Bacteria 2022

DIC 1222 FUNDAMENTAL MICROBIOLOGY

Page 1

  • Course Title: DIC 1222 Fundamental Microbiology

Page 2

  • Instructor: Dr. Mahani Mahadi

  • Topic: Bacteria

Page 3: Learning Outcomes

  • At the end of this lecture, students should be able to:

    • Define bacteria

    • Describe the morphology of bacteria

    • Differentiate between different classes of bacteria

    • List bacterial species commonly found in cosmetics

Page 4: What is Bacteria?

  • Bacteria

    • Prokaryotic cells, oldest and smallest living cells.

    • Single-celled prokaryotes, no true nucleus or membrane-bound organelles.

    • Ubiquitous: Found everywhere, can be harmless or pathogenic.

    • Many species provide industrial, ecological, or medical benefits.

Page 5: Types of Disease Transmission

  • Modes of Transmission:

    • Direct contact

    • By air

    • Indirect contact

    • By food

    • Via insects or rabid animals

Page 6: Bacterial Growth

  • Microbial growth: Increase in number of cells, not cell size.

  • Replication method: Bacteria replicate through binary fission, splitting one bacterium into two and doubling numbers each generation.

Page 7: Factors Influencing Bacterial Growth

  1. Temperature

  2. Oxygen requirement/respiration

  3. CO₂ concentration

  4. Nutrition

  5. Osmotic pressure

  6. pH level (0-14)

Page 8: Rate of Growth by Temperature

  • Bacteria classified based on optimum growth temperature:

    • Psychrotrophs: Cold-loving

    • Psychrophiles: Very cold-loving

    • Mesophiles: Moderate temperature

    • Thermophiles: Heat-loving

    • Hyperthermophiles: Extremely heat-loving

Page 9: Bacterial Morphology

  • Three basic shapes of bacteria:

    • Bacilli: Rod-shaped

    • Cocci: Spherical

    • Spirilla: Spiral-shaped

  • Average size: Diameter = 0.1 - 2 µm, Length = 2 to 8 µm.

Page 10: Bacterial Shapes and Arrangements

  • Examples of shapes and arrangements:

    • Cocci: Diplococci, Neisseriae

    • Bacilli: Rods like Bacillus anthracis

    • Spirilla: Spirillum/Spirochete

  • Arrangements:

    • Tetrads: packets of 4 cocci

    • Sarcinae: packets of 8, 16, or 32 cells.

Page 11: Bacterial Colony Morphology

  • Types vary based on environment and growth conditions.

Page 12: Examples of Bacterial Species

  • Common configurations:

    • Cocci: Diplococci (Streptococcus pneumoniae)

    • Bacilli: Chains (Bacillus anthracis)

    • Spirals: Vibrios (Vibrio cholerae)

Page 13: Additional Notes

  • N/A

Page 14: Bacterial Cell Structures

  • Fimbriae: Help adhere to surfaces.

  • Pilus: Transfers DNA between cells.

  • Flagellum: Pushes the cell forward.

  • Glycocalyx: Gel-like coating; can be a capsule or slime layer.

  • Inclusion Bodies: Store nutrients.

  • Nucleoid: Contains bacterial chromosome.

  • Ribosomes: Protein synthesis sites.

  • Plasma Membrane: Regulates molecule flow.

  • Cell Wall: Provides shape/support.

  • Mesosome: Increases surface area.

Page 15: Endospores as Survival Mechanism

  • Bacteria produce endospores under unfavorable conditions:

    • Contain DNA and cytoplasm, encased in a tough coating.

    • Ability to resist extreme conditions (heat, dehydration).

    • Remain dormant until conditions are favorable for growth.

Page 16: Classification by Gram Stain

  • Gram Positive: Retains the stain, appears purple; uses Crystal Violet.

  • Gram Negative: Does not retain the stain, appears pink; uses Safranin.

Page 17: Gram Positive Cell Wall

  • Many layers of peptidoglycan; thick, provides protection and resistance to enzymes.

