Bacterial Infection of the Host

Infection Process

The sequence of events that pathogens undergo to establish an infection, including exposure, adherence, invasion, and multiplication.

Disease Process

The mechanisms by which pathogens cause disease, including toxicity and invasiveness leading to tissue damage.

Exposure Points

The primary entry routes for pathogens, including the respiratory, gastrointestinal, and urogenital tracts, as well as breaks in the skin.

Mucous Membranes

Protective barriers lining the digestive, respiratory, and reproductive tracts, playing a key role in innate immune defense.

Adherence

The process by which bacteria attach to host cells, facilitated by structures like pili, fimbriae, capsules, and lipoproteins.

Salmonella Typhi

A specific pathogen responsible for typhoid fever, utilizing Type IV pili for adherence to epithelial cells.

Biofilms

Aggregates of bacterial cells encased in a self-produced matrix, providing protection against the immune system and antibiotics.

Biofilm Tolerance

The ability of bacteria in biofilms to withstand antimicrobial agents, influenced by restricted diffusion and the presence of persister cells.

Iron Competition

The critical battle for iron between pathogens and hosts, essential for various metabolic processes.

Iron Oxidation States

The two forms of iron (Fe2+ and Fe3+) and their solubility differences, impacting bacterial iron acquisition.

Nutrient Withholding

A first line of defense against infection, limiting pathogen growth by restricting nutrient availability.

Quorum Sensing (QS)

A communication mechanism among bacterial cells that coordinates group behavior through the secretion of signaling molecules.

Acyl Homoserine Lactones (AHLs)

Auto-inducers used in Gram-negative bacteria for quorum sensing, facilitating coordinated responses.

Two-Component Systems (TCSs)

Regulatory systems that help bacteria adapt to environmental changes through signal transduction.

EnvZ-OmpR System

A TCS that regulates porin expression in response to osmolarity changes, affecting bacterial adaptation.

CheAY System

A TCS involved in chemotaxis, regulating flagellar rotation based on attractant concentration.

RNA Polymerase and Sigma Factors

The role of sigma factors in promoting transcription initiation by recognizing specific promoter sequences.

Stress Responses

Mechanisms by which bacteria respond to environmental stresses, regulated by the availability of sigma factors and adaptor proteins.