microbiology chapter 12 test bank

microbiology chapter 12 test bank Related

Review microbiology chapter 12 test bank related questions and content

A 65-year-old patient with fever and a productive cough had a sputum sample revealing Gram-negative, non-motile, rod-shaped bacteria. What is the most likely causative agent?

  • A. Klebsiella pneumoniae
  • B. Pseudomonas aeruginosa
  • C. Escherichia coli
  • D. Haemophilus influenzae
Correct Answer: A

Rationale: The correct answer is A: Klebsiella pneumoniae. This bacterium is commonly associated with pneumonia in elderly patients. Klebsiella pneumoniae is a Gram-negative, non-motile, rod-shaped bacterium that frequently causes pneumonia in individuals with underlying health conditions. It is known for its ability to produce a distinctive mucoid capsule. Pseudomonas aeruginosa (B) is more commonly associated with hospital-acquired infections, particularly in immunocompromised individuals. Escherichia coli (C) is a common cause of urinary tract infections but is less likely in this case due to the symptoms and sputum sample results. Haemophilus influenzae (D) is another common respiratory pathogen, but in this scenario, Klebsiella pneumoniae is the most likely causative agent based on the patient's age, symptoms, and the characteristics of the bacteria described in the sputum sample.

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The presence of flagella in bacterial cell represents:

  • A. H-antigen
  • B. O-antigen
  • C. K-antigen
  • D. None of the above
Correct Answer: A

Rationale: The presence of flagella in a bacterial cell represents the H-antigen. Flagella are protein structures on the cell surface that play a role in bacterial motility. The H-antigen refers to the flagellar antigen, which is involved in immune responses and bacterial identification. Option A is correct because flagella are specifically associated with the H-antigen.

Summarily, choices B and C are incorrect because the O-antigen and K-antigen are associated with lipopolysaccharide and capsule antigens, respectively, not flagella. Option D is incorrect as well because the correct association is with the H-antigen.

The basic requirements of PCR reaction include:

  • A. DNA segment to be amplified
  • B. Two oligonucleotide primers
  • C. Heat stable DNA
  • D. All of these
Correct Answer: D

Rationale: The correct answer is D because all the options are essential for a PCR reaction.
A: DNA segment is required as the template for amplification.
B: Two oligonucleotide primers are needed to initiate DNA replication.
C: Heat stable DNA polymerase (not just heat stable DNA) is crucial for withstanding the high temperatures during PCR.
In summary, without any of these components, the PCR reaction cannot proceed effectively.

Immunosuppressive drugs are not used for:

  • A. Organ transplantation
  • B. Measles
  • C. Autoimmune diseases
  • D. Hemolytic disease of the newborn
Correct Answer: B

Rationale: The correct answer is B: Measles. Immunosuppressive drugs are not used for treating viral infections like measles as they target the immune system and can worsen the infection. Organ transplantation requires immunosuppressive drugs to prevent organ rejection. Autoimmune diseases involve an overactive immune response, so immunosuppressive drugs are used to reduce this response. Hemolytic disease of the newborn can be treated with immunosuppressive drugs to prevent the destruction of red blood cells.

Microscopic examination of a Gramstained scrape from patient's tongue revealed oval, round, elongated chains of dark-violet gemmating cells. What disease can be caused by this causative agent?

  • A. Candidosis
  • B. Actinomycosis
  • C. Diphtheria
  • D. Staphylococcic infection
Correct Answer: A

Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species.
Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue.
Step 3: Candidosis presents as white patches or plaques on the tongue.
Step 4: Therefore, the correct answer is A: Candidosis.

Summary:
B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells.
C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells.
D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.

The antibiotics penicillin and cephalosporin are produced by:

  • A. algae
  • B. slime molds
  • C. fungi
  • D. protozoans
Correct Answer: C

Rationale: The correct answer is C: fungi. Both penicillin and cephalosporin are produced by certain species of fungi. Penicillin is derived from the Penicillium fungi, while cephalosporin is produced by Cephalosporium fungi. Fungi have the ability to synthesize these antibiotics as part of their defense mechanisms against other microorganisms. Algae (A), slime molds (B), and protozoans (D) do not have the capability to produce antibiotics like penicillin and cephalosporin. Algae are mainly photosynthetic organisms, slime molds are protists that lack the ability to synthesize complex antibiotics, and protozoans are single-celled eukaryotic organisms that do not produce antibiotics like fungi do.

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