[Grace]

Thinking of your current or a past practice area provide an example of the train of transmission specific to that area. Fill in all ‘links’ in the chain with an example for each link:

Infectious Agent:

Reservoirs:

Portals of Exit:

Modes of Transmission:

Portals of Entry:

Susceptible Host:

[Priscilla]

Residents in Long-Term Care Homes
Locations: Dining room, Recreation area, Hallways

Infectious Agent: SARS-CoV-2 (Covid-19)

Reservoirs: Residents can be symptomatic, pre-symptomatic, and asymptomatic carriers.

Portals of Exit: Respiratory tract eg. coughing, sneezing, talking, breathing, shouting.

Modes of Transmission: Droplet (main mode)
Respiratory droplets from coughs, sneezes, or speech within close range, usually <2 meters.
Airborne transmission in enclosed & poorly ventilated spaces such as smaller aerosols that remain suspended in air for longer periods.

Portals of Entry: Respiratory tract such as nose & mouth
Mucous membranes such as eye, nose & mouth.

Susceptible Host: Anyone without immunity such as Elderly individuals, Immunocompromised individuals, Unvaccinated individuals.

[Bolatito Esther]

1. Infectious Agent: Escherichia coli (E. coli) is a common bacterium that causes urinary tract infections, often associated with the use of catheters.

2. Reservoir: The patient’s bowel or skin flora, which can harbour bacteria such as Pseudomonas aeruginosa.

3. Portal of Exit: Bacteria present in urinary secretions can exit through the urethral meatus during urination or drainage.

4. Mode of Transmission: improper sterile technique during catheterization or not placing the drainage bag below the bladder level, or a patient who uses a catheter for a long time

5. Portal of Entry: The urinary tract mucosa or the insertion point of the catheter provides a pathway for bacteria to enter the bladder.

6. Susceptible Host: Catheterized patients, compromised immune systems or the elderly age, are more vulnerable to infection.

[Shanna]

During my clinical placement on a medicine unit, I saw an example of how infection can spread through the chain of transmission. This involved a patient with C. difficile, a bacteria that causes diarrhea.

Infectious Agent: C. difficile bacteria

Reservoirs: The infected patient

Portals of Exit: The patient’s stool

Modes of Transmission: Indirect contact (a healthcare worker touches a dirty surface or doesn’t clean their hands properly).

Portals of Entry: The mouth, if someone eats or touches their face with dirty hands

Susceptible Host: Another patient who is older, sick, or taking antibiotics

It is important to follow proper hand hygiene, use PPE, and clean equipment to stop the spread of infection.

[Nel]

Hi Shanna!
Thank you for sharing this clear and practical example of how the chain of infection works, especially in the context of C. difficile. Your explanation reinforces the crucial role of proper hand hygiene, PPE use, and thorough environmental cleaning in protecting patients. Personally, if I had to choose one type of isolation I least prefer, it would be C. difficile – not only because of the infection risk but also due to the unpleasant smell and discomfort it often brings. 

[Bolatito Esther]

Hi Mebo
Hepatitis A virus is such a good example.
It is a contagious liver infection caused by the hepatitis A virus. It is usually spread through ingestion of contaminated food or water or close contact with an infected person. Nurses need to recognize the symptoms such as Fatigue, nausea, abdominal pain, jaundice, dark urine, and fever. Some individuals, especially young children, may be asymptomatic.
Good hygiene practices, proper handwashing, and vaccination are highly recommended, especially in outbreak situations.

[Shanna]

Hi Priscilla,

Thanks for sharing this clear example. It shows how easily COVID-19 can spread in long-term care homes, especially in places like dining rooms and recreation areas. I like that you mentioned both droplet and airborne spread. It reminds us why good ventilation, masks, and distancing are important. Older and sick residents are at higher risk, so following all steps in the chain of transmission is very important to keep patients safe.

[Nel]

Infectious Agent: VRE
Reservoirs: contaminated equipment (VS machine, stethoscope, glucometer), colonized oncology patient
Portals of Exit: patient’s skin
Modes of Transmission: indirect contact via contaminated equipment or hands of HCP who have not performed hand hygiene
Portals of Entry: mucous membranes, non-intact skin, hands touching face
Susceptible Host: immunocompromised oncology patients

[Mebo]

Infectious Agent: Hepatitis A virus (HAV)

Reservoirs: people infected with HAV, environment for example surfaces

Portals of Exit: feces of infected people

Modes of Transmission: through the stools of infected person

Portals of Entry: fecal -oral route i.e contact of contaminated surfaces, food handlers poor hand hygiene

Susceptible Host: Travelers to poor sanitation places, children in daycare, patients with chronic liver disease, close contact with infected people

[Author]

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