Mycobacterium tuberculosis is

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microbiology an introduction 13th edition test bank Questions

Question 1 of 9

Mycobacterium tuberculosis is

Correct Answer: D

Rationale: The correct answer is D because Mycobacterium tuberculosis is a straight or slightly curved rod with occasional polymorphism. This bacterium does not conform to the characteristics of gram-negative coccus (A), gram-positive coccus (B), or gram-negative rod (C). Mycobacterium tuberculosis is characterized by its unique cell wall composition, which includes high lipid content and mycolic acids, contributing to its acid-fast staining property. The other choices are incorrect because they do not accurately describe the morphology of Mycobacterium tuberculosis.

Question 2 of 9

Which of the following bacteria produces endotoxins that can lead to septic shock?

Correct Answer: D

Rationale: The correct answer is D (All of the above). All three bacteria (Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa) produce endotoxins that can lead to septic shock. Endotoxins are part of the outer membrane of Gram-negative bacteria and can trigger a strong immune response, leading to septic shock when released in large amounts. Escherichia coli and Salmonella enterica are common causes of bacterial septic shock, while Pseudomonas aeruginosa is known for its ability to produce endotoxins that contribute to severe infections and septic shock. Therefore, all three choices are correct in this context.

Question 3 of 9

A 16 y.o. boy from a countryside entered an educational establishment. Scheduled Manteux test revealed that the boy had negative reaction. What are the most reasonable actions in this case?

Correct Answer: C

Rationale: The correct answer is C: To perform serodiagnostics of tuberculosis. Rationale: The negative reaction to the Mantoux test indicates absence of TB infection. Performing serodiagnostics will further confirm the absence of active infection. This is important to rule out TB before considering vaccination or isolation measures. Summary: A: BCG vaccination is not necessary as the boy shows a negative reaction to the Mantoux test. B: Repeating the test in a month is unnecessary as the initial test already showed a negative reaction. D: Isolating the boy is not warranted as there is no evidence of active TB infection.

Question 4 of 9

A patient presents with fever, chill and cough. From his sputum the ovoid Gram-negative bipolar- stained bacilli with a delicate capsule were secured. What is the most likely diagnosis?

Correct Answer: A

Rationale: The correct answer is A: Plague. The presence of ovoid Gram-negative bipolar-stained bacilli with a delicate capsule in the sputum is characteristic of Yersinia pestis, the causative agent of plague. Plague presents with symptoms like fever, chills, and cough. Plague is a zoonotic disease usually transmitted through fleas from rodents. The other choices (B: Tuberculosis, C: Leptospirosis, D: Brucellosis) can be ruled out based on the specific description of the bacteria in the sputum. Tuberculosis is caused by Mycobacterium tuberculosis, which is not Gram-negative. Leptospirosis is caused by Leptospira, which are spirochetes and not ovoid bacilli. Brucellosis is caused by Brucella species, which are small, coccobacilli and not ovoid bacilli.

Question 5 of 9

Sputum smears of a patient with chronic pulmonary disease were stained by Ziehl-Neelsen method and analyzed in the bacteriological laboratory. Microscopy revealed red bacillus. What property of tuberculosis myobacteria was found?

Correct Answer: A

Rationale: The correct answer is A: Acid resistance. Tuberculosis mycobacteria have a unique cell wall structure that makes them resistant to acid-fast staining methods like Ziehl-Neelsen. This is due to the high lipid content of their cell walls, specifically mycolic acids, which prevent the penetration of stains and acids. The red bacilli observed in the smear indicate that the mycobacteria retained the primary stain (carbolfuchsin) after acid-alcohol decolorization, confirming their acid resistance. Summary: - Choice A: Acid resistance is correct due to the unique cell wall structure of tuberculosis mycobacteria. - Choice B: Alkali resistance is incorrect as mycobacteria are not known for being resistant to alkalis. - Choice C: Alcohol resistance is incorrect as mycobacteria are not specifically resistant to alcohols. - Choice D: Encapsulation is incorrect as mycobacteria are not encapsulated bacteria.

Question 6 of 9

Which bacteria are commonly associated with foodborne illnesses?

Correct Answer: D

Rationale: The correct answer is D because all three bacteria - Salmonella enterica, Clostridium botulinum, and Escherichia coli - are commonly associated with foodborne illnesses. Salmonella causes gastroenteritis, Clostridium botulinum causes botulism, and E. coli can lead to severe food poisoning. Each bacterium has different mechanisms of causing illness, but all can be transmitted through contaminated food. Choices A, B, and C alone are incorrect because they do not encompass the full spectrum of bacteria commonly linked to foodborne illnesses.

Question 7 of 9

Which of the following bacteria is known for causing urinary tract infections?

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli. E. coli is the most common bacteria responsible for causing urinary tract infections due to its ability to adhere to the urinary tract lining and multiply rapidly. It is a normal inhabitant of the gut and can enter the urinary tract through improper hygiene practices. Salmonella enterica and Neisseria gonorrhoeae are typically associated with other infections like food poisoning and gonorrhea, respectively. Mycobacterium tuberculosis causes tuberculosis, not urinary tract infections. Thus, based on its prevalence and pathogenicity in the urinary tract, E. coli is the correct choice.

Question 8 of 9

Mycobacterium tuberculosis is

Correct Answer: D

Rationale: The correct answer is D because Mycobacterium tuberculosis is a straight or slightly curved rod with occasional polymorphism. This bacterium does not conform to the characteristics of gram-negative coccus (A), gram-positive coccus (B), or gram-negative rod (C). Mycobacterium tuberculosis is characterized by its unique cell wall composition, which includes high lipid content and mycolic acids, contributing to its acid-fast staining property. The other choices are incorrect because they do not accurately describe the morphology of Mycobacterium tuberculosis.

Question 9 of 9

There was a record of some anthrax cases among animals in a countryside. The spread of disease can be prevented by means of immunization. What kind of vaccine should be used?

Correct Answer: B

Rationale: The correct answer is B: BCG vaccine. Bacille Calmette-Guérin (BCG) vaccine is used to prevent tuberculosis, which is caused by a bacterium related to anthrax. BCG vaccine can provide cross-protection against anthrax due to its similar mechanisms of action. STI live vaccine (choice A) is used for sexually transmitted infections, not anthrax. Salk vaccine (choice C) is used for polio, and Sabin's vaccine (choice D) is also for polio, not anthrax. Therefore, BCG vaccine is the most appropriate choice for preventing the spread of anthrax among animals in the countryside.

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