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Questions and Answers
What factor is crucial for the germination of Clostridium spores?
What factor is crucial for the germination of Clostridium spores?
Which bacterium is responsible for causing botulism?
Which bacterium is responsible for causing botulism?
What type of infection does Clostridium difficile primarily cause?
What type of infection does Clostridium difficile primarily cause?
Which of the following bacteria is classified as a non-spore former?
Which of the following bacteria is classified as a non-spore former?
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What is a characteristic of Lactobacillus spp. and Lactococcus spp.?
What is a characteristic of Lactobacillus spp. and Lactococcus spp.?
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What kind of immune status do Enterococcus spp. most commonly affect?
What kind of immune status do Enterococcus spp. most commonly affect?
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What is a typical treatment for infections caused by Enterococcus spp.?
What is a typical treatment for infections caused by Enterococcus spp.?
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Which bacterium can cause continuous muscular contraction and is associated with tetanus?
Which bacterium can cause continuous muscular contraction and is associated with tetanus?
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What role does the complex mentioned in the context play in the growth of tuberculosis?
What role does the complex mentioned in the context play in the growth of tuberculosis?
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Which of the following statements about Proteobacteria is true?
Which of the following statements about Proteobacteria is true?
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What is the primary distinguishing feature of the outer membrane of gram-negative bacteria?
What is the primary distinguishing feature of the outer membrane of gram-negative bacteria?
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Which of the following best describes the Enterobacteriaceae family?
Which of the following best describes the Enterobacteriaceae family?
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What significant characteristic do many Enterobacteriaceae possess that increases their resistance to antibiotics?
What significant characteristic do many Enterobacteriaceae possess that increases their resistance to antibiotics?
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What does the term 'facultative anaerobic' refer to in the context of Enterobacteriaceae?
What does the term 'facultative anaerobic' refer to in the context of Enterobacteriaceae?
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Which bacterium is noted for being a common cause of urinary tract infections?
Which bacterium is noted for being a common cause of urinary tract infections?
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What is a significant reason for the high mortality rate in children under 5, related to Escherichia coli?
What is a significant reason for the high mortality rate in children under 5, related to Escherichia coli?
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What unique characteristic do Moraxella catarrhalis colonies exhibit when moved on an agar plate?
What unique characteristic do Moraxella catarrhalis colonies exhibit when moved on an agar plate?
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What structure surrounds the cell of spirochetes?
What structure surrounds the cell of spirochetes?
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What mechanism allows spirochetes to move through viscous environments?
What mechanism allows spirochetes to move through viscous environments?
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Which disease is caused by Treponema pallidum?
Which disease is caused by Treponema pallidum?
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Which subspecies of Treponema pallidum causes yaw?
Which subspecies of Treponema pallidum causes yaw?
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What is a notable transmission method for syphilis?
What is a notable transmission method for syphilis?
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How many stages are there in the progression of syphilis?
How many stages are there in the progression of syphilis?
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Which statement is true regarding nonpathogenic spirochetes?
Which statement is true regarding nonpathogenic spirochetes?
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What is the primary characteristic of Spirochaetes?
What is the primary characteristic of Spirochaetes?
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Which bacterial phylum is known for obligate intracellular pathogens?
Which bacterial phylum is known for obligate intracellular pathogens?
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What type of disease is caused by Borrelia burgdorferi?
What type of disease is caused by Borrelia burgdorferi?
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What is a zoonosis?
What is a zoonosis?
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What role do sheltered species play in the evolution of bacteria?
What role do sheltered species play in the evolution of bacteria?
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What does the phylum Firmicutes derive its name from?
What does the phylum Firmicutes derive its name from?
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Which of the following organisms is known to be an obligate anaerobe?
Which of the following organisms is known to be an obligate anaerobe?
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Where do genes causing antibiotic resistance primarily originate?
Where do genes causing antibiotic resistance primarily originate?
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What is a major characteristic of pathogenic species of chlamydiae?
What is a major characteristic of pathogenic species of chlamydiae?
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What role do the elementary bodies play in the chlamydiae life cycle?
What role do the elementary bodies play in the chlamydiae life cycle?
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Which condition can result from a persistent infection with C. Trachomatis?
Which condition can result from a persistent infection with C. Trachomatis?
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What is a key feature of reticulate bodies in the chlamydiae life cycle?
