Biology: Gram Positive Bacteria
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Questions and Answers

Which of the following bacteria can form endospores?

  • Lactococcus
  • Bacillus (correct)
  • Streptococcus
  • Mycoplasma

    • What is the function of dipicolinate in the spore core?

  • Provides heat resistance
  • Increases metabolic activity
  • Protects DNA (correct)
  • Prevents germination

    • Which of the following is NOT a characteristic of the spore core?

  • Dehydrated
  • Abundant SASPs
  • Low pH
  • High metabolic activity (correct)

    • What is the function of the cortex in the spore structure?

    <p>Loosely packed peptidoglycan</p> Signup and view all the answers

    Why do spores remain dormant even in optimal conditions?

    <p>Low metabolic activity</p> Signup and view all the answers

    What is the function of the exosporium in the spore structure?

    <p>Thin delicate layer of mostly protein</p> Signup and view all the answers

    Which of the following is an example of a non-spore former?

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

    Why are endospores highly resistant to heat?

    <p>Due to the low water content</p> Signup and view all the answers

    What is the primary function of the poly-D-glutamate polypeptide capsule in Bacillus anthracis?

    <p>Resists phagocytosis and complement</p> Signup and view all the answers

    What is the primary component of the toxin encoded on the pX01 plasmid?

    <p>Lethal factor (LF)</p> Signup and view all the answers

    Why was the Scottish island of Gruinard used as a testing site for Bacillus anthracis?

    <p>To test its efficacy as a biological warfare agent</p> Signup and view all the answers

    What is the primary method of diagnosis for Bacillus anthracis?

    <p>Measuring specific antibodies in the blood</p> Signup and view all the answers

    What is the primary treatment for Bacillus anthracis infection?

    <p>Penicillin, doxycycline, and fluoroquinolones</p> Signup and view all the answers

    What is the purpose of the pX02 plasmid in Bacillus anthracis?

    <p>Encodes the protective coating of the bacteria</p> Signup and view all the answers

    What is the primary characteristic of Bacillus cereus colonies?

    <p>Distinctive loosely spreading (Medusa) colonies</p> Signup and view all the answers

    What is the purpose of the UK and US vaccines for Bacillus anthracis?

    <p>To prepare a dead cell-free preparation of bacterial filtrates</p> Signup and view all the answers

    What is the extreme behavior of organisms in terms of tissue invasion?

    <p>They may not enter tissue at all or remain at the site of inoculation.</p> Signup and view all the answers

    How toxic are toxins compared to rattlesnake poison?

    <p>1 million times more toxic</p> Signup and view all the answers

    Where is Clostridium botulinum commonly found?

    <p>In soil, water, and decaying vegetation</p> Signup and view all the answers

    Why is botulism often associated with food poisoning?

    <p>Because the spores germinate in anaerobic conditions in food</p> Signup and view all the answers

    How does infant botulism occur?

    <p>Through ingestion of spores in soil and dust</p> Signup and view all the answers

    What is the purpose of administering antitoxin in suspected botulism cases?

    <p>To neutralize the toxin</p> Signup and view all the answers

    What is the characteristic shape of the terminal spore of Clostridium tetani?

    <p>Drumstick shape</p> Signup and view all the answers

    How is tetanus typically introduced into the body?

    <p>Through wounds</p> Signup and view all the answers

    What is the primary cause of death in intestinal anthrax?

    <p>Intestinal perforation</p> Signup and view all the answers

    What is the function of the capsule in anthrax bacteria?

    <p>Inhibits phagocytosis</p> Signup and view all the answers

    What is the incubation period of inhalational anthrax?

    <p>Up to 60 days</p> Signup and view all the answers

    What is the mortality rate of cutaneous anthrax if left untreated?

    <p>20%</p> Signup and view all the answers

    What is the most common form of anthrax?

    <p>Cutaneous anthrax</p> Signup and view all the answers

    What is the primary route of infection for pulmonary anthrax?

    <p>Inhalation of spores</p> Signup and view all the answers

    What is the characteristic skin lesion of cutaneous anthrax?

    <p>Skin ulcer with black eschar</p> Signup and view all the answers

    What is the mortality rate of inhalational anthrax in unvaccinated individuals?

    <p>99%</p> Signup and view all the answers

    What is the primary mechanism by which C. perfringens causes tissue damage?

