Med Microbio

• Bacteria are microscopic organisms that play a crucial role in various ecosystems. These single-celled organisms can be found virtually everywhere.
• One of the most well-known characteristics of bacteria is their ability to cause disease in humans and other animals.
• In addition to their environmental importance, bacteria also have significant applications in biotechnology and medicine.
• Bacteria are truly remarkable organisms with a wide range of functions and capabilities that make them an integral part of our world.
• Objectives


  • Figure out the different kinds of bacteria based on their shapes and structures as well as the kinds of hosts and hosts they attack
  • To provide a more in-depth understanding of the pathogenesis and different immune responses of the body
  • Gain a thorough understanding of the clinical manifestations associated with the assigned bacteria
• Streptococcus pyogenes


  Gram-positive bacteria that causes a variety of pyogenic infections, including strep throat, impetigo (skin infection), cellulitis (skin and soft tissue infection)
• Streptococcus pyogenes


  • Rod or cocci shaped bacteria
  • Has a diameter of 0.5 - 1.25 µm
  • Arranged in chains or pairs
  • Does not have the ability to form spore
  • Facultative anaerobe
  • Can survive at 35°C - 37°C and a pH level of 6.5
  • Non-fermenter

  
• Pathogenesis of Streptococcus pyogenes

  1. Colonization

  2. Evasion of Host Defenses

  3. Tissue damage

  4. Suppurative infections

  5. Invasive disease

  6. Post-infectious sequelae
• Immunity against Streptococcus pyogenes

  • M Protein
  • Hyaluronic Acid Capsule
  • C5a Peptidase
  • Streptolysins
  • Superantigens
  • Immune Evasion Proteins
• Clinical Manifestations of Streptococcus pyogenes


  • Sore throat, Fever, Swollen lymph nodes in the neck (Pharyngitis/Strep Throat)
  • Redness, Swelling, Pain, Sores or blisters (Impetigo)
• Immune response of the human body against Streptococcus pyogenes

  • Innate immune response
  • Adaptive Immune Response (B cells produce antibodies, Activation of T cells)
• Clostridium botulinum


  Gram-positive bacteria found in soil and water that can form spores and produce potent toxins called botulinum toxin
• Types of botulinum toxins

  • Type A
  • Type B
  • Type C
  • Type D
  • Type E
  • Type F
  • Type G
• Clostridium botulinum


  • Rod-shaped bacteria
  • 0.5-1.25 µm in width, 1.6-22.0 µm in length
  • Arranged singly, in pairs or small chains
  • Spore forming
  • Obligate anaerobe
  • Fermenting
• Botulism


  Rare and serious illness caused by a toxin produced by the bacterium Clostridium botulinum, which attacks the nerves in the body leading to muscle weakness and paralysis
• Pathogenesis of Clostridium botulinum

  1. Ingestion of botulinum toxin through contaminated food

  2. The vegetative cells of C. botulinum produce potent toxins known as botulinum neurotoxin

  3. The toxin and spores will travel to the intestinal tract, where the spores germinate into vegetative C. botulinum

  4. The botulinum neurotoxin is absorbed in the intestines and enters the bloodstream

  5. Botulinum neurotoxin binds to presynaptic membranes at the neuromuscular junction, preventing the release of acetylcholine
• Immunity against Clostridium botulinum (Innate)

  • Recognition of Botulinum toxin as foreign
  • Responsible for phagocytosis
  • Triggers inflammation at the site of infection
• Immunity against Clostridium botulinum (Adaptive)

  • Activates B cells to produce antibodies
  • Develops memory response
• Clinical Manifestations of Botulism


  Difficulty swallowing (dysphagia), Muscle weakness, Double vision (diplopia), Drooping eyelids (ptosis), Slurred speech (dysarthria)
• Gardnerella vaginalis


  Gram-variable bacteria that is commonly found in the vaginal flora of women, and can lead to an imbalance in the bacterial population and subsequent infection
• Gardnerella vaginalis


  • Pleomorphic rods
  • 1.0–1.5 μm in diameter, some may reach up to 2–3 µm
  • Classified as a coccobacilli
  • Non-sporulating
  • Obligate anaerobe
  • Uses carbohydrates as its major energy source
  • Optimum growth at 35-37°C and pH 6-6.5
  • Fastidious, does not require hemin or NAD for growth
  • Can ferment but not all
• Bacterial Vaginosis


  Condition where there is too little lactobacilli bacteria and too much Gardnerella bacteria in the vagina, leading to an imbalance in the natural bacterial levels
• Pathogenesis of Gardnerella vaginalis

  1. Adherence of G. vaginalis to Host Epithelium: Initial Steps in Invasion

  2. Mechanism of infection

  3. Dysbiosis of vaginal microbiota

  4. Biofilm formation

  5. Production of organic acids and amines

  6. Sexual activity and behavioral factors
• Immunity against Gardnerella vaginalis (Innate)


  • Vaginal epithelial cells
  • Antimicrobial peptides
  • Inflammatory response
• Immunity against Gardnerella vaginalis (Adaptive)

  • Humoral immunity
  • Cell-mediated immunity
• Immunity against Gardnerella vaginalis


  • Vaginal Microbiota
  • Hormonal Influences
• Clinical Manifestations of Bacterial Vaginosis

  • Vaginal Discomfort
  • Vaginal Discharge
  • Vaginal odor
  • Increased susceptibility to other infections
• Treatment for Bacterial Vaginosis

  • Antibiotics
  • Proper Hygiene
  • Protective Sex
  • Avoiding Irritants
• One notable characteristic that sets V. cholerae apart from most other Vibrio species is its capacity to thrive in laboratory conditions without the need for additional NaCl.
• The genus Vibrio has around 30 documented species, some of which are recognized as food-borne diseases.
• The bacteria Vibrio cholerae exhibits tolerance to moderately alkaline environments and is capable of growing at pH levels of up to 10. However, growth is impeded at lower pH levels.
• Adaptive Immune Response


  • Humoral immunity
  • Cell-mediated immunity
• Immune response of the human body
• Clinical Manifestation of Bacterial vaginosis

  • Vaginal Discomfort
  • Vaginal odor
  • Increased susceptibility to other infections
  • Vaginal Discharge
• Treatment


  • Antibiotics
  • Proper Hygiene
  • Protective Sex
  • Avoiding Irritants
• Vibrio cholerae is one notable characteristic that sets it apart from most other Vibrio species as it can thrive in laboratory conditions without the need for additional NaCl
• The genus Vibrio has around 30 documented species, some of which are recognized as food-borne diseases
• The bacteria Vibrio cholerae exhibits tolerance to moderately alkaline environments and is capable of growing at pH levels of up to 10, but growth is impeded when the pH drops to 6 or below
• The presence of Na+ stimulates the development of Vibrio, however various species have varied needs
• Vibrio cholerae


  • Curved or comma-shaped morphology
  • Gram-negative
  • Motile with a single polar flagellum
  • Produces cholera toxin, a key virulence factor