Bacterial Classification and Taxonomy Quiz

Introduction to Microbiology

• Instructor: Justin Hedlund
• Semester: Fall 2023
• Course: Vet Prep RUSVM
• Email: [email protected]

Learning Objectives (VPRP 0906 - Bacteriology - Dr. Gutierrez)

• Overview of basic bacteriology principles, including cell structure, terminology, virulence factors, taxonomy, and pathogenesis.

• Brief overview of emerging and zoonotic diseases, diagnosis, treatment, and prevention.

• Key characteristics of prokaryotes: Differences with eukaryotes, bacterial cell wall, plasma membrane, nucleoid, flagella, pili/fimbriae, capsule, endospores, Gram staining procedure, and bacterial morphologies.

• Factors for bacterial growth & reproduction (4 phases of the bacterial growth curve).

• Bacteria-specific terminology: symbiotic relationships, pathogen types (obligate, facultative, opportunistic, accidental), infection, inflammation, disease, pathogenesis, pathogenicity, virulence, plasmids, bacteriophages, quorum sensing, aerobic/anaerobic classifications, and culture/antimicrobial media.

• Bacterial pathogenesis: Sequence of events, virulence factors, toxin characteristics (exotoxins, endotoxins), biofilm formation, and virulence factor transfer (conjugation, transduction, transformation).

• Diagnosis of bacterial infections: Direct microscopic observation, cultural and biochemical characteristics, serotyping, molecular techniques, detection of host immune response (serology, cell-mediated immunity).

• Treatment of bacterial diseases: Limiting microbial growth methods, sterilization, antimicrobial classifications (chemical structures, mode of action, spectrum of activity, antimicrobial susceptibility testing).

• Pathogenic bacteria: Specific species (Gram-positive cocci, rods, anaerobes, Gram-negative rods, spirochetes, mycoplasma, rickettsiales) and diseases they cause.

• Bacterial Vaccines: mechanism of action, types, composition, features, and potential vaccination failure.

• Prokaryotes vs. Eukaryotes: Key differences in structure, chromosomes, cytoskeleton, division, cell wall composition, reproduction.

• Bacterial Cell Wall: Functions (protection, transport), differences between structures of various species for pathogenicity, staining properties, peptidoglycan composition (NAG, NAM subunits).

• Gram-positive Bacteria Cell Wall: Multilayered, thick peptidoglycan, resistance to drying, susceptible to ionic detergents, teichoic acids (linked with peptidoglycan and plasma membrane), strong antigenicity for immune responses.

• Gram-negative Bacteria Cell Wall: Thin peptidoglycan layer, outer and inner plasma membranes with a periplasmic space, not resistant to drying/physical disruption, less susceptible to ionic detergents, lipopolysaccharides (LPS), known as endotoxin.

• Gram-staining Technique: How it differentiates bacteria by their physical/chemical properties based upon peptidoglycan composition.

• Mycobacteria Cell Wall: Thick waxy hydrophobic cell wall, mycolic acids, acid-fast staining (Zeihl-Neelsen staining) to visualize it under microscopy.

• Exception: Mycoplasma (lacks cell wall, sterols for plasma membrane rigidity).

• Plasma Membrane: Phospholipids and proteins (no sterols), active transport of nutrients, elimination of metabolites, bacterial respiration, biosynthesis of DNA, cell wall polymers, and lipids. Additional transport systems (Facilitated diffusion, Active transport, Group translocation) and mesosomes.

• Genetic Material Locations: Nucleoid (region where nuclear material is housed, single haploid circular chromosome, double stranded DNA). Plasmids (small DNA that replicate independently, carry virulence factors and resistance genes).

• Flagella: Locomotion structure (filament, hook, basal body), arrangement (monotrichous, amphitrichous, lophotrichous, peritrichous, endoflagella) and function.

• Pili/Fimbriae: Fine hair-like appendages, common in Gram-negative bacteria, composed of pilin protein, host tissue adherence, and antigenicity roles (e.g., E. coli K88 & K99 in neonatal piglets & calves).

