Which bacteria are resistant to antibiotics and commonly found in hospitals?

Correct Answer: A

Rationale: The correct answer is A, Staphylococcus aureus (MRSA), because it is known to be resistant to many antibiotics commonly used in hospitals. MRSA poses a significant threat in healthcare settings due to its resistance, making it difficult to treat. Choice B, Escherichia coli, is not typically resistant to antibiotics. Choice C, Salmonella enterica, and Choice D, Vibrio cholerae, are not commonly associated with antibiotic resistance in hospitals. Therefore, A is the correct answer based on its well-documented antibiotic resistance in healthcare settings.

Correct Answer: C

Rationale: The correct answer is C: Escherichia coli. E. coli is the most common cause of acute cystitis. It typically presents with leukocytes and gram-negative bacilli in the urine. The green pigment production indicates pyocyanin, which is a characteristic of E. coli. Pseudomonas aeruginosa (A) can also produce green pigment, but it is less common in urinary tract infections. Proteus mirabilis (B) is associated with a swarming motility pattern on agar, not mucous colonies. Klebsiella pneumoniae (D) is associated with pneumonia and other respiratory infections, not cystitis.

Correct Answer: A

Rationale: The correct answer is A: Sandfly. Cutaneous leishmaniasis is transmitted by the bite of infected sandflies. These tiny insects are known vectors for Leishmania parasites. Sandflies are active during dusk and night, feeding on blood from mammals, including humans. Tick (B), mosquito (C), and tsetse fly (D) are not vectors for Leishmania parasites. Ticks transmit diseases like Lyme disease, mosquitoes transmit diseases like malaria, and tsetse flies transmit African trypanosomiasis. Therefore, the correct vector for cutaneous leishmaniasis is the sandfly due to its specific role in transmitting the Leishmania parasite.

Correct Answer: B

Rationale: The correct answer is B, Antony van Leeuwenhoek. He was the first to observe and describe "animalcules" (microorganisms) through his early microscopes. Robert Hooke (A) is known for his work with cells but did not discover animalcules. Hans Janssen (C) and John Needham (D) did not make significant contributions to the discovery of microorganisms. Leeuwenhoek's pioneering observations were crucial in the development of microbiology.

Correct Answer: B

Rationale: The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic environments. In aerobic conditions, they use oxygen for energy production, while in anaerobic conditions, they can switch to fermentation or anaerobic respiration. A: Obligate aerobes require oxygen to survive and cannot survive in anaerobic environments. C: Obligate anaerobes cannot survive in the presence of oxygen and only thrive in anaerobic conditions. D: Microaerophiles require low levels of oxygen to survive and cannot thrive in fully aerobic or anaerobic conditions.

Correct Answer: B

Rationale: Memory cells are not part of the non-specific immune response because they are a component of the specific immune response. Non-specific immune responses are immediate and target a broad range of pathogens, whereas memory cells are formed after exposure to a specific pathogen to provide a quicker and stronger response upon subsequent exposure. Lysozyme (A), Interferon (C), and Phagocytosis (D) are all part of the non-specific immune response. Lysozyme is an enzyme that destroys bacterial cell walls, interferon helps to inhibit viral replication, and phagocytosis involves the engulfing and destruction of pathogens by phagocytes. These responses are not specific to particular pathogens and are the body's first line of defense.

Correct Answer: B

Rationale: The correct answer is B: FALSE. The statement is incorrect because the secondary immune response is actually faster than the primary immune response. This is due to memory cells that are formed during the primary response, allowing for a quicker and more robust reaction upon re-exposure to the same antigen. The secondary response produces more antibodies and is more effective in clearing the pathogen. Choice A is incorrect because the secondary response is faster, not slower. Choice C is incorrect because the statement is objectively false, regardless of the situation. Choice D is incorrect as the correct answer is B.

Correct Answer: B

Rationale: The correct answer is B: Hantavirus. Hantaviruses are not arthropod-borne, unlike the other choices. Hantaviruses are transmitted to humans primarily through contact with rodent urine, feces, or saliva. Phlebovirus (A), Nairovirus (C), and Uukuvirus (D) are all bunyaviruses that are transmitted by arthropod vectors such as mosquitoes or ticks. Therefore, Hantavirus is the correct answer as it is not transmitted by arthropods.

Correct Answer: B

Rationale: The correct answer is B: cytopathic effect. When viruses infect cell cultures, they induce degenerative changes known as cytopathic effects, which include cell shrinkage, rounding, detachment, and cell death. This term specifically refers to the damage caused by viral replication within the cells. A: Cytolytic effect refers to the destruction of cells by viruses, which is a more specific type of cytopathic effect involving cell lysis. C: Cytotoxic effect typically refers to the toxic effects of substances on cells, not specifically related to viral propagation. D: The statement that all three answers are correct is incorrect as only option B accurately describes the degenerative changes resulting from viral propagation in infected cell cultures.