Introduction
Breastfeeding of young newborns is undeniably preferable to ensure a healthy child's development Nevertheless, it is not always feasible to breastfeed Powdered infant formula (PIF) is designed to be a supplement to breast milk and can be used as a substitute if mothers are unable to breastfeed their children[1]
PIF is a low water activity non-sterile product Therefore, it might contain a range of bacteria that can grow rapidly following reconstitution[2] Cronobacter spp (formerly Enterobacter sakazakii) is one of the most concerns in powdered infant formula
The Cronobacter spp infections cause neonatal meningitis or necrotizing enterocolitis and bacteremia, which results in an alarming mortality rate has been reported [3] Many cases of Cronobacter spp infections have been researched that is linked epidemiologically to powdered infant formula (PIF) [4]
Cronobacter infections are uncommon, but they can be fatal to neonates
Although the amount of Cronobacter sakazakii has been found only 3 cfu/g in powdered infant formula [5], time-temperature abuse of prepared formula allows modest quantities of pollutants to rise, potentially causing illness Low populations, on the other hand, have been found to induce sickness even in the absence of abuse after preparation [6] According to FAO/WHO in 2008 [7], there were at least 120 reported cases of neonatal and infant Cronobacter spp infections and 27 fatalities worldwide This might be an underestimation due to unreported and misidentified instances [2] [8]
In particular, most recently, in 2022, there were 4 cases of Cronobacter illness with 2 deaths believed to be linked to powdered milk When the source of the infection was thought to be related to Abbott's powdered infant formula, the incident became even more concerning Furthermore, the FDA's recently disclosed inspection results document detailing a pattern of deficiencies with food safety procedures at Abbott's infant formula production plant raises the question of whether the manufacturing process of this factory causes Cronobacter infections
Considering the high risk of Cronobacter infections in formula milk as well as recent infections due to intrinsic contamination or through extrinsic contamination, our team decided to choose the topic: Cronobacter Infections
Linked to Powdered Infant Formula with the desire to better understand
Cronobacter spp., the causes of infection, and as well as offer recommended solutions to limit the risk of infection.
Overview of Powdered infant formula
Processing of powdered infant formula
Dry blending, wet mixing, and a mixture of wet processing and dry blending are the three types of manufacturing processes used to make powdered infant formula [10], [11] The dry blending process begins with the manufacture of individual ingredients, which are then obtained in powdered form from suppliers, heat-treated as needed, dried, and then dry-blended All materials are mixed in a liquid phase and heat-treated in the wet mixing-spray process Pasteurization or sterilization, for example, is required before they are dry spray A mixed approach is sometimes employed, in which some of the ingredients are processed using wet mixing to generate a foundation powder, and the other ingredients are added using dry blending [12], [13] The dry blending technique has the advantage of consuming less energy and requiring less capital for equipment, construction, and maintenance Because there is no water involved in the dry blending process, the risk of microbial contamination is greatly decreased However, there are significant drawbacks to employing the dry blending procedure, such as the microbiological and physical quality of the finished product being dependent on raw materials, the inability to integrate oil, and component de-blending during transportation One of the benefits of the wet mix technique is that all quality parameters, such as wet mixing, concentration by evaporation, and spray drying, may be managed more successfully than with dry mixing As a result, the microbiological, physical, and chemical properties of the powder are improved [14] However, there are certain drawbacks, such as increased equipment costs, more maintenance, and the presence of both wet and dry regions in one manufacturing plant.