• Capsule: Glycocalyx (extracellular polymeric matrix, primarily polysaccharides), nutrient reserve, protection, adherence to host cell surfaces, interferes with phagocytosis.

• Endospores: Survival mechanism (cryptobiotic state of dormancy), durable cell form, ensures survival during adverse conditions.

• Endospores (Sporulation): detailed steps of sporulation from the formation of the forespore with a second membrane, disintegration of the mother chromosomes, and formation of the spore coat to form a mature cell.

• Bacterial Morphology: Details of cell shapes (cocci, streptococci, diplococci, encapsulated diplococci, staphylococci, tetrad, bacillus, diplobacilli, pallisades, streptobacilli, corkscrew, filamentous, spirochete, club rod, helical form, budding/appendaged bacteria). Ability to identify these in microscopy.

• Bacterial Metabolism, Phylogeny, Pathogenesis.

• Factors Required for Bacterial Growth: Gaseous requirements (O2, CO2, aerobic, anaerobic, facultative, microaerophilic, capnophilic), environmental factors (nutrients, pH, ion strength, osmotic pressure, light, temperature).

• Bacterial Reproduction: Binary fission (chromosome replication, cell elongation, and division into two daughter cells). Generation time (time required for bacterial cell division).

• Bacterial Growth Curve: Four phases (Lag, exponential, maximal stationary, decline/death) and associated characteristics (cell size, metabolism, multiplication rate).

• Bacterial Growth Factors: Nutrients (e.g., glucose, nitrates, fatty acids), pH, ionic strength/osmotic pressure, temperature, gaseous requirements (e.g., oxygen, carbon dioxide).

• Methods for Bacterial Counting: Direct smear, counting chamber, spread plate method, pour plate method.

• Phylogeny & Taxonomy: Classification methods (morphology, motility, DNA profiling, metabolism/physiology, biochemical characteristics, 16S rRNA gene sequencing, whole genome sequencing) for polyphasic taxonomy

• We Live in a Microbial World: Types of bacteria (beneficial: Symbionts, commensals, mutualism, free-living), (harmful: obligate, facultative, opportunistic, accidental pathogens).

• Pathogens: Infectious agent, types (obligate, facultative, opportunistic), role in disease.

• Bacterial Pathogenesis: factors impacting disease (host, pathogen, environment) and types of interactions (initial host infection, adherence to epithelial cells, toxin release, invasion/destruction of cells, tissue invasion, systemic infection). Inflammation (local tissue damage, toxins and/or immune response, toxemia, acute/chronic disease).

• Iceberg concept of disease- Majority infections are asymptomatic, others are mild, and a limited number lead to severe illness or death.

• Pathogen Consequences: No colonization, subclinical disease, disease/recovery, disease/persistence, disease/death or disability.

• Time Periods, Symptoms, & Infectiousness: Latent period, incubation period, onset of infectiousness, onset of symptoms, resolution, infectious period.

• Bacterial Virulence Factors: Bacterial traits allowing for pathogenicity (Extracellular, intracellular) including examples of facultative and obligate intracellular pathogens. Discussion of specific virulence factors (toxins, capsules, flagella, fimbriae, etc.).

• Toxin Types: Exotoxins & Endotoxins, properties and how they affect the host. Superantigens- effects of immune system.

• Quorum Sensing: Chemical signals among bacteria for group behavior regulation (e.g., biofilm formation).

• Biofilm Formation: Process from attachment that allows for the spread and resistance to environmental stress.

• Transfer of Virulence Factors: Methods (transformation, transduction, conjugation) and implications.

• Antimicrobial Resistance: Innate and acquired resistance, clinical use of antibiotics.

Additional Information

• Various figures and diagrams accompany the course material(s) to illustrate and explain the concepts mentioned above.
• Quizzes or practice questions were added as part of the slides during the course.