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

  • Sofia Santos Costa1, 2,

    Affiliated with

    • Celeste Falcão1,

      Affiliated with

      • Miguel Viveiros1, 3,

        Affiliated with

        • Diana Machado1, 4,

          Affiliated with

          • Marta Martins1, 4, 5,

            Affiliated with

            • José Melo-Cristino6,

              Affiliated with

              • Leonard Amaral1, 3, 4 and

                Affiliated with

                • Isabel Couto1, 2Email author

                  Affiliated with

                  BMC Microbiology201313:127

                  DOI: 10.1186/1471-2180-13-127

                  Received: 15 May 2013

                  Accepted: 24 May 2013

                  Published: 6 June 2013

                  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

                    

                  QRDR mutationsb

                  MIC (mg/L)c

                      

                  EtBr

                  CIP

                  NOR

                  NAL

                  Isolatea

                  PFGE pattern

                  GrlA

                  GyrA

                  No

                  +

                  +

                  No

                  +

                  +

                  No

                  +

                  +

                  No

                  +

                  +

                  EI

                  TZ

                  CPZ

                  EI

                  TZ

                  CPZ

                  EI

                  TZ

                  CPZ

                  EI

                  TZ

                  CPZ

                  ATCC25923

                  -

                  WT

                  WT

                  6.25

                  0.75

                  0.75

                  0.25

                  0.125

                  0.125

                  0.5

                  0.125

                  0.125

                  64

                  n.d.

                  n.d.

                  ATCC25923EtBr

                  -

                  WT

                  WT

                  200

                  25

                  12.5

                  1

                  0.25

                  0.25

                  2

                  0.25

                  0.25

                  64

                  n.d.

                  n.d.

