Nokea
Which of the following methods can be used for diagnosis of respiratory tract infections
- A. Culture of samples from the respiratory tract
- B. Immunofluorescence
- C. PCR
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D: All are correct. Culture of samples from the respiratory tract can identify specific pathogens, Immunofluorescence can detect viral antigens, and PCR can amplify and detect specific DNA/RNA sequences. Using all methods together provides a comprehensive approach for diagnosing respiratory tract infections. Culture alone may miss fastidious organisms, Immunofluorescence has limitations in sensitivity, and PCR requires specific primers. Therefore, combining these methods increases the likelihood of accurate diagnosis by covering a range of pathogens and improving sensitivity and specificity.
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Which of the following bacteria is responsible for causing cholera?
- A. Shigella dysenteriae
- B. Vibrio cholerae
- C. Salmonella enterica
- D. Escherichia coli
Correct Answer: B
Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by Vibrio cholerae, a bacterium that infects the small intestine, leading to severe diarrhea and dehydration. This bacterium produces a toxin that causes the symptoms of cholera.
A: Shigella dysenteriae causes dysentery, not cholera.
C: Salmonella enterica causes food poisoning, not cholera.
D: Escherichia coli can cause food poisoning but not cholera.
The time response measures all of the following except:
- A. ED50
- B. Peak effect time
- C. Onset of response
- D. Threshold level
Correct Answer: A
Rationale: The correct answer is A: ED50. The time response does not measure the ED50 because ED50 refers to the effective dose needed to produce a response in 50% of the population, which is a dose-related concept, not a time-related one. Peak effect time, onset of response, and threshold level are all time-related measures in pharmacology. Peak effect time is the time taken to reach the maximum response, onset of response is the time taken for the response to start, and threshold level is the minimum dose or concentration required to produce a response. Therefore, A is the correct answer as it is the only choice that is not a time-related measure in this context.
Which of the following bacteria can produce endotoxins that cause septic shock?
- A. Escherichia coli
- B. Salmonella enterica
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all of the mentioned bacteria (Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa) are gram-negative bacteria that produce endotoxins in their cell walls. Endotoxins are released when the bacteria are destroyed, leading to the activation of the immune system and potentially causing septic shock. Escherichia coli and Salmonella enterica are common causes of gastrointestinal infections, while Pseudomonas aeruginosa is known for causing infections in immunocompromised individuals. Therefore, all three bacteria can produce endotoxins that contribute to septic shock. Choices A, B, and C are incorrect because each of these bacteria individually can produce endotoxins that lead to septic shock.
It is often difficult for antibiotics to effectively reach the infection site of osteomyelitis primarily because of:
- A. destruction of the local blood supply
- B. denaturing of the drug by normal flora
- C. inflammation and edema
- D. excessive production of pus at the infection site
Correct Answer: A
Rationale: The correct answer is A: destruction of the local blood supply. In osteomyelitis, the infection occurs in the bone, which has a relatively poor blood supply compared to soft tissues. This limited blood flow makes it challenging for antibiotics to reach the infection site effectively, hindering their ability to combat the infection. Destruction of the local blood supply restricts the delivery of antibiotics and immune cells to the infected bone, leading to poor treatment outcomes.
Summary:
- Option A is correct because the limited blood supply in bones hinders antibiotic delivery.
- Option B is incorrect as denaturing by normal flora does not impact antibiotic reach to the infection site.
- Option C is incorrect as inflammation and edema, while present, do not primarily hinder antibiotic delivery.
- Option D is incorrect as excessive pus production does not directly impede antibiotic access to the infection site.
The infectious (non-sterile) immunity is:
- A. cross-reactivity of antibodies
- B. toxemia and formation of antitoxic antibodies
- C. persistence of infectious agent
- D. neutralization of infectious agent
Correct Answer: C
Rationale: The correct answer is C because infectious (non-sterile) immunity is achieved through the persistence of the infectious agent in the body, allowing the immune system to continuously recognize and combat the pathogen. This type of immunity provides long-lasting protection against future infections by the same agent.
Choice A (cross-reactivity of antibodies) is incorrect as it refers to the ability of antibodies to recognize similar antigens, not necessarily related to infectious immunity.
Choice B (toxemia and formation of antitoxic antibodies) is incorrect as it specifically relates to toxins produced by pathogens and the corresponding antibody response, not the persistence of the infectious agent itself.
Choice D (neutralization of infectious agent) is incorrect as it describes the process of antibodies binding to and inactivating pathogens, but it does not necessarily lead to long-term immunity through the persistence of the infectious agent.