An analysis of the work and tasks of the microbiology laboratory at a multidisciplinary research institute

The comparative analysis of the work of 3 groups of microbiologists at a multiple-discipline clinical research institute has permitted the development of the method for the evaluation of the work of researchers in the microbiological laboratory. The volume of investigations carried out in the laboratory, the relative significance of individual samples of clinical material, the degree of contamination of the samples under study, the level of the identification of microbes and the analysis of the data obtained in the course of investigations have been used as evaluation criteria. The method may be used for the objective quantitative evaluation of the work and the level of professional training of individual researchers, as well as for the calculation of expenditures in materials and time, necessary for performing investigations. According to the data of the analysis carried out by the authors with the use of the proposed method, the work of scientific-practical groups at the institutions of this category holds the greatest promise.     

Rapid microbiology: Applications of bioluminescence in the food industry a review

The bioluminescent assay of ATP is rapid and simple and may be used as an estimate of microbial numbers. It therefore shows great potential as a technique to provied information on the microbiological quality of a food within a few minutes, in comparison with conventional techniques, which provide results retrospectively. Howver, despite the advantages of speed and senstitivity, no food microbiologists are using the technique for routine quality control and hygiene monitoring. This review seeks to highlight the reasons for this, and to offer some ideas for future research to increase the acceptance of ATP assays within the food industry.     

High pressure processing of foods for microbiological safety and quality (a short review)

Consumers are demanding foods that are "natural", of good nutritional and sensory quality, free from chemical preservatives, microbiologically safe and with extended shelf-life. High pressure processing can, potentially, meet these criteria. Recent advances in equipment design now allow foods to be processed up to 900 MegaPascals (130,000 psi). However, further work is required to more fully understand the factors that can affect the response of microorganisms, including pathogens, to pressure so that treatments can be optimised and microbiological safety can be assured. This paper describes how the pressure resistance of microorganisms can vary depending on factors such as species, strain, stage of growth and food composition. Strategies for overcoming the problem of pressure resistance will be discussed, for example the use of pressure cycling and the combination of pressure with mild heat. The current commercial uses of high pressure to preserve foods will be reported and potential applications will also be discussed.     

An introduction to predictive microbiology and the development and use of probability models withClostridium botulinum

Summary Traditionally, food microbiologists have relied on empirical studies to assess the microbiological safety of a particular food. However, these studies are time-consuming and, because only one or two inhibitory factors are usually dealt with, they are often of limited value. Today, the food industry is constantly developing new products with new formulations and alternative packaging strategies, resulting in a wide diversity of factors to be studied. It is therefore advantageous to develop mathematical models describing microbial growth which may be used to predict how changes in formulations or storage conditions may affect microbial growth. A brief overview of the basic concepts and steps of modeling procedures will be presented, along with some of the difficulties encountered therein. The safety of foods with respect toClostridium botulinum depends on the probability (P) of growth or of toxigenesis, andP has been the dependent variable in several models. The development of these probability models will be discussed.Mention of brand or firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

Clostridium botulinum and the safety of minimally heated, chilled foods: an emerging issue?

Foodborne botulism is caused by consumption of preformed botulinum neurotoxin, with as little as 30 ng of neurotoxin being potentially lethal. Consumption of minute quantities of neurotoxin-containing food can result in botulism. In view of the severity of foodborne botulism, it is essential that new foods be developed safely without an increase in incidence of this disease. Minimally heated, chilled foods are a relatively new type of food, sales of which are currently increasing by about 10% per annum. These products meet consumer demand for high-quality foods that require little preparation time. Their safety and quality depends on mild heat treatment, chilled storage, restricted shelf life and sometimes on intrinsic properties of the foods. The principal microbiological hazard is nonproteolytic Clostridium botulinum, and there is a concern that this may become an emerging issue. A considerable amount of research and development over the last 15 years has underpinned the safe production of commercial, minimally heated, chilled foods with respect to foodborne botulism, and it is essential that safe food continues to be developed. In particular, the desire to use lighter heat processes and a longer shelf life presents a challenge that will only be met by significant developments in quantitative microbiological food safety.     

