Microbiology & Infection Control — Human Body Systems as Barriers, Portals, and Targets of Infection

Microorganisms

Bacteria, viruses, fungi, and parasites that interact with humans.

Colonization

Presence of microbes on or in the body without causing disease.

Infection

Microbial invasion of tissues causing harm and symptoms.

Normal microbiota

Microorganisms typically living on body surfaces exposing to the outside world.

Colonization resistance

Normal flora compete with pathogens, making the environment less hospitable.

Opportunistic infection

Organisms that can cause disease when they enter a normally sterile site.

Sterile sites

Body areas that should not contain microbes, such as blood and cerebrospinal fluid.

Non-sterile sites

Body areas that normally contain microbes, like the skin and gut.

Portals of entry

Routes that pathogens use to enter a host, such as the respiratory and gastrointestinal tracts.

Portals of exit

Routes that pathogens use to leave a host, such as respiratory secretions and feces.

Inflammation

An immune response characterized by redness, heat, swelling, and pain.

Skin's antimicrobial functions

Mechanisms such as physical barriers, antimicrobial substances, and normal flora that reduce microbial invasion.

Mucous membranes

Lining of body tracts that open to the outside and provide a sticky barrier.

Mucociliary escalator

A system in the respiratory tract where mucus traps particles and cilia move mucus upward.

Diarrhea

A symptom that spreads pathogens through fecal contamination.

Bacteremia

Presence of bacteria in the bloodstream.

Biofilm

Microbial community attached to a surface and embedded in a protective matrix.

Respiratory tract defenses

Anatomical and physiological features that prevent infections in the airways.

Urinary tract defenses

Mechanisms like urine flow and the urothelial lining that protect against infection.

Antigen-presenting cells

Cells that process and present antigens to T cells to initiate immune responses.

Adaptive immunity

Immune response involving B and T cells that recognize specific antigens.

Innate immunity

Immediate, broad defense mechanisms against pathogens.

Fever

Increased body temperature set-point driven by immune signaling.

Normal healing phases

Processes that wounds undergo: hemostasis, inflammation, proliferation, and remodeling.

Dysbiosis

Disruption of normal microbiota, often due to antibiotics.

Asymptomatic carriage

Presence of pathogens without displaying symptoms.

Aseptic technique

Practices that reduce the introduction of microbes during medical procedures.

Systemic infection

Infection that affects the entire body, often spreading rapidly.

Endotoxins

Toxins released from bacterial cells upon lysis, prompting immune responses.

Urinary catheter infection risk

Increased risk of infection associated with the use of indwelling catheters.

Vaccination

Process that prepares the immune system to recognize and fight pathogens.

Microbial load

The number of microorganisms present, influencing infection risk.

Immune tolerance

The ability of the immune system to ignore non-harmful antigens, maintaining homeostasis.

Local immune responses

Immune reactions occurring at the site of infection.

Contact transmission

Spread of pathogens by direct contact with infected individuals or surfaces.

Immunosuppression

Reduced immune function due to medication or disease, increasing infection risk.

Antimicrobial substances

Chemical compounds in body secretions that inhibit microbial growth.

Circulatory impairment

Reduced blood flow that can hinder healing and increase infection risk.

Portal of exit

Route through which pathogens leave a host, facilitating transmission.

Sepsis

A life-threatening response to infection characterized by systemic inflammation.

Infection control

Methods aimed at reducing the spread of infections in healthcare settings.

Hand hygiene

Practices that prevent the transfer of pathogens via hands.

Fecal-oral transmission

Pathogen spread that occurs via contamination of hands or food with feces.

Vaccination

Immunization process that prepares the immune system to fight specific pathogens.

Systemic inflammatory response

Widespread immune response characterized by symptoms such as fever and increased heart rate.