Figure 2 Manufacturing process of powdered infant formula by wet mixing- spray drying process
The three key stages of the wet mixing-spray drying process are always the same: mix preparation, evaporation, and drying.[15]
The basic components widely used in powdered infant formula are shown in Table 1 The physical qualities of powdered infant formula wet-mixes are influenced by the quality and pre-treatment of the ingredients [16] Fresh skim milk that has been heat-treated, for example, has been reported to have higher viscosities after evaporation than fresh skim milk that has not been heat-treated [17]
Table 1 Typical raw material for powdered infant formula [16]
Casein Source Skim milk powder (SMP), evaporated skim milk, acid casein, sodium/calcium/potassium caseinate, milk protein concentrate (MPC*)
Whey Source Demineralised whey powder (DWP), whey protein concentrates (WPC*), whey protein isolates (WPI), hydrolysed whey ingredients
Soy milk, soy protein isolate, locust bean seed protein, amino acids
Oils Soy, corn, safflower, sunflower, colza, palm, copra, structured lipids
Carbohydrates Lactose, starch, sucrose, corn syrup, corn syrup solids
Major minerals Calcium carbonate, calcium phosphates, dibasic magnesium phosphate, potassium citrate, magnesium chloride
Minor minerals Potassium iodide, ferrous sulphate, manganese sulphate, copper sulphate, zinc sulphate
Vitamins A, D, E, K, B1, B2, B6, B12, niacin, folic acid, pantothenic acid, biotine, choline, inositol
Soy lecithin, mono- and diglycerides
Before mixing, these items must be prepared and hydrated Powder hydration is usually divided into multiple stages, including wetting, sinking, dispersion, and dissolution [18] To minimize hydration time, high shear devices can be utilized to scatter raw materials [19], [20] To guarantee thorough hydration, the mixture is then held in a huge tank Water-soluble minerals are dissolved in hot water separately and then added to the mixture With the addition of alkali or citric acid solution, the pH of the mixture can be changed [21] When oil-soluble vitamins are needed in the mix, they are first dissolved in oil before being added to the oil mix tank The oil- soluble vitamins are premixed and added to the final storage tank before being dried or mixed with the spray-dried powder if they are encapsulated Regardless of whether batch or continuous processing is used, the pipes and tank should be flushed with compressed air at least once a day, and the mixing line should be cleaned in situ (CIP) at least once a day [10] The lactose content of raw materials is particularly crucial for hydration since it preserves the original structure of proteins after drying Lactose, after all, is a somewhat insoluble sugar As a result, there is a critical dry matter concentration at which lactose is no longer soluble during the wet-mixing of powdered infant formula [16].
During the wet-mixing of powdered infant formula, fat stabilization is critical to avoid separation Proteins are amphiphilic molecules with both hydrophobic and hydrophilic areas that play a key role in the emulsification of powdered infant formula Fat is broken down into little globules during homogenization and stabilized by proteins that absorb at the fat-water interface Hydrophobic sections of adsorbed proteins are oriented toward the fat phase, while hydrophilic areas are oriented toward the aqueous phase Furthermore, powdered infant formula, especially powdered infant formula containing hydrolyzed proteins, may contain low molecular weight surfactants that act as emulsifiers Surfactants, like proteins, have hydrophobic areas that soak in the fat-water interface and hydrophilic sections that are in touch with the aqueous phase [16].
Heat treatment is an important control point for powdered infant formula's microbiological purity Heat treatment can be placed at any point in the process Because aggregates of fat globules formed during heat treatment [22] may be disrupted by homogenisation, it may be desirable to position the heat treatment before homogenisation to produce a more stable emulsion [21] McCarthy et al
[19] [20], used heat treatment before homogenization in their research.
To remove water from powdered infant formula wet-mixes before spray drying, evaporation is commonly used Evaporation can remove water at a lower cost of energy than spray drying [23] The dairy business frequently uses falling film evaporators The wet-mix flows by gravity through a series of tubes during falling film evaporation, producing a film on the inside of each tube as it descends The outside of the tubes is sprayed with live steam, which causes the water in the wet- mix to evaporate Evaporation takes place in a vacuum (50 to 70 °C), which permits heat-sensitive wet-mixes to evaporate The amount of concentration that may be achieved is determined by viscosity increase; post-evaporation viscosity of whole milk should not exceed 60 100 mPa.s for efficient drying 3 [24] Evaporation can impact the physical condition of wet-mix elements in addition to viscosity changes Liu et al (2012) found that micellar hydration, aggregation, and the amount of calcium associated with the micelle were all altered by the concentration of skim milk [25] During evaporation, calcium phosphate is transferred from a soluble to a colloidal micellar form, which lowers pH During evaporation, McCarthy et al noticed an increase in the size of fat globules in IMF emulsions [20].
Spray drying is used to make powdered infant formula Wet-mixes that have been atomised into fine droplets (103400 μm) to improve the area of contact with the hot air is removed with hot air [24] Spray dryers with two or three stages are commonly used to make powdered infant formula Spray drying in two or three stages comprises a large drying chamber (stage 1) in which the majority of the water is removed, followed by supplemental drying utilizing an internal fluidised bed (stage 2) and/or exterior fluidised bed (stage 3) Powder particle agglomeration is used to improve the wettability and flowability of powdered baby formula Random collisions of atomized particles during drying will cause spontaneous agglomeration of powder particles The atomised particles from two or more atomising machines are positioned so that they overlap in forced primary aggregation Fine particles that depart the dryer's exhaust air and external fluid bed are reintroduced to the drying chamber in forced secondary agglomeration [26].
