Antunes, Patrícia

Duarte, B.

Freitas, A.R.

Gonzalez, T.M.C.

Hammerum, A.

Hasman, H.

Novais, C.

Peixe, L.

Pereira, A.P.

English

Repositório Aberto da Universidade do Porto

P2334 Identification of a conserved operon in chlorhexidine tolerant Enterococcusfaecium from different clades and originsBarbara Duarte1, Ana P. Pereira2, Ana Raquel Freitas1, Teresa M. Coque Gonzalez3,4, Henrik Hasman5, Anette M.Hammerum5, Patricia Antunes1,6, Luisa Maria Vieira Peixe1, Carla Novais*11 UCIBIO/REQUIMTE. Faculty of Pharmacy. Biological Sciences Department., University of Porto, Porto, Portugal, 2Faculty of Pharmacy. Biological Sciences Department., University of Porto, Porto, Portugal, 3 University HospitalRamón y Cajal, Madrid, Spain, 4 CIBER Epidemiología y Salud Pública, Madrid, Spain, 5 Statens Serum Institut.Department of Microbiology and Infection Control, Copenhagen, Denmark, 6 Faculty of Food Sciences andNutrition, University of Porto, Porto, PortugalBackground: Chlorhexidine-gluconate (CHX) activity against Enterococcus faecium-Efm is scarcely documented,with most available data not addressing the clonal background of the strains (clades A1-infection derived strains,A2-mostly animals, B-human commensal). A P102H-mutation in a conserved DNA-binding-response-regulator(ChtR) has been associated with chlorhexidine tolerance among strains of Efm clade A1, although the regulonremained unidentified (PMID:28242664). Here, we evaluated CHX activity, the distribution of ChtR-P102H, thepredicted ChtR regulon and its variability among Efm from diverse sources and clades.Materials/methods: Efm (n=106) from clades A1 (n=48; human/animal/food/environment), A2 (n=43;human/animal/food) and B (n=15; human/animal/environment) (1995-2016; 5-countries; multidrug-resistant:72%) were included. CHX susceptibility (range:2-32mg/L) was determined by broth-microdilution. EfmMIC distribution was analysed by ECOFFINDER-tool (http://www.eucast.org/mic_distributions_and_ecoffs/). Thirty-five Efm were sequenced (Illumina-NextSeq platform/2X150bp paired-end). DOOR software(http://csbl.bmb.uga.edu/DOOR/index.php) predicted ChtR regulon. Amino-acid mutations in ChtR and otheroperon proteins were identified by comparison (BLASTp-NCBI) with the CHX-tolerant reference strain ChtR-P102H-Efm-E1162 (EFF34003.1; PMID:28242664).Results: CHX-MIC ranged between ≤2-32mg/L (mode=16mg/L; 51% of isolates), with the MICs fitted curveslightly deviated to the left comparing to raw data distribution, suggesting the presence of a non-wild-Efmpopulation. Most of Efm with a MIC≥8mg/L (96%-n=25/26; 3 clades; 14 of infections) presented the ChtR-P102H,while most isolates with a MIC≤4mg/L did not (67%-n=6/9; clades A2/B; 2 of infections). The predicted 4101bp-operon associated with chtR included a previously identified sensor-histidine-kinase as well as a DMT superfamilydrug/metabolite transporter and an amino-acid-polyamine-organocation family transporter genes, firstlydescribed here. The complete operon was present in all 35 Efm sequenced. The 25 Efm-MIC≥8mg/L exhibitedoperon sequences identical to ChtR-P102H-Efm-E1162, contrasting with diverse amino-acid mutations identifiedin the sensor-histidine-kinase and/or in the two new transporters proteins identified in isolates with a CHX-MIC≤4mg/L and lacking ChtR-P102H.Conclusions: The complete characterization of the ChtR-P102H-operon, highly conserved among Efm with highCHX-MICs, is here firstly described. Its wide distribution in Efm of diverse clades and sources suggests occurrenceof horizontal transfer events. The role of each ChtR-operon protein in the CHX-tolerance as well as the occurrenceof other CHX tolerance mechanisms in isolates with MIC≥8mg/L and lacking ChtR-P102H deserves furtherresearch.29TH ECCMID13-16 APRIL 2019 AMSTERDAM, NETHERLANDS POWERED BY M-ANAGE.COM 

Identification of a conserved operon in chlorhexidine tolerant Enterococcus faecium from different clades and origins

Open Repository of the University of Porto

https://repositorio-aberto.up.pt/bitstream/10216/125023/2/372189.pdf

Identification of a conserved operon in chlorhexidine tolerant Enterococcus faecium from different clades and origins

Abstract

Similar works

Full text

Available Versions

Repositório Aberto da Universidade do Porto

Open Repository of the University of Porto