Complexo Burkholderia cepacia isolados de pacientes com fibrose cística: caracterização molecular e aspectos fenotípicos de virulência

Abstract

Cystic fibrosis (CF) is an autosomal recessive genetic disorder common in caucasian individuals, caused by CFTR protein dysfunction. Some microorganisms are traditionally associated to chronic airways infections in CF, such as the species of the Burkholderia cepacia complex (Bcc). This complex currently comprises 21 species that are phylogenetically differentiable, but phenotypically difficult to distinguish. Currently molecular methods, particularly, the amplification and sequencing of recA gene, have been considered the best option to characterize these species. Some of Bcc’s species have been described as highly transmissible and virulent. The motility capacity and the production of biofilm have been described as important virulence factors in bacterias belonging to Bcc. 66 samples obtained from differents clinical specimens between January 2014 and December 2016 were analyzed. The species were identified through sequencing of recA gene as B. vietnamiensis (n= 32; 48.4%), followed by B. cenocepacia (n= 24; 36.6%), B. multivorans (n=7; 10.6%), B. contaminans (n= 2; 3.0%) and B. cepacia (n=1; 1.51%). Among the 66 samples, 55 were from pediatric patients and 11 from adult patients. The patient data showed a standard distribution in sample numbers, except 2 patients that presented 11 samples each. When analyzed the capacity of the 2 types of motility, swarming and swimming, 80.3% of the samples were capable to perform swarming and swimming. B. cenocepacia obtained the largest diameters by swimming and the diameters by swarming didn’t change between species. As the capacity of the biofilm formation, 46 samples were producers, among them, 42 weak producers and 4 moderate producers. Among the species, B. cenocepacia was the weak producer of biofilm with 83.4% of the samples and B. vietnamiensis was the only moderate producer with 4 samples. The biofilm formation was compared between isolated Bcc species from chronic patients and non-chronic patients, however, it wasn’t observed association between the two groups. Swarming and biofilm also didn’t show association, though it was observed a weak association between swimming and the biofilm formation. Bacterial biofilms may have profound implications for the host and have been characterized as highly resistant to antibiotic treatment and immune responses. Despite the important role of flagella in infection, the clinical significance of motility in chronic lung infections of Bcc in CF is unclear.