Tony Cundell, PhD - Principal Consultant, Microbiological Consulting, LLC
Introduction
The title of this review article is somewhat incorrect, as a bacterium has no intent outside survival and passing on its genes to future generations. In contrast, decisions by manufacturers, regulators, governments, and parents do have intent, as well as unanticipated consequences. This review article provides background information on this lesser-known bacterial pathogen Cronobacter sakazakii, rarely found in powdered infant formula, but may cause serious infections in infants if given the opportunity to grow in reconstituted infant formula and a commentary on the timeline associated with the Abbott Nutrition plant shutdown.
What is Infant Formula and How is it Regulated in the United States?
As stated in the 2006 FDA Guidance for Industry: Frequently Asked Questions about the FDA’s Regulation of Infant Formula, the Federal Food, Drug, and Cosmetic Act defines infant formula as “a food, which purports to be or is represented for special dietary use solely as a food for infants by reason of its simulation of human milk or its suitability as a complete or partial substitute for human milk” (FFDCA 201(z)). FDA regulations define infants as persons not more than 12 months old (Title 21, Code of Federal Regulations 21 CFR 105.3(e)).
Types of Infant Formula Consumed in the United States
Infant formula is marketed as a dry powder for reconstitution, a liquid concentrate, which is diluted, or a ready-to-use liquid to nourish infants (Table 1). As neonates with undeveloped immunological systems have a higher risk of bacterial infection they should receive the sterile ready-to-use infant formula. The prevalence of breastfeeding, which is usually the best option for an infant, varies by age of the infant, their special health needs, capability of their mothers, the family socio-economic status, and the state in the union where the mother lives (Table 2).
In a National Health and Nutrition Examination Survey, 2003–2010 it was found that among the 81% of infants who were fed formula or regular milk, 69% consumed cow’s milk formula, 12% consumed soy formula, 5% consumed gentle/lactose-reduced formulas, 6% consumed specialty formulas, and 13% consumed regular milk products (Rossen et al, 2016). The top four manufacturers: Abbott Nutrition, Mead Johnson, Gerber, and Perrigo market approximately 80% of infant formula consumed in the U.S. with Abbott Nutrition distributing 40% of the formula. In 2018, 56% of infant formula was distributed at discounted prices through the Women, Infant and Children’s Nutrition Program (WIC) where companies bid for exclusive state contracts, which many believe may further complicate the supply chain.
Description of the Bacterium Cronobacter sakazakii
Cronobacter sakazakii is a member of the family Enterobacteriaceae, genus Cronobacter and may be viewed as an emerging, opportunistic pathogen, found in low-moisture foods including powdered infant formula. C. sakazakii is a motile, rod-shaped, non-spore-forming, facultative anaerobic, Gram-negative bacterium. Important to this discussion in terms of infant formula preparation and storage, its growth temperature is broad, i.e., 6-47°C with an optimal growth temperature range of 37-43°C (Drudy et al, 2006; Henry and Fouladkhah, 2019) and its extreme resistance to desiccation (Cho, T. J. et al, 2019).
The name by which this bacterium is known to you is a reflection on how long you have been a microbiologist. From the first reports of neonatal meningitis in 1958 (Urmenyi and Franklin, 1961), it was called yellow-pigmented Enterobacter cloacae. In 1980, on the basis of DNA-DNA hybridization, biochemical reactions, pigment production, and antibiotic susceptibility compared to E. cloacae it was re-classified as Enterobacter sakazakii (Farmer et al, 1980). And lastly, a new genus Cronobacter was created using the newer technologies 16SrRNA base sequencing and multi-locus sequence typing (Iversen et al, 2007) that now contains seven named species. Readers of Greek mythology may recognize that the genus is named after Cronos, the Titan who devoured his children, and is the subject of a famous Goya painting that I have viewed with a sense of horror in the Prado, Madrid, Spain.
How Serious a Bacterial Pathogen is C. sakazakii?
Although the numbers of cases of Cronobacter infection are very low and more adults are infected than children, the mortality rate in neonates (<28 days) and infants (<12 months) is very high, approaching 80%.
