Microbiological Risk Research Articles

Addition of selected cereal grains as non-dairy ingredients to dairy products: A microbiological risk assessment approach

The addition of cereal grains to dairy products in the dairy industry has the potential to contaminate final products with pathogenic and spoilage microorganisms. In this study, the microbial risks involved in the addition of cereal grains to dairy products with low, intermediate, and high-water activity/moisture content were assessed using a semi-quantitative risk assessment method.The results showed that the most critical microbiological hazard in the selected cereal grains is Bacillus cereus (B. cereus) due to its ability to form spores and persist in cereal grains. The addition of cereal grains to dairy products with high water activity/moisture content such as liquid breakfast products were found to pose the highest theoretical risk, and processing mitigations, such as UHT, would need to be implemented. The results of this study have identified some knowledge gaps in conducting risk assessments and have also provided background information about the microbial risks involved in the addition of cereal grains to dairy products.

Performance of full-scale rural wastewater treatment plants in the reduction of antibiotic-resistant bacteria and antibiotic resistance genes from small-city effluents

The main objective of this study was to evaluate the performance of full-scale rural wastewater treatment plants (WWTPs) in the reduction of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from small-city effluents. Twenty full-scale WWTPs in rural Chile with different biological treatment technologies (vermifiltration (VF), activated sludge (AS) and biodisc (BD)) and disinfection treatments (chlorination (Cl) and UV irradiation (UV)) were monitored and studied in two campaigns: Campaign 1 (20 WWTPs) and Campaign 2 (6 WWTPs). In both campaigns, the rural WWTPs improved the water quality of the effluents very significantly (90%, 70%, and 40% reductions in TU, COD, and NH4+-N, respectively) and reduced ARB and ARG loads by 2–4 log units. All three biological treatments contributed to the final quality of the effluents, especially in terms of microbiological parameters, with statistically indistinguishable efficiencies between them. These results show the importance of rural WWTPs in improving the water quality of urban effluents while reducing microbiological risk and the spread of antibiotic resistance into the environment. The study demonstrates the utility of a non-centralized, self-managed wastewater treatment scheme that can be implemented in many sparsely populated areas around the world.

Potential pathogenic microorganisms in rural wastewater treatment process: Succession characteristics, concentration variation, source exploration, and risk assessment

Pathogenic microorganisms can cause infection, sepsis, and other diseases in humans. Although municipal wastewater plants are important sources and sinks for potential pathogenic microorganisms, data on rural wastewater treatment processes are limited. The proximity of rural wastewater facilities to human settlements and the trend toward wastewater resourcing could pose risks to humans. Here, a typical village in southern China was selected to analyze potential pathogenic microorganisms in wastewater, sewage sludge, and aerosols during the collection, treatment, and discharge of domestic wastewater. The succession characteristics and concentration variations of potential pathogenic microorganisms throughout the wastewater treatment process were identified using high-throughput sequencing and culture methods. Bacteria-associated health risks in facility aerosols were estimated based on average daily dose rates from inhalation and dermal exposure. Lower amounts of pathogenic bacteria and pathogenic fungi were detected in the effluent of the 1-ton treatment scale and the 10-ton treatment scale facilities, compared to those in the influent. Pathogen effluent concentrations were significantly lower than influent concentrations after treatment in rural wastewater facilities. 16 and 29 potential pathogenic bacteria and fungi were detected in aerosols from wastewater treatment facilities, respectively. Furthermore, the potential pathogen concentrations were higher than those in the background air. Aerobic units are the main source of pathogen emissions from aerosols. There were 42 potential pathogenic bacteria and 34 potential pathogenic fungi in the sewage sludge. Biochemical units were the main source of potential pathogens in sewage sludge, and more potential airborne pathogens originated from wastewater. In rural wastewater resourcing processes with greater pollutant exposure, the effluent of rural wastewater treatment facilities (WWTFs), downstream rivers, and facility aerosols, could be important potential sources of microbial risk. Inhalation is the main pathway of human exposure to airborne bacteria. Therefore, more attention should be focused on microbiological risk in rural wastewater treatment processes.

