Nokea
Which of the following statements regarding S. aureus is not true:
- A. Producing hemolysins, leucocidins, enterotoxin
- B. Colonies with beta-hemolytic zones
- C. Always sensitive to penicillin
- D. None of the above
Correct Answer: C
Rationale: Step 1: S. aureus is known to produce hemolysins, leucocidins, and enterotoxin.
Step 2: S. aureus colonies usually exhibit golden-yellow pigmentation with beta-hemolytic zones.
Step 3: S. aureus has developed resistance to penicillin due to the production of beta-lactamase.
Step 4: Therefore, statement C is not true as S. aureus is not always sensitive to penicillin.
Summary: Choices A and B are correct statements about S. aureus, while choice C is incorrect due to the increasing penicillin resistance seen in S. aureus.
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Infection of several persons without any epidemiological link is
- A. epidemic
- B. sporadic disease
- C. endemic
- D. pandemic
Correct Answer: B
Rationale: The correct answer is B: sporadic disease. Infection of several persons without any epidemiological link is considered sporadic because it occurs in a random and isolated manner, with no clear pattern or connection between cases. It is not classified as an epidemic (A) because it does not involve a sudden increase in the number of cases within a specific population. It is also not endemic (C) as endemic diseases are constantly present in a particular region or population. Lastly, it is not a pandemic (D) which refers to a global outbreak affecting a large number of people across different countries.
A patient consulted a dentist about itching and burning in the oral cavity; high temperature. The patient was diagnosed with trichomonal gingivostomatitis. What drug should be chosen for his treatment?
- A. Metronidazole
- B. Ampicillin
- C. Gentamicin sulfate
- D. Nystatin
Correct Answer: A
Rationale: Step 1: Trichomonal gingivostomatitis is caused by the parasite Trichomonas tenax.
Step 2: Metronidazole is the drug of choice for treating infections caused by anaerobic organisms like Trichomonas.
Step 3: Metronidazole effectively targets and eliminates Trichomonas parasites in the oral cavity.
Step 4: Therefore, the correct drug choice for treating trichomonal gingivostomatitis is Metronidazole.
Summary:
- Ampicillin (B) is an antibiotic effective against Gram-positive bacteria, not parasites.
- Gentamicin sulfate (C) is an antibiotic used for bacterial infections, not parasitic infections.
- Nystatin (D) is an antifungal medication used for treating fungal infections, not parasitic infections like trichomonal gingivostomatitis.
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.
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.
The antibiotics penicillin and cephalosporin are produced by:
- A. algae
- B. slime molds
- C. fungi
- D. protozoans
Correct Answer: C
Rationale: The correct answer is C: fungi. Both penicillin and cephalosporin are produced by certain species of fungi. Penicillin is derived from the Penicillium fungi, while cephalosporin is produced by Cephalosporium fungi. Fungi have the ability to synthesize these antibiotics as part of their defense mechanisms against other microorganisms. Algae (A), slime molds (B), and protozoans (D) do not have the capability to produce antibiotics like penicillin and cephalosporin. Algae are mainly photosynthetic organisms, slime molds are protists that lack the ability to synthesize complex antibiotics, and protozoans are single-celled eukaryotic organisms that do not produce antibiotics like fungi do.