Cell line authentication: a necessity for reproducible biomedical research.

Immortalized or continuous cell lines are invaluable tools in basic and preclinical research. However, the widespread use of misidentified cell lines is a serious threat to scientific reproducibility. Based on the experiences of mandatory cell line authentication at the International Journal of Cancer (IJC), we provide an overview of the issues pertinent to misidentified cell lines and discuss available solutions. We also summarize the lessons learned, revealing that at least 5% of the human cell lines used in manuscripts considered for peer review are misidentified. About 4% of the considered manuscripts are rejected for severe cell line problems, and most are subsequently published in other journals. In order to diminish such malpractice and its consequences for the scientific record, we postulate that strict multi-layered quality control is essential. Besides journals and publishers, we encourage scientists, research institutions, and funders to take action on the matter and revise their respective policies. Hence, we provide concrete recommendations on introducing regular authentication schemes and staff training, and discuss future steps for enhancing good cell culture practices.

From wheat grain to flour: a review of potential sources of enteric pathogen contamination in wheat milled products.

The number of food safety issues linked to wheat milled products have increased in the past decade. These incidents were mainly caused by the contamination of wheat-based products by enteric pathogens. This manuscript is the first of a two-part review on the status of the food safety of wheat-based products. This manuscript focused on reviewing the available information on the potential pre-harvest and post-harvest sources of microbial contamination, and potential foodborne pathogens present in wheat-based products. Potential pre-harvest sources of microbial contamination in wheat included animal activity, water, soil, and manure. Improper grain storage practices, pest activity, and improperly cleaned and sanitized equipment are potential sources of post-harvest microbial contamination for wheat-based foods. Raw wheat flour products and flour-based products are potentially contaminated with enteric pathogens such as Shiga toxin-producing E. coli (STECs), and Salmonella at low concentrations. Wheat grains and their derived products (i.e., flours) are potential vehicles for foodborne illness in humans due to the presence of enteric pathogens. A more holistic approach is needed for assuring the food safety of wheat-based products in the farm-to-table continuum. Future developments in the wheat supply chain should also be aimed at addressing this emerging food safety threat.

The promotion of biofilm dispersion: a new strategy for eliminating foodborne pathogens in the food industry.

Food safety is a critical global concern due to its direct impact on human health and overall well-being. In the food processing environment, biofilm formation by foodborne pathogens poses a significant problem as it leads to persistent and high levels of food contamination, thereby compromising the quality and safety of food. Therefore, it is imperative to effectively remove biofilms from the food processing environment to ensure food safety. Unfortunately, conventional cleaning methods fall short of adequately removing biofilms, and they may even contribute to further contamination of both equipment and food. It is necessary to develop alternative approaches that can address this challenge in food industry. One promising strategy in tackling biofilm-related issues is biofilm dispersion, which represents the final step in biofilm development. Here, we discuss the biofilm dispersion mechanism of foodborne pathogens and elucidate how biofilm dispersion can be employed to control and mitigate biofilm-related problems. By shedding light on these aspects, we aim to provide valuable insights and solutions for effectively addressing biofilm contamination issues in food industry, thus enhancing food safety and ensuring the well-being of consumers.

A comprehensive performance evaluation, comparison, and integration of computational methods for detecting and estimating cross-contamination of human samples in cancer next-generation sequencing analysis.

Cross-sample contamination is one of the major issues in next-generation sequencing (NGS)-based molecular assays. This type of contamination, even at very low levels, can significantly impact the results of an analysis, especially in the detection of somatic alterations in tumor samples. Several contamination identification tools have been developed and implemented as a crucial quality-control step in the routine NGS bioinformatic pipeline. However, no study has been published to comprehensively and systematically investigate, evaluate, and compare these computational methods in the cancer NGS analysis. In this study, we comprehensively investigated nine state-of-the-art computational methods for detecting cross-sample contamination. To explore their application in cancer NGS analysis, we further compared the performance of five representative tools by qualitative and quantitative analyses using in silico and simulated experimental NGS data. The results showed that Conpair achieved the best performance for identifying contamination and predicting the level of contamination in solid tumors NGS analysis. Moreover, based on Conpair, we developed a Python script, Contamination Source Predictor (ConSPr), to identify the source of contamination. We anticipate that this comprehensive survey and the proposed tool for predicting the source of contamination will assist researchers in selecting appropriate cross-contamination detection tools in cancer NGS analysis and inspire the development of computational methods for detecting sample cross-contamination and identifying its source in the future.

