Genotypic and phenotypic characterisation of a collection of Cronobacter (Enterobacter sakazakii) isolates

Enterobacter sakazakii has been identified as the causative agent of serious neonatal infections, associated with high mortality rate. In many cases, powdered infant formula (PIF) has been identified as the source of infection. Recently, E. sakazakii was proposed to be classified in a new genus, Cronobacter. Since knowledge on this pathogen is still incomplete, there is a need for molecular characterization schemes in order to help with epidemiological investigation and evaluate strain variability. The objectives of this study were to combine genotypic (pulsed-field gel electrophoresis [PFGE], 16S rRNA gene sequencing, and automated ribotyping) methods with traditional phenotypic biochemical methods to characterize a collection of Cronobacter isolates from various origins. In addition, the relative growth dynamics were compared by estimating the growth rates for each isolate in non-selective broth (BHI) at 25 degrees C and 37 degrees C. According to biochemical test profiles the majority of isolates were identified as Cronobacter sakazakii, which seemed to be the most common species distributed in the environment of PIF production plants. Furthermore, the PFGE technique displayed very high discriminatory power as 61 distinct pulsotypes were revealed among the 150 Cronobacter isolates. Combining information on sample origin and pulse type, 64 isolates were deemed as unique strains. Although genetic typing data for the strains clearly delineated them into clusters closely corresponding to biochemical speciation results, it was not without discrepancies as some strains did not group as predicted. Important for quantitative risk assessment is the fact that despite the high genetic heterogeneity observed for this collection, most Cronobacter strains displayed similar growth rates irrespective of species designation.

A survey on knowledge and self-reported formula handling practices of parents and child care workers in Palermo, Italy

BACKGROUND

Powdered infant formula (PIF) is not a sterile product, but this information appears to be poorly diffused among child caregivers. Parents and child care workers may behave in an unsafe manner when handling PIF.

METHODS

This study involved parents and child care workers in the 24 municipal child care centres of Palermo. Knowledge and self-reported practices about PIF handling were investigated by a structured questionnaire. A Likert scale was used to measure the strength of the respondent's feelings. Association of knowledge and self-reported practices with demographic variables was also evaluated.

RESULTS

42.4% of parents and 71.0% of child care workers filled in the questionnaire. Significant differences were found between parents and child care workers for age and education. 73.2% of parents and 84.4% of child care workers were confident in sterility of PIF. Generally, adherence to safe procedures when reconstituting and handling PIF was more frequently reported by child care workers who, according to the existing legislation, are regularly subjected to a periodic training on food safety principles and practices. Age and education significantly influenced the answers to the questionnaire of both parents and child care workers.

CONCLUSION

The results of the study reveal that parents and child care workers are generally unaware that powdered formulas may contain viable microorganisms. However, child care workers consistently chose safer options than parents when answering the questions about adherence to hygienic practices.At present it seems unfeasible to produce sterile PIF, but the risk of growth of hazardous organisms in formula at the time of administration should be minimized by promoting safer behaviours among caregivers to infants in both institutional settings and home.

Nutritional deficiencies during normal growth

Nutritional deficiencies have always been a major consideration in pediatrics. Although the classic forms of many of the well-documented nutritional deficiencies are memorized during training as a physician, nutritional deficiencies that can occur in otherwise asymptomatic normally growing children are often overlooked. The two most common deficiencies seen in children who are growing normally are iron and vitamin D deficiencies. These deficiencies are surprisingly common and can have a significant impact on the overall health of a child. This article reviews these nutritional deficiencies and other less commonly seen deficiencies in children who are otherwise growing normally.

The health implications of soy infant formula

Soy formula (SF) has been fed to millions of infants worldwide. It has been shown to promote growth and development as well as milk-based formula (MF). Controversy has developed over the adequacy and safety of SF. Most concerns are based on in vivo and in vitro data that raise the possibility of estrogenic effects of isoflavones contained in SF. There are few studies of children who were fed SF, and thus insufficient data are available to judge if SF feeding results in clinically significant developmental effects and if there are any long-term health consequences (adverse or beneficial). However, the Arkansas Children's Nutrition Center is conducting a prospective longitudinal study comparing growth, development, and health of breastfed children with formula-fed (SF and MF) children from birth through age 6 y. After 5 y of study, children in all 3 groups (n > 300) are growing and developing within normal limits, and there are no indications of adverse effects in the soy-fed children. Neonatal pig studies comparing SF, MF, and breast milk (BM) have shown diet-specific gene expression profiles in various target tissues. Therefore, although SF differed significantly from BM, MF also differed from BM, and SF differed from MF. Nonetheless, these animals grew and developed normally, and SF piglets had several health benefits (eg, increased bone quality) and no observable adverse effects. Thus, to date, our results suggest that SF supports normal growth and may have advantages in promoting bone development.

