iBB

Burkholderia cepacia complex (Bcc) bacteria can adapt to the hostile lung environment of cystic fibrosis (CF) patients leading to chronic infection. While it is unclear why different Bcc species/strains differ in their pathogenic potential, lipopolysaccharides (LPS) are considered a major virulence factor. The O-antigen (OAg) component of LPS is believed to modulate host-pathogen interaction and to be under selective pressure. A study recently published in Frontiers in Cellular and Infection Microbiology was performed to understand whether OAg loss can be considered a general phenomenon that affects immune evasion favoring chronic infection. A systematic retrospective and longitudinal screening was performed based on a collection of 357 isolates involving 21 different Bcc strains of six/seven Bcc species/lineages isolated from CF patients. These isolates were recovered from 1995 to 2016 from 19 CF patients under surveillance at Hospital de Santa Maria over the duration of chronic infection (ranging from 1.2 to 15.2 years). B. cenocepacia and B. multivorans showed a tendency to lose the OAg along chronic infection, with the switch frequency increasing with the duration of infection and level of lung function deterioration. For the first time, this study shows that the rarely found species B. cepacia and B. contaminans keep the OAg even during infections that last for 10 and 15 years. This research, coordinated by Prof. Isabel Sá-Correia and with the BIOTECnico PhD student Amir Hassan as first author, reinforces the relevance attributed to OAg-expression switch suggesting marked differences in the various Bcc species.