Large-scale genome-wide association studies (GWAS) have identified >75 loci associated with adiposity traits. In ongoing analyses by the GIANT consortium, including data of >340,000 individuals, the number of loci for BMI and WHR is set to more than double. While explained variance remains small, each of the loci may harbor genes that are involved in pathways relevant to obesity. As more BMI-associated loci are being identified, the previously implicated pathways that point towards a role for the central nervous system in the regulation of body mass are now described with much greater detail, involving synaptic plasticity and glutamate receptor signaling. The latter is one of the proposed mechanisms through which topiramate, a compound of an FDA-approved weight loss drug, affects body weight and appetite. The increasing number of WHR loci are enriched for genes expressed in adipose tissue and reveal pathways implicated in adipogenesis, angiogenesis, and body fat distribution, that are distinct from the pathways involved the regulation of overall body mass. As GWAS grow larger, loci are revealed that associate not only with obesity-susceptibility, but also with other cardiometabolic traits. While most of such obesity-susceptibility loci are associated with poorer metabolic health, some have protective effects. I will provide an overview of the current state of GWAS-identified loci and how we can learn more about the potential etiology of obesity.

Cronobacter spp. is an opportunistic pathogen possibly occurring in many different foods and environments. This study reports results from a broad survey of foods manufactured or marketed in The Netherlands, including relevant non-food environments, conducted over a 5-years period (2001–2005). Using a specifically designed real-time polymerase chain reaction method for confirmation, Cronobacter spp. was isolated from milk powders (7/175), powdered formulae for consumers <1year (8/395), formulae for consumers >1year (1/5), other powdered instant products (1/182), dry cereals (6/123), raw minced meats (7/222), vegetables (2/47), spices (1/28), human faeces (1/98), and human skin (1/116) samples.

The aim of this study was to determine the survival of two strains of Cronobacter (Enterobacter sakazakii) and six other bacterial strains inoculated into dry powdered infant formula (PIF) stored for 22 weeks at several temperatures between 7 and 42 degrees C. The experimental setup involved a relatively high initial concentration of bacteria, around 10(4) CFU/g of powder, and enumeration of survivors with a minimum detection level of 100 CFU/g. For all strains tested, it was found that the number of bacterial cells decreased faster with increasing temperature. Cronobacter spp. cells generally survived better at high temperatures (37 and 42 degrees C) than the other bacteria, while such a difference in survival was not apparent at other temperatures. To describe the effect of temperature on survival, both the Weibull distribution model and the log-linear model were tested. At 22 degrees C, decline rates of 0.011 and 0.008 log units per day were found for Cronobacter sakazakii ATCC 29544 and Cronobacter strain MC10, respectively. Assuming a linear relationship between log-transformed D-values and temperature, z-values estimated for C. sakazakii ATCC 29544 and Cronobacter MC10 were 13.3 and 23.5 degrees C, respectively. Such differences found in resistance among Cronobacter spp. would be relevant to consider when establishing quantitative risk assessments on consumer risks related to PIF.

Microbiological criteria, food safety objectives and performance objectives, and the relationship between them are discussed and described in the context of risk-based food safety management. A modified method to quantify the sensitivity of attributes sampling plans is presented to show how sampling plans can be designed to assess a microbiological criterion. Examples presented show that testing of processed foods for confirmation of safety is often not a practical option, because too many samples would need to be analysed. Nonetheless, in such cases the classical “ICMSF cases” and sampling schemes still offer a risk-based approach for examining food lots for regulatory or trade purposes.

Enterobacter sakazakii can be present, although in low levels, in dry powdered infant formulae, and it has been linked to cases of meningitis in neonates, especially those born prematurely. In order to prevent illness, product contamination at manufacture and during preparation, as well as growth after reconstitution, must be minimized by appropriate control measures. In this publication, several determinants of the growth of E. sakazakii in reconstituted infant formula are reported. The following key growth parameters were determined: lag time, specific growth rate, and maximum population density. Cells were harvested at different phases of growth and spiked into powdered infant formula. After reconstitution in sterile water, E. sakazakii was able to grow at temperatures between 8 and 47 degrees C. The estimated optimal growth temperature was 39.4 degrees C, whereas the optimal specific growth rate was 2.31 h(-1). The effect of temperature on the specific growth rate was described with two secondary growth models. The resulting minimum and maximum temperatures estimated with the secondary Rosso equation were 3.6 degrees C and 47.6 degrees C, respectively. The estimated lag time varied from 83.3 +/- 18.7 h at 10 degrees C to 1.73 +/- 0.43 h at 37 degrees C and could be described with the hyperbolic model and reciprocal square root relation. Cells harvested at different phases of growth did not exhibit significant differences in either specific growth rate or lag time. Strains did not have different lag times, and lag times were short given that the cells had spent several (3 to 10) days in dry powdered infant formula. The growth rates and lag times at various temperatures obtained in this study may help in calculations of the period for which reconstituted infant formula can be stored at a specific temperature without detrimental impact on health.