Comparison of permitted daily exposure (PDE) values for active pharmaceutical ingredients (APIs) - Evidence of a robust approach.

Permitted Daily Exposure Limits (PDEs) are set for Active Pharmaceutical Ingredients (APIs) to control cross-contamination when manufacturing medicinal products in shared facilities. With the lack of official PDE lists for pharmaceuticals, PDEs have to be set by each company separately. Although general rules and guidelines for the setting of PDEs exist, inter-company variations in the setting of PDEs occur and are considered acceptable within a certain range. To evaluate the robustness of the PDE approach between different pharmaceutical companies, data on PDE setting of five marketed APIs (amlodipine, hydrochlorothiazide, metformin, morphine, and omeprazole) were collected and compared. Findings show that the variability between PDE values is within acceptable ranges (below 10-fold) for all compounds, with the highest difference for morphine due to different Point of Departures (PODs) and Adjustment Factors (AFs). Factors of PDE variability identified and further discussed are: (1) availability of data, (2) selection of POD, (3) assignment of AFs, (4) route-to-route extrapolation, and (5) expert judgement and differences in company policies. We conclude that the investigated PDE methods and calculations are robust and scientifically defensible. Additionally, we provide further recommendations to harmonize PDE calculation approaches across the pharmaceutical industry.

Prevalence, Cross Contamination, Virulence, and Multidrug Resistance Profiles of Staphylococcus aureus Isolates from Four Middle-Scale Dairy Farms in Bareilly, Northern India.

Milk, a nutritious global important food commodity, serves as an excellent medium for microbial growth as well. The foodborne pathogen Staphylococcus aureus is a commensal member of human microflora that enters the food chain through poor hygienic practices and cross contamination and causes various clinical manifestations in humans. During this study, raw milk and swab samples (milker's hand, udder, towel, milking bucket, and farm floor) were collected from four middle-scale buffalo dairy farms. The results revealed S. aureus presence in 11.6% (n = 56/448) bucket raw milk samples and 2.6% (n = 12/448) udder raw milk samples. Contrarily, S. aureus prevalence was significantly higher in farm floors (100%, n = 84/84), towel (35.7%, n = 10/28), milking bucket (11.6%, n = 56/448), milker's hand (10.7%, n = 3/28), and udder swab samples (4.0%, n = 18/448). The chi-square test yielded p values of 0.000, 0.005, and 0.0011 for udder raw milk, udder swab, and milker's hand swab, respectively. The p values of the milking bucket (p = 0.048) and farm floors (p = 0.0183) confirmed their possible role in S. aureus cross contamination. Gene amplifications of nuclease and enterotoxin A indicate potential virulence of S. aureus isolates in collected samples. Antibiotic susceptibility testing revealed multidrug resistance in 44% (n = 239) of S. aureus isolates with the highest resistance of 61% against penicillin. Resistance against ampicillin, streptomycin, and lincomycin was observed. Fewer S. aureus isolates were resistant to kanamycin and erythromycin, whereas the lowest number of resistant isolates was observed against chloramphenicol. A high prevalence of S. aureus in the farm environment and milking equipment suggested the cross contamination of potentially enterotoxin-producing and multidrug-resistant S. aureus to raw milk. Therefore, good hygiene practices should be enforced to avoid foodborne and zoonotic infections.

Re-Evaluating Cross-Contamination: Additional Trials on Co-Ventilation.

