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PubMed2006

Determining the microbiological criteria for lot rejection from the performance objective or food safety objective.

The Microbiological Criteria (MC) is a set of parameters used to determine whether a specific lot of food is acceptable or not. These parameters are the microbial test protocol and its sensitivity, the confidence level that an unacceptable lot will be detected, the number of samples to be taken and the number of positive samples that are allowed before rejecting the lot. Determining the microbiological criteria begins with knowledge of the distribution of contamination from samples within a lot, particularly within a lot that is just at the unacceptable level of the microbial hazard. The just unacceptable lot can be defined by the Food Safety Objective (FSO) or Performance Objectives (PO), the small fraction of samples that can exceed these values and the standard deviation of the samples from the lot. With this information, a microbial test protocol is chosen to have a sensitivity level that would detect between approximately 15% and 45% of the samples. A confidence level for the MC and the number of positive samples that would be acceptable (c value which is usually zero) are also chosen. With this information the number of samples (n) required can be calculated. A critical factor in setting the microbiological criteria is the sensitivity of the microbiological test (m value). The sample size (weight) and sampling procedure can affect the standard deviation of the samples, particularly foods with non-homogeneous distribution and low numbers of microorganisms. Sampling, sample preparation and analytical procedures that reduce the variation between the samples will affect the choice of m value and maximum lot mean that meets the MC.

Colony Count, Microbial↗
PubMed2004

Interference of isonicotinyl hydrazone in the microbiological analysis of rifampicin from anti-tuberculosis FDC products containing isoniazid.

Microbiological assay is a sensitive method for the estimation of rifampicin (R). In the present study, interference due to isonicotinyl hydrazone (HYD), an interaction product of R and isoniazid (H), was checked during microbiological analysis of R, employing Bacillus subtilis and Sarcina lutea. The assays were done by disc diffusion method. Both R and HYD showed linear log response curves in the range of 0.01-10microg. In the presence of HYD, R was overestimated when tested against S. lutea and underestimated in case of B. subtilis. The same extent and type of interference was observed on assay of a marketed anti-tuberculosis fixed-dose combination product, subjected to accelerated stability testing (40 degrees C/75% RH) for 1 month. This means that response of organisms used in microbiological assay of R might vary in the presence of HYD, with possibility of incorrect conclusions. Therefore, the study suggests that before a microbiological method involving a particular organism is extended to the determination of R in FDC formulations containing H, it should be tested for the influence of HYD and used only if non-interfering.

Antitubercular Agents↗
PubMed2004

Microbiological Indices for total coliform and E. coli bacteria in estuarine waters.

Bacterial counts for total coliforms and E. coli in estuaries are normally orders of magnitude greater at the freshwater end than at the seaward end and tidal movements and variations in freshwater flows produce continual change in the freshwater/seawater mix--this causes the bacterial counts to vary greatly throughout the estuary and the complexity creates difficulty in appraising or assessing the bacterial counts (i.e. difficulties arise when deciding if the bacterial counts for estuarine water samples are within an acceptable range--relative to their corresponding salinities). The situation is further complicated in estuaries where sewage is discharged directly. Microbiological criteria and indices that can be used in a practical way to overcome these difficulties were developed. The procedure is summarised as follows: 1. Primary criteria are proposed for total coliform and for E. coli bacteria in the freshwater at the head of the estuary and in full seawater at the mouth of the estuary. 2. For estuarine or transitional waters (i.e. waters with salinity ranging from 0 per thousand to 35 per thousand), distinct criteria are calculated for each individual sample--with a separate criterion for total coliforms and for E. coli--the individual criteria are founded on the primary criteria and vary with salinity on a pro-rata or linear basis. 3. Finally, the Microbiological Index for each result is obtained by dividing the actual bacterial count by the corresponding criterion--the acceptable Index is then equal to 1--at any salinity (i.e. where the Index is <1 then the bacterial count complies with the criterion, and where the Index is >1 then the count breaches the criterion). The Index also indicates the extent of the compliance or non-compliance with the corresponding criteria. An example of the application of the Microbiological Index is also presented--including examples of graphs that demonstrate how microbiological data for estuarine waters can be summarised and presented.

