Microbiology Questions and Answers

Posted on Oct 12, 2024 in Biology

Part 1: Multiple Choice Questions

Amino Acids in Peptidoglycan

Which of the following amino acids are found in peptidoglycan?

  1. L-lysine
  2. Diaminopimelic acid
  3. D-glutamate
  4. L-alanine
  5. None of the above

Vibrio cholerae Characteristics

Vibrio cholerae is characterized by:

  1. Grows on TCBS agar
  2. Is motile in a dark-field staining
  3. Has comma, gull-wing, or circular shapes
  4. Causes watery diarrhea (rice-water stools)
  5. All of the above

Non-Disease-Causing Gram-Positive Cocci

There are catalase-negative, Gram-positive cocci, sometimes streptococcal, that do not cause disease in humans. These are:

  1. Microorganisms of the genus Gemella
  2. Leuconostoc spp.
  3. Microorganisms of the genus Pediococcus
  4. Microorganisms of the genus Aerococcus
  5. All of the above

Common Cause of Enterococcal Infections

There are at least two different species of Enterococcus, but currently, the most common cause of between 85-90% of enterococcal infections is:

  1. Streptococcus agalactiae
  2. Enterococcus faecium
  3. Enterococcus faecalis
  4. Enterococcus casseliflavus
  5. Enterococcus gallinarum

Streptococcus pneumoniae Characteristics

Streptococcus pneumoniae is characterized by:

  1. Alpha-hemolytic
  2. Inhibited by ethylhydrocupreine hydrochloride
  3. Sensitive to 0.04 units of bacitracin
  4. Part of the normal flora of the respiratory tract
  5. All of the above

Klebsiella pneumoniae Characteristics

Klebsiella pneumoniae is characterized by:

  1. Producing extended-spectrum beta-lactamases (ESBLs)
  2. Causing diarrhea and bacterial enterocolitis
  3. Producing urease and being non-motile
  4. Producing hemolysis on blood agar
  5. All of the above

Factors Lowering Resistance to Pneumococcal Infection

Among the factors that lower natural resistance to pneumococcal infection and predispose the host to pneumococci are:

  1. Respiratory viral infections
  2. Alcohol intoxication with drugs that decrease the cough reflex
  3. Pulmonary congestion and heart failure
  4. Malnutrition and general debility
  5. All of the above

Gram-Positive Cocci in Clusters

The organism that appears as Gram-positive cocci in clusters belongs to the genus:

  1. Neisseria
  2. Streptococcus
  3. Staphylococcus
  4. Enterococcus
  5. All of the above

Staphylococcus Enzymes and Toxins

Staphylococcus microorganisms produce enzymes and toxins such as:

  1. Catalase
  2. Coagulase
  3. Leukocidin
  4. Hyaluronidase (characteristic of enterococci)
  5. All of the above

Causative Agent of South American Blastomycosis

The causative agent of South American blastomycosis is:

  1. Coccidioides immitis
  2. Paracoccidioides brasiliensis
  3. Histoplasma capsulatum
  4. Candida albicans
  5. All of the above

Part 2: True or False

Indicate whether the following statements are true or false:

  1. Shigella produces fluorescent pigments.
  2. Shigella produces Shiga toxin.
  3. Salmonella enteritidis causes urinary tract infections.
  4. Salmonella enteritidis causes acute gastroenteritis.
  5. Proteus species are part of the normal intestinal flora.
  6. Proteus can cause nosocomial infections.
  7. Gardnerella vaginalis and Mobiluncus are the cause of bacterial vaginosis.
  8. Bacterial vaginosis attributed to these organisms may be treated with metronidazole.
  9. Chlamydia pneumoniae causes sinusitis and otitis media.
  10. Chlamydia trachomatis may be the most common cause of infant pneumonia.
  11. V factors for the growth of Haemophilus spp. are different from X factors because they are not free in the blood.
  12. Haemophilus ducreyi is transmitted through sexual contact and causes chancroid.
  13. Enterohemorrhagic E. coli (EHEC) produce cytotoxic effects on Vero cells.
  14. EHEC is associated with hemorrhagic enterocolitis and hemolytic uremic syndrome.
  15. Lactobacillus spp. are part of the normal flora of the female genitalia.
  16. Enterococcus spp. are part of the normal flora of the gastrointestinal tract.
  17. Stenotrophomonas maltophilia grows on blood agar and is oxidase-negative and lysine decarboxylase-positive.
  18. Stenotrophomonas maltophilia is an important cause of nosocomial infections.
  19. Chromobacterium violaceum is a Gram-negative bacillus similar to Pseudomonas.
  20. Chromobacterium violaceum is found in subtropical climates, soil, and water.

