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Clostridium tetani produces a neurotoxin known as 'tetanospasmin' that is reversible.
Clostridium tetani produces a neurotoxin known as 'tetanospasmin' that is reversible.
False
Clostridium botulinum can grow in low oxygen environments if spores are not properly killed during canning.
Clostridium botulinum can grow in low oxygen environments if spores are not properly killed during canning.
True
C.difficile was lethal for guinea pigs during the testing of penicillin.
C.difficile was lethal for guinea pigs during the testing of penicillin.
True
Infants with well-developed gut flora are at higher risk for Clostridium botulinum infections.
Infants with well-developed gut flora are at higher risk for Clostridium botulinum infections.
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Aerotolerant fermenters can only grow in anaerobic environments.
Aerotolerant fermenters can only grow in anaerobic environments.
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Treatment for mild Clostridioides difficile infections often involves the continuation of antibiotics.
Treatment for mild Clostridioides difficile infections often involves the continuation of antibiotics.
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Lactobacillus is a genus that contributes to healthy, normal flora.
Lactobacillus is a genus that contributes to healthy, normal flora.
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Clostridium tetani is commonly found in human intestines.
Clostridium tetani is commonly found in human intestines.
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Group A Streptococcus can produce toxins that affect blood cells.
Group A Streptococcus can produce toxins that affect blood cells.
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The symptoms of Clostridium botulinum toxicity can take days to appear after exposure.
The symptoms of Clostridium botulinum toxicity can take days to appear after exposure.
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Both Clostridium botulinum and Clostridium tetani can be treated effectively with antibiotics.
Both Clostridium botulinum and Clostridium tetani can be treated effectively with antibiotics.
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All aerobic chemoorganotrophs can ferment organic compounds for energy.
All aerobic chemoorganotrophs can ferment organic compounds for energy.
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Clostridioides difficile can overgrow in the intestine after normal flora is disrupted by antibiotics.
Clostridioides difficile can overgrow in the intestine after normal flora is disrupted by antibiotics.
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Mycobacterium species are primarily pathogenic and not found in the environment.
Mycobacterium species are primarily pathogenic and not found in the environment.
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Cyanobacteria are classified as anoxygenic phototrophs.
Cyanobacteria are classified as anoxygenic phototrophs.
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Mycolic acids in Mycobacterium help them survive in harsh environments.
Mycolic acids in Mycobacterium help them survive in harsh environments.
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Pseudomonas species can metabolize complex molecules such as plastics.
Pseudomonas species can metabolize complex molecules such as plastics.
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Thermus is a genus of bacteria that grows in extremely low temperatures.
Thermus is a genus of bacteria that grows in extremely low temperatures.
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Enterobacteriaceae are only pathogenic bacteria found in the intestinal tract.
Enterobacteriaceae are only pathogenic bacteria found in the intestinal tract.
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Escherichia is a genus included in the Enterobacteriaceae family.
Escherichia is a genus included in the Enterobacteriaceae family.
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Pseudomonas aeruginosa can grow in nutrient-poor environments.
Pseudomonas aeruginosa can grow in nutrient-poor environments.
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Facultative anaerobes prefer to grow only in the absence of oxygen.
Facultative anaerobes prefer to grow only in the absence of oxygen.
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Salmonella can lead to systemic infections in humans.
Salmonella can lead to systemic infections in humans.
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Deinococcus bacteria are extremely sensitive to radiation.
Deinococcus bacteria are extremely sensitive to radiation.
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Corynebacterium only causes infections when exposed to environmental toxins.
Corynebacterium only causes infections when exposed to environmental toxins.
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Yersinia pestis can cause both bubonic and pneumonic plague.
Yersinia pestis can cause both bubonic and pneumonic plague.
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Vibrio cholerae requires high sodium conditions for survival and triggers dehydration when ingested.
Vibrio cholerae requires high sodium conditions for survival and triggers dehydration when ingested.
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Prokaryotes have evolved primarily to harm humans and establish dominance in the body.
Prokaryotes have evolved primarily to harm humans and establish dominance in the body.
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Once a bacterium is in a human, it can easily evolve to become more beneficial without limitations.
Once a bacterium is in a human, it can easily evolve to become more beneficial without limitations.
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Legionella is a gram-negative bacterium that can thrive in various aquatic environments.
Legionella is a gram-negative bacterium that can thrive in various aquatic environments.
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Clostridia spp are mostly harmless in both terrestrial and aquatic environments.
Clostridia spp are mostly harmless in both terrestrial and aquatic environments.
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The vaccine for diphtheria targets the bacteria itself rather than the toxin produced.
The vaccine for diphtheria targets the bacteria itself rather than the toxin produced.
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The normal human immune system will always defeat all bacteria without exception.
The normal human immune system will always defeat all bacteria without exception.
