Lactonase mediated quorum quenching strategy an alternative therapy against Klebsiella pneumoniae induced hospital acquired pneumonia

Abstract

In the present study, AHL lactonase obtained from Bacillus sp. ZA12 was entrapped inside nano-liposomes to increase its efficacy towards treating pneumonia caused by K. pneumoniae in BALB/c mice. The effectiveness of this treatment is attributed to a sustained release and better stability of AiiA after entrapment inside nano-liposomes at the site of infection. The formulation was characterized by DLS, Fe-SEM, and light microscopy. The rational behind this study was to combine the anti-virulent and anti-bacterial activities of AiiA and azithromycin. In this direction, we could achieve the formation of a stable formulation, which upon intra-nasal instillation inside mice cleared off the pneumonia induced with K. pneumoniae within 7 days of infection. The combination of liposomal AiiA and azithromycin provides an alternative also effective in killing the young as well as mature biofilm of K. pneumoniae with similar efficacy. In the combined treatment, decrease in the effective dose of azithromycin needed to treat the infection was observed. Inhibition of expression of virulence factors including exo-polysaccharide production, newlinehydrophobicity and metabolic activity of Klebsiella at sub-optimal concentration extends support for the anti-biofilm property of combination. The results of cytotoxicity studies showed no change in macrophage cell morphology when treated with the combination even at concentrations as high as 1mg/ml. The results of this study confirm that potential biomaterials comprising of AiiA/azithromycin combination may see the light of day to treat nosocomial pneumonia, caused by K. pneumoniae. newline newline