Klebsiella pneumoniae biofilms and healthcare associated infections

Klebsiella pneumoniae is an important etiological agent of healthcare associated infections (HAIs). In this context, multidrug-resistant and biofilm-producing bacteria are of special public health concern due to the difficulties associated with treatment of human infections and eradication from hospital environments. Here, we started by evaluating the ability of 10 K. pneumoniae isolates responsible for HAIs collected during a period of 31 years. In order to study the impact of medical devices-associated materials on the biofilm dynamics, three isolates were selected for biofilm phenotypic analyses through a classic and a new scanning electron microscopy (SEM) on different surfaces (polystyrene and silicone) and antibiotic susceptibility assay. We also applied whole-genome sequencing (WGS) to search for genetic clues underlying biofilm phenotypic differences. We found major differences in the extracellular polymeric substances (EPS) content among the three strains, which were further corroborated by in-depth EPS composition analysis. WGS analysis revealed a high nucleotide similarity within the core-genome, but relevant differences in the accessory genome that may account for the detected biofilm phenotypic dissimilarities, such as genes already associated with biofilm formation in other pathogenic bacteria (e.g., genes coding haemogglutinins and haemolysins). These data reinforce that the research efforts to defeat bacterial biofilms should take into account that their dynamics may be contingent on the medical devices-associated materials.N/