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Staphylococcus aureus is known to be protective when present on the skin surface.
Staphylococcus aureus is known to be protective when present on the skin surface.
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Helicobacter is the primary cause of stomach ulcers and is adapted to survive the stomach's acidic environment.
Helicobacter is the primary cause of stomach ulcers and is adapted to survive the stomach's acidic environment.
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Campylobacter can contaminate uncooked food and is a common cause of reportable diarrhea in humans.
Campylobacter can contaminate uncooked food and is a common cause of reportable diarrhea in humans.
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Bacteroides is a strict anaerobe that constitutes a significant portion of fecal bacteria and can be easily cultured.
Bacteroides is a strict anaerobe that constitutes a significant portion of fecal bacteria and can be easily cultured.
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Mycoplasma bacteria have a cell wall.
Mycoplasma bacteria have a cell wall.
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Neisseria gonorrhoeae can infect both humans and animals.
Neisseria gonorrhoeae can infect both humans and animals.
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The primary stage of Treponema pallidum infection is symptomatic in all cases.
The primary stage of Treponema pallidum infection is symptomatic in all cases.
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Mycoplasma can cause a mild form of pneumonia known as walking pneumonia.
Mycoplasma can cause a mild form of pneumonia known as walking pneumonia.
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Obligate intracellular bacteria can replicate outside of a host cell.
Obligate intracellular bacteria can replicate outside of a host cell.
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Asymptomatic carriage of Neisseria gonorrhoeae occurs in nearly all men after initial symptoms.
Asymptomatic carriage of Neisseria gonorrhoeae occurs in nearly all men after initial symptoms.
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Treponema pallidum does not grow well in laboratory conditions.
Treponema pallidum does not grow well in laboratory conditions.
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Mycoplasma bacteria are among the largest in size among bacteria.
Mycoplasma bacteria are among the largest in size among bacteria.
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Study Notes
Prokaryotic Diversity
- Scientists are just beginning to understand the vast diversity of microbial life
- Only a fraction of over a million prokaryotic species have been described
- The majority of prokaryotes have not been isolated
- New molecular techniques are aiding in the discovery and characterization of prokaryotes
- The goal of this class is to provide an overview of the diversity of characteristics and habitats of prokaryotes, focusing on medically important species.
Anaerobic Chemotrophs
- The atmosphere was anoxic for approximately 1.5 billion years when prokaryotes first inhabited Earth
- Early chemotrophs likely used anaerobic respiration
- Terminal electron acceptors, such as sulfur, were used
- Anaerobic photosynthesis increased life on the surface
- After glucose became the standard energy molecule, other species likely used fermentation and passed electrons to organic molecules like pyruvate
- This produced, for example, ethanol and CO2
Cyanobacter and Two-Stage Photosynthesis
- Prokaryotes introduced large amounts of oxygen into Earth's atmosphere
- This was a poison to obligate anaerobes
- Anaerobic habitats remain common, even today, and are found in places like mud and tightly packed soil, where gases diffuse with limitations
- Aquatic environments can become limiting, as can any area of limited oxygen replenishment
- Anaerobic conditions are present in human and animal bodies, especially the intestinal tract and in microenvironments such as the skin and oral cavity
- Facultative aerobes contribute by depleting oxygen and maintaining anaerobic conditions.
Anaerobic Chemolithotrophs
- Oxidize inorganic chemicals for energy
- Use alternative electron acceptors, such as sulfur
- Many are in the Archaea domain
- Methanogens are one group
- No major medical agents are associated with this group
Anaerobic Chemoorganotrophs - Anaerobic Respiration
- Chemoorganotrophs oxidize organic compounds (such as glucose) for energy
- Anaerobes often use sulfur or sulfate as electron acceptors
- Produce hydrogen sulfide (rotten-egg smell)
- Important in sulfur cycles
- Desulfovibrio is discussed
Anaerobic Chemoorganotrophs - Fermentation
- Many current-day anaerobic bacteria ferment
- ATP is produced via substrate-level phosphorylation
- Many different organic energy sources are used, and various end products result
- Clostridium and Clostridioides are in this group
- Endospore formers can survive long exposure to oxygen, heat, drying, and chemicals
Medically Important Clostridia
- Clostridium tetani is ubiquitous in rich soils, common in animal intestines
- It causes a classic infection by deep puncture wounds
- It produces a neurotoxin (tetanospasmin), composed of two protein chains
- First protein chain binds to neuron membranes, while the second protein is internalized
- This blocks the release of inhibitory neurotransmitters, thereby permanently preventing muscle relaxation