Cronobacter illnesses linked powdered infant formula
Cronobacter sakazakii
The Cronobacter genus is composed of Gram-negative, facultative anaerobic rods which are members of the Enterobacteriaceae family and closely related to the genera Enterobacter and Citrobacter [9] The genus Cronobacter was originally defined and created by reclassifying the species Enterobacter sakazakii [9] It belongs to the taxonomic class Gammaproteobacteria and the family Enterobacteriaceae [9]
It consists of facultatively anaerobic, Gram-negative, oxidase-negative, catalase-positive, non-spore forming rods that are generally motile, capable of reducing nitrate to nitrite, producing acetoin, and failing the methyl red test [9] Following the initial proposal of the Cronobacter genus, three additional taxonomic revisions have occurred, and the genus now consists of seven species: C sakazakii,
C malonaticus, C turicensis, C universalis, C muytjensii, C dublinensis, and C condimenti [29] [30] [31]
Figure 3 Seven species of Cronobacter genus [9]
Cronobacter sakazakii, previously known as Enterobacter sakazakii [30]
[33], is an opportunistic Gram-negative, rod-shaped pathogenic bacterium that can live in extremely dry environments, known as xerotolerance C sakazakii survives desiccation by utilizing several genes [34], and this xerotolerance may be strain- specific [35]
Cronobacter sakazakii was first isolated from a can of dried milk in 1950, even though these organisms have most likely existed for millions of years [32] Over the next few decades, E sakazakii was linked to dozens of cases of infant meningitis and sepsis, often in conjunction with powdered infant formula [32] Although adults account for the vast majority of C sakazakii cases, low-birth-weight preterm neonates and older infants are particularly vulnerable [32] The pathogen is a rare cause of invasive infection in infants, with historically high case fatality rates (40380%) [32] Around 50 percent of infants who have Cronobacter sakazakii die, and those who survive may experience neurological impairment [36]
According to the Centers for Disease Control and Prevention and in the literature all cases of bloodstream infection or meningitis among infants were reported (1961 2018; n = 183) [37] Most infants were neonates (100/150 [67%]); 3 38% (42/112) died, and 79% (81/102) had reported recent PIF consumption [37]
Table 2 Numbers of reported invasive Cronobacter infections among infants, by country, 1961-2018 [37]
In the final quarter of the study period (2004 2018), case counts were 3 significantly higher (global average 8.7 cases/year); among US cases, significantly higher proportions occurred among full-term (56% [27/48]) and nonhospitalized (78% [42/54]) infants [37]
All Cronobacter species, except C condimenti, have been linked retrospectively to clinical cases of infection in either adults or infants [32] However, multilocus sequence typing [38] has revealed that the majority of neonatal meningitis cases in the last 30 years have been linked to only one genetic lineage of the species Cronobacter sakazakii known as 'Sequence Type 4' or 'ST4', [39] and thus this clone appears to be of greatest concern with infant infections
Figure 4 Sources of C.sakazakii strains [9]
Cronobacter symptoms usually include the following in infants:
A Cronobacter sakazakii infection can also turn into meningitis, an inflammation of the membranes surrounding the brain and spinal cord Signs of meningitis in newborns include:
A bulge in the soft spot on the top of the head
Stiffness of the body and neck
Cases of Cronobacter sakazakii contamination in other products
Most neonatal C sakazakii infections cases have been associated with the use of powdered infant formula [40] [41] with some strains able to survive in a desiccated state for more than two years[42] However, not all cases have been linked to contaminated infant formula [32] In November 2011, several shipments of Kotex tampons were recalled due to a Cronobacter (E sakazakii) contamination
[32] In one study, the pathogen was found in 12% of field vegetables and 13% of hydroponic vegetables [43] [44].