BACKGROUND: Medical equipment can become scarce in disaster scenarios. Prior work has reported that four sheep could be ventilated together on a single ventilator. Others found that this maneuver is possible when needed, but no one has yet investigated whether cross-contamination occurs in co-ventilated individuals. OBJECTIVE: Our goal was to investigate whether an infection could spread between co-ventilated individuals. METHODS: Four 2-L anesthesia bags were connected to a sterilized ventilator circuit that used heat and moisture exchange filters and bacterial and viral filters, as would be expected in this dire scenario. Serratia marcescens was inoculated into "lung" no. 1. After running for 24 h, each lung and three additional points in the circuit were cultured to see whether S. marcescens had spread. These cultures were examined at 24 and 48 h to assess for cross-contamination. This entire procedure was performed three times. RESULTS: S. marcescens was not found in lung no. 2, 3, or 4 or the three additional sites on the expiratory limb at 24 and 48 h in all three trials. CONCLUSIONS: Cross-contamination does not occur within 24 h using the described ventilator circuit configuration.

Distribution and characteristics of bacteria on the hand during oropharyngeal swab collection: Which handwashing points are affected?

AIMS: To identify the contaminated areas of the hand collection and analyse the distribution characteristics of bacteria in the hand after swab collection. DESIGN: This study used a cross-sectional design. METHODS: A cross-sectional study sampling 50 pairs of hands (sampling hand and auxiliary hand) of healthcare workers was performed. Ten samples were collected from each participant. The optimal hand hygiene rates and bacterial colony counts of the whole hand and different hand sections without hand hygiene were identified as the primary outcomes. RESULTS: The optimal hand hygiene rates of the sampling hand and auxiliary hand were 88.8% (222/250) and 91.6% (229/250), respectively. The lowest optimal hand hygiene rates for the sampling hand and the auxiliary hand were both on the dorsal side of the finger and the dorsum of the hand (86.0%, 86.0% vs. 90.0%, 86.0%); the optimal hand hygiene rates for both sites of the sampling hand were 86.0% (43/50), and the optimal hand hygiene rates for the auxiliary hand were 90.0% (45/50) and 86.0% (43/50). The bacteria colony counts did not differ between the sampling hands and auxiliary hand. CONCLUSIONS: The dorsal side of the finger and dorsum of the hand were the most likely to be contaminated during oropharyngeal swab collection. Therefore, it is essential to pay extra attention to hand hygiene care of these two sites during the collection process to minimize the risk of cross-contamination. REPORTING METHOD: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines were adopted in this study.

Comprehensive strategies for controlling Listeria monocytogenes biofilms on food-contact surfaces.

Listeria monocytogenes biofilms formed on food-contact surfaces within food-processing facilities pose a significant challenge, serving as persistent sources of cross-contamination. In this review, we examined documented cases of foodborne outbreaks and recalls linked to L. monocytogenes contamination on equipment surfaces and in the food production environment, provided an overview of the prevalence and persistence of L. monocytogenes in different food-processing facilities, and discussed environmental factors influencing its biofilm formation. We further delved into antimicrobial interventions, such as chemical sanitizers, thermal treatments, biological control, physical treatment, and other approaches for controlling L. monocytogenes biofilms on food-contact surfaces. This review provides valuable insights into the persistent challenge of L. monocytogenes biofilms in food processing, offering a foundation for future research and practical strategies to enhance food safety.

Potential of Powder Rheology for Detecting Unforeseen Cross-Contamination of Foreign Active Pharmaceutical Ingredients.

Unexpected cross-contamination by foreign components during the manufacturing and quality control of pharmaceutical products poses a serious threat to the stable supply of drugs and the safety of customers. In Japan, in 2020, a mix-up containing a sleeping drug went undetected by liquid chromatography during the final quality test because the test focused only on the main active pharmaceutical ingredient (API) and known impurities. In this study, we assessed the ability of a powder rheometer to analyze powder characteristics in detail to determine whether it can detect the influence of foreign APIs on powder flow. Aspirin, which was used as the host API, was combined with the guest APIs (acetaminophen from two manufacturers and albumin tannate) and subsequently subjected to shear and stability tests. The influence of known lubricants (magnesium stearate and leucine) on powder flow was also evaluated for standardized comparison. Using microscopic morphological analysis, the surface of the powder was observed to confirm physical interactions between the host and guest APIs. In most cases, the guest APIs were statistically detected due to characteristics such as their powder diameter, pre-milling, and cohesion properties. Furthermore, we evaluated the flowability of a formulation incorporating guest APIs for direct compression method along with additives such as microcrystalline cellulose, potato starch, and lactose. Even in the presence of several additives, the influence of the added guest APIs was successfully detected. In conclusion, powder rheometry is a promising method for ensuring stable product quality and reducing the risk of unforeseen cross-contamination by foreign APIs.

