[John-paul]

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:

[Saleema]

Infectious Agent: Influenza Virus

Reservoirs: Residents, staff and visitors in LTC home

Portals of Exit: Respiratory secretions such as coughing, sneezing

Modes of Transmission: Droplet during close contact and indirect contact such as contaminated hands.

Portals of Entry: Through the nose, mouth and eyes (mucous membranes)

Susceptible Host:Elderly residents, those with chronic illnesses, weakened immune systems, or incomplete vaccination status

[Yi]

Hi Saleema,
I really liked your example of influenza in long-term care home because it is very realistic and relevant to practice. You clearly explained each link in the chain of transmission, especially the reservoir, portal of exit, and susceptible host. I also agree that elderly residents and those with chronic illnesses are at greater risk of infection and complications. Your post shows why infection prevention measures such as hand hygiene, PPE, respiratory etiquette, and vaccination are so important in LTC settings. Great job.

[Amanda]

Hi Saleema, great connection with your practice area and how you pointed out the mode of transmission. It also made me think how the chain also applies in pediatric settings as well with a high risk population. For example, rather than elderly residents, infants and young children would be considered susceptible hosts – especially those that are premature, immunocompromised or have underlying respiratory issues. In peds, I would even say the transmission risk is even higher with behaviours like frequent hand to mouth or face contact.

[Damilola]

Infectious Agent: MRSA
Reservoirs: Patient,visitors and caregivers hands in the Hospital
Portal of Exit: drainage from wound and skin leision and nasal mucous
Mode of Transmission: Direct contact to infected area, Undisinfected blood pressure cuffs and transfer lifts
Portal of entry: Nose, open wound and perineal area
Susceptible Host: Immunocompromised person e.g Patient in ICU and burn unit. Frequent use of antibiotics

[Melissa]

Hi Damilola, I currently work with residents who are infected with MRSA in a long-term care facility. Because I provide direct personal care to a population of vulnerable people, I need to use contact precautions appropriately when assisting MRSA-infected residents to prevent the spread of the infection. Additionally, maintaining consistent standard precautions, such as frequent hand hygiene with soap and water and alcohol-based sanitizers throughout my shift, is crucial. MRSA is a highly contagious infection. Thank you for sharing the chain of transmission with us. ~Melissa

[Basirat]

Hi Damilola, I agree with your breakdown this is a realistic example of the chain of transmission for MRSA in a healthcare setting. You clearly captured how easily it spreads through direct contact and contaminated equipment, which is a big issue in healthcare practice.

One small addition I would emphasize is the importance of hand hygiene as the key point to break the chain, especially since healthcare workers’ hands are a major reservoir and mode of transmission. Even with proper precautions, missing hand hygiene can quickly lead to spread between patients.

Overall, your post shows a strong understanding of how MRSA transmission occurs and how multiple links in the chain are connected.

[Ochuko Bridget]

Practice Area: (Medical-surgical unit of a GTA hospital during my placement)

Chain of Transmission Example: (Respiratory Infection- COVID-19):

Infectious Agent: SARS-CoV-2 (virus causing COVID-19)
Reservoirs: Infected patients who were placed in shared rooms and hallway spaces, and also healthcare workers who are asymptomatic carriers
Portals of Exit: Respiratory secretions from coughing, sneezing, talking (droplets from nose and mouth)
Modes of Transmission: Droplet spread, especially when two infected patients are placed close together. Indirect contact via contaminated surfaces like the bed rails, IV poles, and curtains in crowded hallway settings
Portals of Entry: Mucous membranes of the eyes, nose, and mouth of nearby patients, staff, and visitors
Susceptible Host: Other hospitalized patients, especially elderly, immunocompromised, and post-surgical patients, healthcare workers with inadequate PPE use, and visitors

[Yi]

Practice Area: Long-Term Care

Chain of Transmission Example: Norovirus in a Long-Term Care Home

Infectious Agent: Norovirus

Reservoirs: Infected residents, staff, visitors, contaminated food, and contaminated environmental surfaces in the long-term care home.

Portals of Exit: Vomitus and feces from an infected person.

Modes of Transmission: Direct contact with an infected resident, indirect contact through contaminated hands, equipment, or surfaces, and ingestion of contaminated food or water.

Portals of Entry: Mouth, especially when hands, food, or fluids are contaminated with the virus.

Susceptible Host: Older adults in long-term care, especially residents with chronic illnesses, weakened immune systems, dehydration risk, or reduced mobility.

Why this is important in LTC: In long-term care, infections such as norovirus can spread quickly because residents live closely together and often share dining areas, washrooms, and common spaces. Hand hygiene, proper PPE use, environmental cleaning, and isolating symptomatic residents are important to break the chain of transmission.

[Damilola]

Hi Yi, Norovirus spreads extremely easily in long-term home care, where residents are older, immunocompromised and live in proximity. Norovirus spreads when stool or vomit particles contaminate hands, surfaces, food or water, and another person ingests them by direct person-to-person contact or touching contaminated surfaces and also eating food handled by an infected person. Hand hygiene and PPE are a quick way to limit the spread. Damilola

[Saleema]

Hi Caroline!
MRSA is a great example to use when discussing the chain of infection. This is a very practical real life example as I work in LTC and we do have residents that do end up having MRSA after returning home from a hospital visit. Allot do have open wounds and sometimes do not understand the importance of keeping the wounds covered. I found that following standard precautions (i.e proper PPE and hand hygiene do help when dealing with MRSA.

