Biofilm formation, interaction and survival within A549 pneumocytes of Klebsiella pneumoniae clinical strains: identification of pulsotypes, multidrug-resistance and genes coding for adhesins: Formação de biofilme, interação e sobrevivência dentro dos pneumócitos A549 de cepas clínicas de Klebsiella pneumoniae: identificação de pulsótipos, multirresistência a drogas e codificação de genes para adesinas

Klebsiella pneumoniaehas become one of the major causes of hospital-acquired infections over decades due to the spread of virulent clones harboring resistant genes to multiple antimicrobial agents. The aim of this study was to investigate phenotypic and genotypic features of virulence mechanism expressed by K. pneumoniae clinical isolates of different PFGE types, including biofilm formation, interaction with pneumocytes A549 lineage and experimental infection by using C. elegans nematodes.  A total of 17 K. pneumoniae strains were isolated from different clinical specimens including blood, urine and respiratory infections. In this present study, 11 strains presented a varied multidrug-resistance profile harboring resistance genes coding for betalactams, aminoglicosydes, fluorquinolones and carbapenemases. PFGE analysis demonstrated the presence of four distinct pulsotypes among K. pneumoniae strains harboring virulence genes for siderophores and fimbiae type 1 and type 3. High adherence and biofilm formation were positively correlated for both polystyrene and glass surfaces in all K. pneumoniae strains analyzed. K. pneumoniae clinical strains showed the ability of adherence, internalization and persistence within human pulmonary epithelial A549 cell line, at different levels. Respiratory infections demonstrated a higher heterogeneity of PFGE types and levels of adherence, intracellular survival and persistence.K. pneumoniae strains were also submitted to Carnohabidits elegans in vivo infection model and data showed that after 24 hr almost 10% of urine-culture isolates worms were dead evidencing virulence profile. Notably, K. pneumoniae strains, presenting virulence genes, was significantly more virulent than those who did not presented any virulence gene after 5 days (survival >60% and >40%)