ABSTRACTPulmonary infection withBurkholderia cepaciacomplex in cystic fibrosis (CF) patients is associated with more-rapid lung function decline and earlier death than in CF patients without this infection. In this study, we used confocal microscopy to visualize the effects of various concentrations of tobramycin, achievable with systemic and aerosolized drug administration, on matureB. cepaciacomplex biofilms, both in the presence and absence of CF sputum. After 24 h of growth, biofilm thickness was significantly reduced by exposure to 2,000 μg/ml of tobramycin forBurkholderia cepacia,Burkholderia multivorans, andBurkholderia vietnamiensis; 200 μg/ml of tobramycin was sufficient to reduce the thickness ofBurkholderia dolosabiofilm. With a more mature 48-h biofilm, significant reductions in thickness were seen with tobramycin at concentrations of ≥100 μg/ml for allBurkholderiaspecies. In addition, an increased ratio of dead to live cells was observed in comparison to control with tobramycin concentrations of ≥200 μg/ml forB. cepaciaandB. dolosa(24 h) and ≥100 μg/ml forBurkholderia cenocepaciaandB. dolosa(48 h). Although sputum significantly increased biofilm thickness, tobramycin concentrations of 1,000 μg/ml were still able to significantly reduce biofilm thickness of allB. cepaciacomplex species with the exception ofB. vietnamiensis. In the presence of sputum, 1,000 μg/ml of tobramycin significantly increased the dead-to-live ratio only forB. multivoranscompared to control. In summary, although killing is attenuated, high-dose tobramycin can effectively decrease the thickness ofB. cepaciacomplex biofilms, even in the presence of sputum, suggesting a possible role as a suppressive therapy in CF.
Epidemiology and Clinical Course of Burkholderia cepacia Complex Infections, Particularly Those Caused by Different Burkholderia cenocepacia Strains, among Patients Attending an Italian Cystic Fibrosis Center