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Correction: Exploring the contribution of efflux on the resistance to fluoroquinolones in clinical isolates of Staphylococcus aureus

Sofia Santos Costa12, Celeste Falcão1, Miguel Viveiros13, Diana Machado14, Marta Martins145, José Melo-Cristino6, Leonard Amaral134 and Isabel Couto12*

Author Affiliations

1 Grupo de Micobactérias, Unidade de Microbiologia Médica, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (IHMT, UNL), Rua da Junqueira, 100, 1349-008, Lisbon, Portugal

2 Centro de Recursos Microbiológicos (CREM), Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516, Caparica, Portugal


4 Unidade de Parasitologia e Microbiologia Médica (UPMM), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 100, 1349-008, Lisbon, Portugal

5 UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, Veterinary Sciences Centre, University College Dublin, Belfield Dublin 4, Ireland

6 Centro Hospitalar Lisboa Norte E.P.E., Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal

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BMC Microbiology 2013, 13:127  doi:10.1186/1471-2180-13-127

The electronic version of this article is the complete one and can be found online at:

Received:15 May 2013
Accepted:24 May 2013
Published:6 June 2013

© 2013 Costa et al.; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


After the publication of our study [1], we became aware that the mutations in the quinolone resistance-determining region (QRDR) of the gene grlA were incorrectly described for some of the Staphylococcus aureus clinical isolates studied in this work. In particular, isolates SM1, SM10, SM14, SM17, SM25, SM27, SM43, SM46, SM47 and SM48 carry the GrlA double mutation S80Y/E84G; isolate SM52 carries the GrlA mutation S80Y; isolates SM3 and SM5 carry the GrlA double mutation S80F/E84G. The correct data can be found in Table 1.

Table 1. Genotypic and phenotypic characterization of S. aureus clinical isolates

All clinical isolates included in this study were selected upon a ciprofloxacin resistance phenotype and all the 25 representative isolates screened for mutations conferring fluoroquinolone resistance carried QRDR mutations in both grlA and gyrA genes. All the mutations found have been described in literature as associated with fluoroquinolone resistance in S. aureus clinical isolates [2]. As stated previously in our study, the majority of the isolates presented a double mutation in GrlA together with a single mutation in GyrA. Eleven isolates carried the GrlA and GyrA mutations S80Y/E84G and S84L, respectively; three isolates carried mutations GrlA S80F/E84K and GyrA S84L and two isolates carried mutations GrlA S80F/E84G and GyrA S84L.The remaining nine isolates carried a single mutation in both genes, in three distinct arrangements (Table 1).

Despite this correction in the QRDR mutations carried by some of the isolates studied, the main findings of our study are not altered. In particular, our data show the potential role played by efflux systems in the development of resistance to fluoroquinolones in clinical isolates of S. aureus, independently of the mutations occurring in the target genes.

We apologize for any inconvenience that this may have caused to the readers.


  1. Costa SS, Falcão C, Viveiros M, Machado D, Martins M, Melo-Cristino J, Amaral L, Couto I: Exploring the contribution of efflux on the resistance to fluoroquinolones in clinical isolates of Staphylococcus aureus.

    BMC Microbiol 2011, 11:241. PubMed Abstract | BioMed Central Full Text | PubMed Central Full Text OpenURL

  2. Hooper DC: Mechanisms of fluoroquinolone resistance.

    Drug Resist Updat 1999, 2:38-55. PubMed Abstract | Publisher Full Text OpenURL