Phages from Ganges River curtail in vitro biofilms and planktonic growth of drug resistant Klebsiella pneumoniae in a zebrafish infection model

Abstract

Bacteriophages are a promising alternative for curtailing infections caused by multi drug resistant (MDR) bacteria. The objective of the present study is to evaluate phage populations from water bodies to inhibit planktonic and biofilm mode of growth of drug resistant Klebsiella pneumoniae in vitro and curtail planktonic growth in vivo in a zebrafish model. Phage specific to K. pneumoniae (MTCC 432) was isolated from Ganges river (designated as KpG). One-step growth curve, in vitro time kill curve study and in vivo infection model were performed to evaluate the efficacy of phage against planktonic growth. Crystal violet assay and colony biofilm assay was done to determine the action of phages on biofilms. KpG phages had a greater burst size, better bactericidal potential and enhanced inhibitory effect against biofilms formed at liquid air and solid air interfaces. In vivo injection of KpG phages revealed that it did not pose any toxicity to zebrafish as evidenced by liver/brain enzyme profiles and by histopathological analysis. In vitro time kill assay showed a 3 log decline and a 6 log decline in K. pneumoniae colony counts, when phages were administered individually and in combination with streptomycin, respectively. The muscle tissue of zebrafish, infected with K. pneumoniae and treated with KpG phages showed a significant 2 log decline in bacterial counts relative to untreated control. Our study reveals that KpG phages has the potential to curtail plantonic and biofilm mode of growth in vivo in higher animal models.