Which of the following characteristics of mumps infection is NOT true:

Correct Answer: A

Rationale: Step-by-step rationale: 1. Mumps is a contagious disease transmitted through air droplets and direct contact. 2. The correct answer is A because mumps can infect both humans and animals. 3. Choice B is incorrect as mumps is vaccine-preventable. 4. Choice C is correct as mumps is highly contagious. 5. Choice D is accurate as mumps is transmitted via air droplets and direct contact. Summary: The correct answer is A because mumps can infect both humans and animals, making it untrue that only humans can be infected. Choices B, C, and D are incorrect as mumps is vaccine-preventable, highly contagious, and transmitted through air droplets and direct contact.

Correct Answer: C

Rationale: The correct answer is C: Lag phase. During the lag phase, bacteria adapt to the new environment before starting to grow and divide. This phase is characterized by a period of low growth as bacteria adjust their metabolism to the available nutrients. The stationary phase (A) is when growth rate equals death rate, the log phase (B) is rapid exponential growth, and the death phase (D) is when cells start to die due to nutrient depletion or accumulation of waste products. Thus, the lag phase is the initial phase where bacteria prepare for growth, making it the correct answer.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Hospital-acquired infections can be caused by a variety of bacteria commonly found in healthcare settings. Staphylococcus aureus is a common cause of surgical site infections. Escherichia coli can cause urinary tract infections. Klebsiella pneumoniae is associated with pneumonia and bloodstream infections. Therefore, all three bacteria are frequently implicated in hospital-acquired infections due to their prevalence and ability to cause different types of infections in healthcare settings. Thus, the correct answer is D, as all of the listed bacteria are commonly associated with hospital-acquired infections.

Correct Answer: A

Rationale: The correct answer is A: Toxoplasma. Toxoplasma gondii causes Toxoplasmosis, a protozoan disease that can affect the brain and lead to vision loss. The halfmoon-shaped unicellular organisms with pointed ends described in the blood analysis are characteristic of Toxoplasma parasites. Toxoplasma infection commonly occurs through ingestion of contaminated food or water, or contact with infected cat feces. Leishmania causes Leishmaniasis, Lamblia causes Giardiasis, Amoeba causes Amebiasis, and Trichomonad causes Trichomoniasis, none of which match the symptoms and blood analysis findings described in the question.

Correct Answer: D

Rationale: The correct answer is D (4) because biosafety levels range from 1 to 4, each corresponding to the level of containment required when handling different types of organisms. BSL-1 is for low-risk agents, while BSL-4 is for dangerous pathogens. Choice A (1) is incorrect as there are multiple levels, not just one. Choice B (2) and C (3) are incorrect as they do not account for all the levels of biosafety required for handling various organisms. Therefore, D is the correct answer as it encompasses the full range of biosafety levels.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. This bacterium is characterized by Gram-positive cocci in clusters, catalase-positive, and coagulase-positive. Staphylococcus aureus is a common pathogen causing wound infections due to its ability to produce toxins and enzymes. Staphylococcus epidermidis (B) is catalase-positive but coagulase-negative, making it less likely to cause infections. Streptococcus pyogenes (C) is catalase-negative and typically causes streptococcal infections, not wound infections. Enterococcus faecalis (D) is catalase-negative and typically associated with urinary tract infections. Thus, Staphylococcus aureus is the most likely causative agent based on the given characteristics.

Correct Answer: D

Rationale: The correct answer is D: Cell cultures. Rotavirus diagnosis involves detecting viral antigens in stool samples using cell cultures. Cell cultures allow for the replication of the virus, facilitating its identification. A: Egg inoculation and B: Sensitive laboratory animals are not commonly used for Rotavirus diagnosis due to ethical concerns and practical limitations. C: Ascoli test is used for detecting specific proteins in serum, not for Rotavirus detection in stool samples. In summary, cell cultures are the most appropriate method for laboratory diagnosis of Rotavirus infection due to their ability to support viral replication and antigen detection.

Correct Answer: A

Rationale: The most likely diagnosis is A: Leptospirosis. Leptospirosis is caused by the spirochete Leptospira interrogans and is commonly transmitted through contact with water contaminated by animal urine, such as in this case of fishing. The symptoms described match those of leptospirosis, including high fever, headache, muscle pain, jaundice, hemorrhagic rash, and bloody urine. The calf muscle pain is a characteristic symptom of leptospirosis known as "Weil's disease." Yersiniosis (B) typically presents with abdominal symptoms, Salmonellosis (C) with gastrointestinal symptoms, and Brucellosis (D) with flu-like symptoms. Therefore, based on the symptoms and history provided, Leptospirosis is the most likely diagnosis.

Correct Answer: A

Rationale: The correct answer is A: Entamoeba histolytica. This is because it is the only choice that matches the description of cysts with four nuclei, characteristic of Entamoeba histolytica. Entamoeba histolytica is a protozoan parasite that causes amoebiasis, leading to symptoms like persistent diarrhea. The other choices can be eliminated for the following reasons: B: Balantidium coli - It is a ciliated protozoan that causes dysentery in humans but does not produce cysts with four nuclei. C: Giardia lamblia - It is a flagellated protozoan that causes giardiasis, but it forms cysts with only two nuclei. D: Trichomonas hominis - It is a flagellated protozoan found in the human intestine, but it does not produce cysts with four nuclei. Therefore, based on the description of cysts with four nuclei in the stool sample,