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Bacteriological Media 2016
This document discusses bacteriological culture media, including definitions of culture and media, types of culture, microbes' ability to be cultured, basic culture equipment, and indications for culture. It classifies media as inanimate or animate, describes commonly cultured and uncultured bacteria. It also covers culture techniques and materials needed. The document further classifies media based on consistency, nutritional ingredients, and use. It discusses important solidifying agents and characteristics of simple, enriched, selective, indicator, and differential media.
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Bacteriological Media 2016
- 1. Bacteriological Media: Cultivation ofMicrobes Dr. Md. Abdullah Yusuf Assistant Professor of Microbiology National Institute of Neurosciences & Hospital Dhaka, Bangladesh Email: ayusuf75@yahoo.com
- 2. Learning Objectives • Definitionof culture/cultivation and media • Types of culture • Types of microbes as per ability of culture • Basic equipment and logistic arrangement for bacterial culture • Indication of culture • Classification, type and use of bacteriological media
- 3. Definition • Cultivation – Processof allowing bacteria to multiply in artificial food providing optimum environment • Culture Medium/media – Artificial food for bacteria for in vitro growth
- 4. Types of Culture •Inanimate – Using nutritional ingredients but no living cells or tissues – Used for culture of bacteria and fungus • Animate – Using nutritional ingredients and metabolic substrate for living cells or tissues to multiply (Tissue/Cell Culture) – Used for in vitro multiplication of virus, rickettsia, chlamydia
- 5. Types of Bacteriaas per ability to Culture • Some bacteria can multiply easily – ordinary • some with difficulties – fastidious • some cannot – uncultivable
- 6. Conti…. • Fastidious – Neisseriagonorrhoea – Neisseria meningitides – Haemophilus influenzae • Uncultivable – Mycobacterium leprae – Treponema pallidum
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- 8. Materials Needed forCulture • Specimen • Sterile Cotton Swab • Bacteriological Wire Loop • Suitable Culture Media • Incubator • Aerobic • CO2/Anaerobic
- 9. Indication of Culture •Isolation- diagnosis • Identification- diagnosis • Antimicrobial susceptibility- treatment • Genomic study- characterization • Progressive research- up to date information
- 10. Culture Media Classification A. Onthe basis of consistency • Liquid • Solid • Semi-solid (gel)
- 11. Conti… B. On thebasis of nutritional ingredients – Simple or basal – Enriched – Selective – Indicator – Differential
- 12. Classification-contd C. On thebasis of use – Primary – Subculture – Transport – preservative
- 13. Important points • Liquidmedia is also called broth • Solid media – Liquid media + solidifying agent in appropriate concentration (5-10%) • Semisolid media – liquid media + solidifying agents at low concentration (study bacterial motility)
- 14. Solidifying agents • Agaragar (sea weeds) – melt at high temperature (55-600 C) – solidified at low temperature (40-450 C) • Egg whole • Gelatin • Potatoes • Tomato powder • Serum
- 15. According to ingredients •Simple/basal – contain basic nutrient support • Enriched – contain growth enhancing substances. e.g.- blood, serum, haemoglobin • Selective – inhibitory substance that do not inhibit one group/species, but inhibit all other • Semi-selective – if allow growth of one family-many members • Highly selective – allow only one species of a particular genus
- 16. According to Ingredients(contd.) • Indicator – contain chemical substance that changes it’s colour with change of pH – indicate particular property of a genus of bacteria • Differential – substance with change of colour (black colour due metalic tellurium) or phenomenon (haemolysis) observed due to growth of a particular bacteria
- 17. According to Use •Primary – first inoculation then transfer or not • Subculture – subsequent inoculation from primary media • Transport – Dissolve or mix clinical specimens or bacteria – allow little growth but no inhibition – transported from one location to another • Preservative – dehydrated media containing metabolically inactive bacteria – kept for prolonged period (lyophilized skimmed milk)
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- 19. How a mediumcan be made selective? • Adding inhibitory substance – bile salt in MacConckey agar • Adding antibiotic – Campybap for Campylobacter • Adding alkali/ Changing pH – Sodium bi carbonate in alkaline peptone water • Removing oxygen – by reducing chemicals or mechanically for anaerobic bacteria • Changing temperature – thermophiles grow at high temperature
- 20. Advantages of solidmedia over liquid media • Discrete growth as separate unit (colony) – hazy or opaque appearance in liquid • Clear colony morphology • Easy to pick-up for subculture • Sensitivity test or further identification tests
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