Infection Control: Microorganisms, Transmission, and Prevention Strategies

Microorganisms

Small living organisms, invisible to the naked eye

Pathogenic

Able to cause disease

Nonpathogenic

Unable to cause disease

Bacteria

unicellular organisms; include coccus, bacilli, and spirilla

Protozoa

Unicellular, animal-like cell, often parasitic

Fungi

Plant-like organisms, includes yeasts and molds

Rickettsiae

Parasites such as lice, fleas, ticks

Viruses

Cannot reproduce without a host, major risk to healthcare workers

Cocci

Round shape bacteria, ex. streptococcus, staphylococcus

Bacilli

Rod-shaped bacteria, ex. tuberculosis, botulism

Spirilla

Spiral-shaped bacteria, ex. Cholera

Chain of Infection

A series of steps that pathogens follow to spread

Causative agent

The pathogen responsible for a disease

Reservoir

The place where the pathogen stays, ex. Human body

Portal of exit

The way the pathogen leaves the reservoir

Mode of transmission

How the pathogen is spread to a reservoir or host

Portal of entrance

A way for the pathogen to enter a susceptible host or reservoir

Susceptible host

Anyone who can contract the disease, especially those with weak immune systems

Fomite

A surface or object that is commonly handled by many people

Endogenous infections

Infections that occur inside the body

Exogenous infections

Infections that occur outside the body

Nosocomial infections

Diseases acquired while seeking help for another disease in healthcare facilities

Opportunistic infections

Infections that only affect the immunosuppressed

Generalized infection

A disease affecting multiple systems at once

Localized

a disease infecting only one system at a time

Avian

relating to birds

Influenza

a contagious disease of the lungs

Domesticated animals

animal that live around human

Contagious

capable of transmitting disease

Pandemic

an infectious disease that affects people globally

Epidemic

an infectious disease specific to one region or area

Zoonotic

an infectious disease passed from animals to humans

Supportive care

medical attention focused on providing comfort rather than curing an illness or disease

Antibiotics

used to kill or remove only bacterial infections

Antiseptics

the aseptic or sterile techniques used on the skin

Disinfectants

used to clean or sterilize a surface or tool

Epidemic vs Pandemic

A pandemic spreads to the entire world while an epidemic is local.

Aseptic techniques

Techniques used to reduce the risk of transmission, such as disinfecting items before using them.

Sterilization

When an environment is unable to support life, and sterile techniques are the maximum use of multiple aseptic techniques that create an environment that massively reduces the risk of transmission.

Zoonotic disease

An infectious disease that can be passed from animal to human.

Vector Borne disease

Transmitted to humans through a vector (mosquito, tick, etc.).

Rabies

Reservoir: primarily bats, also raccoons, cats, and dogs; Agent: virus; Transmission: saliva of infected animals; Human symptoms: seizure, paralysis, fever, hydrophobia; Treatment: vaccines if given immediately after exposure, however, if patient is not treated quickly, rabies is often fatal.

West Nile

Reservoir: birds; Agent: virus; Transmission: mosquito bites bird, picks up virus, bites human; Human symptoms: fever, flu-like symptoms; Treatment: supportive, usually clears in a few weeks for healthy individuals.

Toxoplasmosis

Reservoir: pigs (undercooked pork), cats, rats, deer, sheep; Agent: a single-celled parasite called toxoplasma gondii; Transmission: touching infected cat feces, eating undercooked meat, drinking contaminated water; Human symptoms: flu-like symptoms; Treatment: medication if needed.

Mad Cow Disease (Creutzfeldt Jakob Disease)

Reservoir: cattle; Agent: prion; Transmission: eating infected beef; Human symptoms: memory loss, emotional instability, weakness; Treatment: supportive (usually fatal within one year).

Lyme Disease

Reservoir: deer; Agent: borrelia burgdorferi, a bacteria; Transmission: black legged tick feeds on infected deer, picks up bacterium, and bites humans; Human symptoms: rash, arthritis, fever, swollen lymph nodes, neurological issues, heart problems; Treatment: antibiotics can be used for successful treatment when caught early.

Ringworm

Reservoir: any surface contaminated with fungus; Agent: several kinds of fungus; Transmission: touching a contaminated surface, brushes or combs, cows, horses, and other animals; Human symptoms: rash shaped in a ring on the skin, including scalp, groin area, and feet; Treatment: medicated creams, keeping the area clean and dry.

Avian Flu

Reservoir: birds, especially domesticated poultry; Agent: virus; Transmission: contact with infected poultry or environments; Human symptoms: flu-like symptoms, localized conditions to lungs, coughing, fever, sore throat, pneumonia; Treatment: seasonal flu medications.

Avian Flu Facts

• The deadly flu pandemic of 1918 (Spanish flu) was related to avian influenza

• COVID was a strain of avian influenza

• Wild birds can spread influenza to domestic poultry flocks

• In the 1997 Hong Kong outbreak, every chicken was killed to stop the the spread of disease to humans

• This virus has the ability to affect young, healthy people while most other flus only affect the elderly and infants.

Swine Flu (H1N1)

Reservoir: pigs (swine); Agent: virus; Transmission: airborne like coughs, sneezes, droplet, infected surfaces; Human symptoms: flu-like symptoms, pneumonia, diarrhea, vomiting; Treatment: antiviral medications.

Swine Flu Facts

• Less deadly than avian flu, more contagious

• Descendant of the 1918 Spanish Flu

• H1N1 strand of swine flu was first discovered in 1976

• Normally seen in birds and pigs, mutated to affect humans

Active Adaptive Immunity

A type of immunity characterized by memory cells and a slow response.

Natural Active Immunity

The immune system's reaction to physical illness.

Artificial Active Immunity

Vaccination that causes the body to produce B cells in an immune response.

Passive Adaptive Immunity

A type of immunity characterized by no memory cells and a fast response.

Natural Passive Immunity

Antibody IgA for newborns received from breast milk.

Artificial Passive Immunity

Injection of antibodies such as anti-venom or other antidotes.

Isolation and PPE

Proper isolation and personal protective equipment are essential to prevent the spread of infection in healthcare.

Standard precautions

Basic infection control practices including good hand washing and PPE usage.

Contact Isolation

Requires wearing gowns and gloves, private room, limited transportation, and patient-dedicated equipment.

Airborne Isolation

Requires wearing gowns and gloves, private room, limited transportation, and an N95 respirator.

Droplet Isolation

Requires wearing gowns, gloves, and a mask, private room, limited transportation, and eye protection.

Donning PPE Order

Hand washing, gown, mask, eye protection (if necessary), gloves, hair mask (if necessary).

Doffing PPE Order

Gloves/Hair mask, eye protection, gown, mask, hand washing.