Microbiological risk assessment and resistome analysis from shotgun metagenomics of bovine colostrum microbiome

Colostrum is known for its nutraceutical qualities, probiotic attributes, and health benefits. The aim of this study was to profile colostrum microbiome from bovine in rural sites of a developing country. The focus was on microbiological safety assessments and antimicrobial resistance, taking into account the risks linked with the consumption of raw colostrum. Shotgun sequencing was employed to analyze microbiome in raw buffalo and cow colostrum. Alpha and beta diversity analyses revealed increased inter and intra-variability within colostrum samples' microbiome from both livestock species. The colostrum microbiome was mainly comprised of bacteria, with over 90% abundance, whereas fungi and viruses were found in minor abundance. Known probiotic species, such as Leuconostoc mesenteroides, Lactococcus lactis, Streptococcus thermophilus, and Lactobacillus paracasei, were found in the colostrum samples. A relatively higher number of pathogenic and opportunistic pathogenic bacteria were identified in colostrum from both animals, including clinically significant bacteria like Clostridium botulinum, Pseudomonas aeruginosa, Escherichia coli, and Listeria monocytogenes. Binning retrieved 11 high-quality metagenome-assembled genomes (MAGs), with three MAGs potentially representing novel species from the genera Psychrobacter and Pantoea. Notably, 175 antimicrobial resistance genes (ARGs) and variants were detected, with 55 of them common to both buffalo and cow colostrum metagenomes. These ARGs confer resistance against aminoglycoside, fluoroquinolone, tetracycline, sulfonamide, and peptide antibiotics. In conclusion, this study describes a thorough overview of microbial communities in buffalo and cow colostrum samples. It emphasizes the importance of hygienic processing and pasteurization in minimizing the potential transmission of harmful microorganisms linked to the consumption of colostrum.

Evaluation of clinical and microbiological factors related to mortality in patients with Gram-negative bacterial infections treated with ceftazidime–avibactam: A prospective multicentric cohort study

ObjectivesThis study aimed to evaluate the clinical and microbiological risk factors associated with mortality in patients treated with ceftazidime–avibactam for carbapenem-resistant Gram-negative bacterial infections. MethodsThis multicentric prospective cohort study included hospitalized adult patients with a microbiologically confirmed infection treated with ceftazidime–avibactam for ≥48 hours. The clinical and microbiological risk factors for 30-day mortality were evaluated using a Cox regression model. ResultsOf the 193 patients evaluated from the five tertiary hospitals, 127 were included in the study. Thirty-five patients (27.6%) died within 30 days. Infections with AmpC beta-lactamase-carrying bacteria were independently related to 30-day mortality (adjusted hazard ratio [aHR] 2.49, 95% confidence interval [CI] 1.28–4.84, P < 0.01) after adjusting for time from infection to antimicrobial prescription (P = 0.04). Further, these bacterial infections were also related to higher in-hospital mortality (aHR 2.17, 95% CI 1.24–3.78, P < 0.01). Only one patient developed resistance to ceftazidime–avibactam during treatment. ConclusionsTreatment with ceftazidime–avibactam had worse clinical outcomes in patients with infections with bacteria with chromosomally encoded AmpC beta-lactamase. However, these findings should be confirmed in future studies.

Benzalkonium chloride disinfectant residues stimulate biofilm formation and increase survival of Vibrio bacterial pathogens.

Vibrio spp. are opportunistic human and animal pathogens found ubiquitously in marine environments. Globally, there is a predicted rise in the prevalence of Vibrio spp. due to increasing ocean temperatures, which carries significant implications for public health and the seafood industry. Consequently, there is an urgent need for enhanced strategies to control Vibrio spp. and prevent contamination, particularly in aquaculture and seafood processing facilities. Presently, these industries employ various disinfectants, including benzalkonium chloride (BAC), as part of their management strategies. While higher concentrations of BAC may be effective against these pathogens, inadequate rinsing post-disinfection could result in residual concentrations of BAC in the surrounding environment. This study aimed to investigate the adaptation and survival of Vibrio spp. exposed to varying concentrations of BAC residues. Results revealed that Vibrio bacteria, when exposed, exhibited a phenotypic adaptation characterized by an increase in biofilm biomass. Importantly, this effect was found to be strain-specific rather than species-specific. Exposure to BAC residues induced physiological changes in Vibrio biofilms, leading to an increase in the number of injured and alive cells within the biofilm. The exact nature of the "injured" bacteria remains unclear, but it is postulated that BAC might heighten the risk of viable but non-culturable (VBNC) bacteria development. These VBNC bacteria pose a significant threat, especially since they cannot be detected using the standard culture-based methods commonly employed for microbiological risk assessment in aquaculture and seafood industries. The undetected presence of VBNC bacteria could result in recurrent contamination events and subsequent disease outbreaks. This study provides evidence regarding the role of c-di-GMP signaling pathways in Vibrio adaptation mechanisms and suggests that c-di-GMP mediated repression is a potential avenue for further research. The findings underscore that the misuse and overuse of BAC may increase the risk of biofilm development and bacterial survival within the seafood processing chain.

