures were obtained, respectively. HL-AmpC-Ec was detected in 2 of 16 pig farms and 6 of 15 broiler farms with the prevalence of HL-AmpC-Ec-positive samples varying from 10% to 90%. Mutations in the cAmpC promoter were present in all 10 HL-AmpC-Ec isolates from pig farms and in 2 (10%) of 21 HL-AmpC-Ec isolates from broiler farms. The other 19 (90%) broiler Ec isolates all carried pAmpC (blaCMY-2). Five within-farm wgMLST clusters of 2 to 8 HL-AmpC-Ec isolates were identified in two pig farms and one broiler farm (Figure).

Conclusions: Rectal carriage of HL-AmpC-Ec/Kp was low among patients in Dutch hospitals without evidence for transmission. The prevalence of HL-AmpC-Ec/Kp in livestock farms varied between farms, and within-farm clustering was common.



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