How can contamination be prevented during laboratory analysis of atmospheric samples for microplastics?

Microplastics (MPs) in the air and indoor environments are of growing concern and have led to increased testing for MPs. This study draws attention to the quality and quantitative measures of MP studies by conducting laboratory experiments (on solutions, filters, and blank samples) that were rarely or were not adopted in the airborne and indoor MP literature. Experiments have been conducted to identify contaminations that may come from experimental procedures while determining MPs in the air samples. MPs in different matrices during experiments were counted and categorized by their shapes. Chemical characterization was performed by Raman Spectroscopy. Results showed that laminar flow is the best option over a fume hood or standard laboratory environment for detecting air MPs to reduce blank levels. Blue-green and Black-Grey were the dominant colors; fiber was the predominant type of MPs seen, and most of them fall under the size range from (1-1000 µm) in different indoor environments and blanks. Common MPs seen were PP, PVA, PTFE, PVC, and HDPE. Thermal treatment of fresh unused filters at 450 °C for 4 h was effective as it reduced the MP count by 50%. Working solutions are mainly contaminated, and their pre-filtration is essential. The average deposition of MPs in blank samples during seven days was around 55 MPs. There is an urgent need for studies on developing quality control and quality assurance of airborne and indoor MPs. Hence, a standard protocol needs to be accepted; by harmonizing procedures, comparable results can be found, uncovering the correct levels of MP contamination, as required for risk assessment.

Controlling cleaning agent residues in pharmaceutical manufacturing: A harmonized scientific strategy.

This paper proposes a scientifically justified and harmonized strategy to control cleaning agent ingredients' (CAIs) residues in pharmaceutical manufacturing. Firstly, we demonstrate that worst-case cleaning validation calculations on CAI residues with representative GMP standard cleaning limits (SCLs) are enough to control CAI residues of low concern to safe levels. Secondly, a new harmonized strategy for the toxicological assessment of CAI residues is presented and validated. The results establish a framework applicable to cleaning agent mixtures based on hazard and exposure considerations. This framework is primarily based on the hierarchy of a single CAI's critical effect, where the lowest resulting limit may become the driver of the cleaning validation process. The six critical effect groups are: (1) CAIs of low concern based on safe exposure reasoning; (2) CAIs of low concern based on the mode of action reasoning; (3) CAIs with local concentration-dependent critical effects; (4) CAIs with dose-dependent systemic critical effects for which a route-specific PDE should be calculated; (5) poorly characterized CAIs with unknown critical effect for which a default value of 100 µg/day is proposed; (6) poorly characterized CAIs which should be avoided because of potential mutagenicity and/or potency.

Quantification of Salmonella transfer in cross-contamination scenarios found in chicken slaughterhouses.

Chicken are among the main reservoirs of Salmonella, and slaughterhouses have been identified as key sites for cross-contamination of this pathogen. This study aimed to quantify the transfer rate of Salmonella in different cross-contamination scenarios found in chicken slaughterhouses. To this end, a pool of Salmonella spp. Was inoculated onto chicken carcasses and thighs, reaching out concentrations of 2-5 log10 CFU/g. After inoculation, carcasses and thighs were used to reproduce four cross-contamination scenarios based on industrial reality as follows: 1. Transfer of Salmonella from chicken carcasses to stainless steel and polyethylene surfaces; 2. Transfer of Salmonella between hanging chicken carcasses; 3. Transfer of Salmonella from stainless steel surfaces to chicken carcasses, and 4. Transfer of Salmonella from thighs to stainless steel and polyethylene surfaces. The results showed that the transfer rates (TR) of Salmonella on the chicken carcass to stainless steel and polyethylene were 25.77 ± 22.63% and 24.71 ± 13.93%, respectively, while the TR between hanged chicken carcasses was 5.11 ± 1.71%. When sliding carcasses through a stainless steel ramp, 41.47 ± 1.32% of the Salmonella present on the ramp adhered to the chicken carcasses, and the greater transfer seems to be linked to the wet surfaces. The transfer rates from the thighs to the stainless steel and polyethylene were 1.81 ± 0.66% and 9.0 ± 1.34%, respectively. Cross-contamination occurred regardless of the sample weight, time of contact, and amount of inoculum.

