Microbiology-Phage Typing

Phage Typing-Identification of prokaryotes

1. Phage Typing Dr. Mabel Merlen Jacob Assistant Professor Department of Microbiology St. Mary’s College Thrissur-680020 Kerala

2. Phage Typing,Dr.Mabel Merlen Jacob, St.Mary’s College Identification of prokaryotes Identification of prokaryotes using phenotypic characteristics • Identification of prokaryotes using genotypic characteristics • Characterizing strain differences

3. Phage Typing,Dr.Mabel Merlen Jacob, St.Mary’s College

4. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College Distinguish among different stains of bacteria - Especially when only certain strains cause disease. ( Only certain strains of E. coli cause intestinal disease-presence of virulence factors such as toxin production etc .) Detecting strains differences - helpful in tracing source of an outbreak. Characterizing strain differences

5. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College

6. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College Phage Typing Strains of a given species sometimes differ in their susceptibility to various types of bacteriophages. The zone of clearing around the bacteriophage spot indicate the susceptibility patterns of the test organism to different phages. Different patterns compared to determine strain differences

7. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College

8. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College Phage may be very specific -infect only a few strains of a certain bacterial species or strains of two or more species of a particular genus- h ttp://microamaze.blogspot.com/2015/11/phage-typing-of-salmonella-typhimurium.html

9. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College Phage typing - characterizing and detecting bacterial strains by their reaction (susceptibility/ resistance) to various known strains of phages. employed in epidemiology to identify an infectious agent. eg ; 1) strains of Staphylococcus aureus/ Listeria involved in outbreaks of food poisoning or other infections. 2) identification of Bacillus anthracis , the causative agent of anthrax

10. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College sterile, fairly dried agar plates pre-inoculated with the phage suspensions -up to 25 phage preparations using a multi-syringe applicator agar surface flooded with broth culture of the Listeria strains; observed after overnight incubation The phage particles do not diffuse along the agar surface; remain in the circular area coincident with the original phage drop. Reversed phage typing procedure – Listeria

11. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College prepared plates can be used directly or stored at 4°C until use (two weeks) More than 100 ready-to-use phage typing plates from 1 ml of each of the phage suspensions prepared, ready-to-use typing plates – no need of cloning and titration of phages in each laboratory. a two-fold increase in efficiency than the conventional method.

12. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College Specificity of the phage employed Medium used for testing lytic activity of phage opaque media containing egg/ dense materials to be avoided – visualization of plaques difficult. Media should have no inhibitory action on growth of host bacterium on adsorption of phage eg ; Tween 80, malachite green – mycophages , p resence of bacteriocins or other inhibitory substances and/or proteins liberated by the lysed host cells. Important Considerations

13. Phage Typing,Dr.Mabel Merlen Jacob,St.Mary’s College