Cronobacter Support
03-02-2009, 09:35 AM
Following a request from the 39th Session of the CCFH (http://www.codexalimentarius.net/download/report/686/al31_13e.pdf), FAO and WHO have implemented an expert meeting to look at the risk associated with Enterobacter sakazakii (Cronobacter spp.) in follow-up formula, particularly for infants less than 12 months of age.
The preliminary report of this meeting is now available fao.org/ag/agn/agns/jemra/Sakazaki_FUF_report.pdf.
SUMMARY AND CONCLUSIONS
Enterobacter sakazakii was defined as a species in 1980 by Farmer et al, however it was commented in that paper that these organisms were thought to represent multiple species. Recently molecular methods have been employed to clarify the taxonomic relationship of E. sakazakii strains. These studies showed that E. sakazakii was actually comprised of at least 6 species and form a distinct group of Enterobacteriaceae. This group has now been classified in a new genus, Cronobacter gen. nov., within the Enterobacteriaceae. This change in nomenclature has just been validated with the publication of the paper describing the new genus in the June 2008 edition of the International Journal of Systematic and Evolutionary Microbiology (Iversen et al., 2008).
Cronobacter spp. is synonymous with E. sakazakii. The new genus is composed of six species. There is no data that currently shows that any one of these species is not a risk to neonatal health. Therefore, based on the recent studies the meeting concurred that all six species in the genus Cronobacter should be considered to be pathogenic, as each one has been linked retrospectively to clinical cases of infection in either infants or adults. In addition it was concluded that there are currently no regulatory implications of the new taxonomic changes.
Laboratory methods for the detection of E. sakazakii (Cronobacter spp.) have improved in recent years to allow the reliable detection of the organism. International standardisation of improved methods by the International Standards Organisation (ISO) and FDA-AOAC is currently underway. All currently validated laboratory methods will continue to facilitate the recognition of all species defined within the new taxonomy. These methods remain applicable for the Cronobacter spp.
The response to the call for data revealed a very mixed picture in terms of the extent of surveillance for E. sakazakii (Cronobacter spp.) infections and the resulting numbers and incidence of infections in neonates, other infants, children and adults. Globally, there appear to be very few surveillance data for E. sakazakii (Cronobacter spp.). Although a couple of passive surveillance systems exist, no active surveillance system for E. sakazakii (Cronobacter spp.) disease has been identified. Most countries reported having a foodborne disease surveillance system and/or an outbreak reporting system that would encompass E. sakazakii infection, if cases were linked to a food vehicle and/or occurred as part of a recognized outbreak of disease. However, it is noteworthy that instances were reported where cases were identified by outbreak or voluntary passive reporting but not by the national foodborne disease reporting system or even the mandatory reporting system for E. sakazakii (Cronobacter spp.).
Collectively, there are approximately 120 individually documented cases among infants and children less than 3 years of age. Six well-documented cases are known to have occurred among children 6-11 months and two cases in the age group of 12 - 35 months. Of the 5 invasive (urine, blood, CFS, brain tissue) cases in the 6 – 11 month age group, 3 had other active medical problems. While this appears to indicate few cases in the 6 – 35 month age group, this information must be considered in light of the lack of surveillance systems, underreporting, and other limitations noted in the report in identification of cases.
The data available does not enable a detailed breakdown of numbers of cases by month for infants. However, there were some laboratory surveillance data England and Wales wherein data are available for infants under 1 month for 1992-2007 and the Philippines wherein data were available for infants under 1 month and at 2 month intervals up to 12months for 1998- 2007. Based on the data from England and Wales an estimated annual incidence rate for neonates was 17.60 per 106 population over the period 1992-2007. For infants aged from 1-11 months the estimated incidence rate was 2.06 per 106 population, and among children 1 – 4 years, 0.70 per 106 population. These data indicate a sharply decreasing rate of severe illness between infants <1 month and 1-11 months. While it was not possible to calculate incidence data at monthly intervals based on the information available from the Philippines, these data also indicated a decreasing incidence with age.
While there is general agreement that immunocompromised infants are more susceptible to infection, the meeting was unable to identify a way of clearly defining the immune status of the population of concern. Although some countries, such as the USA estimate that approximately 4% of the total population is immunocompromised, the inability to clearly define immune status was reflected in the lack of information provided by countries responding to the call for data and in the literature. The meeting noted that a number of factors contribute to immune status including nutritional status, HIV status, other clinical conditions, pharmaceutical treatment, low-birth weight and premature birth. The prevalence of such factors vary widely among countries and thus the meeting concluded that there will also be a wide variation in the prevalence of immunocompromised infants. For example, underweight and stunting, two indicators of malnutrition, a major cause of immunodeficiency, vary in prevalence in children under 5 years of age from 5 – 42 % and 12 – 41% respectively. It was therefore considered by the meeting that a similar variation exists for the incidence of infants and young children in an immunocompromised state. Thus, the meeting concluded that in certain parts of the world a substantial proportion of infants and young children are immunocompromised.
