ATI RN
microbiology chapter 11 test bank Questions
Question 1 of 9
Which bacteria produce urease enzyme to neutralize stomach acid?
Correct Answer: C
Rationale: Rationale: 1. Helicobacter pylori is known for producing urease enzyme to neutralize stomach acid. 2. Urease enzyme converts urea into ammonia, buffering the acidic pH. 3. This adaptation allows H. pylori to survive in the acidic environment of the stomach. 4. Salmonella typhi, Escherichia coli, and Shigella flexneri do not produce urease. 5. Therefore, C is the correct answer based on the unique urease-producing capability of H. pylori.
Question 2 of 9
A woman hospitalized in the surgical department complains of pain in her lower abdomen and in the small of her back, frequent and painful urination. Urine culture test revealed gram-negative oxidase- positive bacilli that formed green mucoid colonies with specific smell. What causative agent can be suspected?
Correct Answer: D
Rationale: The correct answer is D: Proteus mirabilis. The patient's symptoms of lower abdominal pain, back pain, frequent/painful urination, and the presence of gram-negative oxidase-positive bacilli forming green mucoid colonies with a specific smell suggest a urinary tract infection caused by Proteus mirabilis. This bacterium is known for causing UTIs and is characterized by its swarming motility and distinctive odor. A: Pseudomonas aeruginosa is commonly associated with hospital-acquired infections but does not typically cause UTIs with the specific characteristics described. B: Mycoplasma pneumonia is a bacterium that causes respiratory infections, not UTIs. C: Str.pyogenes (Streptococcus pyogenes) is a common cause of strep throat and skin infections, not UTIs. D: Helicobacter pylori is associated with gastritis and peptic ulcers, not UTIs.
Question 3 of 9
The pertussis toxin:
Correct Answer: C
Rationale: The pertussis toxin inhibits the adenylate cyclase-mediated conversion of ATP to cyclic AMP, leading to decreased levels of cyclic AMP in the cell. This disrupts important cellular signaling pathways, affecting immune response and causing symptoms of pertussis. Choices A, B, and D are incorrect because the pertussis toxin does not directly affect protein synthesis, provoke overproduction of mucus in tracheal cells, or provoke release of electrolytes.
Question 4 of 9
In which of the following GIT infections, the bacteria adhere to the intestine wall and produce toxins:
Correct Answer: B
Rationale: Rationale: 1. Enteropathogenic E.coli (EPEC) adheres to the intestinal wall using bundle-forming pili. 2. EPEC produces toxins that disrupt cell structure and function, leading to diarrhea. 3. Shigella spp. invade intestinal cells, Salmonella spp. invade and multiply within cells, and Vibrio cholerae produces cholera toxin causing profuse watery diarrhea. Summary: A, C, and D choices are incorrect because they do not specifically adhere to the intestine wall and produce toxins like EPEC does.
Question 5 of 9
During bacteriological examination of sputum of a child with choking cough and fever there were revealed glossy smooth colonies growing on casein-charcoal agar and reminding of mercury drops. Microscopic examination revealed short Gram-negative bacteria. What microorganism was secured from the sputum?
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Glossy smooth colonies growing on casein-charcoal agar resembling mercury drops indicate Bordetella pertussis, the causative agent of whooping cough. The presence of short Gram-negative bacteria further supports this identification. Option B, Haemophilus influenzae, typically grows as small, round, translucent colonies on chocolate agar. Option C, Corynebacterium diphtheriae, forms gray colonies on tellurite agar. Option D, Klebsiella pneumoniae, appears as mucoid colonies on MacConkey agar.
Question 6 of 9
A blood culture from a patient with sepsis revealed Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. This is supported by the characteristics of Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria, as it is a common skin commensal that can cause infections in immunocompromised individuals. Staphylococcus aureus (choice B) is catalase-positive and coagulase-positive. Streptococcus pyogenes (choice C) is catalase-negative. Enterococcus faecalis (choice D) is catalase-negative and not typically seen in clusters. Therefore, based on the given information, Staphylococcus epidermidis is the most likely causative agent.
Question 7 of 9
Which of the following viruses does not belong to family Paramyxoviridae:
Correct Answer: D
Rationale: The correct answer is D: Rubella virus. Rubella virus does not belong to the family Paramyxoviridae because it belongs to the Togaviridae family. The other choices, A (Measles virus), B (Respiratory syncytial virus), and C (Mumps virus) are all members of the Paramyxoviridae family. This classification is based on the genetic and structural characteristics of the viruses. Rubella virus is distinct in its genetic composition and replication cycle compared to the Paramyxoviridae family, making it the correct choice.
Question 8 of 9
Examination of duodenal contents revealed some pyriform protozoa with twin nuclei and four pairs of flagella. There were two supporting filaments between the nuclei and a suctorial disc on the ventral side. What representative of protozoa was revealed in this patient?
Correct Answer: A
Rationale: Rationale for Correct Answer A (Lamblia): 1. Pyriform protozoa with twin nuclei, four pairs of flagella, and a suctorial disc match the characteristics of Giardia lamblia. 2. The presence of two supporting filaments between the nuclei is a unique feature of Giardia lamblia. 3. Giardia lamblia is known to infect the duodenum and cause symptoms such as diarrhea and abdominal pain. Summary of Incorrect Choices: B: Toxoplasma - Toxoplasma gondii is not characterized by four pairs of flagella or supporting filaments in the nuclei. C: Leishmania - Leishmania species do not typically have the described morphology or location in the duodenum. D: Intestinal trichomonad - Intestinal trichomonads do not exhibit the specific features mentioned in the question, such as twin nuclei and supporting filaments.
Question 9 of 9
A veterenary attendant working at a cattle farm complains of joint pain, fever, indisposition and sweating at nighttime that he has been experiencing for a month. Giving the regard to such presentations and occupational history the doctor suspected brucellosis. What material taken from this patient is to be analyzed in a common microbiological laboratory?
Correct Answer: A
Rationale: The correct answer is A: Blood serum. In suspected cases of brucellosis, blood serum is typically analyzed in a common microbiological laboratory. This is because the bacteria causing brucellosis, Brucella species, can be detected through serological tests in the blood serum. The presence of specific antibodies against Brucella in the serum confirms the diagnosis. Spinal fluid (choice B) would be analyzed in cases of suspected central nervous system infections, which are not typical for brucellosis. Vomit mass (choice C) is not a common sample for microbiological analysis in cases of brucellosis. Urine (choice D) is not the preferred sample for detecting Brucella antibodies; blood serum is the primary choice for serological testing.