Gram-Positive Firmicutes Quiz
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Questions and Answers

What is the primary way Yersinia pestis can be transmitted to humans?

  • By contaminated food or water
  • From bodily fluids of infected humans
  • Through infected fleas or respiratory droplets (correct)
  • Through direct contact with infected animals

    • What role does the phospholipase play in the virulence of Yersinia pestis?

  • It digests phospholipids and aids colonization in fleas (correct)
  • It activates the immune response of the host
  • It enhances the formation of bacterial capsules
  • It helps in the production of biofilms in the lungs

    • Which characteristic distinguishes the capsule of Yersinia pestis from most bacterial capsules?

  • It is made of peptides rather than polysaccharides (correct)
  • It is formed from lipids
  • It is composed of polysaccharides
  • It is absent in Yersinia pestis

    • What aspect of Pseudomonas aeruginosa makes it particularly difficult to treat in clinical settings?

    <p>It exhibits resistance to multiple antibiotics</p> Signup and view all the answers

    What misconception about Haemophilus influenzae is commonly held?

    <p>It is a major cause of influenza</p> Signup and view all the answers

    Which bacterium is specifically known to cause anthrax?

    <p>Bacillus anthracis</p> Signup and view all the answers

    What type of environment do Clostridium spores require to germinate and grow?

    <p>Anaerobic conditions</p> Signup and view all the answers

    Which of the following is a resistant bacterium associated with antibiotic treatment in intestinal microbiota?

    <p>Clostridiodes difficile</p> Signup and view all the answers

    What disease is caused by Clostridium tetanus?

    <p>Tetanus</p> Signup and view all the answers

    Which statement is true regarding Enterococcus spp.?

    <p>They are easier to kill than spore formers.</p> Signup and view all the answers

    What is the primary function of Lactobacillus spp. in dairy products?

    <p>To ferment milk</p> Signup and view all the answers

    Which bacterium is known for producing Botox?

    <p>Clostridium botulinum</p> Signup and view all the answers

    What is a primary characteristic of non-spore formers like Enterococcus spp.?

    <p>They lack the ability to form spores due to reductive evolution.</p> Signup and view all the answers

    What is the primary cause of listeriosis?

    <p>Contaminated dairy products</p> Signup and view all the answers

    What characteristic is unique to Listeria monocytogenes compared to other bacteria?

    <p>Can grow at refrigeration temperatures</p> Signup and view all the answers

    How do Staphylococcus aureus bacteria contribute to hospital-acquired infections?

    <p>They produce toxins that can lead to toxic shock syndrome.</p> Signup and view all the answers

    Which of the following is NOT a method for differentiating between Staphylococcus and Streptococcus?

    <p>Sensitivity to antibiotics</p> Signup and view all the answers

    What substance is produced by Staphylococcus epidermidis that inhibits the growth of skin pathogens?

    <p>Short fatty acids</p> Signup and view all the answers

    How do Streptococcus bacteria mainly metabolize nutrients?

    <p>By fermentation</p> Signup and view all the answers

    Which type of hemolysis is characterized by a clear halo around colonies?

    <p>Beta hemolysis</p> Signup and view all the answers

    What is the primary structural form of Staphylococcus bacteria?

    <p>Cocci</p> Signup and view all the answers

    Which of the following characteristics is true about Listeria spp.?

    <p>They can survive refrigeration temperatures.</p> Signup and view all the answers

    Which of the following bacterial properties is relevant to the pathogenicity of Streptococcus species?

    <p>Production of hemolysins</p> Signup and view all the answers

    What unique characteristic allows Mycoplasmas to reproduce faster than other bacteria?

    <p>They lack a cell wall</p> Signup and view all the answers

    Which of the following properties is associated with the ability to identify Actinobacteria through staining?

    <p>Acid fast staining</p> Signup and view all the answers

    What is the primary reason Mycobacterium tuberculosis is difficult to stain?

    <p>It has a thick cell wall with mycolic acids</p> Signup and view all the answers

    Which organism is known to cause leprosy?

    <p>Mycobacterium leprae</p> Signup and view all the answers

    What type of bacteria does Nocardia belong to?

    <p>Actinomycetes</p> Signup and view all the answers

    Why do Mycoplasma pneumoniae and other mycoplasmas lead to atypical pneumonia?

    <p>They lack a cell wall</p> Signup and view all the answers

    What type of cellular structures do Actinobacteria typically form?

    <p>Branching filaments</p> Signup and view all the answers

    What characterizes the cell wall of Corynebacterium diphtheriae?

    <p>It lacks mycolic acids</p> Signup and view all the answers

    Which of the following best describes Mycobacterium tuberculosis' mode of nutrient entry?

    <p>Impeded by its waxy coat</p> Signup and view all the answers

    What type of infections is Cutibacterium acnes primarily associated with?

    <p>Skin infections</p> Signup and view all the answers

    Which organism is known for benefiting from its relationship with humans without causing harm?

    <p>E. coli</p> Signup and view all the answers

    What is the primary pathogenesis associated with Helicobacter pylori?

