Chapter 5: Principle of Human-Microbe Interaction

Vocabulary practice covering the definitions, types, and transmission modes of human-microbe interactions as discussed in the lecture notes.

Normal biota

Microorganisms that live with us stably without causing harm, also referred to as normal flora or normal microflora.

Sterile Anatomical Sites

Internal tissues and organs normally free of microorganisms, including the heart, liver, lungs, brain, and muscles.

Resident Biota

Part of the normal, healthy microbial communities living on and within the human body that play essential roles in digestion and immune system development.

Transient Biota

Microbes that temporarily colonize the human body for a short period but do not become permanent residents.

Opportunists

Microbes that cause infection or disease when the host's immune system is compromised or when they gain access to areas where they are not normally found.

Propionibacterium acnes

Detailed as a normal flora of the skin inhabiting hair follicles that can cause the condition acne vulgaris.

Lysozyme

A limiting factor for microbial growth found in the conjunctiva (tears) and the mouth (saliva).

Stomach pH

A limiting factor for microbes in the upper intestinal tract where the environment is inhospitable due to a level of $pH\,2$.

Helicobacter pylori

A specific bacterium capable of surviving in the stomach's low pH environment, known to cause ulcers.

Vitamin K and Vitamin B12

Supplemental vitamins produced by normal flora as a benefit to the human host.

Commensal

A type of interaction that is beneficial to the microbe but does not help or harm the host.

Mutualistic

A relationship where both the microbe and the host receive benefits.

Parasitic

A relationship where the microbe benefits while the host is harmed, often through the production of endotoxins and exotoxins.

Pathogen

An infectious agent.

Infection

The process where microbes penetrate host defenses, enter tissues, and multiply.

Infectious disease

An infection that causes damage to tissues or organs.

Direct Contact Transmission

Person-to-person transmission involving no intermediate object, such as touching or kissing.

Fomite

A non-living object, such as towels, money, or door handles, used in indirect contact transmission.

Droplet Transmission

The spread of microbes in mucus droplets (more than $5\,\text{microns}$) through sneezing, coughing, or talking.

Airborne Transmission

The spread of microbes by tiny particles (less than $5\,\text{microns}$) that are suspended in the air for longer and travel further than droplets.

Mechanical Transmission

A type of vector transmission involving the passive transport of a pathogen on an insect's body, such as a bee.

Biological Transmission

A type of vector transmission where the pathogen spends part of its life cycle in the vector, such as a mosquito.