The infection chain — breaking the path for microorganisms
The six links in a transmission path and how cleaning interrupts them
Microorganisms do not spread by accident — they follow a chain of links that all must be present for infection to succeed. Break just one link and the infection stops. That is the whole professional logic behind hygienic cleaning: you do not need to remove every single bacterium, but you must break the chain at points where your cleaning makes the biggest difference. The model is particularly important in healthcare, care and institutional settings.
§The six links of the infection chain
The infection chain is often described as six links that follow each other. If you understand the links, you can point to where an intervention works.
| Led | What it is |
|---|---|
| Source of infection | The reservoir where the microorganism is found (humans, animals, water, surfaces) |
| Exit gate. | How it leaves the source (air route, wound, faeces, mucous membranes) |
| Route of transmission | How it is transported (hands, surfaces, drops, equipment) |
| Individually manufactured equipment such as prosthetics and orthotics is considered under MDR as 'custom-made devices', i.e. equipment manufactured to measurements. | How it enters a new host (mouth, eyes, wounds, air routes) |
| Susceptible host | A person who can become ill (weakened sick or without resistance) |
| New source of infection | The infected person becomes a source themselves — and the chain repeats |
§The most important transmission routes
As a service assistant you work especially with the transmission route — the third link — because this is where cleaning and hygiene directly intervene. Most infections in a workplace spread through contact: hands and surfaces. Droplet infection (coughing and sneezing) and airborne infection also play a role but the contact route is the one you have the most influence over through cleaning.
- 01Direct contact transmission: person to person, e.g. via hands
- 02Indirect contact transmission: via surfaces, equipment and contact points
- 03Droplet transmission: coughing, sneezing and talking at short distance
- 04The air you breathe
- 05Foodborne infection: via food and drink with poor hygiene
§Where cleaning breaks the chain
Cleaning primarily targets the transmission route. When you clean contact points – door handles, switches, taps, railings – you remove the surfaces microorganisms 'jump' on to next. When you keep tools separate with colour codes and change cloths from dirty to clean, you avoid becoming a transmission route yourself carrying microorganisms from one area to another. And hand hygiene – both your own and users' – stops the most common route of all.
§The receptive host — that's why the level is higher in some places
The last thing you have influence over is to be mindful of how receptive the hosts are. In a hospital a nursing home or a daycare center many people are weakened sick or have reduced resistance — they get sick from fewer microorganisms. Therefore the hygiene requirements and cleaning level are higher precisely there and therefore cleaning and disinfection come in the right order with extra weight.
§From model to habit
The infection chain is not just theory for an exam — it is the reasoning behind daily routines. Every time you ask 'where do I break the chain here?', you choose the intervention that works: contact points rather than just floors, clean-to-dirty sequence, separate tools and hand hygiene at the right times. It is the difference between cleaning and preventing infection.
“You don't need to defeat every microorganism — you just need to break one link in the chain every time.”
— Hygiene professional basic rule