Interaction of pathogens (with a host)

• Describe how pathogens cause disease and how they overcome the innate host defence • Demonstrate an understanding of basic concepts of epidemiology: how infections are propagated.

what is an Immunocompromised host

An individual with impaired immune system function, often caused by infection, chemotherapy, or age, making them more susceptible to opportunistic infections.

what is Commensal bacteria

Bacteria that live in or on the body without causing harm, and can even provide benefits such as aiding in immune development and colonization resistance.

what are opportunistic pathogens

Commensal bacteria that can cause infection in an immunocompromised host.

what are Obligate human pathogens

Pathogens that solely cause disease in humans and do not survive well outside of the host.

what is a Fomite

An inanimate object that can transmit bacteria, such as a phone.

what is a Vector

An organism, such as a mosquito, that can transmit bacteria through blood feeding.

what is a Vehicle (in case of how viruses spread)

Food or water that can transmit bacteria.

what are Virulence factors

Bacterial products or strategies that contribute to the ability of bacteria to cause infection, including promoting colonization and invasion, and damaging the host.

what are the two main categories of virulence factors

• promote colonisation and invasion

• damage host

Colonization and invasion

The process by which bacteria adhere to and enter the host's cells or tissues, facilitated by structures such as fimbriae/pili, flagella, and capsules.

what are Endotoxins

Toxins released by gram-negative bacteria when they die, triggering a cytokine release and potentially causing harm to the surrounding area.

what are pilli

• Attachment proteins

• Anchored to outer membrane enable the bacteria to adhere to host

what are flagella

Thin hollow, appendages which allow the bacteria to move via rotation

what is capsule

A polysaccharide layer which surround the cell , provides attachment and prevents being stuck in mucus

what are Exotoxins

Bacterial metabolites actively excreted from the site of infection to specific parts of the body.

what is Pneumolysin

• A pore-forming exotoxin produced by Streptococcus pneumoniae, critical in the development of community-acquired pneumonia.

• It causes cell apoptosis and can lead to inflammatory-mediated damage.

CAP (Community-Acquired Pneumonia)

• A type of pneumonia acquired in community or within 48 hours of hospital admission

what are the signs of CAP

• Fever

• Shortness of breath

• Productive cough

• Focal chest signs