Pathology 16

• Bacterial growth is the division of a bacteria into two daughter cells, an increase in number of cells, not cell size, and is asexual reproduction.
• Bacterial growth can be categorized into three primary groups: psychrophiles (cold-loving microbes), mesophiles (moderate-temperature loving microbes), and thermophiles (heat-loving microbes).
• Hyperthermophiles/extreme thermophiles are bacteria that have an optimum growth temperature of 80°C or above.
• Acidophiles are bacteria that tolerate acidity.
• Neutrophiles are bacteria that grow best at neutral pH.
• Alkaliphiles are bacteria that grow under alkaline conditions with a pH above 8.
• Halophilic bacteria are able to grow in high-salt concentration environments.
• Isotonic solution has no net water movement from the bacterial cell.
• High osmotic pressure (hypertonic) removes water from the bacterial cell plasmolysis (plasma membrane shrinks).
• Low osmotic pressure (hypotonic) causes water to enter the bacterial cell cell lysis (cells burst).
• Macronutrients are the main nutrients required for bacterial growth.
• Micronutrients are the trace elements required for bacterial growth.
• Culture media are used to cultivate bacteria.
• Culture methods are used to identify and characterize bacteria.
• Pathogen detection methods include molecular methods such as molecular diagnostics.
• Mutation in the bacterial DNA can lead to its pathogenicity.
• Mutagens are agents that induce/cause mutation.
• Horizontal gene transfer occurs in three ways: transformation, transduction, and conjugation.
• Molecular biology approaches provide accurate and timely diagnosis, initiate proper treatment, and prevent the spread of a contagious disease.
• The death phase is when the number of dead/dying bacterial cells begins to outnumber the new ones.
• Mutations can lead to phenotype changes and can be either spontaneous or induced.
• Accurate replication of DNA is important to the survival of the bacteria.
• Sources of genetic variations include mutations, gene transfer, and mutagens.
• DNA transfer between bacterial cells allows the exchange of genes and characteristics between the cells, thus producing new strains of bacteria (e.g., antibiotic resistance bacteria).
• Pathogenic bacteria can grow in host cells.
• Limited sources and build-up of bacterial waste products limit the growth of a bacterial colony.
• Molecular tests for identification of bacterial pathogens include bacterial growth, which requires proper physical and chemical environment.
• Types of mutations include base-pair substitution, frameshift (deletions/insertions/translocation/inversions).
• Every organism contains unique, species-specific DNA sequences.
• The number of viable cells decreases geometrically (exponentially) during the death phase.
• The lag phase is the adaptation of bacteria to the growth conditions, where cells may be growing in volume and mass, synthesizing enzymes, proteins, RNA and increasing its metabolic activity.
• The log/exponential phase is the doubling time of the bacterial populations, where all cells are dividing regularly by binary fission and are growing by geometric progression.
• The stationary phase is the equilibrium state where the rate of cell death begins to match the rate of cell division.