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

    Which of the following is a characteristic of C. perfringens in Robertsons meat media?

    <p>Rancid smell on meat media</p> Signup and view all the answers

    What is the primary tool used to diagnose C. perfringens infections?

    <p>Clinical picture</p> Signup and view all the answers

    What is the purpose of the Nagler reaction in diagnosing C. perfringens?

    <p>To identify the presence of alpha toxin</p> Signup and view all the answers

    Why are antibiotics often ineffective in treating C. perfringens infections?

    <p>The antibiotic is not effective in necrotic areas</p> Signup and view all the answers

    What is the primary cause of C. difficile-associated diarrhea?

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

    What is the primary risk factor for developing C. difficile-associated colitis?

    <p>Recent antibiotic therapy</p> Signup and view all the answers

    What is the characteristic lesion size of C. difficile-associated colitis?

    <p>2-10 mm</p> Signup and view all the answers

    Spores can survive for millions of years in optimal conditions.

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

    The oldest living cells in Nature are approximately 70 years old.

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

    Bacillus anthracis is an obligate anaerobe.

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

    Bacillus anthracis can survive in soil for up to 10 years.

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

    Spores can be activated by low temperatures.

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

    Heat shock is a treatment that can break the state of dormancy of spores.

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

    The mortality rate of cutaneous anthrax if left untreated is 50%.

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

    Ingestion of undercooked contaminated meat is a common cause of pulmonary anthrax.

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

    The primary route of infection for gastrointestinal anthrax is through skin abrasions.

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

    The incubation period of inhalational anthrax is typically less than 60 days.

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

    Anthrax is a common disease that affects only domestic animals.

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

    The mortality rate of inhalational anthrax in unvaccinated individuals is 50%.

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

    Gastrointestinal anthrax is the most common form of anthrax.

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

    The primary cause of death in intestinal anthrax is due to anthrax toxemia.

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

    The capsule of Bacillus anthracis is made of poly-D-glutamate polypeptide and provides protection against phagocytosis and complement.

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

    The pX02 plasmid of Bacillus anthracis encodes the toxin responsible for the bacteria's virulence.

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

    Bacillus anthracis can be diagnosed by the presence of G- rods in clinical samples.

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

    The UK and US vaccines for Bacillus anthracis are made from live spores.

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

    Bacillus cereus colonies resemble fungi due to their tightly packed structure.

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

    The Georgian/Russian vaccine for Bacillus anthracis has fewer side effects than the UK and US vaccines.

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

    Early treatment of Bacillus anthracis infection can be effective with antibiotics such as penicillin and doxycycline.

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

    The Scottish island of Gruinard was decontaminated after being used as a biological warfare testing site for Bacillus anthracis.

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

    Bacillus cereus can cause two types of poisoning, short-incubation and long-incubation, with symptoms of diarrhea and nausea respectively.

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

    The heat-stable emetic toxin produced by Bacillus cereus can be destroyed by cooking.

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

    Clostridium is a type of anaerobic bacteria.

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

    Clostridia obtain ATP through electron transport phosphorylation.

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

    Pathogenic Clostridia are typically found in the intestinal tract of humans and animals.

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

    Clostridia are known to produce highly toxic proteins (exotoxins).

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

    Bacillus cereus is a type of anaerobic bacteria.

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

    Clostridia are a diverse group with only a few species described.

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

    The toxin produced by Clostridium botulinum is 100 times more toxic than rattlesnake poison.

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

    Clostridium tetani is commonly found in soil and intestines of humans.

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

    The terminal spore of Clostridium tetani produces a spherical shape.

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

    Botulinum toxin is heat stable.

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

    BOTOX is a type of botulinum toxin used to treat patients with underactive muscles.

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

    Tetanus is typically introduced into the body through contaminated food.

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

    Clostridium botulinum is found in air and decaying vegetation.

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

    Infant botulism can result from ingestion of preformed toxin from growth of the organism in food.

