Pseudomonas aeruginosa AND Staphylococcus aureus INTERACTION IN CYSTIC FIBROSIS PEDIATRIC PATIENTS

Los Cocos

Congreso; XVII Congreso Argentino de Microbiología General; 2022

SAMIGE

Microorganisms are frequently found in multispecies communities presenting species interactions like neutralism, mutualism, or antagonism. Particularly, Pseudomonas aeruginosa (PA) and Staphylococcus aureus(SA) are opportunistic human pathogens that can be co-isolated from different infections. Lung infections in cystic fibrosis patients caused by these two bacterial species are the main cause of mortality and morbidity in these patients and coinfections can modify virulence, antibiotic resistance with a worse prognosis for the patient. SA-PA interaction has been described as antagonist with SA displacement, but in-vivo infections showed a more complex interaction that can also include coexistence and metabolic cooperation. Additionally, during infection establishment patoadaptative mutations are selected. Our hypothesis is that during the establishment of S. aureus infection the selected mutations impact on its interaction with P. aeruginosa and the result of it. We stablished apatient recruitment at Hospital General de Niños Dr. Pedro Elizalde that includes a 17 CF pediatric patients monoinfected with SA or coinfected with PA-SA for 18 months (in progress) to analyze this interaction. During the first 12 months of sampling, we determine the phenotypic characteristics of more than 300 SA isolates including DNAse, haemolysis, antibiotic resistance, exopolysaccharides, and competence with P. aeruginosa PAO1. We found out that PA presence was maintained in coinfected patients while SA was displaced intermittently or not depending on the patient. For SA monoifectedpatients we found that transient PA presence was variable. Our first results showed that SA isolates in the sampling initial point from monoinfected patients presented a higher staphyloxantin production and resistance to P. aeruginosa PAO1 presence than those isolates from coinfected patients whilebiofilm formation was similar for both groups. We choose a SA monoinfected patient who never showed PA infection to analyze through time even before the starting sampling point. In this patient DNAse, haemolysis and competence with P. aeruginosa PAO1 were stable through time, while staphyloxantin production was higher in the last sampling points. Additionally, genome sequence ofone clone from this patient was obtained using nanopore technology. Genome size was 2.98 MB with genomic deletions and point mutations when compared to a reference strain. Our results showed that the recruitment design and the phenotypic characterization as well as the competence assays are adequate to analyze S. aureus-P. aeruginosa interaction.