MDS PREP
What is the correct color coding for bio-medical waste that requires incineration or deep burial?
1) Red
2) Yellow
3) Blue/white translucent
4) Black
General Microbiology Answer: 2
Yellow is the designated color for bio-medical waste that is considered hazardous and requires incineration or deep burial. This classification helps in the proper disposal of infectious and potentially harmful materials.
The biologic standard used to test the efficiency of sterilization involves the use of
1. spores of Clostridium tetani
2. streptococcus pneumoniae
3 spores of a harmless bacillus
4. infectious hepatitis virus
Microbiology
Answer: 3
The biologic standard used to test the efficiency of sterilization typically
involves the use of spores of a harmless bacillus. This method is widely
recognized in the scientific community and is based on the principle that if a
sterilization process can effectively destroy the most heat-resistant
microorganisms, it is assumed to be capable of killing all other less resistant
microbes.
The choice of using spores of a harmless bacillus is rooted in the fact that
bacterial spores are the most heat-resistant forms of microbial life. Spores are
metabolically inactive, which makes them very hardy and capable of surviving in
adverse environmental conditions for extended periods. For sterilization
validation, scientists often employ a biological indicator that contains spores
of a known heat-resistant bacterium, such as Geobacillus stearothermophilus
(formerly Bacillus stearothermophilus) or Bacillus subtilis. These organisms are
chosen because they have well-characterized resistance profiles, and their
destruction indicates that the sterilization process has achieved the necessary
lethality to eradicate all microbial life forms, including vegetative bacteria,
fungi, and viruses.
Let's examine the other options provided:
1. Spores of Clostridium tetani: While C. tetani is a spore-forming bacterium,
its spores are not commonly used as a biological indicator for sterilization
efficiency. C. tetani is a pathogen that causes tetanus, a serious disease.
However, it is not typically used for this purpose because there are safer and
more universally accepted biological indicators available.
2. Streptococcus pneumoniae: S. pneumoniae is a bacterium that can cause
pneumonia and other infections, but it is not a spore-former. Moreover, it is
generally less resistant to heat and sterilization methods compared to
spore-forming bacteria. Thus, it is not suitable as a standard for testing
sterilization efficiency.
3. Spores of a harmless bacillus: As previously mentioned, this is the most
appropriate choice for a biologic standard in sterilization testing. These
spores serve as reliable and safe indicators of sterilization efficacy because
they mimic the resistance of pathogenic spores without posing the actual risk of
infection.
4. Infectious hepatitis virus: While viruses can be highly resistant to some
sterilization methods, they are generally more sensitive to heat than bacterial
spores. Moreover, using infectious viruses as biological indicators poses
significant biosafety risks and is not a standard practice in routine
sterilization testing. For viral resistance testing, specific viruses or
virus-like particles may be used, but these are not typically employed as the
primary biological indicators for sterilization validation due to the complexity
and high containment requirements of such testing.
What are the typical clinical features of typhoid fever?
1) High fever, bradycardia, and a palpable spleen
2) Rash, joint pain, and respiratory symptoms
3) Diarrhea, abdominal cramps, and vomiting
4) Headache, photophobia, and neck stiffness
General Microbiology Answer: 1The typical clinical features of typhoid fever can be listed as follows:
1. High fever, bradycardia, and a palpable spleen: Typhoid fever is
characterized by a sustained high fever, often reaching 103°F to 104°F (39°C to
40°C). Bradycardia, or a slower than normal heart rate, occurs in some cases.
The spleen may also become enlarged and palpable due to the infection.
2. Rash, joint pain, and respiratory symptoms: Some patients may develop a rash
known as "Rose spots," which are small, red spots on the abdomen and chest.
Joint pain can occur, and respiratory symptoms may include a dry cough.
3. Diarrhea, abdominal cramps, and vomiting: Diarrhea and severe abdominal
cramps are common in the early stages of typhoid fever, which can lead to
significant dehydration and discomfort for the patient.
4. Headache, photophobia, and neck stiffness: Headaches and sensitivity to light
(photophobia) are often present, and in severe cases, neck stiffness can occur
due to inflammation of the meninges, known as meningitis.
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
The virus which is most resistant to chemical and physical agents is the one which causes
1. infectious hepatitis
2. mumps
3. influenza
4. serum hepatitis
Microbiology
Answer: 4
Infectious hepatitis (Hepatitis A virus): While HAV is
resistant to some environmental conditions, it is generally less resistant
than HBV.
Mumps virus: This is an enveloped virus and is not
particularly resistant to environmental factors.
Influenza virus: This is also an enveloped virus and is
susceptible to heat and many disinfectants.
Serum hepatitis (Hepatitis B virus): HBV is known for
its resilience. It can survive outside the body for long periods and is
resistant to many disinfectants and physical agents, making it one of the
more resistant viruses.
In summary, the correct answer is indeed 4. serum hepatitis
(Hepatitis B virus), as it is more resistant to chemical and physical
agents
Which of the following is NOT a type of C1. Perfringens that can cause food poisoning?
1) C1. Perfringens type A
2) C1. Perfringens type B
3) C1. Perfringens type C
4) C1. Perfringens type D
General Microbiology Answer: 4
C1. Perfringens types A, B, and C are capable of producing toxins that cause food poisoning. Type D, however, is not associated with foodborne illness. It is primarily involved in diseases such as gas gangrene and other infections due to the production of different types of toxins.
Which of the following statements about the fermentation of sugars by Anthracoid bacilli is true?
1) Anthracoid bacilli ferment glucose, maltose, lactose, and sucrose, producing acid and gas.
2) Anthracoid bacilli do not ferment glucose but ferment maltose, lactose, and sucrose.
3) Anthracoid bacilli only ferment glucose.
4) Anthracoid bacilli ferment glucose, maltose, and lactose, but not sucrose.
Anthracoid bacilli ferment glucose, maltose, lactose, and sucrose, producing acid and gas.
What is the purpose of using aluminum hydroxide as an adjuvant in the hepatitis B vaccine?
1) To increase the immunogenicity of the vaccine
2) To prevent bacterial contamination
3) To enhance the stability of the vaccine
4) To reduce the amount of antigen needed for immunization
General Microbiology Answer: 1
Aluminum hydroxide is used as an adjuvant in the hepatitis B vaccine to increase the immunogenicity of the vaccine, enhancing the body's immune response to the antigen.