Listeria monocytogenes cross-contamination during apple waxing and subsequent survival under different storage conditions.

This study evaluated Listeria monocytogenes cross-contamination between inoculated fruits, waxing brush, and uninoculated fruits during apple wax coating and investigated the fate of L. monocytogenes on wax-coated apples introduced via different wax coating schemes. There were 1.8-1.9 log10 CFU/apple reductions of L. monocytogenes on PrimaFresh 360, PrimaFresh 606, or Shield-Brite AP-450 coated apples introduced before wax coating after 6 weeks of ambient storage (22 °C and ambient relative humidity). L. monocytogenes showed a similar trend (P > 0.05) on waxed apples under cold storage (1 °C and ∼ 90% relative humidity); there were 1.8-2.0 log10 CFU/apple reductions of L. monocytogenes during the 12 weeks of cold storage regardless of wax coating type. For cross-contamination study, a waxing brush was used to wax one inoculated apple (6.2 log10 CFU/apple); then, this brush was used to wax five uninoculated apples in a sequence. There were 3.7, 3.5, 3.3, 2.9, and 2.7 log10 CFU/apple and 3.6 log10 CFU/brush of L. monocytogenes transferred from the inoculated apple to uninoculated apple 1 to apple 5, and the waxing brush, respectively. The die-off rate of L. monocytogenes on wax-coated apples contaminated during wax coating was not significantly different from that contaminated on apples before wax coating, and 1.8-1.9 log10 CFU/apple reductions were observed during the 12 weeks of cold storage. The application of wax coatings, regardless of wax coating type, did not impact the survival of endogenous yeasts and molds on apples during ambient or cold storage. L. monocytogenes transferred onto waxing brushes during wax coating remained relatively stable during the 2-week ambient holding. Fungicide application during wax coating reduced (P < 0.05) yeast and mold counts but had a minor impact (P > 0.05) on the survival of L. monocytogenes on apples after 12 weeks of cold storage. Collectively, this study indicated that a high cross-contamination risk of L. monocytogenes during apple waxing, and L. monocytogenes on wax-coated apples introduced via different scenarios is stable during subsequent cold storage, highlighting the need for potential intervention strategies to control L. monocytogenes on wax-coated apples.

Cross-contamination of mature Listeria monocytogenes biofilms from stainless steel surfaces to chicken broth before and after the application of chlorinated alkaline and enzymatic detergents.

The objectives of this study were, firstly, to compare a conventional (i.e., chlorinated alkaline) versus an alternative (chlorinated alkaline plus enzymatic) treatment effectivity for the elimination of biofilms from different L. monocytogenes strains (CECT 5672, CECT 935, S2-bac and EDG-e). Secondly, to evaluate the cross-contamination to chicken broth from non-treated and treated biofilms formed on stainless steel surfaces. Results showed that all L. monocytogenes strains were able to adhere and develop biofilms at approximately the same growth levels (≈5.82 log CFU/cm2). When non-treated biofilms were put into contact with the model food, obtained an average transference rate of potential global cross-contamination of 20.4%. Biofilms treated with the chlorinated alkaline detergent obtained transference rates similar to non-treated biofilms as a high number of residual cells (i.e., around 4 to 5 Log CFU/cm2) were present on the surface, except for EDG-e strain on which transference rate diminished to 0.45%, which was related to the protective matrix. Contrarily, the alternative treatment was shown to not produce cross-contamination to the chicken broth due to its high effectivity for biofilm control (<0.50% of transference) except for CECT 935 strain that had a different behavior. Therefore, changing to more intense cleaning treatments in the processing environments can reduce risk of cross-contamination.

Cross-contamination of Escherichia coli O157:H7 and Listeria monocytogenes in the viable but non-culturable (VBNC) state during washing of leafy greens and the revival during shelf-life.