Ecosystem↗
PubMed2004

Microbiological characterization of food residues for animal feeding.

A description is offered of microbiological characterization of the biodegradable fractions present in food wastes so that those fractions can be transformed in such a way that they will fulfil the specifications involved in their use as raw materials in other production areas. In this way the wastes can be converted into sub-products, hence minimizing the amount of them eventually sent to rubbish dumps. Of all the types of residues analyzed, only those obtained by separate collection from fishmongers' and greengrocers' sections of large supermarkets and small shops were valid for the objectives of the project and were subjected to a heat treatment to test whether or not this treatment was capable of reducing their microbiological content to the point of converting them into acceptable raw materials for animal feed. Residues from butchers' sections of supermarkets and small shops, and residues from restaurants were not included in the final study because of the prohibition by the European legislation in force of using any kind of meat containing wastes for feeding farm animals. In the present work we made a one-year analysis of representative samples of such wastes. We observed that after thermal treatment at a temperature of at least 65 degrees C for 20 min the nutritional and microbiological parameters remained suitable for their possible use as animal feed and that their harmlessness was ensured, with no loss of nutritional characteristics. Regarding the microbiological study of the meals which have been obtained from residues for the production of the feed and the feed itself, and in accordance with the data for nutritional composition, we consider valid and sanitarily adequate their use as animal feed with the concomitant consequent minimization of waste, which has become a priority in view of the recent legislation enacted by the European Union.

Animal Feed↗
PubMed1996

Radical improvements in the display of clinical microbiology results: a Web-based clinical information system.

OBJECTIVE: To evaluate the performance of a novel computerized system for reporting clinical microbiology results. The new system provides a summarized overview of a patient's current (or past) microbiological status, with the option to selectively explore in greater depth. It is deployed using World Wide Web technology, which supports virtually any kind of computer and allows physicians to obtain results via the internet using personal computers in the office or at home. METHODS: In an unblinded crossover study at a university-affiliated medical center, participants used both the new system and a conventional display system to retrieve selected microbiology results for two actual patients, according to standardized questionnaires, with balanced allocation of sequence of system use. Participants also subjectively rated the two systems. The participants were 16 physician, pharmacist, and nurse volunteers. Outcome measures included completion time and number of errors (categorized as major and minor) associated with results retrieval, and participants' ratings of the new system. RESULTS: Mean completion time was 45% shorter (13.9 versus 25.5 minutes; P < 0.001), and there were fewer associated major errors (0 versus 13; P = 0.01) and minor errors (10 versus 21; P = 0.003) with the summarized display system. All participants rated the new system as easier to learn and use than the conventional system. CONCLUSIONS: A system that appropriately summarizes and groups microbiology results can significantly shorten retrieval times and reduce interpretive errors, while providing users with information needed for cost-effective therapy. Such a system can be deployed by leveraging the rapidly evolving technology of the World Wide Web.

Academic Medical Centers↗
PubMed2002

Predictive microbiology: providing a knowledge-based framework for change management.

This contribution considers predictive microbiology in the context of the Food Micro 2002 theme, "Microbial adaptation to changing environments". To provide a reference point, the state of food microbiology knowledge in the mid-1970s is selected and from that time, the impact of social and demographic changes on microbial food safety is traced. A short chronology of the history of predictive microbiology provides context to discuss its relation to and interactions with hazard analysis critical control point (HACCP) and risk assessment. The need to take account of the implications of microbial adaptability and variable population responses is couched in terms of the dichotomy between classical versus quantal microbiology introduced by Bridson and Gould [Lett. Appl. Microbiol. 30 (2000) 95]. The role of population response patterns and models as guides to underlying physiological processes draws attention to the value of predictive models in development of novel methods of food preservation. It also draws attention to the paradox facing today's food industry that is required to balance the "clean, green" aspirations of consumers with the risk, to safety or shelf life, of removing traditional barriers to microbial development. This part of the discussion is dominated by consideration of models and responses that lead to stasis and inactivation of microbial populations. This highlights the consequence of change on predictive modelling where the need is now to develop interface and non-thermal death models to deal with pathogens that have low infective doses for general and/or susceptible populations in the context of minimal preservation treatments. The challenge is to demonstrate the validity of such models and to develop applications of benefit to the food industry and consumers as was achieved with growth models to predict shelf life and the hygienic equivalence of food processing operations.

