Gram Positive Bacteria Classification
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Questions and Answers

What condition can occur due to bacteremia in patients with abnormal heart valves?

  • Acute bacterial endocarditis
  • Viral endocarditis
  • Fungal endocarditis
  • Subacute bacterial endocarditis (correct)

    • Which patients should receive prophylactic penicillin before dental procedures?

  • Patients undergoing orthopedic surgery
  • At-risk patients with valvular disease (correct)
  • Patients with hypertension
  • Patients with asthma

    • What is the composition of the vegetation seen in streptococcal endocarditis?

  • Bacteria, fibrin, and platelets (correct)
  • Fibrin, viruses, and platelets
  • Fibrin, bacteria, and white blood cells
  • Bacteria, viruses, and red blood cells

    • Which species of Staphylococcus is known for causing food poisoning?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    Which Staphylococcus species is primarily associated with urinary tract infections in women?

    <p>Staphylococcus saprophyticus</p> Signup and view all the answers

    What role do coagulase-negative staphylococci primarily play in a hospital setting?

    <p>Associated with prosthetic infections</p> Signup and view all the answers

    Which species is the most virulent among the genus Staphylococcus?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    What is a potential complication of damaged heart valves during bacteremia?

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

    Which characteristic is primarily used for the classification of medically important bacteria?

    <p>Morphologic and biochemical characteristics</p> Signup and view all the answers

    What is the correct way to write the name of a bacterial species in scientific nomenclature?

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

    Which of the following bacteria are classified as Gram-positive cocci?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    What distinguishes β-Hemolytic streptococci in blood agar?

    <p>They result in a clear ring around the colony.</p> Signup and view all the answers

    What is the mortality rate of untreated cutaneous anthrax?

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

    Which of the following bacteria is an example of a spore-forming Gram-positive rod?

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

    Which organism is primarily responsible for causing listeriosis?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    Which term is used to describe the color reaction of α-Hemolytic streptococci on blood agar?

    <p>Green pigment formation</p> Signup and view all the answers

    What typically characterizes pulmonary anthrax?

    <p>Progressive hemorrhagic lymphadenitis</p> Signup and view all the answers

    Which type of infection is associated with Clostridium perfringens?

    <p>Gas gangrene</p> Signup and view all the answers

    How should the family and genus in scientific nomenclature be formatted?

    <p>Family in uppercase, genus in lowercase</p> Signup and view all the answers

    What is a serious consequence of untreated pulmonary anthrax?

    <p>Mortality rate approaching 100%</p> Signup and view all the answers

    Which of the following is NOT a category of Gram-positive bacteria?

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

    Which organism is known to grow at a temperature as low as 4 °C?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    Which of the following diseases is NOT caused by Clostridium species?

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

    What is the primary cause of listeriosis?

    <p>Consumption of contaminated food</p> Signup and view all the answers

    What type of paralysis is caused by the neurotoxin produced by Clostridium botulinum?

    <p>Flaccid paralysis</p> Signup and view all the answers

    Which of the following diseases is associated with Clostridium perfringens?

    <p>Gas gangrene</p> Signup and view all the answers

    What is a common source of spores for Clostridium tetani?

    <p>Contaminated soil</p> Signup and view all the answers

    What is the estimated lethal dose of botulinum toxin for a human?

    <p>2μg or less</p> Signup and view all the answers

    In which scenario can botulism occur?

    <p>Through ingestion of contaminated food</p> Signup and view all the answers

    What is the main reason for the rarity of tetanus in developed countries?

    <p>Extensive immunization against the exotoxin</p> Signup and view all the answers

    Which type of bacteria are Clostridia primarily characterized as?

    <p>Gram-positive and encapsulated</p> Signup and view all the answers

    What complication can result from antimicrobial drug treatment?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    What term describes streptococci that do not cause color change or lysis of red blood cells?

    <p>γ-Hemolytic</p> Signup and view all the answers

    Which group of β-Hemolytic streptococci is clinically the most important?