[Yi]

Hi Damilola,
Thank you for your response. I agree that norovirus spreads very easily in long-term care because residents live closely together and are more vulnerable to infection. You made a very good point about contamination of hands, surfaces, food, and water. Hand hygiene, PPE, and proper environmental cleaning are very important to prevent outbreaks. Thanks for sharing.

[Melissa]

Chain of Transmission Example—A resident acquired Clostridioides difficile when hospitalized and returned to the LTC facility with the infection.

Practice Area: Resident Home Area in a Long-Term Care Facility.

Infectious Agent: Clostridioides difficile (C. diff)—a type of bacteria that causes irritation and swelling of the colon, leading to gastrointestinal symptoms.

Reservoir: Human feces from the infected individual (primary); contaminated surfaces in the LTC environment.

Portal of Exit: Feces from the infected individual.

Modes of Transmission: Contaminated health care workers’ hands due to not washing hands with soap & water after direct resident contact. Subsequently, C. diff spores continued to be transmitted throughout the unit and contaminated many surface areas because spores are resistant to alcohol-based sanitizers.

Portal of Entry: Mouth (fecal-oral)—residents became infected because C. diff spores were ingested from contaminated high-touch surfaces around the unit.

Susceptible Host: Residents (older adults) who are more susceptible to the infection due to having a weaker immune system. As well as residents who may be on antibiotics or who are immunocompromised.

[Caroline]

Hi Melissa, I enjoyed reading your chain of infection!
I wanted to make note, that while yes the residents are at risk if they have an immunocompromised immune system, us as staff are also at risk should we not follow correct donning and doffing, or improper hand hygiene. Exposure without proper protection also puts us at risk.

[Caroline]

A patient with MRSA, wounds on their forearm. With the wound covered, this patient was allowed to partake in floor activities, interact with patients and participate in groups.

However this patient would frequently remove the dressing, they would touch all door knobs/handles. They would enter all shared spaces, and they would require frequent reminders to perform hand hygiene.

Infectious Agent: MRSA
Reservoir: The patient and their wound, blood or body fluid from this wound.
Portal of Exit: The uncovered wound, wound secretions.
Modes of transmission: The patients hands as they would pick at their wounds and then touch various surfaces. Door handles, railings, the kettle and share furniture/appliances if not cleaned right away.
Portal of Entry: Any open wound. If another patient touched the same surface and brought their hand to their mouth or eyes.
Susceptible Hosts: Any patient or staff that has direct contact with any open sores. Many of these patients were susceptible as they were drug users, and many had open sores, and were immunocompromised.

[Ochuko Bridget]

Hello Caroline.
I enjoyed reading your post because it showed how MRSA can spread when one part of the chain of infection is not controlled. The example of the patient removing their wound dressing and touching shared surfaces makes it easy to see how the bacteria can move from person to person due to the behavior of patients/residents, and when hand hygiene is not consistent.
I have seen something similar in practice. In one hospital I worked at, three patients were infected with MRSA because rooms and shared surfaces were not properly cleaned between patient transfers. Even with precautions in place and hand hygiene, missed cleaning of high-touch areas allowed the infection to spread. This shows how important both patient behavior and proper cleaning are in preventing infections on the unit.

[Basirat]

Practice Area: Long Term Care

Infectious Agent:
Vancomycin-resistant Enterococcus (VRE)

Reservoirs:
Newly admitted resident’s gastrointestinal tract
Contaminated environment (bed rails, commode, linens)
Healthcare workers’ hands after contact

Portals of Exit:
Feces (primary)
Possible contact with contaminated bodily fluids

Modes of Transmission:
Direct contact (hands of healthcare workers during personal care, toileting)
Indirect contact (contaminated surfaces or shared equipment not properly disinfected)

Portals of Entry:
Gastrointestinal tract (via ingestion)
Urinary tract (especially if catheter present)
Broken skin or invasive devices

[Catherine]

As many have already expressed, all of us (workers, visitors, patients) can be potentially at risk when caring for patients in any setting. Damilola, Basirat, and Yi highlighted how hand hygiene remains such an important factor when stopping the transmission of infection. Caroline, I appreciated how you also highlighted something we do not always speak enough about, how important patient education and knowledge is around their role in infection prevention. Your example specifically highlighted the danger associated with patients who are unclear or non-adherent to IPAC protocols. Overall, understanding the chain of transmission is vitally important, and allows us as practitioners to know how we can best intervene to prevent the spread of infection. Excellent work everyone on this week’s module!

[Yetunde]

Chain of Transmission – C. difficile (C. diff)

Rehab unit

Infectious Agent:
Clostridioides difficile (C. diff) bacteria

Reservoir:
Infected patient’s stool and contaminated healthcare environment (bedpans, toilets, bed rails, call bells, and other surfaces)

Portal of Exit:
Feces (stool), especially during diarrhea

Mode of Transmission:
Fecal–oral route through indirect contact. Spores are spread via contaminated hands, equipment, or surfaces when proper hand hygiene and cleaning are not followed.

Portal of Entry:
Mouth (ingestion of spores), usually through contaminated hands or objects

Susceptible Host:
Hospitalized or rehabilitation patients, especially older adults, those on antibiotics, or individuals with weakened immune systems

[Amanda]

Practice area: Pediatrics

Infectious Agent: Respiratory Syncytial Virus (RSV)
Reservoirs: Children typically, or contaminated surfaces (toys, crib, bedding, etc). Caregivers can also be resovoirs.
Portals of exit: Respiratory tract
Mode of transmission: droplet – contact
Portal of entry: eyes, nose, mouth
Susceptible hosts: infants, young children, immunocompromised children and elderly

[Author]

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