MDS PREP
Which of the following hepatitis viruses has a single-stranded RNA genome?
1) Hepatitis A
2) Hepatitis B
3) Hepatitis C
4) Hepatitis D
General Microbiology Answer: 1Hepatitis C virus (HCV) is known for its single-stranded RNA genome. This characteristic is crucial for its classification and understanding its replication cycle, which involves RNA-dependent RNA polymerase.
Which of the following tests uses killed Treponema pallidum?
1) TPI test
2) TPA test
3) RPCF test
4) FTA test
General Microbiology Answer: 2The Treponema pallidum agglutination test (TPA) utilizes killed Treponema pallidum organisms to detect antibodies in the serum of patients suspected of having syphilis. This test is more sensitive than other tests and is used for confirming syphilis infections.
What is the effect of Actinomycin D on orthomyxoviruses?
1) Stimulates multiplication
2) Inhibits multiplication
3) No effect
4) Enhances stability
General Microbiology Answer: 2Actinomycin D is an antibiotic that inhibits RNA synthesis. In the case of orthomyxoviruses, it effectively inhibits their multiplication by preventing the transcription of viral RNA, thereby blocking the virus ability to replicate. Actinomycin D inhibits the multiplication of orthomyxoviruses by blocking RNA synthesis, which is crucial for viral replication.
What is the typical finding of eosinophils in amoebic dysentery?
1) Abundant
2) Few
3) Absent
4) Numerous
General Microbiology Answer: 3Amoebic dysentery is not typically associated with a significant eosinophilic response. Eosinophils are a type of white blood cell that is often involved in allergic reactions and parasitic infections, but their presence is usually minimal in the context of amoebic infections. The inflammatory response in amoebic dysentery is mainly composed of neutrophils and macrophages.
What is the definition of the flocculating unit (Lf) of diphtheria toxin?
1) The amount that causes rapid flocculation with one unit of antitoxin
2) The amount that causes the bacteria to clump together
3) The amount that causes the bacteria to produce toxin
4) The amount that confers resistance to bacteriophages
The flocculating unit (Lf) of diphtheria toxin is defined as the amount that causes rapid flocculation with one unit of antitoxin.
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
What is the name of the live oral vaccine for typhoid fever and what is its mechanism of action?
1) Typhoral, a Gal E mutant of S. typhi that "self-destructs" after a few cell divisions
2) CholeraVax, a killed whole-cell vaccine
3) Salmonellosis vaccine, a live attenuated strain of S. paratyphi
4) Shigellosis vaccine, a bacteriophage preparation
General Microbiology Answer: 1the live oral vaccine for typhoid fever is Typhoralx, which is a Gal E mutant of S. typhi. The mechanism of action involves the attenuated bacteria colonizing the intestinal mucosa and inducing an immune response that protects against subsequent infection with the pathogenic strain.
The term cold sterilization has been employed to refer to
1. physical methods of sterilization
2. prolonged exposure to 20° C
3. exposure to low temperature steam
4. chemical disinfection
Microbiology
Answer: 4
chemical disinfection is cold strelization