ATI RN
foundations in microbiology test bank Questions
Question 1 of 9
Which of the following is characteristic of Gram-negative bacteria?
Correct Answer: B
Rationale: The correct answer is B: Outer membrane containing lipopolysaccharides. Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which are important for protection and pathogenicity. This outer membrane is a unique feature of Gram-negative bacteria and is not present in Gram-positive bacteria, making it a key characteristic. A: Incorrect because Gram-negative bacteria have a thin peptidoglycan layer compared to Gram-positive bacteria. C: Incorrect because teichoic acids are a characteristic of Gram-positive bacteria, not Gram-negative bacteria. D: Incorrect because all bacteria, including Gram-negative bacteria, have a cell wall.
Question 2 of 9
A journalist's body temperature has sharply increased in the morning three weeks after his mission in India, it was accompanied with shivering and bad headache. A few hours later the temperature decreased. The attacks began to repeat in a day. He was diagnosed with tropical malaria. What stage of development of Plasmodium is infective for anopheles-female?
Correct Answer: D
Rationale: The correct answer is D: Sporozoites. Sporozoites are the infective stage of Plasmodium for the female Anopheles mosquito. Here's the rationale: After being transmitted to a human host through a mosquito bite, the sporozoites travel to the liver where they mature and reproduce asexually as merozoites (not the infective stage for mosquitoes). The merozoites then infect red blood cells, leading to symptoms like fever, headache, and shivering. During the blood stage, some merozoites develop into male and female gametocytes, which are not infective to mosquitoes. When a mosquito bites an infected person, it ingests gametocytes, which then develop into male and female gametes and fuse to form ookinetes. Ookinetes develop into oocysts in the mosquito's gut, releasing sporozoites that migrate to the salivary glands, ready to infect a new human host when the mosquito bites
Question 3 of 9
The mold responsible for the production of penicillin belongs to the subgroup of:
Correct Answer: B
Rationale: The correct answer is B: Ascomycota. Penicillin is produced by the mold Penicillium, which belongs to the phylum Ascomycota. Ascomycota is known for its sac-like structures called asci that contain ascospores. Penicillium produces penicillin as a defense mechanism against bacteria. Basidiomycota (A) are known for producing mushrooms, Zygomycota (C) includes bread molds like Rhizopus, and Deuteromycota (D) is a classification for fungi with no known sexual reproductive stage.
Question 4 of 9
Which of the following is characteristic of Gram-negative bacteria?
Correct Answer: B
Rationale: The correct answer is B: Outer membrane containing lipopolysaccharides. Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which are important for protection and pathogenicity. This outer membrane is a unique feature of Gram-negative bacteria and is not present in Gram-positive bacteria, making it a key characteristic. A: Incorrect because Gram-negative bacteria have a thin peptidoglycan layer compared to Gram-positive bacteria. C: Incorrect because teichoic acids are a characteristic of Gram-positive bacteria, not Gram-negative bacteria. D: Incorrect because all bacteria, including Gram-negative bacteria, have a cell wall.
Question 5 of 9
Which bacteria is responsible for causing leprosy?
Correct Answer: B
Rationale: The correct answer is B: Mycobacterium leprae. This bacterium is responsible for causing leprosy, also known as Hansen's disease. Mycobacterium leprae specifically targets the skin, peripheral nerves, and mucosa of the upper respiratory tract. It is an acid-fast bacterium with a slow growth rate, making it difficult to culture in the laboratory. Streptococcus pyogenes (choice A) is responsible for various infections such as strep throat, Neisseria gonorrhoeae (choice C) causes gonorrhea, and Escherichia coli (choice D) is commonly found in the gut and can lead to various infections but not leprosy.
Question 6 of 9
A patient with severe pneumonia had a sputum culture revealing Gram-negative rods that are non-lactose fermenters. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas aeruginosa is a common Gram-negative rod that is a non-lactose fermenter and a common cause of severe pneumonia, especially in immunocompromised individuals. It is also known for its resistance to many antibiotics, making it difficult to treat. Summary of other choices: B: Escherichia coli is a lactose fermenter and is not commonly associated with severe pneumonia. C: Klebsiella pneumoniae is a lactose fermenter and is more commonly associated with pneumonia in alcoholics or debilitated patients. D: Enterobacter cloacae is a lactose fermenter and is not a common cause of severe pneumonia.
Question 7 of 9
A patient with a long history of chronic gastritis undergoes a gastroscopy, which detects an ulcer in the duodenum area. Microscopic examination of the tissue biopsy developed Gram-negative curved bacteria and the rapid urease activity test of the biopsy material was highly positive. The most likely cause of the disease is:
Correct Answer: D
Rationale: The correct answer is D: Helicobacter pylori. Helicobacter pylori is a known bacterium associated with causing duodenal ulcers. The presence of Gram-negative curved bacteria in the biopsy along with a highly positive rapid urease test is characteristic of H. pylori infection. Vibrio cholerae causes cholera, not duodenal ulcers. Campylobacter fetus is associated with gastroenteritis, not duodenal ulcers. Acinetobacter baumannii is a nosocomial pathogen, not typically associated with duodenal ulcers. In summary, the unique combination of findings in this case points towards H. pylori as the most likely cause of the disease.
Question 8 of 9
Erysipelas is a bacterial infection characterised by well-defined areas of bright-red, inflamed and rough or leathery skin. Which one is the causative agent:
Correct Answer: C
Rationale: Step-by-step rationale for Choice C (Streptococcus pyogenes) being the correct answer: 1. Erysipelas is a skin infection characterized by well-defined red, inflamed skin areas. 2. Streptococcus pyogenes is a common causative agent of erysipelas. 3. This bacterium produces enzymes that break down skin proteins, leading to the characteristic symptoms of erysipelas. 4. Streptococcus pyogenes is known for causing skin infections, including erysipelas. Summary of why the other choices are incorrect: A. Pseudomonas aeruginosa: Typically causes opportunistic infections, but not commonly associated with erysipelas. B. Staphylococcus aureus: Can cause skin infections, but not typically associated with erysipelas. D. Candida albicans: Fungal infection, not a bacterium, and not known to cause erysipelas.
Question 9 of 9
When a smear is stained by Burri-Gins method a mucous structure that is tightly bound with the cellular wall of bacteria and has well-defined outer boundaries can be detected. This element of a bacteria cell is called:
Correct Answer: A
Rationale: The correct answer is A: Capsule. A capsule is a mucous structure tightly bound to the bacterial cell wall with distinct outer boundaries. This structure helps bacteria evade the host immune system, resist desiccation, and adhere to surfaces. In contrast, spores are resistant structures formed by certain bacteria for survival, filaments are long chains of bacterial cells, and ribosomes are cellular organelles responsible for protein synthesis. Therefore, based on the characteristics described in the question, the most appropriate choice is A: Capsule.