Prospection of Klebsiella quasipneumoniae phages and their efficacy on multidrug-resistant strains of Klebsiella spp.

Abstract

The growing bacterial resistance to antibiotics represents one of the greatest challenges to global public health, particularly with regard to pathogens listed as critical by the World Health Organization, such as multidrug-resistant Klebsiella pneumoniae. In this context, bacteriophages (or phages) emerge as a promising alternative to traditional antibiotic therapy. This study aimed to isolate and characterize phages with lytic activity against K. pneumoniae (ATCC 700603) and other clinically relevant strains, focusing on their potential therapeutic use. Environmental samples were collected and subjected to screening and purification protocols to select phages capable of inducing lysis. The isolates were subsequently evaluated for their host range, physicochemical stability, and morphology, with emphasis on their effectiveness against extended-spectrum β-lactamase (ESBL) and carbapenemase-producing strains. Additionally, assays for biofilm formation inhibition and mature biofilm disruption were performed. In the ATCC 700603 strain, only phage KqP1 significantly reduced established biofilms, with an enhanced effect observed when using a phage cocktail. For strain K2010, phages K2010P2 and K2010P4 showed the highest levels of biofilm disruption, while K2010P5 was the most effective in preventing biofilm formation; the cocktail was also active in both assays. The results demonstrate the feasibility of isolating phages with a promising lytic profile and antibiofilm activity, reinforcing the basis for local implementation of phage therapy and contributing to the fight against antimicrobial resistance, while advancing knowledge on lytic phages active against K. pneumoniae.