Evaluation of a revised U.S. Food and Drug Administration method for the detection and isolation of Enterobacter sakazakii in powdered infant formula: precollaborative study

A revised U.S. Food and Drug Administration (FDA) method for the detection and isolation of Enterobacter sakazakii in powdered infant formula was developed based on real-time PCR technology complemented by culture isolation on chromogenic agars. A validation study was conducted to compare the revised FDA method to the reference FDA method. Casein and soy powdered infant formula inoculated with morphologically typical and atypical strains of E. sakazakii were analyzed. Valid results were obtained from 360 test portions and controls and showed that the revised FDA method is significantly better (P < 0.05) than the reference FDA method for the detection of typical E. sakazakii strains and the two methods are equivalent for the detection of atypical E. sakazakii strains.

Infant formula

Although the American Academy of Pediatrics and the American Academy of Family Physicians recommend breast milk for optimal infant nutrition, many parents still choose formula as an acceptable alternative. The wide variety of available formulas is confusing to parents and physicians, but formulas can be classified according to three basic criteria: caloric density, carbohydrate source, and protein composition. Most infants require a term formula with iron. There is insufficient evidence to recommend supplementation with docosahexaenoic acid or arachidonic acid. Soy formulas are indicated for congenital lactase deficiency and galactosemia, but are not recommended for colic because of insufficient evidence of benefit. Hypoallergenic formulas with extensively hydrolyzed protein are effective for the treatment of milk protein allergy and the prevention of atopic disease in high-risk infants. Antireflux formulas decrease emesis and regurgitation, but have not been shown to affect growth or development. Most infants with reflux require no treatment. Family physicians can use these guidelines to counsel parents about infant formula, countering consumer advertising that is not evidence-based.

[Identification of the new foodborne pathogens Enterobacter sakazakii using modern taxonomy approaches]

The modern data on biological properties and taxonomy of a new kind of pathogenic bacteria Enterobacter sakazakii, capable to cause infections of necrotizing enterocolitis, sepsis and neonatal meningitis in neonates are submitted. The method of detection E. sakazakii, providing testing for presence of any enterobacteria and identification food isolates of E. sakazakii with a number of key phenotypic markers is developed.

Nutrient-enriched formula versus standard term formula for preterm infants following hospital discharge

BACKGROUND

Preterm infants are often growth-restricted at hospital discharge. Feeding infants after hospital discharge with nutrient-enriched formula rather than standard term formula might facilitate "catch-up" growth and improve development.

OBJECTIVES

To determine the effect of feeding nutrient-enriched formula compared with standard term formula on growth and development for preterm infants following hospital discharge.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group were used. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), MEDLINE (1966 - May 2007), EMBASE (1980 - May 2007), CINAHL (1982 - May 2007), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared the effect of feeding preterm infants following hospital discharge with nutrient-enriched formula compared with standard term formula.

DATA COLLECTION AND ANALYSIS

Data was extracted using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two authors, and synthesis of data using weighted mean difference and a fixed effects model for meta-analysis.

MAIN RESULTS

Seven trials were found that were eligible for inclusion. These recruited a total of 631 infants and were generally of good methodological quality. The trials found little evidence that feeding with nutrient-enriched formula milk affected growth and development. Because of differences in the way individual trials measured and presented outcomes, data synthesis was limited. Growth data from two trials found that, at six months post-term, infants fed with nutrient-enriched formula had statistically significantly lower weights [weighted mean difference: -601 (95% confidence interval -1028, -174) grams], lengths [-18.8 (-30.0, -7.6) millimetres], and head circumferences [-10.2 ( -18.0, -2.4) millimetres], than infants fed standard term formula. At 12 to 18 months post-term, meta-analyses of data from three trials did not find any statistically significant differences in growth parameters. However, examination of these meta-analyses demonstrated statistical heterogeneity. Meta-analyses of data from two trials did not reveal a statistically significant difference in Bayley Mental Development or Psychomotor Development Indices. There are not yet any data on growth or development through later childhood.