Some water disinfection treatments, such as chlorine and chlorine dioxide, used in the fresh-cut industry to maintain the microbiological quality of process water (PW), inactivate bacterial cells in the water but they also lead to the induction of an intermediate state between viable and non-viable known as viable but non-culturable (VBNC) state. Viable cells can participate in cross-contamination events but the significance of VBNC cells in PW, transfer to the product and potential resuscitation capacity during storage is unclear. The present study aims to determine first, if VBNC cells present in PW can cross-contaminate leafy greens during washing and secondly its potential revival during shelf-life. Process water characterized by a high chemical oxygen demand, due to the presence of high levels of organic matter, was inoculated with Listeria monocytogenes or Escherichia coli O157:H7. Inoculated PW was then treated for 1 min with chlorine dioxide (3 mg/L) or chlorine (5 mg/L) to generate VBNC cells. Absence of culturable cells was confirmed by plate count and VBNC cells by viability quantitative polymerase chain reaction (v-qPCR) complemented with two dyes, ethidium (EMA) and propidium (PMAxx) monoazide. Cross-contamination of shredded lettuce was demonstrated by monitoring the VBNC cells after washing the product for 1 min in the contaminated PW and during shelf life (15 days at 7 °C). In the case of L. monocytogenes, considering the total concentration of L. monocytogenes VBNC cells present in the PW, only a low proportion of cells were able to cross-contaminate the product during washing. VBNC L. monocytogenes cells were able to resuscitate on the product during shelf life, although levels of cultivable bacteria, close to the limit if detection (0.7 ± 0.0 log CFU/g), were only detected at the end of storage. On the other hand, VBNC cells of E. coli O157:H7 present in PW were not able to cross-contaminate shredded lettuce during washing. Moreover, when shredded lettuce was artificially inoculated with VBNC E. coli O157:H7, resuscitation of the VBNC cells during storage (15 days at 7 °C) was not observed. Based on the results obtained, injured L. monocytogenes cells present in the PW are able to be transferred to the product during washing. If VBNC L. monocytogenes cells present in leafy greens (shredded lettuce and baby spinach), they can resuscitate, although cultivable numbers remained very low. Taking all the results together, it could be concluded that under industrial conditions, VBNC cells can be transferred from water to product during washing, but their capacity to resuscitate in the leafy greens during storage is low.

Modeling of interventions for reducing external Enterobacteriaceae contamination of broiler carcasses during processing.

This article presents a mathematical model for the Enterobacteriaceae count on the surface of broiler chicken during slaughter and how it may be affected by different processing technologies. The model is based on a model originally developed for Campylobacter and has been adapted for Enterobacteriaceae using a Bayesian updating approach and hitherto unpublished data gathered from German abattoirs. The slaughter process in the model consists of five stages: input, scalding, defeathering, evisceration, washing, and chilling. The impact of various processing technologies along the broiler processing line on the Enterobacteriaceae count on the carcasses' surface has been determined from literature data. The model is implemented in the software R and equipped with a graphical user interface which allows interactively to choose among different processing technologies for each stage along the processing line. Based on the choice of processing technologies the model estimates the Enterobacteriaceae count on the surface of each broiler chicken at each stage of processing. This result is then compared to a so-called baseline model which simulates a processing line with a fixed set of processing technologies. The model calculations showed how even very effective removal of bacteria on the exterior of the carcass in a previous step will be undone by the cross-contamination with leaked feces, if feces contain high concentrations of bacteria.

Cross-contamination in the kitchen: A model for quantitative microbiological risk assessment.

