Detection of optrA in the African continent (Tunisia) within a mosaic Enterococcus faecalis plasmid from urban wastewaters

• Type: Article in International Scientific Journal
• Date: 2017

Authors

Freitas, AR (Author) Other; Elghaieb, H (Author) Other; Leon Sampedro, R (Author) Other; Abbassi, MS (Author) Other; Novais, Carla (Author) FFUP; Coque, TM (Author) Other; Hassen, A (Author) Other; Luisa Peixe (Author) FFUP

Journal

Title: Journal of Antimicrobial Chemotherapy

Vol. 72

Pages: 3245-3251

ISSN: 0305-7453

Publisher: Oxford University Press

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 54 Citations

Other information

Authenticus ID: P-00N-A3R

DOI: 10.1093/jac/dkx321

Abstract (EN): Objectives: Oxazolidinone resistance is a serious limitation in the treatment of MDR Enterococcus infections. Plasmid-mediated oxazolidinone resistance has been strongly linked to animals where the use of phenicols might co-select resistance to both antibiotic families. Our goal was to assess the diversity of genes conferring phenicol/oxazolidinone resistance among diverse enterococci and to characterize the optrA genetic environment. Methods: Chloramphenicol-resistant isolates (>16 mg/L, n=245) from different sources (hospitals/healthy humans/wastewaters/animals) in Portugal, Angola and Tunisia (1996-2016) were selected. Phenicol (eight cat variants, fexA, fexB) or phenicol! oxazolidinone [cfr, cfr(B), optrA] resistance genes were searched for by PCR. Susceptibility (disc diffusion/microdilution), filter mating, stability of antibiotic resistance (500 bacterial generations), plasmid typing (S1-PFGE/hybridization), MLST and WGS (Illumina-HiSeq) were performed for optrA-positive isolates. Results: Resistance to phenicols (n=181, 74%) and phenicols + oxazolidinones (n=2, 1%) was associated with the presence of cat(A-8) (40%, predominant in hospitals and swine), cat(A-7) (29%, predominant in poultry and healthy humans), cat(A-9) (2%), fexB (2%) and fexA! optrA (1%). fexA and optrA genes were co-located in a transferable plasmid (pAF379, 72918 bp) of two ST86 MDR Tunisian Enterococcus faecalis (wastewaters) carrying several putative virulence genes. MICs of chloramphenicol, linezolid and tedizolid were stably maintained at 64, 4 and 1 mg/L, respectively. The chimeric pAF379 comprised relics of genetic elements from different Gram-positive bacteria and origins (human/porcine). Conclusions: To the best of our knowledge, we report the first detection of optrA in an African country (Tunisia) within a transferable mosaic plasmid of different origins. Its identification in isolates from environmental sources is worrisome and alerts for the need of a concerted global surveillance on the occurrence and spread of optrA.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7