                  SM1

                  A2

                  S80Y/E84G

                  S84L

                  16

                  4

                  4

                  128

                  32

                  64

                  512

                  128

                  256

                  256

                  64

                  64

                  SM10

                  A4

                  S80Y/E84G

                  S84L

                  16

                  2

                  4

                  128

                  64

                  64

                  512

                  128

                  128

                  128

                  64

                  64

                  SM14

                  A3

                  S80Y/E84G

                  S84L

                  16

                  4

                  4

                  256

                  32

                  128

                  1024

                  128

                  256

                  256

                  64

                  64

                  SM17

                  A4

                  S80Y/E84G

                  S84L

                  16

                  4

                  4

                  256

                  64

                  64

                  1024

                  256

                  512

                  256

                  64

                  64

                  SM25

                  A1

                  S80Y/E84G

                  S84L

                  8

                  2

                  4

                  128

                  32

                  64

                  512

                  64

                  128

                  256

                  32

                  64

                  SM27

                  A4

                  S80Y/E84G

                  S84L

                  16

                  4

                  4

                  256

                  32

                  64

                  512

                  128

                  256

                  256

                  64

                  64

                  SM43

                  A1

                  S80Y/E84G

                  S84L

                  16

                  2

                  4

                  128

                  64

                  64

                  512

                  128

                  128

                  512

                  256

                  64

                  SM46

                  A1

                  S80Y/E84G

                  S84L

                  16

                  4

                  4

                  128

                  64

                  64

                  512

                  128

                  256

                  128

                  64

                  64

                  SM47

                  A1

                  S80Y/E84G

                  S84L

                  8

                  2

                  4

                  256

                  32

                  64

                  512

                  128

                  256

                  256

                  64

                  64

                  SM48

                  A1

                  S80Y/E84G

                  S84L

                  8

                  4

                  4

                  256

                  32

                  64

                  512

                  128

                  256

                  256

                  64

                  64

                  SM50

                  B1

                  S80F/E84K

                  S84L

                  8

                  1

                  2

                  64

                  16

                  16

                  256

                  32

                  64

                  128

                  64

                  64

                  SM52

                  C1

                  S80Y

                  S84L

                  16

                  1

                  2

                  16

                  8

                  8

                  64

                  32

                  32

                  128

                  32

                  64

                  SM2

                  B2

                  S80F/E84K

                  S84L

                  8

                  2

                  2

                  32

                  16

                  16

                  128

                  32

                  32

                  64

                  16

                  64

                  SM3

                  E1

                  S80F/E84G

                  S84L

                  1

                  1

                  1

                  16

                  8

                  8

                  64

                  32

                  32

                  64

                  16

                  16

                  SM4

                  E2

                  S80F

                  S84L

                  4

                  2

                  1

                  8

                  8

                  8

                  64

                  32

                  32

                  64

                  32

                  64

                  SM5

                  E3

                  S80F/E84G

                  S84L

                  4

                  2

                  1

                  32

                  16

                  16

                  128

                  64

                  64

                  64

                  32

                  32

                  SM6

                  A5

                  S80F

                  E88K

                  4

                  2

                  1

                  16

                  16

                  16

                  64

                  32

                  32

                  64

                  32

                  32

                  SM7

                  E1

                  S80F

                  S84L

                  2

                  2

                  1

                  8

                  8

                  4

                  64

                  32

                  32

                  128

                  32

                  64

                  SM8

                  A5

                  S80F

                  E88K

                  4

                  2

                  1

                  16

                  8

                  16

                  128

                  64

                  64

                  128

                  32

                  64

                  SM12

                  E1

                  S80F

                  S84L

                  2

                  2

                  1

                  16

                  8

                  8

                  64

                  32

                  32

                  128

                  32

                  64

                  SM16

                  A6

                  S80F

                  E88K

                  4

                  2

                  1

                  16

                  16

                  16

                  128

                  32

                  64

                  64

                  32

                  64

                  SM22

                  A1

                  S80Y/E84G

                  S84L

                  8

                  4

                  4

                  128

                  16

                  32

                  512

                  128

                  128

                  64

                  32

                  64

                  SM34

                  D1

                  S80F/E84K

                  S84L

                  4

                  2

                  2

                  64

                  16

                  32

                  64

                  16

                  32

                  32

                  16

                  32

                  SM36

                  E1

                  S80F

                  S84L

                  4

                  2

                  2

                  16

                  8

                  8

                  64

                  16

                  32

                  128

                  32

                  64

                  SM40

                  E1

                  S80F

                  S84L

                  8

                  4

                  4

                  32

                  32

                  32

                  512

                  128

                  128

                  16

                  8

                  16

                  aIsolates in bold correspond to the EtBrCW-positive isolates. bWT: wild-type; S: serine; F: phenylalanine; E: glutamate; K: lysine; Y: tyrosine; L: leucine; G: glycine. cValues in bold-type correspond to a MIC decrease of ≥ four-fold in the presence of the efflux inhibitor (EI) in comparison to the values with no EI [10]. The concentration of each EI used is defined in the Methods section. EtBr: ethidium bromide; CIP: ciprofloxacin; NOR: norfloxacin; NAL: nalidixic acid; TZ: thioridazine; CPZ: chlorpromazine; n.d.: not determined.

                  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.

                  Authors’ Affiliations

                  (1)
                  Grupo de Micobactérias, Unidade de Microbiologia Médica, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (IHMT, UNL)
                  (2)
                  Centro de Recursos Microbiológicos (CREM), Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre
                  (3)
                  COST ACTION BM0701
                  (4)
                  Unidade de Parasitologia e Microbiologia Médica (UPMM), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa
                  (5)
                  UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, Veterinary Sciences Centre, University College Dublin
                  (6)
                  Centro Hospitalar Lisboa Norte E.P.E., Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa

                  References

                  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.PubMedView Article
                  2. Hooper DC: Mechanisms of fluoroquinolone resistance. Drug Resist Updat 1999, 2:38–55.PubMedView Article

                  Copyright

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

                  This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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