What is a key feature of reticulate bodies in the chlamydiae life cycle?
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What is the consequence of untreated pelvic inflammatory disease (PID)?
What is the consequence of untreated pelvic inflammatory disease (PID)?
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Which characteristic describes the outer membrane of chlamydiae?
Which characteristic describes the outer membrane of chlamydiae?
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Which species of chlamydiae is a known cause of pneumonia?
Which species of chlamydiae is a known cause of pneumonia?
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What happens to the elementary bodies when the host cell lyses?
What happens to the elementary bodies when the host cell lyses?
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Study Notes
Spirochetes
- Distinctive form: tightly coiled cells enclosed by a sheath, with periplasmic flagella that run underneath the sheath along the cell body.
- Some spirochetes live in soil or water as digestive symbionts of termites.
- Others, like Borrelia burgdorferi, are pathogenic and cause Lyme disease.
Chlamydiae
- Bacteria of the phylum Chlamydiae are obligate intracellular pathogens that grow as inclusion bodies within host cells.
- Cause pneumonia, eye disease trachoma, and the sexually transmitted infection chlamydia.
Pathogens Today
- Continue to evolve.
- New pathogens arise from three sources: zoonotic hosts, shelter species, and the environment.
Zoonotic Hosts
- Some pathogens infect only animals, while others infect both animals and humans.
- Animal diseases are called zoonoses.
- Pathogens can interact with the microbiota of an animal host, forming recombinant genes that could help them evolve into new species that can infect humans.
Shelter Species
- Do not directly interact with humans but provide shelter for bacteria to evolve.
- Mixed bacterial communities within a worm or other shelter species can lead to genetic exchange and evolution.
- Over time, some genes may enable bacteria to cross species barriers and infect animals, plants, or humans.
Natural Environment
- Melting pot where genes are sampled from thousands of species.
- This is where some genes contributing to antibiotic resistance originated.
- Plasmids and transposons first evolved, where phases became phases.
Phylum Firmicutes
- Derived from the Latin word "firmus," meaning "strong," implying their thick peptidoglycan layer, reinforced with teichoic acid.
- Some possess a thick waxy coat that excludes the Gram stain, despite being gram-positive.
Bacillus Species
- Grow best by aerobic respiration.
- Form large, cream-colored colonies on nutrient agar plates exposed to air.
Clostridium Species
- Obligate anaerobes.
- Sporulate at the end of the cell, giving it a club shape.
- Commonly known for:
- C. tetani and C. botulinum.
- The botulism toxin, botulinum or BOTOX.
- Clostridium spores are found in soil and water, ready to germinate and grow once the environment becomes anaerobic.
Gram-Positive Firmicutes
Spore Formers With Cell Walls
- Bacillus anthracis: rod-shaped soil bacterium that causes anthrax.
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Clostridiodes difficile: Rod with bulging spores that causes intestinal disease in patients whose normal microbiota are diminished by antibiotics (pseudomembranous colitis).
- Resistant to most antibiotics.
- Can thrive in the gut when normal microbiota are reduced by antibiotics.
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Clostridium botulinum: Rod with bulging spores that causes botulism and produces Botox.
- Can grow within the colon of very young infants, causing infant botulism.
- Clostridium tetanus: Rod with bulging spores that causes tetanus.
Non-Spore Formers
- They probably lost their ability to form spores through reductive evolution.
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Enterococcus spp.: Enteric microbiota (intestinal/gut); cocci.
- Found in the intestinal tract, but can be invasive for immunocompromised hospital patients.
- Can cause urinary tract infections and bacteremia (bacterial infection in the bloodstream).
- Commonly treated with vancomycin.
- Lactobacillus spp.: Rods; Dairy culture.
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Lactococcus spp.: Cocci; Dairy culture
- Ferment milk to make yogurt and cheese.
- Obligate fermenters: grow in the presence or absence of oxygen, but do not use oxygen to respire.
Phylum Proteobacteria: A Diverse Superphylum
- Includes heterotrophs, lithotrophs, and photosynthesizers.
- Gram-negative!
- Gram-negative envelope includes:
- Outer membrane
- Cell wall of peptidoglycan permeated by the periplasm
- Inner membrane
- The outer membrane is packed with receptor proteins and porins.
- Contains long sugar polymer extensions (LPS)--LPS has toxic effects on the host (risk of endotoxic shock.)