Part 3: Additional Questions

Gram-Negative Bacteria Structure

All of the following are true about the structure of Gram-negative bacteria EXCEPT:

  1. The plasma membrane is called the inner membrane.
  2. It has an outer membrane-like structure, including porins.
  3. It has a thin layer of peptidoglycan.
  4. It does not have enzymes in the periplasmic space.
  5. It is much more complex than Gram-positive bacteria.

Bacterial Chromosome Functions

The functions of the bacterial chromosome include all of the following EXCEPT:

  1. DNA replication
  2. Transcription
  3. Protein synthesis
  4. Chromosome segregation
  5. All of the above

Microorganism Causing Trismus

Which of the following microorganisms causes trismus, sardonic laughter, and seizures in humans?

  1. Klebsiella pneumoniae
  2. Streptococcus pneumoniae
  3. Staphylococcus aureus
  4. Neisseria meningitidis
  5. Clostridium tetani

Microorganism Causing Poliomyelitis

Which of the following causes poliomyelitis in humans?

  1. DNA virus
  2. RNA virus
  3. Influenza virus
  4. Avian influenza virus
  5. All of the above

Bacterial Flagella

Which of the following statements about bacterial flagella is NOT correct?

  1. Filaments are composed of several thousand protein subunits called flagellin.
  2. Flagella increase the length of bacteria and are always located at the poles.
  3. All motile bacteria have flagella.
  4. Flagella move the cell by acting as propellers.
  5. Locomotion by flagella directs bacteria toward nutrients such as sugar.

Gram-Negative Bacteria Without Cell Wall

When Gram-negative bacteria lose their cell wall, they are called:

  1. Prions
  2. Protozoa
  3. Protoplasts
  4. Spheroplasts
  5. Mycoplasma

Sterilizing Agent

A physical or chemical agent that eliminates all microorganisms is called:

  1. Disinfectant
  2. Sterilizing agent
  3. Sporicidal agent
  4. Antiseptic
  5. Bacteriostatic agent

Gene Transfer by Conjugation

Gene transfer in bacteria by conjugation is characterized by:

  1. Uptake of naked DNA
  2. Action of a bacteriophage
  3. Cell fusion
  4. Bridges between donor and recipient cells
  5. All of the above

Topoisomerase Function

What is the function of topoisomerases?

  1. Unwind the helical structure of DNA
  2. Alter the secondary structure of DNA
  3. Alter the supercoiled structure of DNA
  4. Alter the primary structure of DNA
  5. All of the above

Glycocalyx Characteristics

The glycocalyx is characterized by:

  1. A mucoid consistency
  2. Being removable, soluble, and unorganized
  3. Being composed of repeating units of polymers and proteins
  4. Being visualized by negative staining with India ink
  5. Giving a mucoid character to colonies

Biochemical Tests for Enterobacteriaceae

Name biochemical tests used to characterize Enterobacteriaceae.

Answer: Indole, Sulfur, Indole, Motility (SIM), Citrate, Urea, Lysine decarboxylase, Methyl Red

Clinical Significance of Acinetobacter baumannii

What is the clinical significance of Acinetobacter baumannii?

Answer: Causes nosocomial pneumonia, bacteremia, urinary tract infections, meningitis secondary to surgical procedures or traumatic brain injury. Infections related to intravascular catheters, endotracheal tubes, abdominal abscesses, and surgical wound infections.

Bacterial Growth Curve

Describe the phases of the bacterial growth curve.

Answer: Lag phase: Bacteria adapt to environmental conditions and prepare for growth by synthesizing new enzymes and proteins.

RNA Virus Classification

Name the components of the RNA virus classification.

Answer: Picornaviridae, Astroviridae, Caliciviridae, Reoviridae, Togaviridae, Flaviviridae, Arenaviridae, Coronaviridae, Retroviridae, Orthomyxoviridae, Bunyaviridae, Bornaviridae, Rhabdoviridae, Paramyxoviridae, Filoviridae. Other viruses: Viroids, Prions.

Koch’s Bacillus Characteristics

Describe the characteristics of Koch’s bacillus (Mycobacterium tuberculosis).

Answer: Slow growth, resistant to drying, invasive nature, rich in sulfolipids.

Enterobacteriaceae Genera

List some genera included in the Enterobacteriaceae family.

Answer: Citrobacter, Enterobacter, Escherichia, Klebsiella, Morganella, Proteus, Salmonella, Serratia, Shigella.