荧光酶标免疫分析在食品微生物检测中的应用

荧光酶标免疫分析是一种新型的快速检测微生物的方法,具有方便、快速、灵敏、准确等优点,已越来越多地被用于进出口食品中致病菌的检测。本文介绍了荧光酶标免疫分析法的原理、特点以及在食品微生物检测中的应用和未来发展方向。     

A matter of bacterial life and death

Over 50 years ago, standard microbiological methods were established for determining whether bacterial cells were dead or alive. Recently there has been a flurry of reports suggesting that bacteria may exist in an eclipsed state, escaping detection by standard methods. Whether there really is such a state is of more than academic interest, considering the implications for public health. The ensuing debate has been unusually energetic for the normally cultured community of microbiologists.     

Methods for rapid prototyping novel labware: using CAD and desktop 3D printing in the microbiology laboratory

Although the microbiology laboratory paradigm has increasingly changed from manual to automated procedures, and from functional to molecular methods, traditional culture methods remain vital. Using inexpensive desktop fused filament fabrication 3D printing, we designed, produced and tested rapid prototypes of customised labware for microbial culture namely frames to make dip slides, inoculation loops, multi-pin replicators, and multi-well culture plates for solid medium. These customised components were used to plate out samples onto solid media in various formats, and we illustrate how they can be suitable for many microbiological methods such as minimum inhibitory concentration tests, or for directly detecting pathogens from mastitis samples, illustrating the flexibility of rapid-prototyped culture consumable parts for streamlining microbiological methods. We describe the methodology needed for microbiologists to develop their own novel and unique tools, or to fabricate and customise existing consumables. A workflow is presented for designing and 3D printing labware and quickly producing easy-to-sterilise and re-useable plastic parts of great utility in the microbiology laboratory.     

Role of microbiological control in the choice of antibacterial therapy of respiratory infection in surgical patients during the postoperative period

The paper presents data on observation of 416 surgical patients subjected to investigation of sputum and washings from the tracheobronchial tree for estimating the role of clinico-microbiological study of respiratory tract excretions from surgical patients in choice of adequate therapy. On the basis of the obtained data and results of clinical observations a scheme of clinico-microbiological criteria was developed which would be of help for clinicians and microbiologists in difficult differential diagnosis of colonization and infection. The scheme will provide clinical microbiologists with possibility of correct interpretation of the results of studying respiratory tract excretions and presenting information containing preliminary positive or negative indications as to the presence of infection and recommendations for continuation or discontinuation of further clinico-microbiological investigations.     

On the compositing of samples for qualitative microbiological testing

The introduction of legislative microbiological criteria for foods [Official J L338 (2005) 1] has increased the exposure of enforcement and industrial laboratories to the need to test multiple food samples for organisms such as salmonellae. A consequence has been an increase in the number of organizations, both official and commercial, considering whether it is permissible to composite replicate sample units for the purposes of assessing compliance with the criteria. This note summarizes the statistical and practical aspects of compositing sample units for compliance testing. Provided that the method of choice is 'fit for purpose', then there is no statistical difference between testing, say, 30 x 25 g sample units or 3 x 250 g sample units. However, compositing of sample units should be done only when the method has been demonstrated unequivocally to be sufficiently sensitive to detect potentially lower numbers of target organism(s) in the quantity of composited sample under the conditions of test. Different approaches to compositing of samples are considered.     

Does microbiological testing of foods and the food environment have a role in the control of foodborne disease in England and Wales?

This review looks at the contribution of microbiological sampling to the safety of retail foods in England and Wales. It compares sampling methods available and assesses the value of testing as part of outbreaks of foodborne disease, as part of routine management by local authorities, as part of work done or commissioned by the food industry, and as part of research. It confirms that microbiological testing has a role during outbreaks as it makes a significant contribution to help identify foods and other areas of greatest risk for future study. The review suggests that routine testing by local authorities is often of limited use and could be improved by more targeted surveillance. Testing could be better used to validate primary control methods, such as Hazard Analysis and Critical Control Point (HACCP) system. Any public health benefit from testing in the food industry is often restricted by client confidentiality. Microbial research on foods is important as it can lead to significant improvements in safety. Current microbiological methods are slow and, in future, rapid molecular methods may make an even bigger contribution to the control of foodborne disease.     