    <p>Group A</p> Signup and view all the answers

    What is the most frequently encountered bacterial pathogen of humans in Group A β-Hemolytic Streptococci?

    <p>S.pyogenes</p> Signup and view all the answers

    What can happen to individuals infected with certain strains of S.pyogenes?

    <p>Postinfectious sequelae</p> Signup and view all the answers

    Where is Group B streptococci, represented by S.agalactiae, found?

    <p>In the vaginocervical tract and the GI tract</p> Signup and view all the answers

    What type of infections is S.pneumoniae most commonly associated with?

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

    Which group includes many species that are main facultative oral flora?

    <p>Viridans Streptococci</p> Signup and view all the answers

    Which species are the clinically most important enterococci?

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

    Study Notes

    Gram Positive Bacteria

    • Gram-positive bacteria are classified primarily by their morphology and biochemical characteristics.
    • Only medically significant bacteria are included in the classification.
    • Scientific names of bacteria are Italicized.

    Scientific Nomenclature of Bacteria

    • Family, genus, species and varieties should be Italicized.
    • Family and genus names start with a capital letter.
    • Kingdom, phylum, class, order, and suborder also begin with a capital letter

    Classification

    • Gram-positive bacteria are divided into Cocci (round shapes) and Rods.
    • Cocci can be described as Staphylococci, Streptococci, and Enterococci.
    • Rods can be Spore-forming (Bacillus and Clostridium) and Non-Spore forming (Corynebacterium and Listeria).

    Gram-Positive Cocci

    • Streptococcus is a gram-positive cocci

    • Hemolytic properties on blood agar

      • a-hemolytic streptococci cause a chemical change in hemoglobin, resulting in a green pigment around the colony.
      • β-hemolytic streptococci cause gross lysis of red blood cells, and a clear ring around the colony.
      • γ-hemolytic streptococci cause no color change, or lysis of red blood cells.

    • Streptococcus is also classified by Lancefield. The most important groups are A and B.

    • Group A strepococci are medically significant bacteria, easily causing infection of skin and mucous membranes. They cause significant diseases such as: -Pneumonia - Pharyngitis -Impetigo -Facial Erysipelas

    • Group B strepococci are also gram-positive cocci. They are commonly transmitted from mother to child during birth.

    • Other gram positive cocci includes: Streptococcus pneumonia and Enterococci.

    Gram Positive Rods

    • Corynebacterium diphtheriae

      • Most species are facultative anaerobes.
      • Their growth is on selective medium like Tinsdale agar with tellurite,
      • Cause diphtheria, an acute respiratory or cutaneous disease.

    • Listeria species

      • Are gram-positive, short, slender rods.
      • Do not form spores.
      • Commonly found in dairy products.

    • Bacillus (anthrax)

      • Also Gram-positive, spore-making rods.
      • Cause the disease anthrax. Different forms of anthrax include cutaneous, pulmonary, and inhalation.

    Clostridia

    • Clostridia are anaerobic, gram-positive rods.

      • Clostridium perfringens

        • Causes gas gangrene and food poisoning.

      • Clostridium botulinum

        • Causes botulism (neurotoxin).

      • Clostridium difficile

        • Associated with antibiotic use, causes pseudomembranous colitis.

    Filamentous

    • Actinomyces
    • Nocardia

    Staphylococcus

    • Staphylococcus aureus is the most important staph and very virulent.
      • Causes food poisoning, toxic shock syndrome, and various common skin issues.
    • Staphylococcus epidermidis and Staphylococcus saprophyticus
      • Coagulase-negative, and cause various infections related to implants/catheters.

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    Gram Positive Bacteria PDF

    Description

    Explore the classification of gram-positive bacteria, including their morphological and biochemical characteristics. This quiz delves into the distinctions between cocci and rods, along with the scientific nomenclature used to describe these bacteria. Test your knowledge on medically significant strains and their properties!

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