Cronobacter Support
03-06-2009, 08:49 AM
3.2 Rationale behind recommendations
3.2.1 Good hygienic practice
Poor hygiene has been reported as the probable cause of some E. sakazakii outbreaks (Forsythe, 2005). The person preparing the feed should clean and disinfect the preparation surface and wash hands with soap and water before preparing a feed. This is because harmful bacteria can be carried on hands and can also be present on surfaces. Washing hands and cleaning and disinfecting surfaces reduces the risk of feeds becoming contaminated during preparation.
Hands must also be washed after using the toilet and after diaper changing because harmful bacteria, including E. sakazakii (Drudy et al., 2006), have been found in the urine and stools of infants. These bacteria can easily be carried on the hands and contaminate feed during its preparation.
3.2.2 Cleaning and sterilizing feeding and preparation equipment
Outbreaks of E. sakazakii infection have been attributed to equipment used for preparing feeds (Gürtler et al., 2005). E. sakazakii is widespread in the environment and has been shown to attach and grow (form 'biofilms') on surfaces commonly used in infant feeding equipment, such as latex, silicon and stainless steel. It is therefore important that all infant feeding and preparation equipment (e.g. feeding cups, bottles, rings and teats) has been thoroughly cleaned and sterilized before use, since the formation of biofilms on such equipment may result in reservoirs of infection that can continually contaminate feeds (Iversen, Lane and Forsythe, 2004).
3.2.3 Temperature of water for reconstitution
According to the FAO/WHO risk assessment, risk is dramatically reduced when PIF is reconstituted with water that is no less than 70 °C, as this temperature will kill any E. sakazakii in the powder. This level of risk reduction holds even if feeding times are extended (i.e. up to two hours), and even if ambient room temperature reaches 35 °C. Consequently, reconstituting PIF with water no less than 70 °C dramatically reduces the risk to all infants, even slow feeding infants and infants in warm climates where refrigeration may not be readily available (e.g. developing countries).
When PIF is prepared with water cooler than 70 °C, it does not reach a high enough temperature to completely inactivate E. sakazakii present in the powder. This is a concern for two reasons: a) a small number of cells may cause illness, therefore it is important that cells present in the PIF are destroyed; and b) the potential for surviving cells to multiply in the reconstituted formula. This risk is increased when the reconstituted formula is held for extended periods above refrigeration temperature.
Concerns have been raised over the use of very hot water for reconstituting PIF, but risk of E. sakazakii is only dramatically reduced when water at a temperature of no less than 70 °C is used. Currently, the instructions on many PIF products lead to PIF being reconstituted with water that is around 50 °C. But, according to the FAO/WHO risk assessment, reconstitution with 50 °C water generally results in the greatest increase in risk, unless the reconstituted formula is consumed immediately. Under no circumstances is risk reduced when PIF is reconstituted with 50 °C water. Manufacturer's instructions should be reviewed in the light of the findings of the risk assessment.
3.2.4 Storage of prepared feeds
Because PIF may contain harmful bacteria, it is best to prepare it fresh for each feed. However, in practical terms this is not always possible. Feeds may need to be prepared in advance, e.g. for the crèche, babysitter, or if you are going out for the day. In these circumstances, feeds should be prepared using water no less than 70 °C, cooled quickly immediately after preparation, and stored in the refrigerator (at 5 °C or colder) for no more than 24 hours.
Feed stored in the refrigerator should be used within 24 hours of preparation. Even if water no less than 70 °C was used to reconstitute PIF, spoilage bacteria may have survived that can grow at refrigeration temperatures and can cause feeds to spoil. The quality of reconstituted PIF may also deteriorate on prolonged storage.
Feeds should be cooled quickly before placing into the refrigerator, as hot feeds will increase the refrigerator's temperature. Feeds can be rapidly cooled by placing under cold running water or in a bowl of cold water.