  • Contains teichoic acids for wall specificity and prevention of cell lysis.

Page 18: Gram Negative Cell Wall

  • Few layers of peptidoglycan, no teichoic acids.

  • Outer membrane consists of LPS (lipopolysaccharide) which helps avoid phagocytosis and acts as a barrier against antibiotics.

  • Contains O polysaccharides and lipid A (toxic to host).

Page 19: Importance of Gram Staining

  • Invented by Hans Christian Gram.

  • Divides eubacteria into two groups based on cell wall structure; useful for identifying Gram-negative versus Gram-positive bacteria.

Page 20: Layout of Gram-Negative and Gram-Positive Bacteria

  • Breakdown of structural differences in cell walls.

Page 21: Exceptions in Cell Wall Structure

  • Mycobacterium: Acid-fast bacteria with waxy mycolic acids attached to the peptidoglycan layer.

Page 22: Structures of Gram-Negative Bacteria

  • Key components include outer membrane, LPS, and porins that regulate molecule passage.

Page 23: Common Gram Positive Bacteria

  • Examples:

    • Staphylococcus aureus

    • Streptococcus pneumoniae

    • Corynebacterium

    • Mycobacterium

Page 24: Classification of Gram Positive Bacteria

  • Includes species like Staphylococcus, Streptococcus, Clostridium, etc.

Page 25: Examples of Gram Negative Bacteria

  • Includes Neisseria gonorrhoeae, H. influenzae, E. coli, etc.

Page 26: Human Infections due to Anaerobic Bacteria

  • Anaerobic bacterial infections caused by species like Bacteroides and Fusobacterium.

Page 27: Bacterial Species Affected by Cosmetics

  • List of bacteria that contaminate cosmetic products and their potential effects.

Page 28: Cosmetic Contamination Issues

  • Common bacteria found in beauty products.

Page 29: Example Case Study of Cosmetic Infection

  • Patient experienced cellulitis, a serious staph infection due to contaminated products.

Page 30: Hygiene Practices with Makeup Brushes

  • Importance of regular cleaning of beauty tools to prevent contamination.

Page 31: Microbial Tests on Makeup Products

  • Testing outcomes showing contamination with harmful bacteria in various cosmetics (e.g., mascara, lipstick).

Page 32: Study on Makeup Products

  • High rates of contamination in opened products, especially sponges and eyeliners.

Page 33: Hygiene and Cosmetic Safety

  • Importance of hygiene in makeup usage to prevent infection.

  • Necessity for cosmetic products to have a date of minimum durability.

Page 34: Harmful Bacteria in Cosmetics

  • Strictly prohibited bacteria:

    • Pseudomonas aeruginosa

    • Staphylococcus aureus

    • Any E. coli or Enterobacteriaceae.

Page 35: Key Organisms in Bacteriology

  • Overview of bacteria related to infections and diseases, highlighting Staphylococcus and E. coli.

Page 36: Staphylococcus Overview

  • Characteristics: facultative anaerobes, commonly found on skin.

  • Notable species:

    • S. aureus: More virulent, causing various infections.

    • S. epidermidis: Opportunistic pathogen.

Page 37: Signs of Staphylococcal Infections

  • Common signs include boils, wound infections, toxic shock syndrome.

Page 38: Symptoms of Staph Infections

  • Presentation of various staphylococcal infections, including cellulitis and boils.

Page 39: Overview of Escherichia coli

  • Characteristics: facultative anaerobes, normal flora in GIT, responsible for various infections.

Page 40: E. coli Infection Symptoms

  • Signs include diarrhea, abdominal cramps, and loss of appetite.

Page 41: Enterohemorrhagic E. coli (EHEC)

  • Pathogenic strains pose serious health risks, with symptoms including severe diarrhea and potential complications.

Page 42: Pseudomonas Overview

  • Can cause fatal infections in immunocompromised individuals.

Page 43: Conclusion on Pseudomonas Infections

  • Risks include significant health complications, especially in vulnerable populations.

Page 44: Summary

  • Thank You for Listening!

  • Open to questions.