29 Questions
What is the primary advantage of using Solid Media in bacterial culture?
To allow identification of the organism and isolation in pure culture
Which of the following media is used to cultivate Streptococcus spp. and differentiate organisms into alpha, beta and gamma haemolysis?
Blood Agar
What is the primary objective of bacterial culture in terms of antimicrobial susceptibility?
To test the antimicrobial susceptibility of bacteria
What is the main difference between Enriched Media and Selective Media?
Enriched Media contains additional nutrients while Selective Media allows the growth of specific microorganisms
Which of the following is NOT a type of culture media?
Oil Immersion Lens
What is the primary purpose of using Differential Media?
To differentiate between microorganisms based on their characteristics
What is the primary purpose of Mannitol salt agar (MSA agar) in microbiological culture?
To select for gram-positive bacteria, specifically Staphylococci
What is the characteristic feature of colonies of bacteria that ferment lactose and sucrose?
They produce a green metallic sheen
What is the primary difference between media for bacteria and media for fungi?
Media for bacteria are usually slightly alkaline, while media for fungi prefer a slightly acid medium
What is the purpose of Hoekton Enteric agar?
To inhibit the growth of gram-positive bacteria
Which type of bacteria turns the agar into yellow on Mannitol salt agar (MSA agar)?
Staphylococcus aureus
What is the source of carbon in media for fungi?
Carbohydrates
What is the characteristic of an individual with blood group AB?
Having both A and B antigens on RBC surface and no A or B antibodies in blood plasma
What is the term for the spontaneous agglutination of RBCs by certain viruses?
Haemagglutination
What is the purpose of adding antibody (patient's serum) to the Influenza virus and RBC mixture?
To inhibit haemagglutination
What is the term for the reaction in which antigens and antibodies diffuse towards each other and form bands of precipitates?
Double immunodiffusion
What is the characteristic of an individual with blood group O?
Having neither A nor B antigens on RBC surface and both A and B antibodies in blood plasma
What is the term for the reaction in which RBCs agglutinate spontaneously when mixed with a certain virus?
Haemagglutination
What is the primary purpose of applying iodine in the Gram stain procedure?
To act as a mordant, allowing the dye to bind to the bacterial cell
What is the consequence of over-decolorization in the Gram stain procedure?
The bacterial smear will be completely decolorized, making it difficult to distinguish between Gram-positive and Gram-negative bacteria
Why is it necessary to sterilize the loop with flame before taking bacterial suspension?
To kill any bacteria that may be present on the loop
What is the purpose of washing the bacterial smear with a stream of tap water after applying crystal violet and iodine?
To remove excess dye and prevent overstaining
What is the consequence of not heat-fixing the bacterial smear before applying the Gram stain?
The bacterial smear will not take up the stain properly
What happens to the cell when a complement is fixed to an antigen-antibody complex?
The cell undergoes a process of lysis
What is the primary role of the complement in the complement fixation test?
To detect the presence of antibody in the patient's serum
What is the result of adding a patient's serum that contains antibody to a known antigen and complement serum?
Complement fixation and lysis of the cell
What is the purpose of using sheep RBCs in the complement fixation test?
To detect the presence of antibody in the patient's serum
What is the difference between a patient's serum that contains antibody and one that does not contain antibody in the complement fixation test?
The presence or absence of complement fixation
What is the relationship between the antigen and antibody in the complement fixation test?
The antigen is a component of the patient's serum
Identify the correct steps in performing a Gram stain procedure, including preparing the bacterial smear, sterilizing the loop, and spreading the bacterial suspension. Learn the proper technique for this important microbiology laboratory test.
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