Gram-Positive Firmicutes Overview
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Questions and Answers

What is the primary reason tuberculosis takes a long time to cure?

  • It slows down the growth rate but defends against host defenses and antibiotics. (correct)
  • It forms spores that resist treatment.
  • It is easily detected by the immune system.
  • It replicates quickly within the host.
  • Which of the following characteristics describes gram-negative bacteria?

  • They lack an outer membrane.
  • They do not have receptor proteins.
  • They include an outer membrane, cell wall of peptidoglycan, and inner membrane. (correct)
  • They have a thick peptidoglycan layer.
  • What is a common feature of the Enterobacteriaceae family?

  • They all produce endospores.
  • All are obligate anaerobes.
  • Most appear as rod-shaped organisms. (correct)
  • They are primarily found in soil.
  • Which bacterium is identified as a common cause of urinary tract infections (UTIs)?

    <p>Escherichia coli</p> Signup and view all the answers

    What distinguishes Pseudomonas species from other bacteria?

    <p>They are obligate respiring organisms requiring oxygen.</p> Signup and view all the answers

    The primary method for differentiating closely related Enterobacteriaceae species is through what process?

    <p>Fermentation pathways indicated by pH changes.</p> Signup and view all the answers

    What is the toxic component found in the outer membrane of gram-negative bacteria known for having endotoxic effects?

    <p>Lipopolysaccharides (LPS).</p> Signup and view all the answers

    Which characteristic of bacteria helps them develop resistance to antibiotics?

    <p>Formation of biofilms.</p> Signup and view all the answers

    What is the primary function of the elementary bodies in Chlamydiae?

    <p>To adhere to the host cell surface</p> Signup and view all the answers

    Which statement correctly describes the reticulate body of Chlamydiae?

    <p>It is metabolically active but cannot cause infection.</p> Signup and view all the answers

    What serious condition can persistent infection with C. Trachomatis lead to?

    <p>Pelvic inflammatory disease (PID)</p> Signup and view all the answers

    Chlamydia lacks a classic cage-like structure in its cell wall but has a narrow ring of what?

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

    What role does the outer membrane of Chlamydiae play?

    <p>It protects against osmotic shock.</p> Signup and view all the answers

    Which organism is responsible for causing pneumonia and is linked to cardiovascular disease?

    <p>Chlamydophila pneumoniae</p> Signup and view all the answers

    What happens to the elementary bodies when the host cell lyses?

    <p>They can infect new cells.</p> Signup and view all the answers

    What is a potential consequence of untreated pelvic inflammatory disease (PID)?

    <p>Infertility due to permanent adhesions</p> Signup and view all the answers

    What is the primary transmission method of Yersinia pestis to humans?

    <p>From respiratory droplets when an infected person coughs</p> Signup and view all the answers

    Which component of Yersinia pestis aids in its colonization of the flea midgut?

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

    What is a unique characteristic of the capsule formed by Yersinia pestis?

    <p>It is composed of peptide</p> Signup and view all the answers

    What type of bacteria is Pseudomonas aeruginosa primarily classified as?

    <p>Obligate aerobic bacilli</p> Signup and view all the answers

    Which bacteria is incorrectly identified as the cause of influenza?

    <p>Haemophilus influenzae</p> Signup and view all the answers

    What role does the protease secreted by Yersinia pestis play in its virulence?

    <p>Dissolves blood clots</p> Signup and view all the answers

    What can Pseudomonas aeruginosa commonly form in the lungs of cystic fibrosis patients?

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

    What is the main symptom caused by Yersinia pseudotuberculosis?

    <p>Gastrointestinal disease</p> Signup and view all the answers

    Which bacterium is known to cause botulism and is also used in the production of Botox?

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

    What characteristic do Clostridium spores exhibit when the environment becomes anaerobic?

    <p>They thrive and grow.</p> Signup and view all the answers

    What is the primary complication when a patient is treated with antibiotics concerning Clostridiodes difficile?

    <p>Depletion of normal gut microbiota.</p> Signup and view all the answers

    Which of the following describes Clostridium tetanus?

    <p>Causes continuous muscle contractions.</p> Signup and view all the answers

    Which property distinguishes non-spore formers from spore formers in bacteria?

    <p>Reduced ability to resist antibiotics.</p> Signup and view all the answers

    What role do Lactobacillus spp. and Lactococcus spp. play in food production?

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

    What is the main clinical significance of Enterococcus spp. in a hospital setting?

    <p>Causes urinary tract infections.</p> Signup and view all the answers

    What characteristic is observed when colonies of Moraxella catarrhalis are moved on an agar plate?

    <p>They move together like a hockey puck.</p> Signup and view all the answers

    What is a common treatment for infections caused by Enterococcus spp.?

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

    How do the flagella of spirochetes contribute to their movement in viscous environments?

    <p>They rotate and corkscrew the entire cell through the medium.</p> Signup and view all the answers

    What is the nature of the cell wall of spirochetes?

    <p>Thin peptidoglycan, completely separating the sheath from the plasma membrane.</p> Signup and view all the answers

    Which species of Treponema is responsible for the sexually transmitted infection syphilis?

    <p>Treponema pallidum</p> Signup and view all the answers

    What distinguishes the different subspecies of Treponema pallidum in terms of disease?

    <p>Different subspecies produce distinct diseases.</p> Signup and view all the answers

    In what stages can syphilis present itself?

    <p>Primary, secondary, and tertiary.</p> Signup and view all the answers

    Which of the following statements is true about Treponema pallidum pertenue?

    <p>It causes yaws and cannot cross the placenta.</p> Signup and view all the answers

    Which type of organisms are nonpathogenic spirochetes typically associated with?