3.2.5 Re-warming and use of stored feeds
Because of the possibility of growth of harmful bacteria at temperatures above 5 °C, stored formula should not be removed from the refrigerator and re-warmed until immediately before feeding. Feeds should not be left warming for more than 15 minutes as re-warming for extended periods means that the feed will be held at a temperature that is ideal for the growth of harmful bacteria. Holding feed in bottle warmers for lengthy periods was reported as one of the probable causes of an outbreak of E. sakazakii infection (Gurtler, Kornacki and Beuchat, 2005).
3.2.6 Transporting feeds
Transporting prepared feeds poses a risk as it increases the time from preparation to consumption, providing the opportunity for growth of harmful bacteria. Because of this potential for growth, feeds that need to be transported should be quickly cooled and refrigerated until they are cold before transporting.
In order to minimize growth of harmful bacterial, cooled feeds should only be removed from the refrigerator at the last minute and transported in a cool bag. At the destination, feeds can be re-warmed for feeding. Feeds held in a cool bag should be used within two hours. Alternatively, if transported feeds are returned to a refrigerator within two hours, they can be stored for up to 24 hours from preparation. By following these steps, feeds will be kept cool, which will slow down or prevent the growth of harmful bacteria.
3.2.7 Holding and feeding times
Minimizing the time from preparation to consumption is an effective measure for controlling the risk of infection with E. sakazakii. Prepared feed should be discarded after two hours, unless it has been stored in the refrigerator since preparation (see Section 3.1.3). Leftover feed should never be saved for later, or added to a freshly prepared feed, as harmful bacteria may have had the chance to grow during the feeding period.
It is recommended that formula is not held at room temperature for more than two hours, even if water at no less than 70 °C is used to reconstitute PIF. This is because the feed may have become contaminated during preparation, or harmful bacteria may have been introduced into the cup or feeding bottle from the infant's mouth. Also, hot water (70 °C) may have activated bacterial spores of harmful bacteria in the formula. Holding prepared feeds above refrigeration temperature for extended periods provides the opportunity for such bacteria to grow.
3.2.1 Good hygienic practice
Poor hygiene has been reported as the probable cause of some E. sakazakii outbreaks (Forsythe, 2005). The person preparing the feed should clean and disinfect the preparation surface and wash hands with soap and water before preparing a feed. This is because harmful bacteria can be carried on hands and can also be present on surfaces. Washing hands and cleaning and disinfecting surfaces reduces the risk of feeds becoming contaminated during preparation.
Hands must also be washed after using the toilet and after diaper changing because harmful bacteria, including E. sakazakii (Drudy et al., 2006), have been found in the urine and stools of infants. These bacteria can easily be carried on the hands and contaminate feed during its preparation.
3.2.2 Cleaning and sterilizing feeding and preparation equipment
Outbreaks of E. sakazakii infection have been attributed to equipment used for preparing feeds (Gürtler et al., 2005). E. sakazakii is widespread in the environment and has been shown to attach and grow (form 'biofilms') on surfaces commonly used in infant feeding equipment, such as latex, silicon and stainless steel. It is therefore important that all infant feeding and preparation equipment (e.g. feeding cups, bottles, rings and teats) has been thoroughly cleaned and sterilized before use, since the formation of biofilms on such equipment may result in reservoirs of infection that can continually contaminate feeds (Iversen, Lane and Forsythe, 2004).
3.2.3 Temperature of water for reconstitution
According to the FAO/WHO risk assessment, risk is dramatically reduced when PIF is reconstituted with water that is no less than 70 °C, as this temperature will kill any E. sakazakii in the powder. This level of risk reduction holds even if feeding times are extended (i.e. up to two hours), and even if ambient room temperature reaches 35 °C. Consequently, reconstituting PIF with water no less than 70 °C dramatically reduces the risk to all infants, even slow feeding infants and infants in warm climates where refrigeration may not be readily available (e.g. developing countries).