Bacteria↗
PubMed2003

Microbiology of wheat and flour milling in Australia.

A survey was undertaken to determine the microbiological status of Australian wheat and the distribution of microorganisms in the flour milling fractions and end products. A total of 650 milling process and end product samples was obtained from nine flour mills located in New South Wales (4), Queensland (2), Victoria (2) and Western Australia (1) during the 1997-1998 and 1998-1999 wheat seasons. Most frequent (modal) counts in wheat and flour were, respectively, as follows: aerobic mesophilic plate count, 10(5) and 10(2) colony forming units/gram (cfu/g); coliforms, 10 and 1 most probable number/gram (MPN/g); Bacillus spp., 10(4) and 10(2) cfu/g; B. cereus, 1 and 0.1 MPN/g; mesophilic aerobic spores, 10 and 1 cfu/g; aerobic thermophiles, both 10 cfu/g; yeasts, 10(3) and 10(2) cfu/g, and moulds, 10(3) and 10(2) cfu/g. Bacillus spp., coliforms, yeasts and moulds were the most frequently detected microorganisms throughout the survey. The most common moulds isolated were Aspergillus, Penicillium, Cladosporium and Eurotium spp. Environmental serovars of Salmonella were isolated from two samples. Escherichia coli and B. cereus were present at very low levels, a majority of positive samples being at the minimum level of detection (3 and 0.3 MPN/g, respectively). As wheat grain layers are separated, surface-adhering contaminants are concentrated in end product bran, wheat germ and pollard, which comprise the outer layers of the grain. Consequently, the inner endosperm fraction contains lower microbial counts, and flour is the cleanest end product of the milling process. Higher microbiological counts midstream in the milling process indicate that equipment contamination may contribute to microbiological contamination; however, the microbiological quality of incoming wheat has a strong influence on the ultimate quality of milling end products.

Australia↗
PubMed2001

Principles of molecular microbiology testing methods.

Molecular testing methods have the potential to replace many conventional microbiology laboratory assays. Recent refinements in technology have resulted in more user-friendly testing platforms. These platforms are automated and have lowered risks for contamination, decreased costs, and are faster than older platforms. The success of these technologies depends on their successful application to patient care. Quality issues include appropriate specimens for analysis, performance characteristics of different analytical methods, optimal specimen processing, the effects of PCR inhibitors, and false-positive results caused by contaminating nucleic acids. Quality control guidelines for molecular microbiologic diagnostic assays are in their infancy and require further development. Additionally, the problem of "too much" sensitivity (brought on by the extreme sensitivity of these techniques coupled with the potential presence of small numbers of pathogenic organisms in asymptomatic individuals) should be considered. Potential problems when monitoring therapy (because molecular detection techniques do not generally have the ability to determine whether an organism is dead or alive) can also occur. Cost-effective test use, pathogen- or disease-targeted algorithms, and standardized methods will be necessary for the true value of these technologies to be realized. This is especially important, because, unlike traditional culture methods, most molecular microbiology methods are pathogen-specific. Clinicians familiar with the reasons why "pan-culture" (i.e., requesting all culture possibilities at once) is inadvisable should not use the same irrational approach when requesting molecular tests. The clinical usefulness of molecular testing will be maximized as targeted algorithms are developed and an understanding of molecular test ordering patterns is realized. Laboratory technicians and physicians must continue to apply and combine theories of traditional microbiology, clinical chemistry, and general medicine to the understanding and application of molecular diagnostics.