A quantitative microbiological risk assessment model for the cross-contamination transmission route in the kitchen (KCC) is presented. Bacteria are transmitted from contaminated (chicken) meat to hands, kitchen utensils, and other surfaces, subsequently contaminating a salad. The model aims to estimate the fraction of bacteria on the meat that is ingested due to cross-contamination, determine the importance of the different transmission routes, and assess the effect of scenarios (interventions) on the fraction ingested. The cross-contamination routes defined, bacterial source-to-recipient transfer fractions as available and derived from literature, and important characteristics (e.g., washing in cold water vs. hot water with soap) shaped the KCC model. With this model, 32 scenarios of an eight-step preparation of a "meat and salad" meal in a domestic kitchen were stochastically simulated. The "cutting board-salad" route proved dominant and the salad plays a major role in the final exposure. A realistic scenario (washing hands, cutting board, and knife with cold water after cutting the meat) estimates that a mean fraction of 3.2E - 3 of the bacteria on the meat is ingested. In the case of "hand washing with hot water and soap" and "cutting board and knife replacement," the mean fraction ingested is 3.6E - 6. For a subsequent meal, where the contaminated sources were kitchen fomites, the estimated mean fraction is 4.3E - 4. In case of hamburger, part of the bacteria is unavailable for cross-contamination, resulting in a mean fraction ingested of about 5.4E - 5. The role of the dishcloth in cross-contamination transmission proved to be minor.

Quantitative microbiological risk assessment of nontyphoidal Salmonella in ground pork in households in Chengdu, China.

Foodborne disease caused by nontyphoidal Salmonella (NTS) is one of the most important food safety issues worldwide. The objectives of this study were to carry out microbial monitoring on the prevalence of NTS in commercial ground pork, investigate consumption patterns, and conduct a quantitative microbiological risk assessment (QMRA) that considers cross-contamination to determine the risk caused by consuming ground pork and ready-to-eat food contaminated during food handling in the kitchen in Chengdu, China. The food pathway of ground pork was simplified and assumed to be several units according to the actual situation and our survey data, which were collected from our research or references and substituted into the QMRA model for simulation. The results showed that the prevalence of NTS in ground pork purchased in Chengdu was 69.64% (95% confidence interval [CI], 60.2-78.0), with a mean contamination level of -0.164 log CFU/g. After general cooking, NTS in ground pork could be eliminated (contamination level of zero). The estimated probability of causing salmonellosis per day was 9.43E-06 (95% CI: 8.82E-06-1.00E-05), while the estimated salmonellosis cases per million people per year were 3442 (95% CI: 3218-3666). According to the sensitivity analysis, the occurrence of cross-contamination was the most important factor affecting the probability of salmonellosis. To reduce the risk of salmonellosis caused by NTS through ground pork consumption, reasonable hygiene prevention and control measures should be adopted during food preparation to reduce cross-contamination. This study provides valuable information for household cooking and food safety management in China.

An assessment of bacterial contamination of indirect ophthalmoscopes and condensing lenses used in clinical practice: A multi-center study.

PURPOSE: To investigate bacterial contamination of indirect ophthalmoscopes and condensing lenses used in three UK veterinary referral centers, and the impact of an implemented cleaning protocol. METHODS: Bacteriology samples from 10 indirect ophthalmoscopes and 10 condensing lenses were taken at each center (n = 30 T0), before initiating one of three cleaning frequencies (every 2 weeks/once weekly/daily) for 28 days. The most contaminated indirect ophthalmoscope and condensing lens from each center were re-sampled 30 min prior to (T1; n = 9) and 30 min after (T2; n = 9) the final clean. Sensitivity testing was completed using MIC. RESULTS: Seventy-three isolates representing 15 different bacterial populations (genus/species) were cultured from 36 of 48 (75%) swabs tested. The most frequently cultured isolates were Staphylococcus spp. 30%, Micrococcus 22%, and Bacillus 14%. Pseudomonas aeruginosa, Pantoea, and Staphylococcus pseudintermedius demonstrated resistance to >50% of antibiotics against which they were tested. Eighty-three percent of T0 samples (54 isolates across 11 species, median 2 isolates/swab), all T1 samples (15 isolates across 8 species, median 2 isolates/swab), and 22% of T2 samples (4 isolates across 4 species, median 0 isolates/swab) were contaminated. Head contact points were most contaminated irrespective of time point. A T1 sample was 57 times more likely (95% CI: 2.4-1376) to have a positive culture than a T2 sample (p = .01). CONCLUSIONS: Baseline contamination was high, representing a potential source of nosocomial infection in ophthalmic patients and handlers of diagnostic equipment. No center implemented a cleaning protocol prior to this study. Routine cleaning reduces bacterial contamination.