Some reported cases of Cronobacter spp infections related to powdered
Cronobacter spp (formerly Enterobacter sakazakii) infection is rare but can kill 40% 80% of infected infants[41] The first two documented cases of 3
Cronobacter species occurred in 1958 at St Albans, England[45] According to the Centers for Disease Control and Prevention (CDC) [46] and FAO/WHO [7], from
1958 to 2009, there was 120 cases of Cronobacter infection in infants have been reported, and at least 27 deaths from all parts of the world
The below table is the summary of some outbreaks and cases of Cronobacter species until 2017, according to Song et al in 2018[45]
Table 3 Outbreaks and cases of infections
Location Year Cease/Death References
St Albans, England 1958 2/2 Urmenyi and Franklin, 1961
Denmark 1965 1/None Joker et al., 1965
Macon, GA, USA 1979 1/Not mentioned
Indianapolis, IN, USA 1981 1/None Kleiman et al., 1981
The Netherlands 1983 8/None Muytjens et al., 1983; Muytjens,
Arseni et al., 1985 Reykjavik, Iceland 1986-1987 3/1 Biering et al., 1989; Clark et al.,
Memphis, TN, USA 1988 4/Not mentioned
Baltimore, MD, USA 1990 1/Not mentioned
Cincinnati, OH, USA 1990 1/Not mentioned
Belgium 1998 12/2 Van Acker et al., 2001
Israel 1997-2000 5/None Block et al., 2002; Bar-Oz B et al.,
2001 Knoxville, TN, USA 2001 10/1 Himelright et al., 2002; Weir, 2002
CDC unpublished data, Bowen and
CDC unpublished data; Bowen and
Coignard et al., 2004; Bowen and
CDC unpublished data; Bowen and
CDC unpublished data; Bowen and
New Mexico, USA 2008 2/None CDC, 2009
Queretaro, Mexico 2010 2/None Flores et al., 2011
Not mentioned 2012 1/None Broge and Lee, 2013
As can be seen, there are several reported cases of Cronobacter infection in neonates and infants However, before 1994, C sakazakii was not identified as a substantial source of newborn infection, and its relationship with PIF had not yet been established Since then, contaminated PIF has been recognized as the primary risk factor for neonatal Cronobacter spp infections in a plethora of published papers and research[4] Below are some cases that have been associated with a powdered infant: o For 8 cases in the Netherlands, there was the first description of an association between Cronobacter spp and infant milk formula reported by Muytjens et al in 1983[47] [48] It was said that these cases might have been caused by inadequate hygiene or contamination of powdered infant formula due to improper handling methods o In Belgium, the out outbreak involved 12 infants and resulted in the death of twin brothers The infant formula powder that was used to feed the infants was stopped temporarily until further tests were carried out After the initial analysis indicated that the formula powder was not contaminated, there was a resumption of the use of the product However, these preliminary tests were incorrect, but this was discovered only when a female child suffered
Cronobacter-associated necrotizing enterocolitis The research of Van Acker et al in 2001[49] showed that C sakazakii was isolated from both the implicated prepared formula milk and numerous unopened cans from the single batch Further investigations found that the manufacturer's quality control regime concerning coliforms did not comply with Belgian legislation, and all and all contaminated products were ultimately recalled[48] o In the United Stage, many cases of Cronobacter infection were also reported In 1989, the outbreak in a hospital in Memphis involved four infants that of who had been fed with the same infant formula prepared in the same food blender Cronobacter spp at 8 CFU/100 g and E cloacae at 48 CFU/100 g were found in the powdered infant formula[50] The food blender was also contaminated with Cronobacter spp., Pseudomonas fluorescens, and
Pseudomonas maltophil The outbreak was said may have originated at the food blender[48] In 2001, there was the first report of C sakazakii infection associated with infant formula prompting the recall of a commercial product in the United States[40] In this case, a cohort analysis was conducted on the
49 patients who were evaluated to identify potential risk factors for C sakazakii infection or colonization There were nine case patients and forty noncase individuals among the 49 patients found in the cohort The research pointed to specific infant formula as the cause of the infection, and testing on both open and unopened cans of the infant formula was positive for
Cronobacter spp o In 2007, the case that Cronobacter spp was identified as the cause of meningitis in a 17-day-old infant in Canada was linked to powdered infant formula In addition, in the same year, in India the first two cases of Cronobacter spp infection was documented Powdered infant formula was suspected of being the source of infection for at least one of the babies, although the pathogen was not isolated from the formula due to a lack of testing[48]
In particular, most recently, in 2022, there were four cases of illness believed to be linked to powdered milk This incident was initially believed to be related to Abbott Laboratories which is a United State health care company well-known for many nutrition brands such as Pedialyte, Ensure, Glucerna, and Similac Especially Similac is one of the famous baby formula infants that most parents choose for their children According to the statistical data in 2020, there were 3.18 million consumers in the U.S[14] There were, however, four customer complaints involving