Steps in the Preparation of a Feeding of Infant Formula
Typical steps in the preparation of infant formula are as follows:
- Boil water
- Cool to 70°C
- Reconstitute the quantity of powdered infant formula required
- Store in the refrigerator as a bulk volume or distribute into single servings for up to 24 hours
- Re-warm to 37°C
- Feed the infant within 1 hour
Source: FAO/WHO 2006 Enterobacter sakazakii and Salmonella in powdered infant formula. Meeting Report. Rome, Italy 16-20 January 2006
Given the broad growth temperature profile of C. sakazakii, from 10 to 47°C with an optimum of 37-43°C, prolonged storage especially at above ambient temperature for extended periods may have disastrous consequences (Reij and Zwietering, 2008).
Detection of C. sakazakii from Powdered Infant Formula
A traditional enrichment culture with isolation on selective solid media or a PCR amplification method may be used for C. sakazakii detection in powdered infant formula (See FDA Bacteriological Analytical Manual (BAM), 2nd edition).
The BAM instructions are summarized as follows:
“Aseptically weigh out 100 g of PIF and add to 2-L Erlenmeyer flask. Add 900 mL (1:10 dilution) of sterile buffered peptone water (BPW), gently shake by hand until the powder is uniformly suspended, and incubate for 22 to 26 hours at 35 to 37° C. Thoroughly mix the enrichment and remove four 40-mL aliquots and place them in 50-mL centrifuge tubes. Centrifuge the aliquots at 3,000 g for 10 minutes in a swinging bucket centrifuge and aspirate the supernatant and fat residues. Suspend the resultant pallet in 200 uL by vortexing for at least 20 seconds. Duplicate preparations will be used for PCR and the other two for confirmatory culture, if necessary.”
“To extract the DNA, centrifuge 200 uL of the suspended cells in PBS at 3000 g for five minutes in 1.5 mL microcentrifuge tube. The bacterial cells are the third layer of four layers after centrifugation. Discard the supernatants and fat residues. Add 400 uL of PrepMan Ultra reagent to each tube, vortex, and heat the sample for 10 minutes at 100°C in a boiling water or a heating block, then cool the sample to room temperature. Centrifuge the sample for two minutes at 15,000 g to remove the cell debris. Transfer 50 uL of the DNA extract supernatant to a new tube and run suitable PCR protocols with and without an internal positive control.”
“For the isolation of Cronobacter, spread 100 uL aliquots of suspended cells onto duplicate DFI chromogenic agar and R&F Cronobacter chromogenic plating agar and incubate the plates at 35 to 37° C for 18 to 24 hours.”
The previous FDA BAM method for detection of C. sakazakii, which resembles the USP<62>Test for Specified Microorganism, includes a pre-enrichment procedure in BPW, enrichment in Enterobacteriaceae enrichment (EE) broth, plating on violet red bile glucose (VRBG) agar and picking of five grown colonies onto tryptone soy agar (TSA) plates, which are incubated at 25°C for 48–72 hours. Yellow-pigmented colonies, typical for C. sakazakii, on the TSA plates are confirmed using the API 20E system.
How Strong is the Evidence that the Abbott Infant Formula was Responsible for the Outbreak?
Despite not being a notifiable disease, infectious disease specialists believe that cases of infant meningitis, septicemia and necrotizing enterocolitis linked to C. sakazakii are extremely rare, not exceeding double figures annually in the U.S., so a cluster of four cases implicating powdered infant formula from a single manufacturing plant with reports of serious unsanitary conditions and multiple GMP violations when C. sakazakii has been isolated from product contact surfaces, and in release testing of two lots of product is good evidence that the plant was responsible to this author. If the cause were unsanitary conditions during household preparation of infant formula, and the cleaning and storage of associated bottles, dispensing spoons, and bulk containers, the frequency of infant infection would be expected to be higher and less clustered by manufacturing source. We do not see this pattern.
As reconstituted and incorrectly stored infant formula may grow the bacterium and cause infection, powdered infant formula with overall counts even as low as 1 CFU/kg pose a potential risk. Low level of product contamination unevenly distributed in a lot will be difficult to find in a can of formula.