Microbial contamination of food products consumed by infants and babies in Korea

Aims: The objectives of this study were to investigate the microbiological safety of various foods intended for consumption by infants and babies. Methods and Results: The incidence of Cronobacter spp. and Enterobacteriaceae from powdered infant formula (PIF, n = 75) and baby soy milk (n = 10) was examined. Additionally, aerobic plate count, coliforms and the prevalence of foodborne pathogens were investigated in 230 samples from a variety of infant and baby foods, including cereal‐based follow‐up formulas (FUF), liquid FUF and other infant foods. High APCs were observed in nutrient supplements and cereal‐based FUF. Coliforms were found in 6 (2·6%) products, and Cronobacter spp. was isolated in 10 (4·4%) samples, including four PIF and six cereal‐based FUF. Bacillus cereus was detected in 48 (20·9%) samples: cereal‐based FUF items (23·0%), rice soups (20·6%), honey samples (40·0%), biscuits (40·0%) and liquid FUF (7·4%). Conclusions: New safety criteria, along with hygienic control measures and consumer education strategies, are essential to improve the microbiological safety of infant or baby foods. Significance and Impact of the Study: This study provides comprehensive information about the prevalence and level of contamination of infant and baby food products by Cronobacter spp. and other major foodborne pathogens.     

Estimates of measurement uncertainty from proficiency testing schemes, internal laboratory quality monitoring and during routine enforcement examination of foods

AIMS: To determine the levels of measurement uncertainty (MU) obtained in proficiency testing and routine microbiological analyses of foods and to compare these with estimates of MU obtained for results of analyses obtained in collaborative interlaboratory studies of microbiological methods. METHODS AND RESULTS: Raw data submitted by participants in the Food Examination Proficiency Assessment Scheme were obtained from the Central Science Laboratory (York). Internal quality monitoring data were obtained from Health Protection Agency (HPA) laboratories, together with data from routine food examinations undertaken in HPA laboratories. The data sets were analysed to determine the relative standard deviations of reproducibility (RSD(R)), based on log(10) colony count values, and thence the relative measures of expanded uncertainty. Analysis of proficiency test data showed extreme values of RSD(R) up to +/-30% depending upon the organism, the laboratory and the method of examination. RSD(R) values on routine samples averaged around +/-12% but ranged up to +/-41% in a few instances. Internal quality assessments for different organisms ranged up to +/-27%, depending upon the particular organism and examination procedure. The results show little difference in uncertainty for counts obtained using different plating systems (e.g. pour plates, spread plates or spiral plating) on the same dilutions of the same food samples. The data are compared with estimates of microbiological uncertainty derived in interlaboratory studies. CONCLUSIONS: The estimates of uncertainty ranged widely, both within and between laboratories, and appeared to bear little relationship to the foodstuff under examination. The extent of MU associated with many routine microbiological examinations is generally no worse than those produced in inter-laboratory trials, although notable exceptions were seen. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge of the levels of MU may have wide impact on the establishment of international standard methods for microbiological examination of foods and the ability to set realistic microbiological criteria.     

Microbial production of fructosyltransferases for synthesis of pre-biotics

Fructooligosaccharides (FOS) are prebiotic substances found in several vegetable or natural foods. The main commercial production of FOS comes from enzymatic transformation of sucrose by the microbial enzyme fructosyltransferase. The development of more efficient enzymes, with high activity and stability, is required and this has attracted the interest of biotechnologists and microbiologists with production by several microorganisms being studied. This article reviews and discusses FOS chemical structure, enzyme characteristics, the nomenclature, producer microorganisms and enzyme production both in solid state fermentation and submerged cultivation.     

Probabilistic modeling approach for evaluating the compliance of ready-to-eat foods with new European Union safety criteria for Listeria monocytogenes