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

    Study Notes

    Gram Positive Bacteria

    • Gram positive bacteria include:
      • Firmicutes (Low GC Gram positive bacteria)
      • Actinobacteria (High GC Gram positive bacteria)
    • Examples of non-spore forming bacteria:
      • Lactic acid bacteria (Streptococcus, Lactococcus, Lactobacillus)
      • Streptomyces, Corynebacteria, Mycobacteria, Staphylococcus, Listeria
      • Mycoplasma

    Spore Forming Bacteria

    • Examples of spore forming bacteria:
      • Clostridium
      • Bacillus
    • Main characteristics of spore forming bacteria:
      • Form a distinctive type of dormant cell - the endospore
      • Highly resistant to heat, UV, toxic chemicals, and ionizing radiation
      • Typical G+ cell wall, but stain variably
      • Typical habitat is soil

    Endospore Forming Bacteria

    • Spore structure:
      • Exosporium: thin delicate layer of mostly protein
      • Spore coat(s): multiple layers of spore specific proteins
      • Cortex: loosely packed peptidoglycan
      • Spore protoplast or core: normal cell wall, plasma membrane, cytoplasm, and nucleoid
    • Properties of the core:
      • Dipicolinate protects DNA
      • Dehydrated, only 10-30% of the water content of the vegetative cell
      • pH is more acidic than vegetative cell
      • Abundant small acid-soluble spore proteins (SASPs) give resistance to dry heat, desiccation, and UV
      • Carbon source during outgrowth
    • Properties of the core:
      • Low metabolic activity (low O2 uptake)
      • No macromolecular synthesis
      • Low enzymatic activity
      • Low or absent mRNA synthesis

    Germination

    • Spores will remain dormant for decades, even in optimal conditions
    • Examples of Bacillus species: Bacillus cereus, Bacillus anthracis

    Bacillus Anthracis

    • Causes anthrax, a serious infectious disease that occurs naturally in soil and affects domestic and wild animals
    • Forms:
      • Cutaneous anthrax: most common form, affects animal workers, spores germinate in skin abrasions, symptoms include skin ulcer, black eschar, and can become systemic
      • Gastrointestinal anthrax: ingestion of undercooked contaminated meat, symptoms include nausea, severe abdominal pain, vomiting, and bloody diarrhea
      • Pulmonary anthrax: inhalation of spores, symptoms include flu-like symptoms, fever, myalgia, cough, headache, vomiting, and chest pain
    • Virulence:
      • Capsule made of poly-D-glutamate polypeptide
      • Smooth mucoid colonies
      • pX02 plasmid
      • Toxin encoded on pX01 plasmid, consisting of 3 parts: PA (binding domain), EF (Edema factor), and LF (Lethal factor)
    • Diagnosis:
      • G+ rod
      • Central (non-staining spore) occurs in soil and in culture, but not in clinical samples
      • Identified in blood, skin lesions, or respiratory secretions, or by measuring specific antibodies in the blood
    • Treatment:
      • Penicillin, doxycycline, and fluoroquinolones (such as ciprofloxacin)
      • To be effective, treatment should be initiated early
    • Prevention:
      • Pasteur demonstrated efficacy of vaccine
      • Attenuated vaccine possesses some toxicity
      • Used for occupational exposure
      • Control also relies on sterilization of wool, etc. from areas where anthrax is endemic
      • Three vaccines: Georgian/Russian, UK, and US vaccines

    Bacillus Cereus

    • One of the most abundant aerobic sporeformers found in soil
    • Distinctive loosely spreading (Medusa) colonies, superficially resembling fungi
    • Toxins are amongst the most powerful poisons known to man, 1 million times more toxic than rattlesnake poison

    Clostridium Botulinum

    • Found in soil, water, and decaying vegetation
    • Fatal food poisoning that follows ingestion of preformed toxin from growth of organism in food
    • Intoxification
    • Anaerobic conditions (incompletely sterilized canning) may germinate spores, grow into vegetative cells, and produce deadly toxin
    • Botulinum toxin:
      • May occasionally infect wounds
      • Infant botulism can result from ingestion of spores in soil and dust, germinating in intestine (anaerobic)
      • Honey added to formula feed found to contain spores
    • Diagnosis:
      • Clinical
      • ELISA for toxin in food or suspect food is injected into mice
      • Culture is attempted
    • Prevention:
      • Antitoxin is given to suspected cases
      • In contrast to spores, toxin is heat labile, therefore cooking inactivates
      • BOTOX (Botulinum toxin type A) is used to treat patients with overactive muscles, lasting for several months

