Developing Bacteriophages for Therapeutic Application against Gram-Negative Bacteria Causing Lower Respiratory Tract Infections / by Bishoy Maher Zaki Mauwad ; Under the Supervision of Assoc. Prof. Dr. Reham Samir Mohamed, Prof. Dr. Ayman Abdelmagid Ahmed El-Shibiny

Thesis (Ph.D)-Cairo University, 2023.

Bibliography: pages 133-168.

The rise of infections by antibiotic-resistant bacterial
pathogens is alarming. Among these, Klebsiella pneumoniae and Acinetobacter
baumannii are leading causes of death by hospital-acquired infections, and their
multidrug-resistant strains are flagged as a global threat to human health, which
necessitates finding novel antibiotics or alternative therapies. One promising
therapeutic alternative is phage therapy. This work aimed to discover specific
bacteriophages with therapeutic potential against multiresistant clinical isolates
belonging to K. pneumoniae and A. baumannii.
Methods and Results: Among the isolated phages, Klebsiella phage
vB_Kpn_ZCKp20p and Acinetobacter phage vB_Aba_ZC1 were selected to
conduct comprehensive characterization. Transmission electron microscopy
suggests vB_Kpn_ZCKp20p and vB_Aba_ZC1 be tailed phages of siphoviral
and myoviral morphotypes, respectively. In vitro evaluation indicated a high
lytic efficiency of both phages with medium burst sizes. Both phages were
stable at temperatures up to 70°C and a wide pH range of 2-12. Additionally,
the phages’ antibiofilm effect was evaluated by the crystal violet assay. While
phage vB_Kpn_ZCKp20p possesses inhibition and clearing antibiofilm effect,
phage vB_Aba_ZC1 only demonstrated clearing efficiency of a mature biofilm.
Additionally, neither phage demonstrated any antiproliferative activity on
human skin fibroblast. Moreover, the whole genome of phages
vB_Kpn_ZCKp20p and vB_Aba_ZC1 were sequenced and annotated. Genomic
analysis of phage vB_Kpn_ZCKp20p uncovered one tRNA gene and 33
putative proteins with assigned functions out of 85 predicted genes. On the
other hand, the genome of phage vB_Aba_ZC1 does not contain any tRNA
genes, while 39 out of 79 predicted protein-coding genes were assigned to
functions. Furthermore, comparative genomics and phylogenetic analysis
suggest that phage vB_Kpn_ZCKp20p, most likely, represents a new species
but still belongs to the same genus of Klebsiella phages ZCKP8 and 6691.
Also, phage vB_Aba_ZC1 is highly suggested to be a novel species in the
genus of Obolenskvirus. Finally, comprehensive genomic and bioinformatics
analyzes substantiate the safety of the phages and their strictly lytic lifestyle.
Conclusion: vB_Kpn_ZCKp20p and vB_Aba_ZC1 are novel phages with
high potential to be used against MDR pathogens and could be promising
sources for antibacterial and antibiofilm products.

Issued also as CD

Text in English and abstract in Arabic & English.