AUTHORS' CONCLUSIONS

The available data do not provide strong evidence that feeding preterm infants following hospital discharge with nutrient-enriched formula compared with standard term formula affects growth rates or development up to 18 months post-term.

Potential contaminants in the food chain: identification, prevention and issue management

Contaminants are a vast subject area of food safety and quality. They are generally divided into chemical, microbiological and physical classes and are present in our food chain from raw materials to finished products. They are the subject of international and national legislation that has widened to cover more and more contaminant classes and food categories. In addition, consumers have become increasingly aware of and alarmed by their risks, whether rightly or not. What is the food industry doing to ensure the safety and quality of the products we feed our children? This is a valid question which this article attempts to address from an industrial viewpoint. Chemical food safety is considered a complex field where the risk perception of consumers is often the highest. The effects of chronic or acute exposure to chemical carcinogens may cause disease conditions long after exposure that can be permanently debilitating or even fatal. It is also a moving target, as knowledge about the toxicity and occurrence data of new chemical contaminants continues to be generated. Their identification, prevention and management are challenges to the food industry as a whole. A reminder of the known chemical hazards in the food chain will be presented with an emphasis on the use of early warning to identify potential new contaminants. Early warning is also a means of prevention, anticipating food safety concerns before they become issues to manage. Current best management practices including Hazard Analysis and Critical Control Points relating to the supply chain of baby foods and infant formulae will be developed. Finally, key lessons from a case study on recent contamination issues in baby food products will be presented.

The Year of the Salmonella Seekers-1977

In 1977 two major outbreaks of salmonella infection originated in Victoria. The first of these, involving Salmonella Bredeney, continued over some seven months and was traced to contamination of powdered milk-based infant formulae during manufacture. This caused cases of gastroenteritis among young children throughout Australia. Another incident led to the discovery that salmonella serovars were colonising not one, but a number of dairy factories through the State. The second outbreak was of typhoid, stemming from a carrier working in a sandwich bar, and occurred during the course of the first, almost overwhelming public health resources and delaying investigation of the first outbreak. The background, recognition, course, investigation and resolution of these, previously unpublished, outbreaks are described, drawing upon the experiences of authors involved at the clinical, public health and laboratory levels, and preserved, contemporary records. Taken together, these outbreaks directly stimulated radical improvements in the construction and management of dairy factories in the State; initiated the adoption of risk management concepts in food factories; caused the launch of regional regulations compelling notification of salmonellas found in food manufacture; and led to the setting-up of an enhanced national, laboratory-based system for the collection, analysis and dissemination of information on enteric pathogens.

Enterobacter sakazakii bacteriophages can prevent bacterial growth in reconstituted infant formula

Reconstituted infant formula has been implicated in outbreaks of Enterobacter sakazakii infections, causing high mortality and serious sequelae. Current prevention methods appear to be insufficient to ensure that such foods are free of E. sakazakii. In this study, the usefulness of bacteriophages for biocontrol of E. sakazakii was investigated. Of a total of six new E. sakazakii phages isolated from sewage and UV irradiated cultures, two were selected for further study by electron microscopy, DNA restriction analysis and SDS-PAGE of structural proteins. Purified phages were used to control bacterial growth in broth medium and reconstituted infant formula. Both phages effectively prevented development of E. sakazakii in formula at various temperatures (12, 24 and 37 degrees C), the efficiency of which was dependent upon intrinsic lysis properties and the applied phage concentration. We conclude that application of specific bacteriophages may provide a means for efficient prevention of E. sakazakii infection through reconstituted infant formula.

Post-discharge nutrition: what does the evidence support?

Although there are no official recommendations for specific nutrient intakes in premature infants after hospital discharge, it is agreed that the goal should be to achieve the body composition and rate of growth of that of a normal fetus of the same postmenstrual age during the entire first year of life. A general recommendation to use the special formulas designed for preterm infants after hospital discharge in place of the formulas for term infants cannot be made from the available evidence at this time. Infants fed human milk after discharge are of the greatest concern as human milk does not in theory meet the requirements for growth in these infants. Such infants should remain on supplemental vitamins and Fe while breastfeeding, and growth as well as serum levels of phosphorus and alkaline phosphatase should be carefully monitored. The increased risk of preterm infants for obesity and the metabolic syndrome secondary to the metabolic/nutritional events early in life (programming) is likely to be small compared with the contribution of other risk factors, such as parental size, weight as an adolescent, and various lifestyle factors such as physical activity.