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

By Meissiner Gomes Fernandes, Maisem Laabei, Natalia Pagan Maldonado, Jessica Hidalgo, Sònia Molinos Abós, Raquel Villar Hernandez, Dídac Domínguez Villanueva, Andrew Toby A. Jenkins, Alicia Lacoma, Cristina Prat i Aymerich and Universitat Autònoma de Barcelona


Altres ajuts: This work has been funded by the project PI13/01418 which is part of "Plan Nacional de I+D+I" and co-funded by ISCIII-Subdirección General de Evaluacioón and "Fondo Europeo de Desarrollo Regional"(FEDER).D. Domínguez-Villanueva is funded by "Plan Nacional de I+D+I" and co-funded by ISCIII-Subdirección General de Evaluación and "Fondo Europeo de Desarrollo Regional"(FEDER). M. Gomes-Fernandes is funded by CAPES Foundation, Ministry of Education of Brazil (Brasılia, Brazil). Maisem Laabei was supported by a joint ERS/SEPAR fellowship (LTRF2015).This work also received a grant from the Spanish Society of Pneumology and Thoracic Surgery (SEPAR054/2011).Objective. 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. Methods. 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). Results. 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. Conclusions. 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

Publisher: 'Public Library of Science (PLoS)'
Year: 2017
DOI identifier: 10.1371/journal.pone.0175552
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