OpenStax Microbiology Test Bank

OpenStax Microbiology Test Bank Related

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A patient has been brought to the hospital with the complaints of headache, pain in left hypochondrium. He has been ill for 1,5 weeks. The sudden illness began with the increase of body temperature up to 39, 90C. In 3 hours the temperature decreased and hydropoiesis began. The attacks repeat rhythmically in 48 hours. The patient had visited one an African country. The doctors have suspected malaria. What method of laboratory diagnostics is necessary to use?

  • A. Blood examination
  • B. Immunological tests
  • C. Stool examination
  • D. Urine examination
Correct Answer: A

Rationale: The correct method of laboratory diagnostics for suspected malaria is blood examination. Malaria is diagnosed by detecting the presence of the Plasmodium parasite in the patient's blood. This can be done through microscopy to identify the parasite in a blood smear or through rapid diagnostic tests (RDTs) that detect specific antigens produced by the parasite. Blood examination allows for the direct visualization of the parasite, making it the most accurate method for diagnosing malaria. Immunological tests, stool examination, and urine examination are not suitable for diagnosing malaria as the parasite primarily resides in the red blood cells. Stool and urine examinations are more commonly used for diagnosing gastrointestinal or urinary tract infections, respectively.

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Which of the following bacteria are capable of forming spores?

  • A. Staphylococcus aureus
  • B. Clostridium botulinum
  • C. Escherichia coli
  • D. Neisseria gonorrhoeae
Correct Answer: B

Rationale: The correct answer is B, Clostridium botulinum. This bacterium is capable of forming spores, which are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores. Staphylococcus aureus is a gram-positive bacterium that does not produce spores. Escherichia coli is a gram-negative bacterium that also does not form spores. Neisseria gonorrhoeae is a gram-negative bacterium and does not have the ability to form spores. Therefore, the only bacteria among the options that can form spores is Clostridium botulinum.

A patient with diarrhea had stool microscopy revealing flagellated protozoa with two nuclei. What is the most likely causative agent?

  • A. Giardia lamblia
  • B. Entamoeba histolytica
  • C. Trichomonas vaginalis
  • D. Balantidium coli
Correct Answer: A

Rationale: The correct answer is A: Giardia lamblia. Giardia lamblia is a flagellated protozoan with two nuclei, known as the "falling leaf" appearance. It causes diarrhea in humans through ingestion of contaminated water or food. Entamoeba histolytica causes amoebic dysentery, characterized by bloody diarrhea and colitis. Trichomonas vaginalis is a sexually transmitted protozoan causing vaginal discharge but is not found in stool. Balantidium coli is a ciliated protozoan causing diarrhea but does not have flagellated forms.

Which of the following is a type of acute infection generally caused by group A Streptococcus?

  • A. Carbuncle
  • B. Impetigo
  • C. Erysipelas
  • D. Acne
Correct Answer: C

Rationale: The correct answer is C: Erysipelas. Erysipelas is a type of acute infection caused by group A Streptococcus bacteria. This bacteria infects the upper dermis and superficial lymphatics, leading to a distinct raised, well-demarcated, erythematous skin lesion. The other choices are incorrect because: A Carbuncle is a deep skin infection involving hair follicles, B Impetigo is a superficial skin infection caused by Staphylococcus or Streptococcus bacteria, and D Acne is a chronic inflammatory skin condition not typically caused by group A Streptococcus.

The sepsis is:

  • A. Presence of bacteria in the blood
  • B. Bacteremia, accompanied with chemical and laboratory data for systemic information
  • C. Massive proliferation of toxins in the blood with organ failure
  • D. All of the above
Correct Answer: D

Rationale: The correct answer is D. Sepsis is a systemic response to infection resulting in organ dysfunction.
A: Sepsis can be caused by bacterial infection, but it is not solely defined by the presence of bacteria in the blood.
B: Bacteremia is the presence of bacteria in the blood, which can be a component of sepsis, but sepsis involves a broader systemic response beyond just bacteremia.
C: Sepsis can lead to the release of toxins and organ failure, but sepsis itself is not defined solely by the massive proliferation of toxins.

Therefore, the correct answer is D, as sepsis can involve the presence of bacteria, bacteremia, systemic manifestations, and organ failure.

A 70-year-old man has developed prosphetic stomatitis. Apart of this he was found to have an evident lesion of mouth corners. Microscopical examination revealed large ovoid gram-positive cells. What microorganisms are most likely to be the leading etiological agent of such a lesion?

  • A. Candida fungi
  • B. Streptococci
  • C. Staphylococci
  • D. Neisseria
Correct Answer: A

Rationale: The correct answer is A: Candida fungi. In the context of a 70-year-old man with angular cheilitis (lesion at the corners of the mouth) and stomatitis, the presence of large ovoid gram-positive cells points towards Candida species, which are yeast fungi. Candida is a common opportunistic pathogen that can cause oral thrush and angular cheilitis in immunocompromised individuals, such as elderly people. Candida fungi are known to appear as large ovoid cells under microscopic examination.

Summary of other choices:
B: Streptococci are gram-positive bacteria and are not typically associated with large ovoid cells seen in this case.
C: Staphylococci are also gram-positive bacteria and are not known to present as large ovoid cells in this context.
D: Neisseria are gram-negative bacteria and are not the usual etiological agents for oral lesions like angular cheilitis.

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