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Impact case study

Safer Feeds For Babies: International Recognition and Detection of Cronobacter spp as an Emergent Bacterial Pathogen Associated with Neonatal Meningitis

Unit(s) of assessment: Allied Health Professions, Dentistry, Nursing and Pharmacy

Research theme: Safety and Security of Citizens and Society

School: School of Science and Technology


Microbiology research at NTU has had a worldwide impact through helping to lower the risk of severe infections among new-born babies from consuming bacterially-contaminated powdered infant formula.

The work addressed widespread public concern over the emerging dangers of the bacterial pathogen Cronobacter spp. Research findings by Professor Stephen Forsythe and his team have informed and facilitated improvements in methods for Cronobacter spp detection and the understanding of neonatal exposure routes and risk factors. In turn, this knowledge has contributed to:

  • safer production of the formula itself
  • changes in international legislation and regulation
  • from 2008, the implementation of new World Health Organisation (WHO) infant formula preparation guides.

Research findings and advice from Professor Forsythe's team have led to:

  • revisions in international regulations on the safe feeding of infants in hospitals and in the home
  • improvements in the microbiological safety of manufactured powdered infant formula.

Influence on international regulatory affairs

Three risk assessments by the Food and Agriculture Organisation (FAO)-WHO on the microbial safety of powdered infant formula (2004, 2006, 2008) made recommendations to worldwide regulatory authorities.

WHO risk communication guidelines on the hygienic preparation of powdered infant formula were revised in 2007 and were used to inform individual governmental regulatory authorities.

The recommendations above were adopted (2008 onwards) by the worldwide regulatory community regarding the safe preparation of formula in hospitals and homes.

The development of an online risk assessment model by the Joint FAO-WHO Expert Meetings on Microbiological Risk Assessment (JEMRA) was based on the FAO-WHO reports above for use by formula manufacturers and regulatory bodies.

Prior to 2008 there was no international requirement for the detection of Cronobacter in powdered infant formula. The research has led to changes in risk management by the Codex Alimentarius Commission, with the introduction of international microbial criteria (<1 Cronobacter cell / 10g powdered infant formula) for commercially-produced powdered infant formula.

Cronobacter genus recognition and detection methodology implementation

A consequence of the FAO-WHO risk assessments was the new international legal requirement for the absence of Cronobacter spp. in powdered infant formula. Therefore robust and reliable detection methods were needed to ensure both consumer protection and manufacturer protection. Professor Forsythe, in collaboration with industry, co-developed the selective DFI chromogenic agar for Cronobacter spp. This agar is now:

  • commercially available from international microbiological media manufacturers
  • used by powdered infant formula manufacturers
  • compliant with International Standards Organization (ISO) standard ISO/TS 22964
  • a Food and Drug Administration (USA) recommended method (FDA 2012).

Size of at-risk population (beneficiaries) and commercial interest

The size of the at-risk population is estimated to be 150,000-300,000 per annum.

Award-winning research

The impact of Professor Stephen Forsythe's research was recognised as part of NTU's Queen's Anniversary Prize 2015 Award. This is the highest national honour for a UK university.

Research background

Since 2003, Steve Forsythe (Professor of Microbiology since 2008) and colleagues (Drs Georgina Manning, Michael Loughlin, S Townsend, Benjamin Dickins and J. Caubilla-Barron) have led research into the then newly-emergent bacterial pathogen Cronobacter spp. They have published 46 peer reviewed papers on the organism, 33 of which since January 2008.

Initial studies (2003-2005) on the general nature of the organism revealed its ubiquity in foods, its rate of growth in reconstituted infant formula and its ability to adhere to inert surfaces. Iversen and Forsythe published the first risk evaluation of the bacterium before the international regulatory community responded to international concerns (FAO-WHO 2004). Additionally, the then approved detection protocols were inadequate (due to poor taxonomic designation of the organism) and this led to inadequate control measures. A research collaboration led to a new chromogenic agar for detecting the bacterium, the Druggan-Forsythe-Iversen chromogenic agar (DFI), and official recognition of the genus Cronobacter in place of Enterobacter sakazakii.