- Treatment involves antitoxin vaccination against the toxin
Medically Important Clostridia
- Clostridium botulinum is ubiquitous in rich soils, and is present in low levels in the human gut
- It is important that infants' gut flora is developed
- Improper canning can allow botulinum spores to grow in airtight environments
- It releases neurotoxins that block excitatory neurons
- Classic diseases include headaches, blurred vision, dry mouth, and progressive weakness, which can be treated with antitoxin and ventilation support
Medically Important Clostridia
- Clostridium difficile is commonly found in normal intestinal flora
- Antibiotic treatment can disrupt normal flora in the gut, allowing Clostridium difficile to overgrow
- This often leads to mild disease that resolves when antibiotics are discontinued
- However, severe disease may require high-dose antibiotics
Aerotolerant Fermenters - Lactic Acid Bacteria
- Gram-positive bacteria produce lactic acid as a fermentation product
- Most can grow in aerobic environments, but lack catalase, and only ferment
- Medical important genera include Lactobacillus (part of healthy flora, e.g., vaginal) and Streptococcus (in oral cavity)
- Others, such as Streptococcus pyogenes, are pathogens (e.g., strep throat, scarlet fever)
Intervening Prokaryotic Types (Environmental Impact)
- Various prokaryotic types are involved in environmental impacts, including Anoxygenic Phototrophs, Oxygenic Phototrophs, Aerobic Chemolithotrophs
Aerobic Chemoorganotrophs
- Oxidize organic compounds for energy
- Use oxygen as a terminal electron receptor
- Obligate aerobes cannot ferment
Mycobacterium
- Additional components to the cell wall, such as mycolic acids (long-chain fatty acids), help them survive in dry environments and withstand chemical attack, as in various harsh environments
- Identification is accomplished using acid-fast staining
- Examples of key medical agents include M. tuberculosis and M. leprae
Pseudomonas
- Wide range of degradative activities, including the metabolism of complex molecules (e.g. plastics)
- Widespread in soil and water
- medically important microbes, such as P. aeruginosa, grow in nutrient-poor environments, and can contaminate "just water"
- Resistant to various disinfectants. Can be opportunistic infections in a hospital environment
Side Bar: Scientific Interest
- Thermus, a prokaryotic type, grows at high temperatures and produces heat-stable enzymes
- Deinococcus is extremely radiation resistant
- Has mechanisms for multiple genomes and active DNA repair
Facultative Anaerobes
- Preferentially use aerobic respiration but can ferment if oxygen is limited
- Play a major role in maintaining anaerobic environments
- Useful for understanding the environment because it can readily grow in a test tube
Medically Important Family: Enterobacteriaceae
- Common intestinal residents in humans and other animals
- Include Enterobacter, Klebsiella, Proteus, and Escherichia
- Can cause intestinal or systemic disease in certain individuals
- Salmonella and Shigella cause food poisoning or systemic infections
- Yersinia pestis causes bubonic and pneumonic plague
Other Medically Important Genera
- Corynebacterium and Vibrio are important genera
- Require some sodium ions for growth, especially in high-saline environments
- Medical examples include V. cholerae
Note on Environmental Factors
- A few prokaryotes have evolved to live in the human body and often take advantage of what humans offer them, including food and environment
- Generally, the human body can outcompete them to prevent them from growing in unwanted ways.
Out of Balance
- Prime examples of terrestrial environments include Clostridium spp.
- Another prime example of aquatic environments is Legionella
- Gram-negative bacteria thrive in various aquatic environments
- Bacteria that are ingested in the lung are immediately attacked by macrophages
- Occasionally, bacteria have evolved to successfully fight back against the human macrophage immune system
Animals as Habitats
- Skin, Mucus Membranes, and Intracellular Environments are key locations in animals
Skin
- Staphylococcus epidermidis and aureus are key bacteria species present in skin, commonly associated with higher salt/low-water conditions.
Mucous Membranes: Respiratory, Genitourinary, and Intestinal Tracts
- Important bacterial species include Streptococcus, Lactobacillus, and Enterobacteriaceae
- Other medically important species are Helicobacter and Campylobacter
- Bacteroides is a commensal species in the intestines, also one of the most common bacterial species in feces
Other Mucosal: Respiratory
- Mycoplasma is a unique species of bacteria that lack cell walls.
Other Mucosal -- Genitourinary
- Neisseria gonorrhoeae and Treponema pallidum are important species
Obligate Intracellular Bacteria
- Bacteria that cannot replicate outside a host cell
- Possess advantages because of the abundance of resources within a host
- Example: Chlamydia
- Invades epithelial cells of mucous membranes
- Can survive or invade white blood cells
- Range of infections, including STIs
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Description
Explore the fascinating world of prokaryotic life, focusing on the vast diversity and significance of these microorganisms. This quiz covers key concepts about their habitats, characteristics, and the role of anaerobic chemotrophs in early Earth's anoxic environment. Deepen your understanding of bacteria that contribute to ecological and medical advancements.
