Sterilising

Advice to help parents sterilise their baby’s feeding equipment

Why sterilise?

During their first year of life, babies are at their most vulnerable to viruses, bacteria and parasitic infections, which can lead to anything from a mild attack of oral thrush to the more serious condition of gastroenteritis.

Milk is the perfect medium for growth of bacteria, and therefore poorly cleaned feeding equipment can be a potent source of infection for babies.¹The organisms of most concern are reported to be Salmonella² and Cronobacter sakazakii (formerly called Enterobacter sakazakii).^2,3 To reduce contamination by these organisms, the British and Irish governments recommend that formula feeds are made up using boiled water that is at least 70^oC (i.e. water that has been boiled and left to cool for no more than 30 minutes) and that formula is made up fresh for each feed.⁴

A report by the European Food Safety Authority (EFSA)² concludes that cleaning and sterilisation of equipment in the home is a critical part of the avoidance of infection; recommendations include the use of ‘sterile bottles, achieved by heating and chemical methods’, although no evidence is provided on the relative effectiveness of these methods.

The recent World Health Organisation (WHO) guidelines published in 2006 and updated in 2007⁵ are consistent with the EFSA recommendations and suggest that manufacturer’s instructions should be followed for chemical or steam sterilisation procedures. These guidelines are stated to be ‘largely based’ on the findings of a quantitative microbiological risk assessment for Cronobacter sakazakii.

Effective cleaning and sterilisation of infant feeding equipment offers the opportunity to minimise risks to the baby and could result in significant clinical and cost benefits.⁶

Sterilising advice for parents

When?

For at least the first six months, all feeding equipment must be sterilised before each use. If you are still using a bottle and teat after six months, sterilise before each use

What equipment is needed?

Either a steam steriliser, a cold-water steriliser with sterilising fluid or tablets, or a large lidded pan that has never been used for cooking
Bottles and teat brush
Teat tongs
Feeding equipment which is not cracked, scratched or damaged in any way

How?

Before sterilising, parents should:

Wash their hands and clean the surface where the bottles will be assembled
Wash the feeding equipment they will be using thoroughly in hot, soapy water
Scrub inside and outside of any bottles using a bottle brush
Scrub teats with a teat brush and squirt water through them to help remove all traces of milk
Rinse all equipment thoroughly under running water

For more information have a look at our video ‘sterilising’, or our helpsheet

Milk feeds should be made up one at a time, so parents should sterilise as they go, not in batches.

Sterilising Methods

Sterilising by boiling

Check that the equipment is suitable for boiling
Fill a large clean pan (which has not been used for cooking) with tap water
Completely immerse all of the equipment, including teat tongs, ensuring there are no trapped air bubbles
Cover the pan and boil for at least 10 minutes, ensuring the pan doesn’t boil dry and all utensils remain under the boiling water
Keep the lid on the pan and allow the contents to cool slightly
Assemble bottles using teat tongs to avoid contaminating sterile equipment
Equipment will stay sterile for three hours in the water with the lid on

Check that the equipment is suitable for boiling
Fill a large clean pan (which has not been used for cooking) with tap water
Completely immerse all of the equipment, including teat tongs, ensuring there are no trapped air bubbles
Cover the pan and boil for at least 10 minutes, ensuring the pan doesn’t boil dry and all utensils remain under the boiling water
Keep the lid on the pan and allow the contents to cool slightly
Assemble bottles using teat tongs to avoid contaminating sterile equipment
Equipment will stay sterile for three hours in the water with the lid on

Cold water sterilising

Fill the cold-water steriliser with the required amount of water following the manufacturers’ instructions
Add the required amount of sterilising liquid or tablets, again following the manufacturers’ instructions
Completely immerse all of the equipment, including teat tongs, ensuring there are no trapped air bubbles, and put the lid on (use a float tray to keep everything under the water)
Keep items immersed for at least 30 minutes
Rinse all items with cooled, boiled water before use
Items remain sterile if kept in the solution for 24 hours, after which time the water should be discarded

Fill the cold-water steriliser with the required amount of water following the manufacturers’ instructions
Add the required amount of sterilising liquid or tablets, again following the manufacturers’ instructions
Completely immerse all of the equipment, including teat tongs, ensuring there are no trapped air bubbles, and put the lid on (use a float tray to keep everything under the water)
Keep items immersed for at least 30 minutes
Rinse all items with cooled, boiled water before use
Items remain sterile if kept in the solution for 24 hours, after which time the water should be discarded

