A Colour Coding System and Infection Control for Cleaners – Part III

Bacteria Routes of Transmission

In Knowledge Resource, Training, Infection Control, Colour Coding

Bacteria Routes of Transmission

Transmission of bacteria can be achieved in a number of ways including:

Routes of Transmisson1. Contact Direct - Pathogens can be transmitted with direct contact with body fluids or items contaminated with it e.g. tissues, disposable nappies, incontinence pads/bags etc.

Indirect - This is probably the most significant route for the spread of harmful bacteria and include:

  • Other people, via unprotected hands
  • Animals such as rats, pigeons, domestic pets etc via droppings, hairs and other deposits
  • Contaminated water
  • Furniture, fixtures and fittings including bedding, upholstery, contact surfaces, tap heads, door handles etc.
  • Contaminated food

2.Airborne Pathogens themselves are incapable of propelling themselves through the air. As such, they rely on airborne particles for transmission via the air. Transmission is achieved in the following ways:

Respiratory droplets - coughing and sneezing can transmit large droplets infected with pathogens capable of causing common cold and influenza-like infections.

Dust - contains dead skin cells that can contain harmful bacteria and spores.

Water - transmission can occur in small droplets from infected sources e.g. legionella via untreated shower heads.

3. Insects Insects, or anthropoids, include flies, bugs, ticks, lice, cockroaches and fleas. Insect-born pathogens are normally transmitted by sucking, biting, burrowing or via droppings. Diseases associated with insects include salmonella.

(The problems associated with all building pests are covered thoroughly in the Biohazards Guide).

Susceptible hostSusceptible host The susceptibility to infection differs significantly from person to person. Generally, however, susceptibility to infections increases in people at the extremes of the age spectrum.That is why extra care should be taken when cleaning buildings primarily used by young children and elderly people. Also, people already suffering from the effects of a disease or infection, or recovering from it have an increased susceptibility to infections.

Taking all of this into consideration it becomes clear that infection control measures in nurseries, elderly care environments and clinical premises are critical in protecting users of the building from infections and diseases.

Points of entry

In order for the body to become adversely affected by bacteria and viruses, it must come into contact with them. There are a number of ways this can happen:


Airborne particles contaminated with bacteria can be breathed in causing infections. Dry cleaning processes such as dusting and vacuuming can increase the amount of particles in the air and care should be taken by operatives to control the amount of dust disturbed and allowed to become airborne. For instance, when dusting, surfaces can be damped down with water or furniture polish and vacuum cleaner filters should be cleaned regularly.


Contaminated items and surfaces can be touched and the bacteria inadvertently transferred to the mouth by touching the mouth and lips. This way the bacteria is ingested and can cause problems with the digestive system leading to stomach upsets, vomiting, diarrhoea and other serious infections.

Contact with broken and unbroken skin.

Point of EntryIf an operative has an open, undressed wound, bacteria will enter the body if it is allowed contact with it. Therefore, all open wounds must be covered with waterproof dressings before cleaning can commence.

Also, if the operative has an intolerance to certain organisms in the environment and the intolerance manifests itself in the form of rashes with areas of broken skin (i.e. eczema), these rashes can become further infected and must be suitably dressed. It should also be pointed out that bacteria in contact with unbroken skin can still lead to an infection.

The way in which we prevent certain harmful bacteria entering or coming into contact with the body is by the issue of Personal Protective Equipment (PPE). In most cases PPE can be used to protect the respiratory and gastro-intestinal tracts, as well as the skin, especially the hands, which are the most significant parts of the body susceptible to infection by viruses, bacteria and certain fungi.

Conditions for MO Growth

Now that we have an understanding of the way in which harmful bacteria can cause infections, we must consider the conditions that affect the ability of these micro-organisms to survive and multiply. In general terms there are four main factors that directly influence the growth of bacteria. These are:

1.Temperature All bacteria, like most living organisms, thrive if the temperature is just right i.e.not too warm and not too cold. The following chart indicates the affects on bacteria growth through a range of temperatures:

Temp Chart

As you can see from the chart, extremes of temperature allow bacteria to be controlled effectively and they will grow rapidly within the mid-range.

2. Moisture Again, like all living things, bacteria require water or moisture to survive. High levels of humidity will encourage bacteria growth.

3.Time The longer bacteria are allowed to dwell on a surface without disinfection, the more they will continue to grow in numbers, increasing the risk of infection.

4. Food Certain foods are more susceptible to infection than others. For instance, soups,gravies,meat, eggs, milk and dishes made from them are considered to be high-risk foods in terms of contamination. Also, the more food is handled or reheated will increase the likelihood of contamination. Foods that are less likely to become contaminated are those with high levels of salt and sugar or products contained in vinegar. Nevertheless, all foodstuffs are potential sources of bacteria contamination and care should be taken that all are handled and stored safely and correctly. Waste foods should be disposed of immediately to remove the risk of contamination.


To download our Free Guide, click the link below:

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Related Articles:

A Colour Coding System and Infection Control for Cleaners - Part I

A Colour Coding System and Infection Control for Cleaners - Part II

A Colour Coding System and Infection Control for Cleaners - Part IV

A Colour Coding System and Infection Control for Cleaners - Equipment




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