Base Sequence↗
PubMed2003

Microbiological examination of ready-to-eat stuffing from retail premises in the north-east of England. The 'Get Stuffed' survey.

AIMS: To establish the microbiological quality of ready-to-eat stuffing from retail premises in the north-east of England. To establish threshold levels of bacteria in the product for acceptance as a ready-to-eat food. To determine the relationship between the microbiology of the product and production processes. METHODS AND RESULTS: A microbiological study of ready-to-eat stuffing using validated methods was performed on 147 samples from 139 retail premises. The determinants investigated were as follows: aerobic colony count, Escherichia coli, Enterobacteriaceae, Staphylococcus aureus, Bacillus spp., Salmonella spp. and Campylobacter spp. Results indicate that using current guidelines 76.3% were satisfactory, 15.6% were acceptable and 8.2% were of unsatisfactory quality. CONCLUSIONS: Unsatisfactory results were due to high aerobic colony counts, E. coli, Enterobacteriaceae and S. aureus. There were significant associations between bacteriological quality and temperature of storage, food hygiene training, product discard policy and confidence in management scores. SIGNIFICANCE AND IMPACT OF THE STUDY: The microbiology of ready-to-eat stuffing suggests that this is a relatively safe product. It is suggested that the product be placed in food category 3 in the current guidelines for ready-to-eat foods.

Bacteria↗
PubMed2000

Quantal microbiology.

Quantal microbiology describes a similarity between physics and microbiology. In both sciences there is an apparent dichotomy between the certainty and stability of the macro-subject and the uncertainty/complexity of the individual atom/cell. Classical physics is to quantum mechanics as classical microbiology is to quantal microbiology.

Bacteria↗
PubMed2001

The microbiological examination of ready-to-eat organic vegetables from retail establishments in the United Kingdom.

AIMS: A microbiological study of uncooked ready-to-eat organic vegetables was undertaken to determine the microbiological quality of these vegetables on retail sale in the UK. METHODS AND RESULTS: Organic vegetables were collected and examined according to a standardized protocol. The majority (3185 of 3200; 99.5%) of samples were found to be of satisfactory/acceptable quality whilst only 15 (0.5%) were of unsatisfactory quality. Unsatisfactory results were due to Escherichia coli and Listeria spp. (not L. monocytogenes) levels in excess of 102 cfu g-1. CONCLUSIONS: The absence of pathogens (L. monocytogenes, Salmonella, Campylobacter and E. coli O157) and the low incidence (1.5%) of E. coli and Listeria spp. associated with these organic vegetables indicates that overall agricultural, hygiene, harvesting and production practices were good. SIGNIFICANCE AND IMPACT OF THE STUDY: There has been a significant expansion of the UK organic market since 1998/99. Of the various commodity sectors making up the organic market, fruit and vegetables is the largest sector and this has been reflected in an increased interest in their microbiological safety. This is the first study to provide information on the microbiological quality of organic vegetables.

Colony Count, Microbial↗
PubMed1999

Defining the microbiological quality of dialysis fluid.

With increasing awareness about the degree and the potential impact of microbiological contamination in dialysis fluids, there is a desire to improve their microbiological quality. To achieve this goal, the origin of the microbiological contamination has to be identified. The water, the bicarbonate concentrate, and the fluid distribution system can be major contributors. Regular disinfection of the entire fluid path is necessary to prevent the formation of biofilm. The bicarbonate concentrate should be handled with special attention because it constitutes an excellent growth medium for microflora that may not be detected with regular assays. With a well maintained reverse osmosis (RO) system, frequent disinfection of the entire flow path, and microbiological awareness, it is possible to produce dialysis fluid that meets the most stringent standard (<10(2) colony forming units (CFU)/ml and <0.25 IU/ml of endotoxin). Adding a step of ultrafiltration just before the dialyzer can make the dialysis fluid ultrapure (<10(-1) CFU/ ml and <0.03 IU/ml). One additional step of controlled ultrafiltration provides sterile and pyrogen-free fluids (<10(-6) CFU/ml and <0.03 IU/ml) that can be used for infusion.