Microwave steam sterilising

Add the required amount of water to the steriliser according to the manufacturers’ instructions
Load the steriliser with the equipment, including teat tongs, making sure that no items are facing upwards/able to fill with water
Put the lid on the steriliser and put it in the microwave on the required power setting for the required amount of time, again following the manufacturers’ instructions
Keep the lid on the steriliser and allow the contents to cool slightly before opening
Assemble bottles using the teat tongs to avoid contaminating the sterile equipment
Equipment will stay sterile until the lid is removed
This type of steriliser may require occasional de-scaling, depending on the hardness of the water

Add the required amount of water to the steriliser according to the manufacturers’ instructions
Load the steriliser with the equipment, including teat tongs, making sure that no items are facing upwards/able to fill with water
Put the lid on the steriliser and put it in the microwave on the required power setting for the required amount of time, again following the manufacturers’ instructions
Keep the lid on the steriliser and allow the contents to cool slightly before opening
Assemble bottles using the teat tongs to avoid contaminating the sterile equipment
Equipment will stay sterile until the lid is removed
This type of steriliser may require occasional de-scaling, depending on the hardness of the water

Electric steam sterilising

Add the required amount of water to the steriliser, following the manufacturers’ instructions
Load the steriliser, with equipment, including teat tongs, making sure that no items are facing upwards or able to fill with water
Put the lid on the steriliser and switch it on
Keep the lid on the steriliser and allow the contents to cool slightly before opening
Assemble bottles using the teat tongs to avoid contaminating the sterile equipment
Equipment will stay sterile until the lid is removed
This type of steriliser needs de-scaling on average once a month

Add the required amount of water to the steriliser, following the manufacturers’ instructions
Load the steriliser, with equipment, including teat tongs, making sure that no items are facing upwards or able to fill with water
Put the lid on the steriliser and switch it on
Keep the lid on the steriliser and allow the contents to cool slightly before opening
Assemble bottles using the teat tongs to avoid contaminating the sterile equipment
Equipment will stay sterile until the lid is removed
This type of steriliser needs de-scaling on average once a month

After sterilising

Wash your hands and clean the surface where the bottles will be assembled before removing equipment
Remove equipment just before it’s needed
If not being used immediately, bottles should be fully assembled with teat and lid in place. This prevents the inside of the sterilised bottle as well as inside and outside of the teat from being contaminated for a short period, which depends on the method of sterilisation

References

Thompson J (2002) Benefits of breastfeeding and current controversies: part two. Community Pract 75, 106–107.
European Food Safety Authority (2004) Opinion of the Scientific Panel on Biological Hazards on a request from the Commission related to the microbiological risks in infant formulae and follow-on formulae. EFSA Journal 113, 1–35.
Forsythe SJ (2005) Enterobacter sakazakii and other bacteria in powdered infant milk formula. Matern Child Nutr 1, 44–50.
Food Standards Agency (2006) Guidance on preparing infant formula February 2006. http://www.food.gov.uk/news/newsarchive/2007/jul/nonsterile
World Health Organization/Food and Agriculture Organization of the United Nations (2007) Safe preparation, storage and handling of powdered infant formula: Guidelines. http://www.who.int/foodsafety/publications/micro/pif_guidelines.pdf (accessed May 2009).
Rowan N & Anderson J (1998) Effectiveness of cleaning and disinfection procedures on the removal of enterotoxigenic Bacillus cereus from infant feeding bottles. J Food Prot 61, 196–200.

Thompson J (2002) Benefits of breastfeeding and current controversies: part two. Community Pract 75, 106–107.
European Food Safety Authority (2004) Opinion of the Scientific Panel on Biological Hazards on a request from the Commission related to the microbiological risks in infant formulae and follow-on formulae. EFSA Journal 113, 1–35.
Forsythe SJ (2005) Enterobacter sakazakii and other bacteria in powdered infant milk formula. Matern Child Nutr 1, 44–50.
Food Standards Agency (2006) Guidance on preparing infant formula February 2006. http://www.food.gov.uk/news/newsarchive/2007/jul/nonsterile
World Health Organization/Food and Agriculture Organization of the United Nations (2007) Safe preparation, storage and handling of powdered infant formula: Guidelines. http://www.who.int/foodsafety/publications/micro/pif_guidelines.pdf (accessed May 2009).
Rowan N & Anderson J (1998) Effectiveness of cleaning and disinfection procedures on the removal of enterotoxigenic Bacillus cereus from infant feeding bottles. J Food Prot 61, 196–200.