The second research phase (2005-2008) secured international approval and subsequent commercialisation of the DFI agar for the reliable and robust recovery of the bacterium from powdered infant formula. On the basis of his expertise, Professor Forsythe was the sole academic invited to participate in all FAO-WHO risk assessments meetings for the microbiological safety of powdered infant formula (2004, 2006, 2008). In response to the FAO-WHO (2008) call for data on the microbiological safety of follow-up formulas, Professor Forsythe organised a collaborative survey across seven countries for Cronobacter spp. in follow-up formulas (intended age up to six months). These data were submitted to the FAO-WHO (2008) to evaluate risk and were published separately.

The third research phase (2009 onwards) uses genotyping and whole genome studies with Professor McClelland (Vaccine Research Institute of San Diego, and University of California) to advance our knowledge of the diversity of the organism and support regulatory requirements. This is essential for method validation which requires the target organism to be precisely defined such that all species and strain variations are detectable. The formal acceptance of a new bacterial genus, Cronobacter, in place of E. sakazakii, enables industry and regulators to detect and control the organism in powdered infant formula. A multilocus sequencing typing scheme (MLST) supported by an open access, curated database was established in conjunction with Professor Chris Dawson of Warwick University and hosted by Dr Keith Jolley at Oxford University.

The genotyping and genomic analyses have:

  • contributed to the definition of the new bacterial genus Cronobacter, and recognition of two new Cronobacter species.
  • guided whole genome sequencing projects across the genus.
  • extended our knowledge of the diversity of Cronobacter, while also confirming the reliability of the recovery methods during phase two of the research.
  • identified a clonal lineage as causing the majority of neonatal meningitis cases; 30-year retrospective study and highly-publicised cases in the USA in 2011.


International regulatory agencies’ use of data generated by Professor Forsythe’s team.

  • FAO-WHO recommendations are used by the Codex Alimentarius Commission (CAC) for harmonising international food standards, guidelines and codes of practice for consumer protection and fairness in the food trade. The Commission also promotes coordination of all food standards work undertaken by international governmental and non-governmental organisations.
    Professor Forsythe co-authored the microbiological sections of the three FAO-WHO reports, the final one being: FAO-WHO (2008) Third Workshop on Cronobacter (Enterobacter) sakazakii in powdered follow-up formula, Microbiological Risk Assessment Series 15.
  • Guidelines for the safe preparation, storage and handling of powdered infant formula (WHO 2007), which was used to inform individual governmental regulatory authorities, cited Professor Forsythe's research.
  • JEMRA (Joint FAO / WHO Expert Meetings on Microbiological Risk Assessment), which aims to make risk assessment tools more accessible and user-friendly to the wider food safety community, is linked to the Codex Alimentarius Commission and guides countries to adopt risk-based approaches. JEMRA used the data from Professor Forsythe's team in its risk model for infant formula and this guide has not been superseded.

Governmental regulatory authorities'  implementation of feeding practices guidance, worldwide (includes UK, USA, Canada, Germany and New Zealand) which have used Prof Forsythe's data.

Examples are:

  • United Kingdom
    Also, in January 2013, Professor Dame Sally Davies, Chief Medical Officer for England, and Viv Bennett, Director for Public Health Nursing, sent a letter to health professionals stating that water at 70oC or above should be used to make up powdered feed in agreement with the WHO guidelines.
  • USA
  • Germany

International standard methods approval for DFI agar usage

Commercialisation of DFI agar and infant formula product protection

The chromogenic DFI agar is compliant and approved by ISO and FDA standards, and the testing requirements of Codex Alimentarius, for use by infant formula manufacturers (eg. Mead Johnson Nutraceuticals (USA) and Nestle) for the surveillance and control of Cronobacter.

News story about an infant formula manufacturer’s financial loss due to concerns about product safety: