Nokea
The ability of Clostridium tetani to produce exotoxins is encoded by?
- A. genes with chromosomal location
- B. clostridium tetani is not capable of producing exotoxins, it has only endotoxin activity
- C. genes with plasmid location
- D. chromosomal and plasmid location
Correct Answer: C
Rationale: The correct answer is C: genes with plasmid location. Clostridium tetani produces exotoxins through genes located on plasmids. Plasmids are extrachromosomal genetic elements that carry additional genes. These genes encode for the production of exotoxins in Clostridium tetani. Choices A, B, and D are incorrect because Clostridium tetani does produce exotoxins, it does not have only endotoxin activity, and the genes responsible for exotoxin production are located on plasmids, not solely on the chromosome or both chromosome and plasmid.
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Which one is FALSE:
- A. Tissue samples and aspirations are better specimens than the swabs for diagnosis of skin and soft tissue infections
- B. To prove anaerobic agents. The specimen should be collected from the surface of the wound.
- C. The skin rash in some infections is due to the excessive production
- D. Healthy skin is an impenetrable barrier for the microorganisms
Correct Answer: B
Rationale: The correct answer is B because collecting specimens from the surface of a wound does not provide adequate samples for anaerobic agent detection. Anaerobic agents thrive in deep tissue environments with low oxygen levels, making surface specimens unreliable. Tissue samples and aspirations (choice A) are superior for diagnosing skin infections. Excessive production of toxins, not skin rash (choice C), causes symptoms in some infections. While healthy skin provides some protection, it is not completely impenetrable to microorganisms (choice D).
A 36-year-old man provisionally diagnosed with renal tuberculosis has undergone urinary sediment analysis. Microscopy revealed acid-fast bacteria, but Pryce method detected no cord factor. Name the most reliable method of investigation that can confirm or refute this provisional diagnosis:
- A. Inoculation of laboratory animals
- B. Phage typing of the obtained culture
- C. Allergy skin test
- D. Toxigenicity testing
Correct Answer: B
Rationale: The correct answer is B: Phage typing of the obtained culture. This method is used for typing Mycobacterium tuberculosis strains based on susceptibility to specific bacteriophages. If the culture shows susceptibility, it confirms the presence of M. tuberculosis. In this case, the absence of cord factor indicates that the bacteria are unlikely to be M. tuberculosis.
Option A (Inoculation of laboratory animals) is unethical and not necessary when other methods are available. Option C (Allergy skin test) is not relevant for confirming a diagnosis of renal tuberculosis. Option D (Toxigenicity testing) is not specific for confirming or refuting a diagnosis of M. tuberculosis.
Koch apparatus uses temperature of:
- A. 90°C
- B. 95°C
- C. 100°C
- D. 110°C
Correct Answer: C
Rationale: The correct answer is C (100°C) because the Koch apparatus is used for sterilization, and the standard temperature for sterilization is 100°C. At this temperature, most microorganisms are killed, making it an effective method for sterilization. Choice A (90°C), B (95°C), and D (110°C) are incorrect because they are not commonly used temperatures for sterilization purposes. Choosing a temperature lower than 100°C may not effectively kill all microorganisms, while choosing a temperature higher than 100°C may lead to unnecessary energy consumption without providing additional sterilization benefits.
A dentist has detected symptoms of parodontosis in a patient. What antiprotozoal drug should be prescribed?
- A. Metronidazole
- B. Levamisole
- C. Griseofulvin
- D. Mykoseptin
Correct Answer: A
Rationale: The correct answer is A: Metronidazole. Parodontosis is a condition caused by bacterial infection, not protozoal infection. Metronidazole is an effective antibiotic commonly used to treat bacterial infections in the oral cavity, including those associated with parodontosis. Levamisole is an anthelmintic drug used to treat parasitic worm infections, not suitable for parodontosis. Griseofulvin is an antifungal medication used for fungal infections, not indicated for parodontosis. Mykoseptin is not a recognized drug and is likely a distractor. Therefore, based on the bacterial nature of parodontosis, Metronidazole is the appropriate choice.
In Transmissive infections, the vector is:
- A. Air
- B. Objects
- C. Medical devices
- D. Water
Correct Answer: A
Rationale: The correct answer is A: Air. In transmissive infections, the vector refers to the means by which the infectious agent is transmitted from one host to another. Air can carry pathogens such as viruses and bacteria, leading to respiratory infections like the flu or tuberculosis. Airborne transmission occurs when droplets containing the pathogens are inhaled. Objects (B), medical devices (C), and water (D) can also transmit infections, but they are not specifically related to transmissive infections. Objects and medical devices can harbor pathogens, while waterborne infections are transmitted through contaminated water sources. However, in the context of transmissive infections, the primary vector is the air due to its ability to carry infectious agents over distances.