Medical Bacteriology Lecture 7
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Questions and Answers

Which bacteria is associated with neonatal meningitis?

  • Proteus
  • Shigella
  • Klebsiella
  • Escherichia coli (correct)

    • Which of the following bacteria is non-motile?

  • Klebsiella (correct)
  • Escherichia coli
  • Salmonella
  • Proteus

    • What condition is primarily caused by Salmonella?

  • Enteric fever (correct)
  • Bacillary dysentery
  • Urinary tract infection
  • Pneumonia

    • Which of the following is a common infection caused by Proteus?

    <p>Urinary tract infection</p> Signup and view all the answers

    Shigella is primarily associated with which condition?

    <p>Bacillary dysentery</p> Signup and view all the answers

    What type of anthrax is characterized by spore germination in the skin leading to a malignant pustule?

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

    Which form of anthrax is also known as 'Wool sorter's disease'?

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

    What type of poisoning is associated with Bacillus cereus?

    <p>Food poisoning</p> Signup and view all the answers

    Which of the following anthrax types is associated with gastrointestinal symptoms?

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

    What is a characteristic feature of Bacillus cereus food poisoning?

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

    Study Notes

    Lecture 7: Medical Bacteriology (II)

    • Lecture covered bacilli bacteria, spirochetes, mycobacterium, and normal flora
    • Presented by Dr. Rasha Mokhtar Elnagar
    • Included Gram-positive and Gram-negative bacilli
    • Also included normal flora and pathogenic organisms

    Gram-Positive Bacilli

    • Divided into spore-forming and non-spore-forming types
    • Spore-forming aerobes: Bacillus anthracis, Bacillus cereus
    • Spore-forming anaerobes: C. perfringens, C. Tetani, C. botulinum, C. difficile
    • Non-spore-forming types: Corynebacterium, Lactobacillus

    Bacillus

    • Morphology: Gram-positive, spore-forming, aerobic or facultative anaerobic bacilli.
    • Important Species: Bacillus anthracis (has a polypeptide capsule) and Bacillus cereus
      • Both are exotoxin producers
    • Diseases:
      • Bacillus anthracis: Zoonotic disease
        • Cutaneous anthrax: Spore germination in skin forms malignant pustule.
        • Pulmonary anthrax: "Wool sorter disease"
        • Intestinal anthrax
      • Bacillus cereus: Food poisoning caused by enterotoxins

    Clostridium

    • Morphology: Gram-positive, spore-forming, obligate anaerobes
    • Important Species: Clostridium tetani, Clostridium botulinum, Clostridium perfringens, Clostridium difficile
    • Note: All species are exotoxin producers
      • Clostridium tetani = Motile.
      • Clostridium botulinum = Motile.
      • Clostridium perfringens = Non-motile
    • Diseases:
      • Clostridium tetani: Tetanus (Spastic muscle paralysis)
      • Clostridium perfringens: Gas gangrene (myonecrosis), often post-trauma.
      • Clostridium botulinum: Botulism (Shellfish, Salted fish, Canned food) (flaccid muscle paralysis)
      • Clostridium difficile: Antibiotic-associated diarrhea & pseudomembranous colitis

    Corynebacterium

    • Morphology: Gram-positive bacilli with club-shaped ends, arranged in Chinese-letter arrangement.

    • Important Species: Corynebacterium diphtheria

    • Important Points: Produces exotoxin

    • Culture conditions: Grows on Löffler's medium, aerobically, at 37°C

    • Disease: Diphtheria (upper respiratory tract infection)

    Gram-Negative Bacilli

    • Divided based on shape and lactose fermentation

      • Rod-shaped: Enterobacteriaceae (lactose fermenters and non-lactose fermenters)
        • E. coli, Klebsiella
        • Salmonella, Shigella, Proteus
      • Curved shape: Vibrio cholera, Campylobacter, Helicobacter pylori
      • Coccobacilli: Brucella, Haemophilus influenzae

    • diseases of Enterobacteriaceae: urinary tract infection, neonatal meningitis, pneumonia, urinary tract infection, bacteremia.

    • Salmonella: enteric fever, food poisoning, septicemia

    • Shigella: bacillary dysentery (bloody diarrhea).

    • Vibrio cholera: Cholera (Rice water diarrhea)

    • Helicobacter pylori: Peptic ulcer

    • Brucella: Malta fever, zoonotic, Brucella melitensis (goats & sheep), Brucella abortus (cows & cattle)

    • Haemophilus influenzae: meningitis, pneumonia in infants

    Pseudomonas aeruginosa:

    • Morphology: Gram-negative rod (pleomorphic), motile, obligate aerobes
    • Symptoms: urinary tract infections, bacteremia, bone and joint infections, particularly in patients with severe burns and immunosuppressed patients

    Spirochetes: Treponema pallidum

    • Morphology: Spiral shape, motile (endoflagella)
    • Staining: Difficult to see by Gram stain, stained by Giemsa and Silver stain
    • Observation: Dark Field microscopy for motility
    • Culture: Cannot be cultured
    • Disease: Syphilis (sexually transmitted disease)

    Mycobacterium

    • Morphology: Acid-fast, non-motile, non-spore-forming bacilli
    • Staining: Cannot be stained by Gram stain due to presence of waxy lipid (mycolic acid) in cell wall
    • Important Species: Mycobacterium tuberculosis (pulmonary tuberculosis), Mycobacterium leprae (Leprosy)
    • Diseases:
      • Mycobacterium tuberculosis: Chronic cough, night fever, and sweating
      • Mycobacterium leprae: Leprosy

    Normal Flora (Commensal Bacteria)

    • Normally inhabit the human body
    • Mostly bacteria, but may include fungi like Candida
    • Do not cause disease in immunocompetent individuals
    • Beneficial roles: compete for nutrients, produce antimicrobial substances, important in newborn development
    • harmful effects: infections in immunocompromised individuals, change of site in body, changes in normal flora (due to antibiotics)
      • Colon: Clostridium difficile and pseudomembranous colitis
      • Vagina: Lactobacilli depletion and Candidiasis.
    • Distribution: Skin, Nose, Eyes, Mouth, Intestinal Tract, Female Vagina

    Pathogenicity

    • Source of Infection

      • The environment (soil, air, water)
      • Animals (zoonotic diseases)
      • Humans (patients, carriers)

    • Case patients: Patients carrying the pathogen

    • Carrier: Persons without the disease that carry the pathogen, can spread infection without exhibiting signs of illness.

    Mode of Transmission

    • Contact (direct, indirect)
    • Airborne
    • Droplet
    • Ingestion (fecal-oral)
    • Bloodborne
    • Arthropod-borne (insect-borne)
    • Vertical (mother to fetus)
    • Tran-placental transmission

    Case Study

    • 25-year-old woman with dysuria, afebrile, mild tenderness.
    • Urine analysis: Many pus cells, Gram-negative bacilli present.
    • Diagnosis: Urinary tract infection
    • Most likely cause: Escherichia coli

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    Related Documents

    Lecture 7 Medical Bacteriology Part II PDF

    Description

    Explore the fascinating world of medical bacteriology, focusing on bacilli bacteria, including Gram-positive and Gram-negative types. This lecture, presented by Dr. Rasha Mokhtar Elnagar, delves into spore-forming and non-spore-forming bacilli, their morphology, important species, and related diseases. Test your knowledge on pathogenic organisms and normal flora.

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