    <p>Causes gastritis and stomach cancer</p> Signup and view all the answers

    What is a characteristic feature of Legionella pneumophila?

    <p>It requires amino acids for growth.</p> Signup and view all the answers

    Which pathogen is primarily transmitted through inhalation of aerosolized ameba?

    <p>Legionella pneumophila</p> Signup and view all the answers

    What bacterial shape and arrangement does Neisseria gonorrhoeae exhibit?

    <p>Diplococcus arrangement</p> Signup and view all the answers

    Which organism is responsible for causing cholera?

    <p>Vibrio cholera</p> Signup and view all the answers

    What vector is primarily involved in the transmission of Rickettsia rickettsii?

    <p>Ticks</p> Signup and view all the answers

    Which of the following pathogens is closely related to the Enterobacteriaceae family and can cause enteric diseases?

    <p>Salmonella enterica</p> Signup and view all the answers

    What is the key characteristic of Neisseria meningitidis?

    <p>Infects the brain and spinal cord lining</p> Signup and view all the answers

    Which organism is primarily associated with chronic gastritis?

    <p>Helicobacter pylori</p> Signup and view all the answers

    Study Notes

    Gram-Positive Firmicutes

    • Clostridium spores are found in soil and water. They germinate and grow when the environment becomes anaerobic.
    • Bacillus anthracis is a rod-shaped soil bacterium that causes anthrax.
    • Clostridiodes difficile is a rod-shaped bacterium with bulging spores. It causes intestinal disease in patients whose normal microbiota are diminished by antibiotics.
      • C. Difficile is resistant to most antibiotics.
    • Clostridium botulinum is a rod-shaped bacterium with bulging spores. It produces Botox and causes botulism.
      • C. Botulinum can grow in the colon of infants and cause infant botulism.
    • Clostridium tetanus is a rod-shaped bacterium with bulging spores that causes tetanus.
    • Enterococcus spp. are cocci found in the intestinal tract. They are part of the normal microbiota but can cause urinary tract infections and bacteremia in immunocompromised patients.
      • Enterococcus spp. are commonly treated with Vancomycin.
    • Lactobacillus spp. are rods that are used in dairy cultures.
      • Lactobacillus spp. are obligate fermenters. They ferment milk to make yogurt and cheese.
    • Lactococcus spp. are cocci that are used in dairy cultures.
      • Lactococcus spp. are obligate fermenters. They ferment milk to make yogurt and cheese.
    • Listeria spp. are rods. They are intracellular pathogens that can grow at refrigerator temperature.
      • Listeria spp. are facultative anaerobic rods.
      • Listeria Monocytogenes is an enteric pathogen that causes listeriosis. It can spread to the central nervous system.
        • Listeria Monocytogenes can grow in soil, but they also invade mammalian cells.
    • Staphylococcus aureus is a coccus that infects skin and can cause toxic shock syndrome and MRSA.
      • Staphylococcus aureus is a serious skin pathogen. It can cause pneumonia, impetigo, toxic shock syndrome, and osteomyelitis.
      • MRSA is the most dangerous strain of Staphylococcus aureus. It is methicillin-resistant.
      • Staphylococcus aureus is salt-tolerant.
    • Staphylococcus epidermidis is a coccus that is part of the normal skin microbiota.
      • Staphylococcus epidermidis is salt tolerant. It generates short fatty acids during fermentation that inhibit the growth of skin pathogens.
    • Streptococcus is a chain of cocci. They are aerotolerant but metabolize using fermentation.
      • Streptococcus commonly lives on oral and dental surfaces.
      • Streptococcus causes pneumonia, strep throat, erisipelas, and scarlet fever.
      • Streptococcus can be grouped using antibody reactions to cell-surface glycoproteins (Lancefield grouping).
      • Streptococcus and Staphylococcus can be differentiated by their ability to hemolyze red blood cells.
        • Alpha Streptococcus partially hemolyze RBCs via hydrogen peroxide reaction. This generates a greenish halo.
        • Beta Streptococcus fully hemolyze RBCs via hemolysis enzymes. This generates a clear halo.
      • Streptococcus and Staphylococcus can be analyzed using hockey pucks.

    Mollicutes (Lack of Cell Wall)

    • Mollicutes were formerly part of the phylum Firmicutes. They have only a cell membrane and are Gram-negative.
    • Mollicutes only grow in the tissue of host organisms.
    • Mollicutes have a faster reproduction rate because they do not need to produce a cell wall.
    • Mycoplasmas infect all classes of multicellular organisms.
    • Mycoplasmas cause pneumonia and meningitis in humans.

    Selected Gram-Positive Actinobacteria

    • Actinobacteria contain high GC gram-positives. This includes major pathogens and antibiotic producers, as well as decomposers in the natural environment.
    • Actinobacteria are identified using an acid-fast stain.
    • The acid-fast property is associated with unusual cell wall lipids, such as the mycolic acids of Mycobacterium Tuberculosis.

    Actinomycetes Group

    • Actinomycetes form mycelia which are branching filaments.
      • Actinomycetes behave like fungi!
    • Nocardia are hairlike. It is believed that they are inhaled from the environment.
    • Actinomyces Israelii forms branched mycelia filaments. It causes actinomycosis.