Underreporting of C. sakazakii Infection
The Center for Disease Control and Prevention (CDC) website states that case surveillance is foundational to public health practice as it helps the CDC to understand diseases and their spread and determine appropriate actions to control outbreaks. Case surveillance occurs each time public health agencies at the local, state, or national levels collect information about a person diagnosed with a disease that poses a serious health threat to Americans. These diseases and conditions include
- infectious diseases, such as coronavirus disease 2019 (COVID-19);
- foodborne outbreaks, such as E. coli; and
- non-infectious conditions, such as lead poisoning.
As the CDC describes, case surveillance starts at local, state, and territorial public health departments. Local laws and regulations specify which diseases and conditions must be reported. The state health departments work with healthcare providers, laboratories, hospitals, and other partners to get the information needed to monitor, control, and prevent these reportable diseases and conditions in their communities.
Health departments then notify CDC about certain conditions so the CDC can track them for the whole country. They monitor the order of 120 notifiable diseases at the national level. This important step helps protect the health of individual communities and the nation. Not all infectious diseases are reportable. For example, infant botulism is both reportable and notifiable whereas C. sakazakii infection is only reportable in Minnesota, hence it is not notifiable. This absence of data means that the incident rate of infant C. sakazakii infection is largely unknown and outbreaks may go undetected.
Reversed Timeline with the Abbott Sturgis, MI Infant Formula Manufacturing Plant Shutdown
Although hindsight has 20/20 vision, the performance of the manufacturer, Abbott Nutrition and the FDA, the regulator, was less than we should expect from these organizations. Abbott Nutrition failed to maintain their major U.S. infant formula plant providing sanitary manufacturing conditions, and in operation in compliance with cGMPs to produce quality, and safe formula for a vulnerable infant population. The FDA missed the opportunity during the September 20-24, 2021 plant inspection to force improvements to the plant and was slow to react to the whistleblower’s disclosure and a cluster of C. sakazakii infections implicating Abbott Nutrition’s product. The author believes that action delayed, inevitably results in overreaction by regulators, politicians, and the public alike. More timely responses by the manufacturer and the FDA may have avoided a national infant formula shortage. To illustrate how these events unfolded, a reverse timeline, derived from different news sources (including The New York Times, FDA Updates, Politico, CDC Weekly Reports, the Abbott website, and the Food Poison Journal), is presented.
June 25, 2022 – According to press reports, the Food and Drug Administration said on Wednesday it was notified of one more infant death in January potentially related to Abbott Laboratories’ baby formula and the agency has started an investigation. Abbott initiated a recall of its infant formula products and closed its Michigan plant in mid-February after reports of serious bacterial infections in four infants. The recall and closure worsened an infant formula shortage that began with pandemic supply chain issues. Abbott produces Similac and other popular brands of infant formulas. The date of death and state of death of the fifth infant was not announced. The FDA apparently became aware of the death on June 10, 2020. So far, the FDA has received 129 complaints linked to Abbott formula products, including 119 since the product recall in February.
June 5, 2022 - Abbott announced on their website that they are restarting infant formula production at its Sturgis, MI, facility today after meeting initial requirements agreed to with the U.S. Food and Drug Administration (FDA) as part of the consent decree entered into on May 16.
Abbott is starting production of EleCare and other specialty and metabolic formulas, with initial EleCare product release to consumers beginning on or about June 20. They stated they also are working hard to fulfill the steps necessary to restart production of Similac and other formulas and will do so as soon as they can.
June 2, 2022 – The U.S. Department of Health and Human Services’ Office of Inspector General (OIG), according to a notice posted on its website on Thursday, said the OIG will investigate the FDA’s actions leading up to the recall in February. “We will determine whether FDA followed the inspections and recall process for infant formula in accordance with federal requirements,” OIG said
May 25, 2022 – FDA Commissioner Robert Califf M.D. told the House Energy and Commerce committee about “egregiously unsanitary” conditions at Abbott Nutrition’s Sturgis, Michigan facility. Califf also owned up to the agency’s lacking response, telling the committee that “FDA’s timeliness of interviewing the whistleblower and getting into the facility for a for-cause inspection were too slow and some decisions could have been more optimal.”
