Phage typing

[3] Phage typing was used to trace the source of infectious outbreaks throughout the 1900s, but it has been replaced by genotypic methods such as whole genome sequencing for epidemiological characterization.

[6] Virulent phages enter the lytic cycle where they replicate and lyse the bacterial cell.

[7] Virulent phages can differentiate between different species of bacteria based on their specific lytic action.

[12] The size, morphology, and pattern of the lysed region are important criteria for differentiating bacterial species and strains.

In 1938, Craigie and Yen adapted Vi phages by selective propagation and used them at their critical test dilutions to differentiate 11 types of B.

[19] In 1943, Felix and Callow extended the method to Salmonella paratyphi B. in 1943 and differentiated 12 types with 11 phages.

In 1959, Callow improved her initial scheme to differentiate 34 types of Salmonella typhimurium with 29 phages.

[25] It also relies on the interpretation of the individual lysis pattern and comparison to a standard which has led to conflicting results from different laboratories in the past.

A culture of bacteria infected by bacteriophages, the "holes" are areas where the bacteria have been killed by the virus. The culture is 10cm in diameter.