AUTHOR=Manohar Prasanth , Tamhankar Ashok J. , Lundborg Cecilia Stalsby , Nachimuthu Ramesh 

TITLE=Therapeutic Characterization and Efficacy of Bacteriophage Cocktails Infecting Escherichia coli, Klebsiella pneumoniae, and Enterobacter Species

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00574

DOI=10.3389/fmicb.2019.00574

ISSN=1664-302X

ABSTRACT=<p>Infections due to antibiotic resistant bacteria are increasing globally and this needs immediate attention. Bacteriophages are considered an effective alternative for the treatment of bacterial infections. The aim of this study was to isolate and characterize the bacteriophages that infect <italic>Escherichia coli</italic>, <italic>Klebsiella pneumoniae</italic>, and <italic>Enterobacter</italic> species. For this, clinical bacterial isolates of the mentioned species were obtained from diagnostic centers located in Chennai, Tamil Nadu, India. The bacteriophages were isolated from sewage water samples collected from Tamil Nadu, India. Phage isolation was performed using enrichment method and agar overlay method was used to confirm the presence of bacteriophages. All the phages were characterized for their life cycle parameters, genome analysis, and <italic>in vitro</italic> phage cocktail activity. The three bacteriophages exhibited broad host range activity: <italic>Escherichia</italic> virus myPSH2311 infecting <italic>E. coli</italic> belonging to six different pathotypes, <italic>Klebsiella</italic> virus myPSH1235 infecting <italic>K. pneumoniae</italic> belonging to four different serotypes and <italic>Enterobacter</italic> virus myPSH1140 infecting four different species of <italic>Enterobacter</italic>. Morphological observations suggested that the bacteriophages belonged to, <italic>Phieco32virus</italic> (<italic>Escherichia</italic> virus myPSH2311), <italic>Podoviridae</italic> (<italic>Klebsiella</italic> virus myPSH1235), and <italic>Myoviridae</italic> (<italic>Enterobacter</italic> virus myPSH1140). The life cycles (adsorption, latent period, and cell burst) of <italic>Escherichia</italic> virus myPSH2311, <italic>Klebsiella</italic> virus myPSH1235 and <italic>Enterobacter</italic> virus myPSH1140 were found to be 26, 40, and 11 min, respectively. Genomic analysis revealed that <italic>Escherichia</italic> virus myPSH2311 is closely related to <italic>Escherichia</italic> phage vB_EcoP_SU10, <italic>Klebsiella</italic> virus myPSH1235 is closely related to <italic>Klebsiella</italic> phage vB_KpnP_KpV48 and <italic>Enterobacter</italic> virus myPSH1140 is closely related to <italic>Enterobacter</italic> phage PG7 and <italic>Enterobacter</italic> phage CC31. When phage cocktail was used against multiple bacterial mixtures, there was a reduction in bacterial load from 10<sup>6</sup> to 10<sup>3</sup> CFU/mL within 2 h. All the three characterized phages were found to have a broad host range activity and the prepared phage cocktails were effective against mixed bacterial population that are resistant to meropenem and colistin, two last resort antibiotics. Infections caused by drug resistant bacteria will be a serious threat in the future and the use of virulent bacteriophages in therapy may offer an effective solution.</p>