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

• Published in: PloS one 2017-04, Vol.12 (4), p.e0175552-e0175552
• Main Authors: Gomes-Fernandes, Meissiner, Laabei, Maisem, Pagan, Natalia, Hidalgo, Jessica, Molinos, Sònia, Villar Hernandez, Raquel, Domínguez-Villanueva, Dídac, Jenkins, A Toby A, Lacoma, Alicia, Prat, Cristina
• Format: Article
• Language: English
• Subjects: Assaying; Bacteremia; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biology; Biology and Life Sciences; Causes of; Clinical isolates; Colonization; Complications; Cyclic AMP; Deoxyribonucleic acid; DNA; DNA microarrays; DNA, Bacterial - genetics; DNA, Bacterial - metabolism; Gene expression; Genes, Regulator - genetics; Genetic aspects; Genetic variation; Genotype; Hemolysin Proteins - genetics; Hemolysin Proteins - metabolism; Hospitals; Humans; Infections; Infectious diseases; Lysis; Medicine and Health Sciences; Methicillin-Resistant Staphylococcus aureus - genetics; Methicillin-Resistant Staphylococcus aureus - isolation & purification; Pathogens; Phenols; Physiological aspects; Polymerase chain reaction; Real-Time Polymerase Chain Reaction; Research and analysis methods; Respiratory tract; Respiratory tract diseases; Respiratory tract infection; Respiratory tract infections; Respiratory Tract Infections - microbiology; Respiratory Tract Infections - pathology; Signal transduction; Staphylococcus aureus; Staphylococcus aureus - genetics; Staphylococcus aureus - isolation & purification; Staphylococcus infections; Statistical analysis; Strains (organisms)
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0175552

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.