Bioprospecting and Evaluation of Lytic Bacteriophages against Extensively Drug-Resistant Salmonella Enterica Serovar Typhi from Diverse Biological Matrices
DOI:
https://doi.org/10.31580/pjmls.v9i1.3478Keywords:
Biological matrices, Double-layer agar overlay plaque assay, Extensively drug-resistant, Lytic phages, Salmonella enteric, Serovar typhi, TyphoidAbstract
Extensively drug-resistant (XDR) Salmonella enterica serovar Typhi has posed a public health challenge globally and predominantly in LMIC countries. Pakistan serves as a country with the highest burden of typhoid, and Karachi is known as an epicenter. Lytic Phages are the natural killers of bacteria and can be exploited for the development of countermeasures. This study aimed to explore various biological matrices for the isolation of lytic phages against XDR Salmonella enterica serovar Typhi. It is also intended to evaluate the isolated phages on the basis of their plaque size, reproducibility in the laboratory environment, phage titers and stability during storage in a controlled environment. A total of 45 environmental samples were collected, comprising 13 sewage, 14 drainage water, 8 poultry waste, 4 marine samples and 6 tap water samples. Sequential enrichment, centrifugation, membrane filtration, and the double-layer agar overlay plaque assay were applied. The bacterial host (ST-1) used in this study was identified and characterized as XDR Salmonella enterica ssp. enterica through the MALDI-TOF MS, Vitek 2 compact system and serological test. Most of the sewage samples, indeed, hospital-associated sewage, yielded phages with significant titers in a reproducible manner. We also found phages in poultry waste, drainage, and marine water, whereas no phages were isolated from tap water. Our findings provide ecological and microbiological insight into various biological matrices for specific lytic phages. In conclusion, hospital-associated sewage at Karachi, Pakistan, is a good source of phages. Our results indirectly verify the prevalence of XDR S. typhi in the community.
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