MICRO - 2ND SEM MIDTERMS EXAM

• It is essential that scientists are able to grow or culture them under controlled conditions.
• Culture medium is a liquid or gel designed to support the growth of microorganisms or cells or small plates.
• There are two fundamental types of culture media. These are cell culture and microbiological culture.
• For the culture of microorganisms, the most common include the following: Nutrient broths and Agar plates
• Nutrient broths – contains amino acids and nitrogen although its source may contain other compounds with unknown composition.
• Nutrient broths - these contain all the elements that most bacteria need to grow.
• Nutrient broths - these are non-selective so it is used for general cultivation and maintenance of bacteria kept in laboratory culture collections.
• Agar plates – a petri plate that contains a growth medium in order to culture or grow microorganisms or even small plants such as moss.
• In some instances, selective growth compounds can be added to the media such as antibiotics.
• Minimal media – contain minimum nutrients possible for colony growth usually in the absence of amino acids.
• Selective media – used for the culture of only select microorganism.
• Differential media – also known as indicator media, used to differentiate one microorganism from another grown on the same media using the biochemical characteristics of microorganisms
• Transport media – used as a temporary storage of specimens being transported to the laboratory for cultivation contains only buffers and salt.
• Enriched media – contain nutrients required to support the growth of variety of microorganism, including fastidious species.
• Blood agar plate – contains mammalian blood used to isolate fastidious organisms and detect hemolytic activity such as Streptococcal species.
• Thayer-Martin agar – chocolate agar used to isolate Neisseria gonorrheae.
• Chocolate agar – a type of blood agar plate where the blood cells have been blissed by heating the cells to 56C and is used to culture fastidious respiratory bacteria such as Haemophilus influenzae.
• Thiosulfate citrate bile salts sucrose-enriched agar – a type of blood agar plate the enhances the growth of Vibrio species including V. cholerae.
• Bile esculin agar – used to isolate Enterococci and group D Streptococci.
• Centrimide agar – used to isolate Pseudomonasaeruginoss.
• Cysteine-lactose electrolyte deficient (CLED) agar –used to isolate and differentiate urinary tract bacteria through in inhibition of Proteus species from swarming can also differentiate lactose-fermenters and non-lactose fermenting bacteria
• Hektoen enteric agar (HEA) - used to isolate and recover fecal bacteria of the family Enterobacteriaceae especially Salmonella and Shigella species.
• Mannitol salt agar (MSA) - used to isolate organisms, especially halophiles that ferment mannitol which produce lactic acid.
• McConkey agar (MAC) - used to differentiate between Gm- and Gm+ bacteria through inhibition of Gm+ bacterial growth.
• Mueller-Hinton agar (MHA) - used to test antibiotic susceptibility.
• Nutrient agar – used to culture non-fastidious organisms and observe pigment production one of the safest culture media since it does not selectively grow pathogenic bacteria.
• Onoz agar – used to rapid diagnosis of Salmonella and Shigella species as differentiated from other members of the Enterobacteriaceae family
• Phenylethyl alcohol agar (PEA) – used to isolate Staphylococcus species through inhibition of Gram- bacilli such as E. coli, Shigella and Proteus among others.
• Tinsdale agar – used toisolate Corynebacteriumdiptheriae.
• R2A agar – used for water analysis.
• Tryptic soy agar (TSA) – used as general purpose media serving as a base media for agar types, it is used to support the growth of Bracella, Cornynobacterium, Listeria, Neisseria and Vibrio species.
• Xylose – lysine deoxycholate agar (XLD) – used to culture stool samplers especially to allow Gram- bacterial growth and inhibiting Gm+ growth
• Hay infusion agar – used to culture slime molds.
• Malt extract agar – used to isolate fungal microorganisms.
• Potato dextrose agar – used to culture some type of fungi
• Sabouraud agar - used to culture fungi, has a low pH that inhibits bacterial growth especially Gm- bacteria
• TECHNIQUES FOR CONTROLLING PATHOGENIC MICROORGANISMS: 1. By killing microorganisms 2. By inhibiting the growth of microorganisms
• The control of microbial growth usually involves the use of agents.
• Agents which kill cells are called “cidal” agents
• agents which inhibit the growth of cells (without killing them) are referred to as “static” agents.