Cronobacter sakazakii or Salmonella Newport in infants who had taken powder baby formula prepared in this plant Below are some more detailed descriptions of this Abbott9s recall: o Abbott voluntarily recalled Similac, Alimentum, and EleCare products made in Sturgis, Michigan on February 17, 2022 This action follows after four consumer reports of Cronobacter sakazakii or Salmonella Newport in children who had taken powder infant formula processed in this plant[51] o According to FDA, during testing in Sturgis, Michigan facility, they found evidence of Cronobacter sakazakii in the plant in non-product contact areas but no evidence of Salmonella Newport Besides, the retained samples related to the four complaints about Cronobacter sakazakii, and Salmonella Newport had negative results for all samples Nevertheless, it cannot be denied that there have been 4 cases of infants who consumed formula produced at this facility infected with Cronobacter[51] More investigations were taking place at this time o Consumers were also advised not to use recalled Similac, Alimentum, or EleCare by FDA.[52]:
Figure 5 Recall for Similac, Alimentum, and EleCare powdered infant formulas
Products are included in the recall if they have all three items below[52]:
- The first two digits of the code are 22 through 37 and
- The code on the container contains K8, SH, or Z2, and
- The expiration date is 4-1-2022 (APR 2022) or later
Figure 6 Recall products have a code beginning from 22 to 37 and containing
K8, SH, or Z2 o On February 28, 2022, Abbott continue volunteer recalled one lot of Similac PM 60/40 (Lot # 27032K80 (can) / Lot # 27032K800 (case)) manufactured in Sturgis, Michigan The action is being taken in response to the death of a child who tested positive for Cronobacter sakazakii and was said to have drunk Similac PM 60/40 from this batch
Figure 7 Similac PM 60/40 was recalled o The FDA has released documents revealing a pattern of issues with food safety measures at the infant formula manufacturing factory The inspection findings are documented in FDA Form 483 and include:
+The factory did not test a representative sample of a powdered infant formula production aggregate at the final product stage and before distribution to confirm that the production aggregate met the requisite microbiological quality criteria
+ The factory did not keep a building utilized in the production, processing, packing, or storage of infant formula clean and sanitary
+ Personnel who worked directly with infant formula9s raw components, packaging, equipment, or utensil contact surfaces did not properly wash their hands in a handwashing facility at an appropriate temperature after the hands may have become dirty or contaminated
+ The factory did not implement a process control system that covered all stages of processing to guarantee that infant formula did not get contaminated due to the presence of microorganisms in the formula or the processing environment Especially, positive environmental sites for
Cronobacter sakazaldi were found in the packaging room for the filler line, and some other places in the factory
+ The factory failed to ensure that all surfaces that came into contact with the products were maintained clean to prevent contamination of infant formula from any source
These released documents showed the high potential risk for Cronobacter sakazaldi infection in Abbott9s infant formula
However, the later analysis revealed that these patient samples were not genetically linked to the various strains of Cronobacter detected in environmental samples taken from Abbott Nutrition's Sturgis, MI location[51] It seems that the cause of the contamination in these cases is not directly related to powdered milk during production Nevertheless, a pattern of issues with food safety measures at Abbott Nutrition's Sturgis, MI factory can not be denied These problems should be improved to prevent the high risk of Cronobacter sakazaldi and other pathogen microorganisms infection Besides, one positive result came from an open container in the infant's home It tested positive for two strains of Cronobacter sakazakii, one of which matched the strain that caused the infant's infection, and the other matched a strain found on a bottle of distilled water in the infant's home that was used to mix the formula[56] During this investigation, FDA collected additional product samples from the facility and FDA analysis is ongoing As a result, there were four cases of infection in total, with Cronobacter infections possibly contributing to the deaths of two newborns in Ohio.[51] These cases of Cronobacter infections might be related to inadequate hygiene or contamination of powdered infant formula due to improper handling methods
From past and recent infections, they can indicate the relationship between Powdered infant formula and Cronobacter infection Moreover, according to WHO/FAO in the Meeting report for the