Nokea
The family Reoviridae includes the genera:
- A. Genus orthoreovirus, Rotavirus, Orbivirus
- B. Genus orthoretrovirus, Retrovirus, Orbfiloviridae
- C. Genus orthoretrovirus, Retrovirus, orbivirus
- D. Genus orthoretrovirus, Retrovirus, Orbarenaviridaefiloviridae
Correct Answer: A
Rationale: The correct answer is A because it lists the genera that belong to the family Reoviridae accurately. Orthoreovirus and Rotavirus are well-known genera within the family Reoviridae. Orbivirus is another genus belonging to the same family.
Choice B is incorrect because Orthoretrovirus and Retrovirus are not part of the Reoviridae family. Orbfiloviridae is also not a valid genus within this family.
Choice C is incorrect because Orthoretrovirus and Retrovirus are not part of the Reoviridae family. Orbivirus is the correct genus but the other two are inaccurate.
Choice D is incorrect because Orthoretrovirus and Retrovirus are not part of the Reoviridae family. Orbarenaviridaefiloviridae is not a valid genus within Reoviridae.
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A Gram-stained sputum smear revealed Gram-positive rods in chains with central spores. The patient presented with severe pneumonia. What is the causative agent?
- A. Bacillus anthracis
- B. Clostridium tetani
- C. Streptococcus pneumoniae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bacillus anthracis. The presence of Gram-positive rods in chains with central spores on the Gram stain indicates Bacillus anthracis. This bacterium is known to cause severe pneumonia. Clostridium tetani does not typically cause pneumonia but rather tetanus. Streptococcus pneumoniae is a Gram-positive cocci, not rods. Klebsiella pneumoniae is a Gram-negative bacterium commonly associated with pneumonia, but it does not form central spores.
Which of the following statements for measles is NOT true?
- A. It is a childhood infection manifested with exanthema
- B. A characteristic clinical signs are the spots of Koplik
- C. Finding negris bodies is important for diagnosis
- D. Prophylaxis is done via live attenuated vaccine
Correct Answer: C
Rationale: The correct answer is C. Negri bodies are not associated with measles but with rabies. Step 1: Measles is a childhood infection with a rash (A). Step 2: Koplik spots are small white spots on a red base found inside the mouth and are characteristic of measles (B). Step 3: Negri bodies are eosinophilic cytoplasmic inclusions found in neurons infected with rabies virus, not measles (C). Step 4: Prophylaxis for measles is through the MMR vaccine, which is a live attenuated vaccine (D). Therefore, choice C is incorrect as it does not pertain to measles.
When cultured on solid growth media, bacteria with long O-specific chains form:
- A. Smooth S colonies
- B. Rough R colonies
- C. Mucoid -M colonies
- D. H colonies
Correct Answer: A
Rationale: The correct answer is A: Smooth S colonies. Bacteria with long O-specific chains are known as smooth strains, and when cultured on solid growth media, they form smooth colonies due to the presence of the O antigen. This gives them a glossy appearance. Rough R colonies (Choice B) lack O antigen and appear rough. Mucoid -M colonies (Choice C) are associated with capsules, not O-specific chains. H colonies (Choice D) are not relevant to the O-specific chains. Smooth S colonies are the characteristic phenotype of bacteria with long O-specific chains when cultured on solid media.
The basic requirements of PCR reaction include:
- A. DNA segment to be amplified
- B. Two oligonucleotide primers
- C. Heat stable DNA
- D. All of these
Correct Answer: D
Rationale: The correct answer is D because all the options are essential for a PCR reaction.
A: DNA segment is required as the template for amplification.
B: Two oligonucleotide primers are needed to initiate DNA replication.
C: Heat stable DNA polymerase (not just heat stable DNA) is crucial for withstanding the high temperatures during PCR.
In summary, without any of these components, the PCR reaction cannot proceed effectively.
Microscopic examination of a Gramstained scrape from patient's tongue revealed oval, round, elongated chains of dark-violet gemmating cells. What disease can be caused by this causative agent?
- A. Candidosis
- B. Actinomycosis
- C. Diphtheria
- D. Staphylococcic infection
Correct Answer: A
Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species.
Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue.
Step 3: Candidosis presents as white patches or plaques on the tongue.
Step 4: Therefore, the correct answer is A: Candidosis.
Summary:
B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells.
C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells.
D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.