May 19, 2022 - FDA Commissioner Robert Califf M.D. testified to the House Appropriations subcommittee and replied to criticisms for failing to prevent the shortage of infant formula. He noted that to ensure the safety and adequate nutrition of infant formula the FDA Center for Food Safety and Applied Nutrition (CFSAN) only has funding for 13 staff members and the FDA has no authority to respond to supply chain disruptions. It is the opinion of this author that the responsibilities of the Department of Agriculture and the FDA in regulating the nation’s food supply should be consolidated in a single agency to ensure focus as occurs in most advanced countries.
May 18, 2022 - To ensure that manufacturers have the necessary ingredients to make safe, healthy infant formula here at home, President Biden is invoking the Defense Production Act. The President is requiring suppliers to direct needed resources to infant formula manufacturers before any other customer who may have ordered that good.
May 17, 2022 - Congresswoman DeLauro, Connecticut (D) to allocate $28 million to address the shortage of infant formula in the United States, introduced an emergency supplemental appropriation bill. Despite 192 Republicans voting against the bill, it passed, and will move to the Senate for approval.
May 15, 2022 - Abbott Nutrition and the U.S. Federal Department of Justice acting on behalf of the FDA entered into a consent decree with Abbott admitting to the distribution of adulterated infant formula and accepting the conditions of future operations of the plant. This regulatory response occurred within two months of the March 18, 2022 issuance of an adverse Form 483 Inspectional Observations, skipping the usual FDA warning letter.
May 14, 2022 - The Center for Food Safety and Applied Nutrition published the FDA Guidance for Industry Infant Formula Enforcement Discretion Policy that will be in effect until November 14, 2022 to help increase the supply of infant formula from foreign FDA-registered plants.
May 13, 2022 - The U.S. Department of Agriculture (USDA) urged states to take advantage of flexibilities the department is offering in the Special Supplemental Nutrition Program for Women, Infants, and Children, commonly known as WIC, to help families get the safe infant formula they need.
March 18, 2022 - FDA investigators issued their nine page Form 483 inspectional observations on the Abbott Sturgis, MI infant formula plant stating that the product was adulterated due to Cronobacter sakazakii in the formula and the processing environment. The inspection was conducted using 12 investigators, including Elizabeth P. Mayer, over 24 days from January 31 to March 18, 2022. Many observers have questioned the three–month delay from the receipt of the whistle-blowers report to the most recent FDA plant inspection.
March 7, 2022 - Abbott voluntarily recalled one lot of Similac PM 60/40 after learning of the death of an infant who tested positive for Cronobacter sakazakii and whom they were informed had consumed Similac PM 60/40 from this lot. February 17, 2022 - Abbott voluntarily recalled these multiple infant formula products after four consumer complaints related to the bacterial Cronobacter sakazakii or Salmonella Newport infections in infants who had consumed powder infant formula manufactured in their facility.
February 10, 2022 - CDC was notified of the FDA’s investigation of consumer complaints of infant illness related to products from Abbott Nutrition in Sturgis, Michigan. The most recent CDC investigation details are summarized below:
From September 16, 2021, to January 5, 2022 - CDC received reports of three Cronobacter cases in infants that were later found to be included in FDA’s ongoing investigation. On February 16, 2022, CDC asked clinicians and state and local health departments to provide information on other Cronobacter infections associated with infant formula from November 2020 through the present and only one additional case of Cronobacter infection in an infant who consumed formula produced at this facility was found. The cases were as follows:
- Four infants with Cronobacter infections in Minnesota (1), Ohio (2), and Texas (1) consumed formula produced at the Sturgis, Michigan facility before they got sick.
- Formula types included Similac Sensitive, Similac Pro-total Comfort, Similac Advance, and Similac PM 60/40.
- Cronobacter infections may have contributed to the deaths of two infants in Ohio.
CDC performed whole genome sequencing (WGS) on Cronobacter bacteria isolated from two available patient samples to compare them with environmental samples taken at the facility to determine if there is any relation and there were none. Is the evidence strong enough to exonerate Abbott Nutrition?