    <p>Digestion symbionts in specific hosts like termites and cattle.</p> Signup and view all the answers

    Study Notes

    Gram-Positive Firmicutes

    • Clostridium spores are found in soil and water, ready to germinate and grow in anaerobic environments.
    • Bacillus anthracis is a rod-shaped soil bacterium that causes anthrax.
    • Clostridiodes difficile is a rod-shaped bacterium with bulging spores that causes intestinal disease in patients whose normal microbiota are diminished by antibiotics, leading to pseudomembranous colitis.
    • Clostridium botulinum is a rod-shaped bacterium with bulging spores that causes botulism and produces Botox.
    • Clostridium tetanus is a rod-shaped bacterium with bulging spores that causes tetanus, resulting in continuous muscular contraction.
    • Enterococcus spp. are cocci found in the intestinal tract and are a common cause of urinary tract infections (UTIs) and bacteremia in immunocompromised patients.
    • Lactobacillus spp. and Lactococcus spp. are rods and cocci, respectively, involved in dairy culture.
    • Lactobacillus and Lactococcus spp. are obligate fermenters, meaning they can grow in the presence or absence of oxygen, but they don't use oxygen to respire.

    Phylum Proteobacteria: A Diverse Superphylum

    • Proteobacteria are gram-negative and include heterotrophs, lithotrophs, and photosynthesizers.
    • The gram-negative envelope consists of an outer membrane, a peptidoglycan cell wall permeated by the periplasm, and an inner membrane.
    • The outer membrane contains receptor proteins, porins, and lipopolysaccharide (LPS), which can have toxic effects on the host and pose an endotoxic shock risk.
    • Enterobacteriaceae is a family of proteobacteria, mostly appearing as rods.
    • Pseudomonadaceae contain pseudomonas, which are rod-shaped obligate respirers, requiring oxygen as a terminal electron acceptor for energy production.

    Escherichia coli

    • A rod-shaped bacterium that is a main vehicle for biotechnology and can cause intestinal and bladder infections.
    • It is part of the Enterobacteriaceae family and plays a crucial role in the human intestine, producing vitamins.
    • E. coli is a major cause of death in children under 5.
    • It is also the causative agent of the bubonic plague.

    Yersinia spp.

    • Gram-negative bacilli that can be transmitted from animals to humans through infected fleas or respiratory droplets.
    • Y. Pestis is a variant of Y. Pseudotuberculosis, arising from horizontal gene transfer, and causes the bubonic plague.
    • Y. Pseudotuberculosis causes gastrointestinal disease resembling appendicitis.

    Pseudomonas aeruginosa

    • Obligate aerobic bacilli related to Enterobacteriaceae.
    • Commonly found in soil as a decomposer, but in humans, it can infect surgical wounds or form biofilms in the lungs of cystic fibrosis patients.
    • Known to cause hospital-acquired infections and can be resistant to many antibiotics.
    • Produces a characteristic greenish color on agar plates.

    Haemophilus influenzae

    • An intracellular symbiont and predator.
    • Frequently mistaken for the cause of influenza, which is actually caused by a virus.
    • Causes pneumonia.

    Moraxella catarrhalis

    • Exhibits a "hockey puck" behavior on agar plates, where the colony moves as a single unit when disturbed.

    Phylum Spirochaetes: Twisted-Cell Pathogens and Symbionts

    • Spirochetes are a distinctive group of bacteria with a long, tight, and flexible spiral shape, resembling a coiled telephone cord.
    • They have a thin peptidoglycan cell wall completely separating the sheath from the plasma membrane.
    • Most spirochetes are slow-growing heterotrophs and are difficult to culture.
    • Many are free-living in soil and water, and some are digestive symbionts in hosts like termites and cattle.
    • The cell is surrounded by a thick outer sheath of lipopolysaccharides and proteins.
    • One or more flagella extend from each end of the cell and double back within the periplasmic space, propelling the cell in a corkscrewing motion.

    Treponema pallidum

    • Causes syphilis, a sexually transmitted infection.
    • Syphilis is caused by T. pallidum pallidum and progresses in three stages: primary, secondary, and tertiary.
    • Can cross the placenta and infect a developing fetus.

    Treponema pertenue

    • Causes yaws, a multistage disease transmitted through direct skin contact, prevalent in developing countries.
    • Unlike syphilis, it cannot cross the placenta and infect a fetus.

    Phylum Chlamydiae: Intracellular Pathogens

    • Chlamydiae are a group of bacteria with cell walls containing very little peptidoglycan.
    • Pathogenic species lack the classic cage-like form of peptidoglycan but have a narrow ring at mid-cell for cell division.
    • They are obligate parasites or pathogens and spend their entire life cycle within a host cell.
    • They possess an outer membrane cross-linked by disulfide bonds, providing osmotic stability despite lacking a proper cell wall.
    • Chlamydia trachomatis is a major cause of sexually transmitted infections in the U.S. and can lead to pelvic inflammatory disease (PID).
    • Chlamydia trachomatis also causes trachoma, an eye disease.
    • Chlamydophila pneumoniae causes pneumonia and has been implicated in cardiovascular disease.
    • Chlamydiae alternate between two developmental stages: elementary bodies and reticulate bodies.
    • Elementary bodies are metabolically inert and responsible for transmission.
    • Reticulate bodies are metabolically active and multiply rapidly inside the host cell, but lack infectivity and are vulnerable to osmotic shock.
    • PID can lead to permanent adhesions and infertility.

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    Description

    Explore the fascinating world of Gram-positive Firmicutes, including key species like Bacillus anthracis and Clostridium spp. This quiz covers their characteristics, pathogenic potential, and ecological roles. Test your knowledge on these essential bacteria and their impacts on health and environment.

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