Posted from fao.org
The preliminary report of this meeting is now available fao.org/ag/agn/agns/jemra/Sakazaki_FUF_report.pdf.
SUMMARY AND CONCLUSIONS
Enterobacter sakazakii was defined as a species in 1980 by Farmer et al, however it was commented in that paper that these organisms were thought to represent multiple species. Recently molecular methods have been employed to clarify the taxonomic relationship of E. sakazakii strains. These studies showed that E. sakazakii was actually comprised of at least 6 species and form a distinct group of Enterobacteriaceae. This group has now been classified in a new genus, Cronobacter gen. nov., within the Enterobacteriaceae. This change in nomenclature has just been validated with the publication of the paper describing the new genus in the June 2008 edition of the International Journal of Systematic and Evolutionary Microbiology (Iversen et al., 2008).
Cronobacter spp. is synonymous with E. sakazakii. The new genus is composed of six species. There is no data that currently shows that any one of these species is not a risk to neonatal health. Therefore, based on the recent studies the meeting concurred that all six species in the genus Cronobacter should be considered to be pathogenic, as each one has been linked retrospectively to clinical cases of infection in either infants or adults. In addition it was concluded that there are currently no regulatory implications of the new taxonomic changes.
Laboratory methods for the detection of E. sakazakii (Cronobacter spp.) have improved in recent years to allow the reliable detection of the organism. International standardisation of improved methods by the International Standards Organisation (ISO) and FDA-AOAC is currently underway. All currently validated laboratory methods will continue to facilitate the recognition of all species defined within the new taxonomy. These methods remain applicable for the Cronobacter spp.
The response to the call for data revealed a very mixed picture in terms of the extent of surveillance for E. sakazakii (Cronobacter spp.) infections and the resulting numbers and incidence of infections in neonates, other infants, children and adults. Globally, there appear to be very few surveillance data for E. sakazakii (Cronobacter spp.). Although a couple of passive surveillance systems exist, no active surveillance system for E. sakazakii (Cronobacter spp.) disease has been identified. Most countries reported having a foodborne disease surveillance system and/or an outbreak reporting system that would encompass E. sakazakii infection, if cases were linked to a food vehicle and/or occurred as part of a recognized outbreak of disease. However, it is noteworthy that instances were reported where cases were identified by outbreak or voluntary passive reporting but not by the national foodborne disease reporting system or even the mandatory reporting system for E. sakazakii (Cronobacter spp.).
Collectively, there are approximately 120 individually documented cases among infants and children less than 3 years of age. Six well-documented cases are known to have occurred among children 6-11 months and two cases in the age group of 12 - 35 months. Of the 5 invasive (urine, blood, CFS, brain tissue) cases in the 6 – 11 month age group, 3 had other active medical problems. While this appears to indicate few cases in the 6 – 35 month age group, this information must be considered in light of the lack of surveillance systems, underreporting, and other limitations noted in the report in identification of cases.
The data available does not enable a detailed breakdown of numbers of cases by month for infants. However, there were some laboratory surveillance data England and Wales wherein data are available for infants under 1 month for 1992-2007 and the Philippines wherein data were available for infants under 1 month and at 2 month intervals up to 12months for 1998- 2007. Based on the data from England and Wales an estimated annual incidence rate for neonates was 17.60 per 106 population over the period 1992-2007. For infants aged from 1-11 months the estimated incidence rate was 2.06 per 106 population, and among children 1 – 4 years, 0.70 per 106 population. These data indicate a sharply decreasing rate of severe illness between infants <1 month and 1-11 months. While it was not possible to calculate incidence data at monthly intervals based on the information available from the Philippines, these data also indicated a decreasing incidence with age.
While there is general agreement that immunocompromised infants are more susceptible to infection, the meeting was unable to identify a way of clearly defining the immune status of the population of concern. Although some countries, such as the USA estimate that approximately 4% of the total population is immunocompromised, the inability to clearly define immune status was reflected in the lack of information provided by countries responding to the call for data and in the literature. The meeting noted that a number of factors contribute to immune status including nutritional status, HIV status, other clinical conditions, pharmaceutical treatment, low-birth weight and premature birth. The prevalence of such factors vary widely among countries and thus the meeting concluded that there will also be a wide variation in the prevalence of immunocompromised infants. For example, underweight and stunting, two indicators of malnutrition, a major cause of immunodeficiency, vary in prevalence in children under 5 years of age from 5 – 42 % and 12 – 41% respectively. It was therefore considered by the meeting that a similar variation exists for the incidence of infants and young children in an immunocompromised state. Thus, the meeting concluded that in certain parts of the world a substantial proportion of infants and young children are immunocompromised.
Posted from fao.org