Open Access

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

  • Sofia Santos Costa1, 2,
  • Celeste Falcão1,
  • Miguel Viveiros1, 3,
  • Diana Machado1, 4,
  • Marta Martins1, 4, 5,
  • José Melo-Cristino6,
  • Leonard Amaral1, 3, 4 and
  • Isabel Couto1, 2Email author
BMC Microbiology201313:127

DOI: 10.1186/1471-2180-13-127

Received: 15 May 2013

Accepted: 24 May 2013

Published: 6 June 2013

The Research article to this article has been published in BMC Microbiology 2011 11:241

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.

Notes

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
(3)
COST ACTION BM0701 (ATENS
(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: 241-10.1186/1471-2180-11-241.PubMedPubMed CentralView Article
  2. Hooper DC: Mechanisms of fluoroquinolone resistance. Drug Resist Updat. 1999, 2: 38-55. 10.1054/drup.1998.0068.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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