Bacteria↗
PubMedDate not supplied

Managing the microbiological risks of drinking water.

The microbiological contamination of drinking water supplies can have serious health consequences for consumers, and this has been dramatically illustrated in recent years by two disease outbreaks in Canada. In this paper, some factors that can influence the microbiological quality of drinking water and its management are examined. Frameworks have been proposed that help to clarify the main elements of health risk assessment and risk management, and, in accordance with these, risks can be logically characterized, evaluated and controlled. A protocol has been developed for microbiological risk assessment and a risk management framework now guides the development of Canada's national guidelines for drinking-water quality. Monitoring of indicator organisms and the application of adequate water treatment are the primary means recommended in the Canadian guidelines to safeguard health from the presence of water-borne pathogens. Understanding the biological characteristics of microbial pathogens is necessary for assessing their impact on community health and appraising the rationale behind drinking-water testing methods and their limitations. Improvements in health surveillance, monitoring, and risk characterization and application of concepts such as multiple barriers (source-to-tap) and total quality management should contribute to better management of the microbiological quality of drinking water.

Canada↗
PubMed1996

Quality perceptions of microbiology services. A survey of infectious diseases specialists.

Opinions about the quality of their primary microbiology laboratory were received from more than 500 practicing infectious diseases specialists by a nationally distributed questionnaire. Approximately 92% of the respondents' primary laboratories were hospital-based. These sophisticated users rated the quality of their microbiology laboratories to be generally high, with bacteriology receiving highest scores and parasitology the lowest scores. Fortunately, the serious problems, such as failing to call a critical result and culture mishandled in the laboratory, were experienced rarely. Laboratories directed by pathologists with specialty microbiology training, PHD microbiologists, and infectious diseases specialists were judged to be of highest quality. American Board of Medical Microbiology certification of the laboratory director was related to higher overall quality perceptions. Whereas physician-customer opinions may not directly measure a laboratory's analytic quality, they are an important performance measure on which laboratories can base quality improvement activities in both service and analytical aspects of performance.

Clinical Laboratory Techniques↗
PubMed1984

Workload, space, and personnel of microbiology laboratories in teaching hospitals.

The resources needed to operate a microbiology laboratory are known only as rough approximations. In order to gather more information about these resources, a 13-page questionnaire was completed by 50 pathology departments, of which 38 departments provided adequate information about their microbiology sections to permit data analysis. This study reports the results for resource and work load factors and significant regression analyses among these factors for the whole microbiology section and the subsections of aerobic bacteriology, anaerobic bacteriology, mycobacteriology , mycology, parasitology, virology, and antibiotic sensitivity. These data provide a basis for evaluating the current needs of microbiology laboratories and for making projections for the future.

Equipment Design↗
PubMed2005

Microbiological, biochemical and sensory assessment of mussels (Mytilus galloprovincialis) stored under modified atmosphere packaging.