Enterobacteriaceae
- A family of Proteobacteria that mostly appear as rods.
- Distinguished by a variety of biochemical tests.
- Ph indicator test: pH changes during the process of fermentation.
- All are facultative anaerobic rods that may grow in human or animal digestive tracts or in lakes and streams.
- Many species have flagella that make them motile (swimmers or swarmers).
- Some form biofilms that increase their resistance to antibiotics.
Pseudomonadaceae
- Pseudomonas are rod-shaped obligate respirers (require a terminal electron acceptor like oxygen to make energy).
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P. aeruginosa: Commonly grows in soil as a decomposer, but can infect humans.
- Can cause surgical wound infections.
- Forms biofilms in the lungs of cystic fibrosis patients.
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Escherichia coli: Rod; Main vehicle for biotechnology.
- Strains cause intestinal and bladder infections.
- Part of Enterobacteriaceae - produces vitamin K.
- Most commonly growing in the human intestine.
- Most common reason why children die under 5.
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Moraxella catarrhalis:
- Exhibits a hockey puck-like behaviour when moved on agar plates.
Phylum Spirochaetes: Twisted-Cell Pathogens and Symbionts
- A distinctive clade of bacteria with a long, tight, flexible spiral cell structure.
- The cell wall is similar to the outer membrane of proteobacteria.
- The peptidoglycan cell wall completely separates the sheath from the plasma membrane.
- Most spirochetes are slow-growing heterotrophs and difficult to culture.
- Many are free-living organisms in soil and water.
- Many nonpathogenic spirochetes are digestive symbionts of hosts as diverse as 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, doubling back around the cell body within the periplasmic space.
- They rotate using proton-driven motors, like extracellular flagella.
- The rotation of the flagella forces the entire cell to twist, corkscrewing through the medium.
- This is advantageous in highly viscous environments.
Treponema pallidum
- Causes the sexually transmitted infection syphilis.
- Only strains of the subspecies pallidum (T. pallidum pallidum) cause syphilis.
- Three stages of syphilis: primary, secondary, and tertiary (both may present with a lesion that heals).
- Can cross the placenta and infect the fetus.
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T. pallidum pertenue produces a different disease called yaws.
- A multistage disease, transmitted through direct skin contact, predominantly in developing countries.
- Heals spontaneously and is followed by a rash.
- Cannot cross the placenta and infect a developing fetus.
Phylum Chlamydiae: Intracellular Pathogens
- Large group of bacteria with cell walls that have very little peptidoglycan.
- Pathogenic species of chlamydiae lack the classic cage-like form of peptidoglycan, but they do have a narrow ring at mid-cell to guide cell division.
- Obligate parasites or pathogens.
- Spend their entire lifecycle within a host cell for survival.
- Lack a cell wall, but possess an outer membrane whose proteins are cross-linked by disulfide bonds, making a tough coat that provides osmotic stability.
- Persistent infection with C. trachomatis can lead to pelvic inflammatory disease (PID).
- Causative agent of a major sexually transmitted infection.
- Causes trachoma, an eye disease.
- Chlamydophila pneumoniae causes pneumonia and has been implicated in cardiovascular disease.
- Can infect a wide range of host cells.
- Alternate between two developmental stages with different functions: elementary bodies and reticulate bodies.
- Elementary bodies (EB): Transmitted outside host cells; resemble endospores in that they are metabolically inert.
- To reproduce, EB must adhere to a host cell surface, be endocytosed, and transform itself into a larger reticulate body (RB).
- Reticulate bodies (RB): Have active metabolism and divide rapidly, but are incapable of infection and are vulnerable to osmotic shock.
- Must divide and transform back into EB before exiting the host to infect new cells.
- Elementary bodies (EB): Transmitted outside host cells; resemble endospores in that they are metabolically inert.
- When the host cell lyses, EB can infect new cells.
- Without treatment, this cycle can continue indefinitely, causing inflammation of the fallopian tubes and ovaries (PID).
- PID can leave permanent adhesions (fibrous tissue), leading to infertility.
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Description
Explore the fascinating world of spirochetes and chlamydiae in this quiz. Learn about their distinctive forms, pathogenic roles, and evolution in the context of zoonotic diseases. Test your knowledge on how these microorganisms interact with their hosts and the environment.