This article is based on a background paper prepared for the ILSI Europe workshop on “The impact of Food Safety Objectives on Microbiological Food Safety Management”. It describes the how the concept of “Food Safety Objectives” (FSOs) can be used to target HACCP plans. FSOs describe the level of a hazard at the moment of consumption, they are considered to be “acceptable levels” of pathogens. Control measures applied from farm to fork must assure that such levels are not exceeded. In order to achieve such levels, Performance Criteria (PCs) are set to assure that a certain killing effect of a process or treatment is achieved or that a potential increase in numbers does not result in unacceptable levels of pathogens in a product. For reasons explained in this article, the term Performance Objective (PO) is introduced to designate levels of pathogens at stages in the food chain before the moment of consumption. In order to meet PCs, POs or FSOs, process criteria (such as time and temperature) and product criteria (such as pH and aw) need to be specified in the HACCP plans or in other documents. FSOs and POs are food safety targets and differ as such from Microbiological Criteria which are designed to accept or reject foods based on test results. Examples are given to illustrate that, although some of the terms may be new to certain sectors in the food chain, the concepts have been applied for many years in food processing.

Enterobacter sakazakii is a motile, peritrichous, gram-negative rod that was previously known as a yellow pigmented Enterobacter cloacae. It is documented as a rare cause of outbreaks and sporadic cases of life-threatening neonatal meningitis, necrotizing enterocolitis, and sepsis. E. sakazakii has been isolated from milk powder-based formulas, and there is thus a need to investigate whether and where E. sakazakii occurs in these manufacturing environments. For this purpose, a simple detection method was developed based on two features of E. sakazakii: its yellow pigmented colonies when grown on tryptone soy agar and its constitutive alpha-glucosidase, which is detected in a 4-h colorimetric assay. Using this screening method, E. sakazakii strains were isolated from three individual factories from 18 of 152 environmental samples, such as scrapings from dust, vacuum cleaner bags, and spilled product near equipment. The method is useful for routine screening of environmental samples for the presence of E. sakazakii.

Enterobacter sakazakii occasionally causes illness in premature babies and neonates. Contamination of infant formulae during factory production or bottle preparation is implicated. Advice to health-care professionals focuses on bottle preparation, but the effectiveness of prevention depends on the degree of contamination and contamination sites, which are generally unknown. To keep contamination to a minimum in the finished product depends on knowledge of the occurrence of E sakazakii. We used a refined isolation and detection method to investigate the presence of this micro-organism in various food factories and households. Environmental samples from eight of nine food factories and from five of 16 households contained E sakazakii. The widespread nature of this micro-organism needs to be taken into account when designing preventive control measures.

Authors' reply Maaike Arts asks why we did not include in our Research Letter other recommendations about Enterobacter sakazakii in infant formulae. We believe that our conclusion “The widespread nature of this micro-organism needs to be taken into account when designing preventive control measures” is the only one justified on the basis of the results we reported. The purpose of our study was to gain a better understanding of the ecology of E sakazakii as a starting point for designing effective control strategies. On the basis of the research we reported, we cannot substantiate the recommendations suggested by Arts. However, we would like to draw readers' attentions to the joint FAO/WHO Expert Workshop on E sakazakii and other micro-organisms in powdered infant formula (held in Geneva, Switzerland, Feb 2–5, 2004)1Food and Agriculture Organization/World Health Organization Joint FAO/WHO workshop on Enterobacter sakazakii and other microorganisms in powdered infant formula, Geneva.http://who.int/foodsafety/micro/meetings/feb2004/en/Date: 2–5 February 2004Google Scholar as a potential source of information. With respect to the suggested conflict of interest, we are convinced that we clearly disclosed our affiliations and financial support as required by the journal. As stated in the original publication, “The sponsor had no role in the study design, data collection, data analysis, and data interpretation, or in writing the report.” Enterobacter sakazakii in factories and householdsThe isolation of Enterobacter sakazakii from various factories, including infant formula factories (Jan 3, p 39),1 and the related contamination of infant formulae with E sakazakii are causes for concern. I was surprised to see only one recommendation from the authors at the end of the article: “The widespread nature of this micro-organism needs to be taken into account when designing preventive control measures.” Full-Text PDF

Recontamination of food products can cause foodborne illnesses or spoilage of foods. It is therefore useful to quantify this recontamination so that it can be incorporated in microbiological risk assessments (MRA). This paper describes a first attempt to quantify one of the recontamination routes: via the air. Data on the number of airborne microorganisms were collected from literature and industries. The settling velocities of different microorganisms were calculated for different products by combining the data on aerial concentrations with sedimentation counts assuming that settling is under the influence of gravity only. Air movement is not explicitly considered in this study. Statistical analyses were performed to clarify the effect of different products and seasons on the number of airborne microorganisms and the settling velocity. For both bacteria and moulds, three significantly different product categories with regard to the level of airborne organisms were identified. The statistical distribution in these categories was described by a lognormal distribution. The settling velocity did not depend on the product, the season of sampling or the type of microorganism, and had a geometrical mean value of 2.7 mm/s. The statistical distribution of the settling velocity was described by a lognormal distribution as well. The probability of recontamination via the air was estimated by the product of the number of bacteria in the air, the settling velocity, and the exposed area and time of the product. For three example products, the contamination level as a result of airborne recontamination was estimated using Monte Carlo simulations. What-if scenarios were used to exemplify determination of design criteria to control a specified contamination level.