Among the new microbiological criteria that have been incorporated in EU Regulation 2073/2005, of particular interest are those concerning Listeria monocytogenes in ready-to eat (RTE) foods, because for certain food categories, they no longer require zero tolerance but rather specify a maximum allowable concentration of 100 CFU/g or ml. This study presents a probabilistic modeling approach for evaluating the compliance of RTE sliced meat products with the new safety criteria for L. monocytogenes. The approach was based on the combined use of (i) growth/no growth boundary models, (ii) kinetic growth models, (iii) product characteristics data (pH, a(w), shelf life) collected from 160 meat products from the Hellenic retail market, and (iv) storage temperature data recorded from 50 retail stores in Greece. This study shows that probabilistic analysis of the above components using Monte Carlo simulation, which takes into account the variability of factors affecting microbial growth, can lead to a realistic estimation of the behavior of L. monocytogenes throughout the food supply chain, and the quantitative output generated can be further used by food managers as a decision-making tool regarding the design or modification of a product's formulation or its "use-by" date in order to ensure its compliance with the new safety criteria. The study also argues that compliance of RTE foods with the new safety criteria should not be considered a parameter with a discrete and binary outcome because it depends on factors such as product characteristics, storage temperature, and initial contamination level, which display considerable variability even among different packages of the same RTE product. Rather, compliance should be expressed and therefore regulated in a more probabilistic fashion.     

Membrane filtration of food suspensions.

Factors affecting the membrane filtration of food suspensions were studied for 58 foods and 13 membrane filters. Lot number within a brand, pore size (0.45 or 0.8 micrometer), and time elapsed before filtration had little effect on filterability. Brand of membrane filter, flow direction, pressure differential, age (microbiological quality) of the food, duration of the blending process, temperature, and concentration of food in the suspension had significant and often predictable effects. Preparation of suspensions by Stomacher (relative to rotary blender) addition of surfactant (particularly at elevated temperature) and prior incubation with proteases sometimes had dramatic effects of filterability. In contrast to popular opinion, foods can be membrane filtered in quantities pertinent to the maximums used in conventional plating procedures. Removal of growth inhibitors and food debris is possible by using membrane filters. Lowering of the limits of detection of microorganisms by concentration on membrane filters can be considered feasible for many foods. The data are particularly relevant to the use of hydrophobic grid-membrane filters (which are capable of enumerating up to 9 X 10(4) organisms per filter) in instrumented methods of food microbiological analysis.     

Bioremediation of organic waste sites: A critical review of microbiological aspects

An overview is presented of the potential for bioremediation of a range of contaminated sites. Most of the compounds belong to groups that are widespread and are generally persistent or toxic. Although attention has been focused on microbiological aspects of their application, it is pointed out that a successful programme requires integrated input from geologists, engineers, chemists and microbiologists. It is emphasized that a protocol must be available for evaluating the success of the procedures that have been implemented. Attention is directed to critical issues, including partial degradation, formation of metabolites, and recalcitrance of specific components in complex mixtures. An attempt is made to discuss the basic aspects of the biodegradation of components specific to the various sites and to illustrate the outcome of experiments in bioremediation in laboratory-based, pilot-scale or full-scale field operations. Brief discussion is given of some less commonly perceived contaminants that may be present simultaneously.     

The better use of food resources for infants and mothers

The nutritional and food safety characteristics of the foods customarily eaten by infants and mothers in The Gambia are discussed. Special emphasis is placed on their low energy and nutrient density and the consequent difficulty of meeting internationally recommended levels of intake. The consequences of an inadequate diet during pregnancy and lactation are considered in terms of their effect on the size of the baby at birth, the mother's lactational performance, and the growth and development of the baby. The microbiological contamination of locally introduced weaning foods is also highlighted. Suggestions are made concerning the desirable characteristics of new foods that need to be introduced to overcome these problems. Attention is paid to a more rational distribution and use for aid foods.     

Microbial environmental monitoring of the refectory in the monastery of St. Anna in Foligno, Italy

For the preservation of monuments and sites of cultural heritage, microbiological methods based on defined standards are needed to evaluate the problems associated with biodeterioration. In this study Microbial Environmental Monitoring (MAM from the Italian acronym Monitoraggio Ambientale Microbico) was applied to air and surface monitoring of art works before and during restoration. Microbial monitoring of the refectory in the monastery of St. Anna (Foligno, Italy) was performed on frescos from 1400. The results obtained with MAM were consistent, reproducible, and beneficial in the evaluation of the efficacy of restoration. Microbial monitoring of solid surfaces using membrane filters was not destructive and allowed the study of microbial fall-out on the surface of art works. The application of MAM proved to be a valuable means not only for monitoring but also for a better understanding of microbial pollution and its dynamics on the surface of art works. The constant application of MAM could be a valuable tool in the preservation of cultural heritage through strict collaboration with microbiologists, restorers, and authorities.