Which of the following bacteria are capable of surviving in both aerobic and anaerobic environments?

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: The correct answer is B: Hepatitis B virus. This is because Hepatitis B virus is a DNA virus, not an RNA virus. The other choices, A (Hepatitis G virus), C (Hepatitis A virus), and D (Hepatitis E virus) are all RNA viruses. Hepatitis B virus is unique as it contains partially double-stranded DNA. DNA viruses replicate through a DNA intermediate, unlike RNA viruses which directly use RNA. Therefore, Hepatitis B virus stands out as the only DNA virus among the given options.

Correct Answer: C

Rationale: The correct answer is C because Gram staining after culture on Loeffler's medium or tellurite-containing medium will show the characteristic Chinese letter arrangement of Corynebacterium diphtheriae. This arrangement consists of metachromatic granules that stain more deeply than the rest of the cell. This specific staining pattern is a key diagnostic feature of C. diphtheriae in microbiological diagnosis of diphtheria. Choice A is incorrect because simply identifying the isolate as C. diphtheriae is not sufficient for diagnosis. Choice B is incorrect as C. diphtheriae can be stained via Gram staining despite its small cell size. Choice D is incorrect as option C is indeed correct for microbiological diagnosis of diphtheria.

Correct Answer: C

Rationale: Rabbit fever, or tularemia, is caused by Francisella tularensis. This bacterium is known to infect a wide range of animals, including rabbits. The other choices, Bartonella henselae (causes cat scratch fever), Spirillum minus (causes rat bite fever), and Yersinia pestis (causes plague) are not associated with rabbit fever. Therefore, the correct answer is C based on the specific pathogen responsible for causing tularemia.

Correct Answer: C

Rationale: The correct answer is C: nosocomial infections. Nosocomial infections are infections acquired in healthcare settings. This term specifically refers to infections that occur during the course of receiving medical treatment. The other choices are incorrect because: A: Incidental infections do not necessarily occur in healthcare settings. B: Accidental infections is not a commonly used term in healthcare for infections acquired in healthcare settings. D: Secondary infections refer to infections that occur as a result of a primary infection, not specifically related to healthcare settings.

Correct Answer: B

Rationale: The correct answer is B: serratia spp. This is because serratia spp. are not typically found in the normal skin microflora. Normal skin microflora primarily consist of bacteria such as diphtheroids, alpha-hemolytic streptococci, and epidermidis. Serratia spp. are more commonly associated with healthcare-associated infections rather than being a part of the skin's natural bacterial flora. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect as they are commonly found in the normal skin microflora.

Correct Answer: D

Rationale: The correct answer is D: Agar media. Influenza viruses cannot be isolated in agar media because they require specific conditions present in laboratory animals, embryonated eggs, or cell cultures for successful isolation and propagation. Agar media lack the necessary components and environment needed for influenza virus replication. In laboratory animals, such as mice, the viruses can replicate and cause infection. Embryonated eggs provide a suitable environment for influenza virus growth and isolation due to the presence of necessary nutrients and factors. Cell cultures offer controlled conditions for virus propagation and study, making them a valuable tool in influenza virus research.

Correct Answer: A

Rationale: The correct answer is A: Hemolytic streptococci. Hemolytic streptococci are pathogenic bacteria that can cause severe infections in humans, indicating direct epidemiological danger. Hemolytic streptococci are commonly found in the respiratory tract and can be transmitted through the air, making them a good indicator of pathogenic microorganisms in the air. Summary: - B: Sarcina, molds, yeast, and Micrococci are not typically indicators of direct epidemiological danger related to pathogenic microorganisms in the air. - Hemolytic streptococci, on the other hand, are pathogenic bacteria that can cause serious infections and are commonly transmitted through the air, making them a suitable indicator in this context.

Correct Answer: A

Rationale: The correct answer is A: Neisseria meningitidis. This bacterium fits the description of Gram-negative diplococci that are oxidase-positive and fermentative. Neisseria meningitidis commonly causes pneumonia and meningitis. Choice B: Neisseria gonorrhoeae is also a Gram-negative diplococci but is not fermentative. Choice C: Moraxella catarrhalis is oxidase-positive but not fermentative. Choice D: Haemophilus influenzae is not fermentative and typically appears as pleomorphic rods, not diplococci.