    Clostridium Tetani

    • Causative agent of tetanus
    • First described by Hippocrates
    • Etiology discovered in 1884 by Carle and Rattone
    • Commonly found in soil and intestines of animals (humans transiently)
    • Terminal spore produces a drumstick shape
    • Tetanus:
      • Spores are introduced into the body through a wound
      • After germination, organisms secrete exotoxins, causing more tissue damage, resulting in rapid spread of the organisms
      • Carbohydrate may be fermented, resulting in the production of large quantities of gas in tissue, constricting blood vessels
    • Diagnosis and Identification:
      • Clinical picture
      • X-ray for gas
      • Definitive diagnosis requires isolation and identification
    • Prevention and Treatment:
      • Cleansing of wounds
      • Antibiotics have little effect in necrotic areas
      • Surgery may be necessary to remove affected parts

    Clostridium Perfringens

    • Diagnosis and Identification:
      • Clinical picture
      • X-ray for gas
      • Usually on clinical picture (smell from protein digestion is characteristic)
      • Organism may be cultivated on Robertsons meat media and on blood agar incubated anaerobically
      • G+ large rods
      • Rancid smell on meat media
      • Hemolytic
    • Prevention and Treatment:
      • Cleansing of wounds
      • Antibiotics have little effect in necrotic areas
      • Surgery may be necessary to remove affected parts
      • Additionally, C. perfringens is an important cause of food poisoning in man and animals by production of enterotoxins

    Clostridium Difficile

    • Causes pseudomembranous colitis, a severe colitis following antibiotic therapy
    • Overgrowth of Clostridium difficile, a normal flora of many people
    • Produces toxins
    • Diarrhea is a common complication of antibiotic therapy, 20% of cases are caused by Clostridium difficile
    • C. difficile is recognized as the most common nosocomial gastrointestinal infection
    • Lesions: 2-10 mm

    Spores and Activation

    • Spores can be activated by various treatments, including heat shock, storage at low temperature (4°C), and germination in favorable conditions.
    • The process of activation involves three stages: activation, germination, and outgrowth.

    Longevity of Spores

    • Spores are extremely stable and can survive for long periods, with some recorded instances of 70 years and even 25-40 million years.
    • The oldest living cells in nature are spores, which can remain dormant for millions of years.

    Bacillus

    • Bacillus is a type of aerobic or facultative anaerobe that can form spores.
    • They are mainly found in soil, but some species can be parasites or pathogens.
    • Bacillus anthracis is a specific species that causes anthrax, a disease that affects animals and humans.

    Anthrax

    • Anthrax is a serious infectious disease that occurs naturally in soil and commonly affects domestic and wild animals.
    • There are three main forms of anthrax: cutaneous, gastrointestinal, and pulmonary.
    • Cutaneous anthrax is the most common form, accounting for around 2000 cases per year, and typically affects animal workers.
    • Gastrointestinal anthrax is rare and occurs when contaminated meat is ingested, leading to symptoms such as nausea, vomiting, and diarrhea.
    • Pulmonary anthrax is the most severe form, with a high mortality rate, and occurs when spores are inhaled.

    Bacillus cereus

    • Bacillus cereus is a type of aerobic sporeformer that is commonly found in soil.
    • It can cause food poisoning, with two types of poisoning: short-incubation (emetic) and long-incubation (diarrheal).
    • The short-incubation type occurs within 1-6 hours of eating and is caused by a heat-stable emetic toxin, while the long-incubation type occurs 6-18 hours after eating and is caused by an enterotoxin.

    Clostridium

    • Clostridium is a type of anaerobic sporeformer that is found in soil, water, and the intestinal tract of animals.
    • They are fermentative and lack a cytochrome system and electron transport phosphorylation.
    • They can produce highly toxic proteins (exotoxins) that can cause disease.
    • Clostridium botulinum is a specific species that causes botulism, a fatal food poisoning.

    Botulism

    • Botulism is a fatal food poisoning that occurs when preformed toxin from Clostridium botulinum is ingested.
    • The toxin is produced when the organism grows in food, and can be inactivated by heat.
    • The disease can also occur when spores are ingested and germinate in the intestine, causing infant botulism.

    Clostridium tetani

    • Clostridium tetani is a specific species that causes tetanus, a disease that occurs when spores are introduced into the body through a wound.
    • The organism is commonly found in soil and intestines of animals.
    • The disease can be treated with antitoxin, and prevention involves proper wound care and vaccination.

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