When PIF is prepared with water cooler than 70 °C, it does not reach a high enough temperature to completely inactivate E. sakazakii present in the powder. This is a concern for two reasons: a) a small number of cells may cause illness, therefore it is important that cells present in the PIF are destroyed; and b) the potential for surviving cells to multiply in the reconstituted formula. This risk is increased when the reconstituted formula is held for extended periods above refrigeration temperature.
Concerns have been raised over the use of very hot water for reconstituting PIF, but risk of E. sakazakii is only dramatically reduced when water at a temperature of no less than 70 °C is used. Currently, the instructions on many PIF products lead to PIF being reconstituted with water that is around 50 °C. But, according to the FAO/WHO risk assessment, reconstitution with 50 °C water generally results in the greatest increase in risk, unless the reconstituted formula is consumed immediately. Under no circumstances is risk reduced when PIF is reconstituted with 50 °C water. Manufacturer's instructions should be reviewed in the light of the findings of the risk assessment.
3.2.4 Storage of prepared feeds
Because PIF may contain harmful bacteria, it is best to prepare it fresh for each feed. However, in practical terms this is not always possible. Feeds may need to be prepared in advance, e.g. for the crèche, babysitter, or if you are going out for the day. In these circumstances, feeds should be prepared using water no less than 70 °C, cooled quickly immediately after preparation, and stored in the refrigerator (at 5 °C or colder) for no more than 24 hours.
Feed stored in the refrigerator should be used within 24 hours of preparation. Even if water no less than 70 °C was used to reconstitute PIF, spoilage bacteria may have survived that can grow at refrigeration temperatures and can cause feeds to spoil. The quality of reconstituted PIF may also deteriorate on prolonged storage.
Feeds should be cooled quickly before placing into the refrigerator, as hot feeds will increase the refrigerator's temperature. Feeds can be rapidly cooled by placing under cold running water or in a bowl of cold water.
3.2.5 Re-warming and use of stored feeds
Because of the possibility of growth of harmful bacteria at temperatures above 5 °C, stored formula should not be removed from the refrigerator and re-warmed until immediately before feeding. Feeds should not be left warming for more than 15 minutes as re-warming for extended periods means that the feed will be held at a temperature that is ideal for the growth of harmful bacteria. Holding feed in bottle warmers for lengthy periods was reported as one of the probable causes of an outbreak of E. sakazakii infection (Gurtler, Kornacki and Beuchat, 2005).
3.2.6 Transporting feeds
Transporting prepared feeds poses a risk as it increases the time from preparation to consumption, providing the opportunity for growth of harmful bacteria. Because of this potential for growth, feeds that need to be transported should be quickly cooled and refrigerated until they are cold before transporting.
In order to minimize growth of harmful bacterial, cooled feeds should only be removed from the refrigerator at the last minute and transported in a cool bag. At the destination, feeds can be re-warmed for feeding. Feeds held in a cool bag should be used within two hours. Alternatively, if transported feeds are returned to a refrigerator within two hours, they can be stored for up to 24 hours from preparation. By following these steps, feeds will be kept cool, which will slow down or prevent the growth of harmful bacteria.
3.2.7 Holding and feeding times
Minimizing the time from preparation to consumption is an effective measure for controlling the risk of infection with E. sakazakii. Prepared feed should be discarded after two hours, unless it has been stored in the refrigerator since preparation (see Section 3.1.3). Leftover feed should never be saved for later, or added to a freshly prepared feed, as harmful bacteria may have had the chance to grow during the feeding period.
It is recommended that formula is not held at room temperature for more than two hours, even if water at no less than 70 °C is used to reconstitute PIF. This is because the feed may have become contaminated during preparation, or harmful bacteria may have been introduced into the cup or feeding bottle from the infant's mouth. Also, hot water (70 °C) may have activated bacterial spores of harmful bacteria in the formula. Holding prepared feeds above refrigeration temperature for extended periods provides the opportunity for such bacteria to grow.