(NIDOC)
THE RISE of clinical concern about antibiotic-resistant Salmonella enterica serovar
Typhi is mainly attributed to the frequent contamination of food and drinking water.
The aim of this study is to assess the sensitivity of S. Typhi to antibiotics as well as
isolation of lytic bacteriophages specific to the bacterium and investigate their ability to
enhance the safety of tap water and milk. S. Typhi clinical isolates recovered from infected
blood specimens were included in this study. The bacterial isolates were identified by
conventional biochemical tests; Vitek analyzer in addition to Widal test to determine
the serotypes of Salmonella isolates. Four lytic bacteriophages specific to S. Typhi were
isolated and characterized using TEM and designated as vb_StyM,EN-1, vb_StyM,EN-2,
vb_StyS,EN-3 and vb_StyP,EN-4. The results showed resistance of S. Typhi isolates to
various antibiotics. Phage cocktail was prepared and applied for controlling S. Typhi
growth in milk and drinking water at 4⁰C and room temperature. After treatment, complete
eradication of bacterial growth was observed in broth medium at 4°C and room temperature
after 24hrs. In addition to that, phage cocktail showed complete inhibition of S. Typhi growth
in treated tap water at 25°C after 24hrs and in milk at 4°C. A significant reduction; nearly
five log reductions was observed in skim milk while one log reduction was obtained in full
fat milk at 25°C. These results indicate that S. Typhi is resistant to some antibiotics and
bacteriophages could be promising antimicrobial alternatives.
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