October 21, 2021 - A former quality assurance employee at the Abbott Sturgis, MI plant made a 34-page confidential disclosure to the FDA alleging multiple regulatory violations. To whom was this document given? Was it the FDA Detroit District Office? At a May 2022 congressional hearing, the Deputy Commissioner Frank Yiannas, from Center for Food Safety and Applied Nutrition, acknowledged that it was over three months before he saw the whistle blower’s report. This may be symptomatic of the dominance of drug regulators in the FDA or at least the siloing of the different FDA Centers.
October 15, 2021 - Daniel Arricus, FDA Investigator and Elizabeth P. Mayer, National Expert issued a comprehensive 39-page Establishment Inspection Report (EIR) that included the Form 483 from the September 20-24, 2021 inspection. Besides the need for voluntary improvements in plant sanitization, the inspection did not uncover any serious concerns that justified issuance of a Warning Letter.
September 21, 2021 – An infant infection with Cronobacter sakazakii was reported by the Minnesota Health Department, the only state where C. sakazakii infection was reportable.
Recommendations
As a casual observer of policy matters around infant formula, I would make the following recommendations for consideration:
- Encourage states to make infant Cronobacter sakazakii infections reportable to the local health departments, so that the CDC can in turn make it notifiable.
- Restructure the FDA so that the Center for Food Safety and Applied Nutrition has more prominence within the organization especially in the Office of Regulatory Affairs, which is responsible for inspection and regulatory actions.
- Encourage the USP to include a test for the absence of Cronobacter sakazakii in USP <2023>Microbiological Procedures for Absence of Specified Microorganisms—Nutritional and Dietary Supplements
- Encourage additional research on environmental C. sakazakii to help separate extrinsic from intrinsic contamination of infant formula
- Implement HACCP programs for infant formula manufacturers
- Determine the statistical power of microbial testing sampling plans for powdered infant formula
- Combine the regulatory functions of the U.S. Department of Agriculture (meat, poultry, and egg products) and the Food and Drug Administration (dairy, seafood, produce, packaged foods, bottled water, and whole eggs) into a single regulatory agency responsible for foods in the U.S., as in Europe.
References
Anon., 2021 Confidential Disclosure re Abbott Laboratories Production of Infant Formula – Sturgis, Michigan Site 19 October 2021
Cho, T. J. et al, 2019 Underestimated risks of infantile infectious disease from the caregiver’s typical handling practices of infant formula Scientific Reports 9: 9799 doi.org/10.1038/s41598-019-46181-0
Drudy, D. et al, 2006 Enterobacter sakazakii: an emerging pathogen in powdered infant formula Clin. Infect. Dis. 42:996-1002
Farmer III, J. J. et al, 1980 Enterobacter sakazakii: a new species of Enterobacteriacea isolated from clinical specimens. Int. J. Syst. Bacteriol. 30: 569-584
FDA Form 483 issued to Abbott Nutrition, Sturgis, MI dated 18 March 2022
FDA Guidance for Industry – Infant Formula Enforcement Discretion Policy, May 2022
Henry, M and A. Fouladkhah, 2019 Outbreak history, biofilm formation, and preventive measures for control of Cronobacter sakazakii in infant formula and infant care settings. Microorganisms 7, 77; doi.10.3390/ microorganisms7030077
Iversen, C. et al, 2008 Cronobacter gen. nov., a new genus to accommodate the biogroups of Enterobacter sakazakii Int. J. Sys. Evol. Microbiol. 55:1442-1447
Reij, M. W. and M.H. Zwietering 2008 Integrating concepts: a case study using Enterobacter sakazakii in infant formula in Microbial Risk Analysis of Foods D.W. Schaffner (editor) ASMPress, Washington, D. C. pp177-204
Strysko, J. et al 2020 Food safety and invasive Cronobacter infections during early infancy, 1961-2018. Emerg. Infect. Dis. 26(5): 857-865
Urmenyi, A.M. and A. W. Franklin 1961 Neonatal death from pigmented coliform infection Lancet 1:313-315
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