Accessory gene regulator (Agr) functionality in Staphylococcus aureus derived from lower respiratory tract infections

Meissiner Gomes-Fernandes, Maisem Laabei, Natalia Pagan, Jessica Hidalgo, Sònia Molinos, Raquel Villar Hernandez, Dídac Domínguez-Villanueva, A Toby A Jenkins, Alicia Lacoma, Cristina Prat

Research output: Contribution to journalArticle (Academic Journal)peer-review

26 Citations (Scopus)


Characterization of Staphylococcus aureus clinical isolates derived from lower respiratory tract infections (LRTIs), and correlation between the functionality of the accessory gene regulator (Agr) and genotypic and phenotypic characteristics, clinical variables and clinical outcome.

S aureus isolates derived from LRTIs and control groups (nasal carriage and bacteraemia) were genotyped using StaphyType DNA microarray. Agr activity was evaluated using the CAMP synergistic haemolysis assay and the Vesicle Lysis Test (VLT). Discordant strains were analysed by quantitative reverse-transcriptase real-time PCR (qRT-PCR).

Agr was functional in 79.7% and 84.5% of strains according to the CAMP and VLT assays respectively. Higher concordance with RNAIII expression measured by qRT-PCR was observed with the VLT assay (76.2%) compared with the CAMP assay (23.8%). No statistically significant differences were observed in Agr functionality between the study groups, nor the phenotypical/genotypical bacterial characteristics. No association between increased mortality/respiratory complications and Agr function was observed.

Agr activity was high (82.2%) in isolates from LRTIs suggesting the importance of this global regulator in lower respiratory tract colonisation and infection. However, equally high Agr activity was observed in isolates derived from nasal carriage and bacteraemia, contradictory to previous observations. Agr functionality measured by the VLT assay was superior to CAMP assay.
Original languageEnglish
Article numbere0175552
Number of pages14
JournalPLoS ONE
Issue number4
Publication statusPublished - 14 Apr 2017

Bibliographical note

Publisher Copyright:
© 2017 Gomes-Fernandes et al.


  • Bacterial Proteins/genetics
  • DNA, Bacterial/genetics
  • Genes, Regulator/genetics
  • Genotype
  • Hemolysin Proteins/genetics
  • Humans
  • Methicillin-Resistant Staphylococcus aureus/genetics
  • Real-Time Polymerase Chain Reaction
  • Respiratory Tract Infections/microbiology
  • Staphylococcus aureus/genetics


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