Selective Media PDF

SELECTIVE MEDIA Presentation by Group 9 WHAT IS SELECTIVE MEDIA? Used for the growth of only selected microorganisms Selective inhibition - Adding dyes, antibiotics, salts or specific inhibitors which affect the metabolism or enzyme systems of the organisms Certain microbe is resistan...

SELECTIVE MEDIA Presentation by Group 9 WHAT IS SELECTIVE MEDIA? Used for the growth of only selected microorganisms Selective inhibition - Adding dyes, antibiotics, salts or specific inhibitors which affect the metabolism or enzyme systems of the organisms Certain microbe is resistant to a particular antibiotic (e.g., novobiocin), the antibiotic can be added to the medium to prevent other organisms (not resistant) from growing MECHANISM OF SELECTIVE MEDIA Contains ingredients which act as an inhibitor in the media which could favor growth of desired microorganism, while inhibiting growth of undesirable microbes.  Common types of selective agent used in selective media Could select sodium salts to chemical specific virus microbes that has select halophilic substance select bacteria that can antibiotic bacteria that is gram positive or destroy selective resistance gene. resistance to gram negative and targeted Eg: Quinolones conc NaCl bacteria bacteria Gorilla Gorilla Gorilla Gorilla Bonnet, M., Lagier, J. C., Raoult, D., & Khelaifia, S. (2020). Bacterial culture through selective and non-selective conditions: The evolution of culture media in clinical microbiology. New Microbes and New Infections, 34(34), 100622. https://doi.org/10.1016/j.nmni.2019.100622 Selective bacteriophages Isolation and characterization of lytic bacteriophages from various sources in Addis Ababa against antimicrobial-resistant diarrheagenic Escherichia coli strains and evaluation of their therapeutic potential examples of selective media Mannitol salt agar (MSA) The "salt" selects for bacteria that can grow in high salt environments Selection of halophilic bacteria that ferment mannitol Staphylococci thrive on the medium because of their adaptation to salty habitats (human skin) Eosin methylene blue (EMB) Presence of methylene blue dyes will inhibit the growth of Gram-positive bacteria Lactose-fermenting coliforms such as Escherichia coli produce blue-black colonies with a green metallic sheen examples of selective media YM (yeast and mold) Selective growth medium with low pH Useful for cultivating yeasts, molds or other acidophilic organisms Deterring bacterial growth MacConkey Only grows gram-negative bacterial species Selectively isolate coliform bacteria Further differentiate the coliform organisms based on their lactose metabolism  APPLICATION MacConkey agar, are crucial in clinical laboratories for identifying pathogens. MacConkey agar specifically isolates Gram-negative bacteria, including Escherichia coli and Salmonella. It contains bile salts and crystal violet to inhibit Gram-positive bacteria. On this medium, lactose fermenters like E. coli produce pink colonies, while non-fermenters such as Salmonella remain colorless, aiding in the differentiation of these pathogens during gastrointestinal infection diagnostics. The medium differentiates between lactose fermenters (which turn pink) and non-fermenters (which remain colorless). This property helps in quickly identifying pathogens like Escherichia coli and Salmonella based on their metabolic capabilities  advantages disadvantages ISOLATION OF SPECIFIC LIMITED SCOPE ORGANISMS Only designed for the Allow for the growth of target specific groups of organisms while inhibiting others organisms REDUCTION OF COMPLEXITY CONTAMINATION Complex to prepare and The inhibitory agents reduce the require precise formulation chances of contamination (improving the accurate results) SPEED AND EFFICIENCY Reduce the need of additional steps SUMMARY Essential for isolating specific microorganisms in diagnostics, safety testing, and research. Uses targeted inhibitors to cultivate desired organisms and reduce contamination. Provides precise microbial identification and increases diagnostic efficiency. Limitations include scope specificity and complex preparation requirements. Overall, selective media are invaluable in both clinical and research applications Thank You