Where does Burkholderia contaminans localize in the respiratory tract of patients with cystic fibrosis?

RODRIGUEZ, MARIA EUGENIA; IRIGOYEN NATALIA; LAMBERTI YANINA; BOSCH ALEJANDRA; VESCINA CECILIA; BETTIOL MARISA; RENTERÍA FERNANDO; LEÓN BELTINA; CASCO DANIELA

Dublin

Workshop; 21st International Burkholderia Cepacia Working Group IBCWG; 2018

The International Burkholderia cepacia Working Group

Burkholderia contaminans was reported as the most prevalent species of the Burkholderia cepacia complex recovered from sputum samples of patients with cystic fibrosis (CF) in Argentina. While infection by these bacteria could be transient, in most cases it results in a chronic lung infection very difficult to eradicate. For numerous bacterial infections it has been reported that microorganisms may persist in the host extracellularly in biofilm-like structures, or/and intracellularly in respiratory tract or immune cells. Particularly, the localization of B. contaminans in CF lungs, during long-term infections has not been reported, so far. The aim of this work is to try to elucidate the different strategies that B. contaminans may employ to persist in chronic infections within the host.For this purpose sputum samples from 5 pediatric patients chronically colonized by B. contaminans attended at Hospital de Niños, La Plata, Argentina, were collected. A portion of each specimen was used for Gram and Hematoxylin and Eosin stain observations and another for the recovery of the clinical isolates (cultured in selective medium BCSA). Each isolate obtained from the clinical samples was identified by MLST typing method. The clinical isolates and the B. contaminans LMG23361 reference strain were further tested for biofilm formation capacity and for invasion and intracellular survival capacity by immunofluorescence staining and antibiotic protection assay.The light microscopy smears analysis showed small bacterial aggregates within mucus and a few bacteria dispersed (in general associated to cells). Although the biofilm formation capacity was isolate dependent, we observed that all the isolates were able to produce biofilms in vitro. Interestingly, data from infection assays showed the presence of viable bacteria inside A549 cells. These results are compatible with the hypothesis that B. contaminans may also persist intracellularly in the host. Therefore, these preliminary results showed that B. contaminans could be colonizing patients´ airways using more than one adaptive strategy, probably persisting as biofilm in the upper respiratory tract and possibly intracellularly in the lower respiratory tract.