When bacteria attach to the walls of pipelines, they can form biofilms, which can cause the recontamination of food products. In order to quantify such recontamination, a one-dimensional biofilm. model was developed taking into account adsorption, desorption, and the growth of cells. The model consisted of two mass balances describing increases in biofilm formation at the wall and the accumulation of cells in the liquid phase. The necessary parameters for the model were obtained in laboratory biofilm experiments. These experiments involved a flowing system and the use of Staphylococcus aureus as a model pathogen and silicon tubing as a testing material. S. aureus was inoculated into the system for 2 h, and then the system was changed to a sterile medium. Both biofilm formation and the release of cells into the flowing liquid were measured until steady-state conditions were reached (for up to 9 days). The experiments were performed in duplicate for different flow conditions (i.e., for Reynolds numbers of 3.2, 32, and 170). It was shown that at higher Reynolds numbers, the biofilm developed faster, probably owing to an increase in the transfer of nutrients to the surface. The proposed biofilm model was capable of describing the data obtained for the three different flow conditions with the use of the specific growth rate in the biofilm and the desorption coefficient as fit parameters. The specific growth rates were 0.16, 0.27, and 0.49 h(-1) for Reynolds numbers of 3.2, 32, and 170, respectively, and the desorption coefficients were about 1% of these values.

Recontamination of food products can be the origin of foodborne illnesses and should therefore be included in quantitative microbial risk assessment (MRA) studies. In order to do this, recontamination should be quantified using predictive models. This paper gives an overview of the relevant modelling approaches that are available in the literature to quantify recontamination via factory environment. Different recontamination routes are described: recontamination via air, via processing equipment or via hand contact. Unfortunately, not many available models are directly applicable to the food industry; most models are developed for aquatic or environmental systems. Finally, a general systematic approach is proposed for modelling contamination from surfaces via air, hands or liquid into the product and ranges for the parameters are given.

The international workshop on "Promotion of Technical Harmonisation on Risk-Based Decision Making" reviewed the use of risk-based decision making across a range of industry sectors and countries. This paper presents the contribution to the workshop covering microbiological risk assessment of foods in international trade. The format is a response to a set of questions prepared by the organisers of the workshop covering the use and performance of risk assessment, evaluation of the acceptability of the risk and the use of risk assessment in the decision-making process (see "Preface" of this special issue).Risk Assessment of foods has been developed for chemical hazards rather than for Microbiological ones. Acceptable or tolerable levels of food additives and contaminants have been included in many food standards worldwide. As part of the FAO/WHO Food Standards programme, the Codex Alimentarius Commission has issued many such standards, based on recommendations from two FAO/WHO expert bodies, the Joint FAO/WHO Expert Committee on Food Additives and Contaminants (JECFA) and the Joint FAO/WHO Meeting on Pesticide Residues (JMPR). This need to establish Food Standards on Risk Assessment procedures was reinforced by the signing of the Uruguay Round of Multilateral Trade Negotiations, presently known as WTO Agreements. The agreement on Sanitary and Phytosanitary (SPS) measures put particular emphasis on the establishment of acceptable or tolerable levels for microorganisms important. The SPS text specified that science and risk assessment should be the basis for the determination of the safety of food. Food safety standards issued by Codex Alimentarius were mentioned as the reference, and Codex was also the preferred international body to develop methods for their establishment. (C) 2001 Elsevier Science Ltd. All rights reserved.

Although numerous papers on Microbiological Risk Assessment (MRA) of food products have been published, a number of issues related to it remain unresolved. This paper explains the role of Microbiological Risk Assessment in the context of Risk Analysis as outlined by Coder Alimentarius. It reviews some representative work in the area, with particular emphasis on the objectives, outputs and conclusions of the studies, and on how researchers propose using the resulting Risk Estimate for decision making. Several problems and sources of confusion concerning MRA are identified, such as terminology, the application of Risk Estimates to establish Food Safety Objectives and microbiological criteria for foods, lack of data, and the difference between Risk Assessment and the Hazard Analysis and Critical Control Point system (HACCP). In the context of Codex Alimentarius, MRA was developed as a tool for decision making and priority setting by government risk managers. However, elements of Risk Assessment can be used for other purposes. A transparent description of a Risk Assessment study is useful for Risk Communication. Industrial food safety managers can compare the effect of various hypothetical production scenarios using estimates of the level and the probability of a pathogen in the product at the time that it is consumed. This limited form of Risk Assessment could better be called Safety Assessment, and can be used as a tool for food product and process development.