    Actinobacteria that are not Actinomycetes:

    • These organisms are not hairlike. They contain mycolic acids and their cells stain acid-fast.
      • Corynebacterium diphtheriae is an irregular rod that causes diphtheria.
      • Cutibacterium acnes is a rod-shaped bacterium that causes acne.
      • Mycobacterium leprae is a short rod that causes leprosy. It is acid-fast.
      • Mycobacterium tuberculosis is a short rod that causes tuberculosis. It is acid-fast.
        • Mycobacterium tuberculosis has a thick cell wall with mycolic acids. It stains gram-negative because of the mycolic acids.
        • Mycobacterium tuberculosis is detected via acid-fast stain in the tiny rods associated with sloughed cells in sputum.
        • Mycobacterium tuberculosis has an exceptionally thick, complex membrane that includes some of the longest chain acids known (up to 90 carbons).
        • Mycolic acid is linked to arabinogalactan. This complex forms a waxy coat that inhibits nutrients from entering through porins.

    Gram-Negative Bacteria (Proteobacteria & Others)

    • Escherichia coli is a commensal bacterium. It is part of the normal intestinal microbiota.
      • E.Coli O157:H7 is a pathogen.
    • Helicobacter pylori is a wide spiral cell that survives in the stomach acid. It causes gastritis.
    • Legionella pneumophila is a rod that grows within amoebas or macrophages. It causes Legionellosis.
      • Legionella pneumophila is related to Pseudomonas.
      • Legionella pneumophila is incapable of growth on sugars. It requires oxygen to grow on amino acids.
      • Legionella pneumophila is transmitted to humans through the inhalation of aerosolized amoebas.
      • Legionellosis cause a serious lung disease.
    • Neisseria gonorrhoeae is a diplococcus (pair of cocci). It causes gonorrhea.
      • Neisseria is a family of bacteria that occur as paired cocci.
    • Neisseria meningitidis is a diplococcus. It causes meningitis.
      • It causes an infection of the brain and spinal cord lining.
    • Rickettsia rickettsi is a rod-shaped, intracellular pathogen. It causes Rocky Mountain Spotted Fever.
      • Rickettsia rickettsi is part of the family Rickettsiaceae.
      • Rickettsia rickettsi is carried by tick vectors.
    • Salmonella enterica is a rod. It is an enteric pathogen that may grow intracellularly.
      • Salmonella enterica is part of the genus Enterobacteriaceae.
      • Salmonella enterica causes diseases like enteritis and typhoid fever.
    • Vibrio cholerae is a comma-shaped rod that causes cholera.
      • Vibrio cholerae has a single flagellum.
      • Vibrio cholerae causes diarrheal disease. It is a major problem in countries with poor sanitation.
    • Yersinia pestis is a rod that causes bubonic plague.
      • Yersinia pestis is part of the genus Enterobacteriaceae.
      • Yersinia pestis causes the bubonic plague.
        • Bubonic plague inflames the lymph node and creates buboes.
      • Y. Pestis can be transmitted from animals to humans through infected fleas or through respiratory droplets from coughing.
      • Y. Pestis is a variant of Yersinia pseudotuberculosis. It only diverged thousands of years ago.
        • Yersinia pseudotuberculosis causes gastrointestinal disease. It is transmitted from animals to humans by contaminated food and water.
    • Plasmids are short circular pieces of DNA that can be acquired from the environment by transformation or from donor bacterial cells by conjugation.
      • Yersinia Pestis has two plasmids that are important virulence factors:
        • Phospholipase digests phospholipids.
          • Phospholipase inactivates a toxic component of ingested blood, helping the microbe colonize the flea midgut.
          • Phospholipase allows Yersinia Pestis to replicate in large numbers.
        • Protease (plasminogen activator) dissolves clots in the human bloodstream.
        • Yersinia Pestis has a unique capsule made of peptides.
          • This capsule is different from most bacterial capsules, which are made of polysaccharides.
          • Yersinia Pestis's capsule protects it from the host's immune system.
    • Pseudomonaceae is a family of obligate aerobic bacilli. They are related to Enterobacteriaceae.
      • P. aeruginosa is commonly found in soil as a decomposer.
      • P. aeruginosa can cause infections in humans such as surgical wounds or biofilms in the lungs of cystic fibrosis patients.
      • P. aeruginosa are a major cause of intra-hospital infections. They are hard to treat, and there are resistant species.
      • P. aeruginosa produces greenish colonies characteristically in agar plates.
    • Haemophilus influenzae is an intracellular symbiont and a predator.
      • Haemophilus influenzae is the most common cause of influenza.
        • This is a bacteria! It is not a virus.
      • Haemophilus influenzae causes pneumonia.

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    Description

    Test your knowledge on gram-positive Firmicutes, including bacteria such as Clostridium and Enterococcus. This quiz covers their characteristics, pathogenic roles, and the diseases they cause. Perfect for microbiology enthusiasts and students alike!

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