Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 May 3;11(5):615.
doi: 10.3390/antibiotics11050615.

Antimicrobial Susceptibility of Enterococcus Isolates from Cattle and Pigs in Portugal: Linezolid Resistance Genes optrA and poxtA

Joana Gião  1   2 , Célia Leão  1   3 , Teresa Albuquerque  1 , Lurdes Clemente  1   4 , Ana Amaro  1
Affiliations

Antimicrobial Susceptibility of Enterococcus Isolates from Cattle and Pigs in Portugal: Linezolid Resistance Genes optrA and poxtA

Joana Gião et al. Antibiotics (Basel). .

Abstract

Enterococci are part of the commensal gut microbiota of mammals, with Enterococcus faecalis and Enterococcus faecium being the most clinically relevant species. This study assesses the prevalence and diversity of enterococcal species in cattle (n = 201) and pig (n = 249) cecal samples collected in 2017. Antimicrobial susceptibility profiles of E. faecium (n = 48) and E. faecalis (n = 84) were assessed by agar and microdilution methods. Resistance genes were screened through PCR and nine strains were analyzed by Whole Genome Sequencing. A wide range of enterococci species was found colonizing the intestines of pigs and cattle. Overall, the prevalence of resistance to critically important antibiotics was low (except for erythromycin), and no glycopeptide-resistant isolates were identified. Two daptomycin-resistant E. faecalis ST58 and ST93 were found. Linezolid-resistant strains of E. faecalis (n = 3) and E. faecium (n = 1) were detected. Moreover, oxazolidinone resistance determinants optrA (n = 8) and poxtA (n = 2) were found in E. faecalis (ST16, ST58, ST207, ST474, ST1178) and E. faecium (ST22, ST2138). Multiple variants of optrA were found in different genetic contexts, either in the chromosome or plasmids. We highlight the importance of animals as reservoirs of resistance genes to critically important antibiotics.

Keywords: Enterococcus spp.; Linezolid resistance; WGS; cattle; optrA gene; pigs.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Distribution of Enterococcus species in cattle and pigs.
Figure 2
Figure 2
Diversity of multidrug resistance profiles found in (a) E. faecalis (n = 84) and (b) E. faecium (n = 48) strains from swine using the agar dilution susceptibility test. MDR, Multidrug-resistant; TET, Tetracycline; ERY, Erythromycin; LZD, Linezolid; AMP, Ampicillin; CLO, Chloramphenicol; CIP, Ciprofloxacin; GEN, Gentamicin.
Figure 3
Figure 3
Distribution of linezolid MIC values among strains of E. faecalis (n = 6) and E. faecium (n = 2) carrying the optrA gene using the EUVENC microdilution plates.
Figure 4
Figure 4
Alignment of the optrA-containing contigs of strains INIAV168 and INIAV171 with the previously described optrA-carrying plasmid p10-2-2 (GenBank accession number KT862775).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. LPSN—List of Prokaryotic Names with Standing in Nomenclature. Genus Enterococcus. 1997. [(accessed on 20 December 2021)]. Available online: https://www.bacterio.net/genus/enterococcus.
    1. Staley C., Dunny G.M., Sadowsky M.J. Advances in Applied Microbiology. Volume 87. Elsevier; Amsterdam, The Netherlands: 2014. Environmental and Animal-Associated Enterococci; pp. 147–186. - DOI - PubMed
    1. Devriese L.A., Hommez J., Wijfels R., Haesebrouck F. Composition of the Enterococcal and Streptococcal Intestinal Flora of Poultry. J. Appl. Bacteriol. 1991;71:46–50. doi: 10.1111/j.1365-2672.1991.tb04585.x. - DOI - PubMed
    1. Lebreton F., Willems R., Gilmore M. Enterococcus Diversity, Origins in Nature, and Gut Colonization. In: Gilmore M.S., Clewell D.B., Ike Y., editors. Enterococci: From Commensals to Leading Causes of Drug Resistant Infection. Massachusetts Eye and Ear Infirmary; Boston, MA, USA: 2014. - PubMed
    1. Molina M., Cyterski M., Maimes J., Fisher J., Johnson B. Comparison of the Temporal Variability of Enterococcal Clusters in Impacted Streams Using a Multiplex Polymerase Chain Reaction Procedure; Proceedings of the 2007 Georgia Water Resources Conference; Athens, GA, USA. 27–29 March 2007.

LinkOut - more resources