ATI RN
microbiology chapter 14 test bank Questions
Question 1 of 9
A patient with a sore throat had a throat smear revealing Gram-positive cocci in pairs. The bacteria were catalase-negative and beta-hemolytic. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. Rationale: 1. Gram-positive cocci in pairs suggest Streptococcus species. 2. Catalase-negative rules out Staphylococcus. 3. Beta-hemolytic indicates Streptococcus pyogenes due to its beta-hemolytic properties. Summary: B: Streptococcus pneumoniae is catalase-negative but not beta-hemolytic. C: Enterococcus faecalis is not typically beta-hemolytic. D: Staphylococcus aureus is catalase-positive and not typically in pairs.
Question 2 of 9
Which scientist is most responsible for ending the controversy about spontaneous generation?
Correct Answer: C
Rationale: The correct answer is C: Louis Pasteur. He conducted experiments that definitively disproved the theory of spontaneous generation through his famous swan-neck flask experiment. By showing that microorganisms only appeared in the broth when exposed to air, Pasteur demonstrated that they did not arise spontaneously. John Needham's experiments were inconclusive, Joseph Lister is known for his contributions to antiseptic surgery, and Robert Koch is credited with developing Koch's postulates for identifying the causative agents of diseases, but neither of them directly contributed to ending the controversy about spontaneous generation.
Question 3 of 9
Which enzyme is one of the most important and constant criteria for pathogenicity of staphylococcus aureus?
Correct Answer: B
Rationale: The correct answer is B: plasma coagulase. This enzyme is essential for the pathogenicity of Staphylococcus aureus as it can convert fibrinogen to fibrin, forming a protective barrier around the bacteria. This helps the bacteria evade the host's immune system. Beta lactamase (A) is not directly related to pathogenicity but rather resistance to beta-lactam antibiotics. Catalase (C) is produced by many bacteria, including Staphylococcus aureus, but it is not a specific indicator of pathogenicity. Choice D is incorrect as plasma coagulase is indeed an important criterion for the pathogenicity of Staphylococcus aureus.
Question 4 of 9
Infections of the reproductive tract resulting from the introduction of microorganisms through a medical procedure are called:
Correct Answer: D
Rationale: The correct answer is D: iatrogenic infections. Iatrogenic infections refer to infections caused by medical or surgical treatment, including procedures that introduce microorganisms into the body. In this case, infections of the reproductive tract caused by medical procedures fall under this category. A: Chronic infections do not specifically refer to infections caused by medical procedures. B: Endogenous infections arise from organisms already present in or on the body, not introduced through medical procedures. C: Systemic infections affect the entire body, not specific to infections caused by medical procedures. Therefore, the term "iatrogenic infections" is the most appropriate choice in this context.
Question 5 of 9
Aflatoxins are produced by:
Correct Answer: D
Rationale: The correct answer is D: Genus Aspergillus. Aflatoxins are toxic compounds produced by certain species of fungi, particularly Aspergillus species. Aspergillus flavus and Aspergillus parasiticus are well-known producers of aflatoxins. These fungi can contaminate crops such as peanuts, corn, and tree nuts, leading to potential health risks. Cryptococcus (A), Actinomyces (B), and Streptococcus (C) are not known to produce aflatoxins. It is important to be aware of the sources and implications of aflatoxin contamination to ensure food safety and public health.
Question 6 of 9
Which statement related to the mumps vaccine is true:
Correct Answer: D
Rationale: The correct answer is D: it is a live attenuated vaccine. This is true because the mumps vaccine is indeed a live attenuated vaccine, meaning it contains a weakened form of the virus to stimulate an immune response without causing the disease. This type of vaccine provides long-lasting immunity. A, B, and C are incorrect: A: the vaccine is recommended, not obligatory - this is incorrect because the mumps vaccine is typically recommended for all individuals to prevent the spread of the disease. B: the vaccine is not given in combination with other vaccines - this is incorrect as the mumps vaccine is often given in combination with measles and rubella vaccines as the MMR vaccine. C: the vaccine is administered orally - this is incorrect because the mumps vaccine is usually administered via injection, not orally.
Question 7 of 9
An adult patient with type 2 diabetes attends the emergency room. He reported that two days ago he was accidentally injured in the left leg, but he did not seek medical care. At the time of examination, an infected wound was found, surrounded by a large area of inflammation with characteristic tissue crepitation on palpation and with foul odor. Blood (for hemoculture) and wound secretions were taken for microbiological testing. The microscopic examination reveals large Gram-positive bacteria, with centrally located spores. These bacteria were unable to grow in vitro at presence of oxygen. The most likely cause of this disease is:
Correct Answer: B
Rationale: The correct answer is B: Clostridium perfringens. In this case, the patient's presentation of infected wound with tissue crepitation, foul odor, and Gram-positive bacteria with centrally located spores that cannot grow in the presence of oxygen is indicative of gas gangrene caused by Clostridium perfringens. This anaerobic bacterium produces various toxins that lead to tissue destruction and gas production in the affected area. Clostridium tetani (choice A) causes tetanus, characterized by muscle stiffness and spasms. Clostridium botulinum (choice C) causes botulism, leading to muscle paralysis. Clostridium difficile (choice D) is associated with antibiotic-associated diarrhea. These choices are incorrect as they do not match the clinical presentation described in the question.
Question 8 of 9
A 22-year-old patient is a clerk. His working day runs in a conditioned room. In summer he was taken by an acute disease with the following symptoms: fever, dyspnea, dry cough, pleural pain, myalgia, arthralgia. Objectively: moist rales on the right, pleural friction rub. X-ray picture showed infiltration of the inferior lobe. In blood: WBC - 11 · 109/l, stab neutrophils - 6%, segmented neutrophils - 70%, lymphocytes - 8%, ESR - 42 mm/h. What is the etiological factor pneumonia?
Correct Answer: C
Rationale: The correct answer is C: Streptococcus. Streptococcus pneumoniae is the most common etiological factor for community-acquired pneumonia in young adults. The symptoms described align with typical pneumococcal pneumonia presentation. Presence of pleural friction rub and infiltration in the X-ray support the diagnosis. The blood work showing elevated WBC count with a left shift (increased neutrophils and low lymphocytes) and elevated ESR is consistent with a bacterial infection. Legionella and Mycoplasma typically present with atypical pneumonia symptoms such as headache, confusion, and GI symptoms, which are not described in the case. Staphylococcus pneumonia is not a common cause of community-acquired pneumonia in young adults.
Question 9 of 9
Which bacteria is responsible for causing the disease known as whooping cough?
Correct Answer: B
Rationale: The correct answer is B: Bordetella pertussis. This bacterium causes whooping cough by infecting the respiratory tract. It produces toxins that lead to severe coughing fits characteristic of the disease. Clostridium botulinum (A) causes botulism, Streptococcus pneumoniae (C) causes pneumonia, and Neisseria meningitidis (D) causes meningitis, not whooping cough. B. pertussis is the only bacterium specifically associated with whooping cough.