For prevention of tuberculosis is used

Correct Answer: B

Rationale: The correct answer is B: BCG. Bacille Calmette-Guérin (BCG) vaccine is used for the prevention of tuberculosis. BCG is a live attenuated strain of Mycobacterium bovis that helps the immune system recognize and fight off tuberculosis bacteria. Specific anti-tuberculosis serum (A) is not used for prevention but for treatment. DTP (C) stands for diphtheria, tetanus, and pertussis vaccine, not specific for tuberculosis prevention. PPD (D) is a tuberculin skin test used for diagnosis, not prevention. Thus, BCG is the correct choice for tuberculosis prevention.

Correct Answer: A

Rationale: Step-by-step rationale: 1. IgG is the most abundant immunoglobin in a normal healthy adult due to its long half-life and diverse functions. 2. It plays a crucial role in immune response by neutralizing pathogens and enhancing phagocytosis. 3. IgA is mainly found in mucosal areas, IgE is involved in allergic reactions, and IgD's function is not fully understood. 4. Therefore, IgG is the correct answer as it is the predominant immunoglobin in circulation, providing broad immune protection.

Correct Answer: B

Rationale: The correct answer is B: Transformation. Frederick Griffith discovered bacterial transformation, where genetic material can be transferred between bacteria. He observed this phenomenon while studying pneumonia-causing bacteria in 1928. Transformation is the process by which bacteria take up external DNA and incorporate it into their own genome. This discovery was crucial in understanding how genetic information can be transferred between organisms. Rationale for other choices: A: Translation - This term refers to the process of protein synthesis from mRNA, not relevant to Griffith's discovery. C: Transcription - This term refers to the process of synthesizing RNA from DNA, not related to Griffith's discovery. D: Conjugation - This term refers to the direct transfer of genetic material between bacterial cells through cell-to-cell contact, which is different from the phenomenon Griffith observed.

Correct Answer: A

Rationale: The correct answer is A because the NSP4 nonstructural protein of rotaviruses indeed acts in a toxic-like manner by disrupting calcium homeostasis, leading to diarrhea. Choice B is incorrect as rotaviruses can cause significant disease in infants, but not typically in adults. Choice C is incorrect as rotaviruses are resistant to stomach acid. Choice D is incorrect as rotaviruses cause a net secretion of water and loss of ions, contributing to diarrhea.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Gram-positive rods with terminal spores suggest Clostridium genus. 2. Terminal spores are characteristic of Clostridium perfringens. 3. C. perfringens is known to cause wound infections. 4. Therefore, the most likely causative agent is Clostridium perfringens. Summary: A: Clostridium perfringens is correct due to its characteristic features and association with wound infections. B: Bacillus anthracis does not typically form terminal spores. C: Clostridium tetani causes tetanus, not wound infections. D: Bacillus cereus does not produce terminal spores like Clostridium perfringens.

Correct Answer: A

Rationale: The correct answer is A: endogenous infections. This term refers to infections caused by microorganisms that are normally present in or on the body. In the context of vaginal infections, an overgrowth of the normal flora can lead to an imbalance and result in infection. Choice B, chronic infections, does not specifically address the source of the infection. Choice C, iatrogenic infections, refers to infections caused by medical intervention, not normal flora overgrowth. Choice D, fatal infections, is incorrect as it does not describe the nature or source of the infection. In summary, the term "endogenous infections" accurately describes the scenario of vaginal infections caused by an overgrowth of normal flora.

Correct Answer: B

Rationale: The correct answer is B: Vibrio cholerae. Cholera is caused by Vibrio cholerae, a bacterium that produces a toxin leading to severe diarrhea and dehydration. Clostridium botulinum (A) causes botulism, Salmonella enterica (C) causes salmonellosis, and Escherichia coli (D) can cause various illnesses but not cholera. Vibrio cholerae is the only bacteria specifically known for causing cholera.

Correct Answer: D

Rationale: The correct answer is D, chemotherapy combined with surgical therapy. Actinomycosis is a bacterial infection that requires a combination of antibiotics to target the bacteria and surgery to remove abscesses or infected tissues. Antibiotics alone may not penetrate abscesses effectively. Waiting for self-clearance can lead to complications. Surgical treatment alone may not eradicate the infection entirely. Therefore, the most effective therapeutic plan is to combine chemotherapy to treat the infection systemically and surgery to remove localized infections.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Adenoviruses are DNA viruses, so choices B and C (ssRNA and DNA) are incorrect. 2. Adenoviruses have a middle-sized, naked icosahedral capsid, making choice A the correct description. 3. Choice D is incorrect as adenoviruses do have specific characteristics, making "None of the above" an inaccurate option. In summary, the correct answer A is supported by the fact that adenoviruses have a middle-sized, naked icosahedral capsid and contain double-stranded DNA. Choices B, C, and D are incorrect as they do not align with the characteristics of adenoviruses.