AIMS: To determine the microbiological, biochemical and sensory changes of mussels during storage under aerobic, vacuum packaging (VP) and modified atmosphere packaging (MAP) conditions at 4 degrees C, and to determine shelf-life of mussels under the same packaging conditions using the above assessment parameters. METHODS AND RESULTS: Aqua-cultured mussels (Mytilus galloprovincialis) were obtained from a local culture farm, packaged aerobically under VP and MAP (50%/50% CO2/N2: M1, 80%/20% CO2/N2: M2, 40%/30%/30% CO2/N2/O2: M3), and stored at 4 degrees C. Quality evaluation was carried out using microbiological, chemical and sensory analyses. Microbiological results revealed that the M2 and VP delayed microbial growth compared with that of air-packaged samples. The effect was more pronounced for total viable count (TVC), Pseudomonas spp., lactic acid bacteria (LAB) and H2S-producing bacteria. TVC was reduced by 0.9-1.0, Pseudomonas spp. by 0.7-0.8, LAB by 1.0-2.2, H2S-producing bacteria by 0.7-1.2. Enterobacteriaceae were not significantly affected by MAP conditions. Of the chemical indices determined, the total volatile basic nitrogen and trimethylamine nitrogen values remained lower than the proposed acceptability limits of 35 mg N 100 g(-1) and 12 mg N 100 g(-1), respectively, after 15 days of storage. Both the VP and air-packaged mussel samples exceeded these limits. The thiobarbituric acid value of all MAP and VP mussels remained lower than the proposed acceptability limit of 1 mg malondialdehyde kg(-1). The air-packaged samples exceeded this limit. All samples retained desirable sensory characteristics during the first 8 days of storage. CONCLUSIONS: Based on odour and taste evaluation, the M1 and M3 samples remained acceptable until ca day 11-12, the M2 samples remained acceptable until ca day 14-15 days while the VP and air-packaged mussel samples remained acceptable until ca days 10-11 and 8-9 of storage respectively. Based primarily on sensory, but also on biochemical and microbiological parameters determined, M2 gas mixture was the most effective for mussel preservation achieving a shelf-life of ca 14-15 days. SIGNIFICANCE AND IMPACT OF THE STUDY: MAP (M2) can be used to increase the shelf-life of refrigerated mussels. A shelf-life extension of refrigerated mussels by ca 5-6 days under MAP may be obtained.

Animals↗
PubMed1991

Determination of lomefloxacin in biological fluids by high-performance liquid chromatography and a microbiological method.

A high-performance liquid chromatographic method (HPLC) was developed for the determination of lomefloxacin in plasma and urine and was compared to a microbiological assay. Lomefloxacin and norfloxacin (internal standard) were extracted from plasma and urine samples using chloroform. Measurements were carried out with a fluorescence detector using an excitation wavelength of 280 nm and an emission wavelength of 430 nm with a mercury lamp. Quantification was achieved by the measurement of the peak-height ratio and the analytical recovery of the drug from plasma and urine was found to be (mean +/- SD) 99.3 +/- 3.74% and 95.7% +/- 3.82%, respectively. In the microbiological assay, E. coli ATCC 1346 was the test organism using an agar diffusion technique. The coefficients of variation for within-day analysis for both the HPLC method and microbiological assay from plasma samples were less than 7%. The minimum detectable concentration for both the HPLC and the microbiological method was 50 ng/ml and 100 ng/ml, respectively. Both methods were used to determine the lomefloxacin level in plasma following intravenous administration to mice. Excellent agreement was obtained between the results of the two methods. The HPLC method offers significant advantages in accuracy, precision, speed of analysis and turnover-time.

Animals↗
PubMed1996

Division of labour in clinical microbiology. Co-operation and fragmentation.

The aim of this study was to describe clinical microbiological practices in a hospital setting. A grounded theory was developed from qualitative data in two steps: initial participant observation to describe the clinical work-flow, and a main case study based in depth interviews and analyses of work practices using a video-based stimulated recall technique. Six physicians, 2 senior medical laboratory technologists and one head nurse were interviewed in depth based on their organizational positions. Stimulated recall interviews were conducted with 11 nurses, 6 secretaries, 6 medical laboratory technologists, and 3 physicians. An informal clinical microbiological 'workgroup' was found to co-operate around two physical objects: the microbiological sample and the laboratory request form. Work organization was divided into planning, based on science and legislations, and performance based on tradition and local supervision. None of the practitioners had a total overview of an analysis cycle, all being occupied with a discrete part of planning, practical work and information management. The conclusion of the study is that fragmentation in the division of labour may be a critical hindrance to development in clinical microbiology. If a common strategy is not shared between specialties and professions, even minor changes in routines by individual practitioners may influence patient outcome.

Cooperative Behavior↗