MDS PREP
Which medium is suitable for the transport of Salmonella and Shigella?
1) Cary-Blair medium
2) Thiosulfate-citrate-bile salts-sucrose (TCBS) agar
3) Hektoen enteric (HE) agar
4) Blood agar
General Microbiology Answer: 1the medium suitable for the transport of Salmonella and Shigella is Cary-Blair mediumx. This medium is designed to maintain the viability of these organisms during transport and is selective for enteric pathogens by inhibiting the growth of other non-target bacteria. TCBS agar and HE agar are used for the selective isolation and growth of these organisms, while blood agar is a general purpose medium used for various bacteria.
Which of the following is a characteristic microscopic feature of amoebic dysentery that distinguishes it from bacillary dysentery?
1) Presence of RBCs in the stool
2) Presence of pus cells in the stool
3) Presence of Charcot-Leyden crystals
4) Presence of ghost cells
The presence of Charcot-Leyden crystals is a characteristic microscopic feature of amoebic dysentery that distinguishes it from bacillary dysentery.
There are some enzymes that cause protein to coagulate rather than to produce simpler compund These are known as
1. lab enzymes
2. coagulase
3. proteolytic enzymes
4. wenmycin
Microbiology
Answer: 1
There are some enzymes that cause protein to coagulate rather than to produce simpler compund These are known as lab enzymes
1. Coagulase:
Definition: Coagulase is an enzyme produced by certain
bacteria, most notably Staphylococcus aureus. It catalyzes the
conversion of fibrinogen (a soluble plasma protein) into fibrin (an
insoluble protein), leading to the clotting of blood.
Function: The production of coagulase is a virulence
factor for Staphylococcus aureus, as it helps the bacteria evade
the host's immune system by forming a protective clot around the bacterial
cells. This clot can shield the bacteria from phagocytosis and other immune
responses.
Clinical Relevance: Coagulase is used in laboratory
tests to differentiate between pathogenic Staphylococcus aureus (coagulase-positive)
and non-pathogenic staphylococci (coagulase-negative).
2. Proteolytic Enzymes:
Definition: Proteolytic enzymes, also known as
proteases or peptidases, are enzymes that catalyze the breakdown of proteins
into smaller peptides or amino acids by cleaving the peptide bonds between
amino acids.
Function: These enzymes play crucial roles in various
biological processes, including digestion, protein turnover, cell signaling,
and immune responses. They are found in many organisms, including humans,
where they are involved in the digestion of dietary proteins in the stomach
and small intestine.
Types: Proteolytic enzymes can be classified based on
their mechanism of action (e.g., serine proteases, cysteine proteases,
aspartic proteases, and metalloproteases) and their substrate specificity.
Wenmycin is an antibiotic that is derived from the
bacterium Streptomyces wenyangensis. It belongs to the class of
compounds known as macrolide antibiotics, which are
characterized by their large lactone ring structure. Wenmycin has been studied
for its antimicrobial properties, particularly against certain types of
bacteria.
Which of the following bacteriophage types of diphtheria bacilli are associated with avirulent strains?
1) Type I and II
2) Type IV and VI
3) Type III
4) Type VII
Type VII bacteriophage types of diphtheria bacilli are associated with avirulent strains.
What is the typical microscopic finding in amoebic dysentery?
1) Numerous pus cells
2) Abundant Charcot-Leyden crystals
3) Many motile bacteria
4) Abundant pyknotic bodies
The typical microscopic finding in amoebic dysentery includes numerous pus cells and abundant Charcot-Leyden crystals.
What type of antibodies are known as "coproantibodies"?
1) IgA
2) IgM
3) IgG
4) Antibodies found in feces
General Microbiology Answer: 4Copro antibodies are antibodies found in feces These are typically IgA antibodies that are produced in response to infections in the gastrointestinal tract, including typhoid fever. They can be detected in stool samples and are used in diagnostic tests.
What is the primary mode of action of exotoxins?
1) Enzymatic
2) Non-enzymatic
3) Structural disruption
4) Inhibition of protein synthesis
General Microbiology Answer: 1
The primary mode of action of exotoxins is enzymatic, as they often act as enzymes that modify or damage host cell functions.
What is the typical color of Salmonella colonies on MacConkey agar, except for Sh. Sonnei?
1) Colorless
2) Pink
3) Red
4) Yellow
General Microbiology Answer: 1Salmonella species, excluding Shigella sonnei, which is lactose non-fermenting, will ferment lactose in MacConkey agar, turning the colonies pink due to the formation of acidic end-products