A patient with pulmonary tuberculosis is prescribed the most effective antituberculosis antibiotic. Name this drug:

Correct Answer: C

Rationale: Rifampicin is the correct answer because it is a first-line antibiotic for treating pulmonary tuberculosis. It has excellent bactericidal activity and penetrates well into lung tissues where the infection is located. Rifampicin is also known for preventing the development of resistance. Tetracycline (A) and Furasolidone (B) are not commonly used for tuberculosis treatment. Bactrim (D) is a combination of sulfamethoxazole and trimethoprim, not effective for tuberculosis treatment.

Correct Answer: D

Rationale: The correct answer is D, Kitt-Tarozzi medium. This medium is specifically designed for the isolation and cultivation of Clostridium tetani, the bacteria responsible for tetanus. The other options, Sabouraud agar, Endo agar, and Hiss medium, are not suitable for the growth of Clostridium tetani. Sabouraud agar is used for fungal cultures, Endo agar is a selective medium for enteric bacteria, and Hiss medium is used for the cultivation of anaerobic bacteria other than Clostridium tetani. Therefore, the Kitt-Tarozzi medium is the most appropriate choice for isolating and identifying the tetanus agent in this scenario.

Correct Answer: B

Rationale: The correct answer is B: Personal eyewash. Personal eyewash is designed for immediate flushing until the victim reaches a more suitable safety unit. It provides a controlled flow of water to safely flush eyes while transporting the victim. The emergency shower (A) is meant for full-body coverage, not just for the eyes. Handheld drench hose (C) may not provide adequate flushing pressure. Combination unit (D) may not be easily portable for immediate use.

Correct Answer: D

Rationale: The correct answer is D: Positive strand RNA viruses. These viruses have RNA genomes that can be directly translated by host ribosomes without the need for transcription. In contrast, single-strand DNA and double-strand DNA viruses require transcription to generate mRNA for translation. Choice A is incorrect as there is a correct answer. Choice B and C are incorrect because both single-strand DNA and double-strand DNA viruses require transcription for mRNA synthesis.

Correct Answer: A

Rationale: The correct answer is A: Bacterial DNA. PCR analysis detects specific DNA sequences, so a positive result for H. pylori indicates the presence of the bacterial DNA in the gastric biopsy specimen. This method identifies the genetic material of the bacterium, not the bacterium itself (choice C) or its toxins (choice B). Additionally, PCR does not directly detect bacterial enzymes (choice D) but rather focuses on genetic material for accurate identification. Therefore, in this case, the detection of H. pylori in the PCR analysis points to the presence of bacterial DNA, confirming the etiology of peptic ulcer disease.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Clostridium botulinum produces botulinum toxin causing botulism, Vibrio cholerae produces cholera toxin leading to severe diarrhea, and certain strains of Escherichia coli produce toxins causing gastrointestinal illness. Therefore, all three bacteria are known for producing toxins that can cause severe gastrointestinal illness. Choices A, B, and C individually represent bacteria known for producing toxins that can cause severe gastrointestinal illness, making them incorrect individual choices.

Correct Answer: D

Rationale: The correct answer is D: Altered penicillin binding proteins. MRSA (Methicillin-resistant Staphylococcus aureus) achieves resistance to beta-lactam antibiotics, such as penicillin, by producing altered penicillin binding proteins that have reduced affinity for these antibiotics. This alteration prevents the antibiotics from binding to their target sites on the bacterial cell wall, thus rendering them ineffective. Choice A, extended spectrum beta-lactamases, are enzymes produced by some bacteria to break down beta-lactam antibiotics, but MRSA does not use this mechanism. Choice B, penicillin efflux pump, is a mechanism where bacteria pump out antibiotics from their cells, but this is not how MRSA develops resistance. Choice C, altered peptide sequence in peptidoglycan, does not directly relate to how MRSA resists beta-lactam antibiotics.

Correct Answer: A

Rationale: The most probable diagnosis is A: Malaria. The patient's symptoms of periodic chills, high fever, and profuse sweating, along with living in Africa where malaria is endemic, strongly suggest malaria. The enlarged liver and spleen are consistent with malaria infection. The low erythrocyte count indicates hemolysis, a common feature of malaria. Spotted fever and sepsis do not typically present with the same pattern of symptoms and travel history as seen in this case. Haemolytic anaemia would not explain the patient's fever episodes and other symptoms. Therefore, based on the symptoms, travel history, and laboratory findings, malaria is the most likely diagnosis.

Correct Answer: A

Rationale: The correct answer is A: HSV-1. Herpes simplex infections on lips and in the mouth are most commonly caused by HSV-1 due to its preference for infecting oral mucosa. HSV-2 typically causes genital herpes. HSV-6 and HSV-7 are less common and not typically associated with oral infections. Therefore, based on the typical presentation and epidemiology of herpes simplex infections, HSV-1 is the most likely cause in this scenario.