Association Between Periodontal Pathogens and Severity of Periodontal Diseases Among Adolescents in Kunming City: China

Objective: To investigate the association between periodontal pathogens and periodontal status among adolescents in Kunming City.Material and Methods: A total of 560 adolescents from five high schools within five urban districts in Kunming participated in this study. Clinical periodontal examination was assessed, and the levels of Porphyromonas gingivalis (P. gingivalis), Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Prevotella intermedia (P. intermedia), and Fusobacterium nucleatum (F. nucleatum) in saliva samples were examined using a real-time polymerase chain reaction (PCR). The relationship between periodontal pathogens and the severity of periodontal disease was investigated using multivariate logistic regression analysis. Results: The presence of P. gingivalis, A. actinomycetemcomitans, and P. intermedia was positively correlated with the extent of probing depth, clinical attachment level (CAL), and bleeding on probing. P. gingivalis and A. actinomycetemcomitans were detected at approximately 55-58% among adolescents with healthy periodontal status. P. gingivalis and A. actinomycetemcomitans were detected in all adolescents diagnosed with periodontitis (stage I or II), which was an increased number compared to healthy adolescents. It was found that P. gingivalis (odd ratio (OR)=7.03, 95% confidence interval (CI) 3.77-13.11) and A. actinomycetemcomitans (OR=5.37, 95% CI 2.73-10.57) were strongly associated with stage II periodontitis. F. nucleatum had no significant relationship with the occurrence of gingivitis and periodontitis.Conclusion: P. gingivalis, A. actinomycetemcomitans, and P. intermedia are important microbiological risk factors for periodontal diseases in adolescents.

Association Between Periodontal Pathogens and Severity of Periodontal Diseases Among Adolescents in Kunming City: China

Objective: To investigate the association between periodontal pathogens and periodontal status among adolescents in Kunming City.Material and Methods: A total of 560 adolescents from five high schools within five urban districts in Kunming participated in this study. Clinical periodontal examination was assessed, and the levels of Porphyromonas gingivalis (P. gingivalis), Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Prevotella intermedia (P. intermedia), and Fusobacterium nucleatum (F. nucleatum) in saliva samples were examined using a real-time polymerase chain reaction (PCR). The relationship between periodontal pathogens and the severity of periodontal disease was investigated using multivariate logistic regression analysis. Results: The presence of P. gingivalis, A. actinomycetemcomitans, and P. intermedia was positively correlated with the extent of probing depth, clinical attachment level (CAL), and bleeding on probing. P. gingivalis and A. actinomycetemcomitans were detected at approximately 55-58% among adolescents with healthy periodontal status. P. gingivalis and A. actinomycetemcomitans were detected in all adolescents diagnosed with periodontitis (stage I or II), which was an increased number compared to healthy adolescents. It was found that P. gingivalis (odd ratio (OR)=7.03, 95% confidence interval (CI) 3.77-13.11) and A. actinomycetemcomitans (OR=5.37, 95% CI 2.73-10.57) were strongly associated with stage II periodontitis. F. nucleatum had no significant relationship with the occurrence of gingivitis and periodontitis.Conclusion: P. gingivalis, A. actinomycetemcomitans, and P. intermedia are important microbiological risk factors for periodontal diseases in adolescents.

Valorization of poultry slaughterhouse waste into fertilizers with designed properties.

Climate change, soil erosion, air and water pollution, or problems related to waste management are just some of the many problems in the modern world. Comprehensive solutions are sought to reduce the effects of progressive environmental degradation according to the assumptions of the concept of sustainable development. The paper presents a technological concept that may be a response to these problems. The presented solution assumes full utilization of slaughterhouse waste with the simultaneous recovery of nutrients and the production of functional fertilizing products with designed properties. Four liquid fertilizer formulations with the following composition were prepared: N - 2.30-3.64%, P2O5 - 2.18-9.66%, and K2O - 0.11-4.49%. The manufactured products were characterized by a high sulfur content and the addition of microelements. The tests carried out on plants confirmed their effectiveness similar to commercial mineral fertilizers. An increase in green matter yield of peas by 5 t/ha and maize by 2 t/ha was observed. The lack of microbiological risk associated with their use has been proven. Good efficiency with a simultaneous reduction in production costs resulting from the use of waste materials, as well as limiting the negative impact of poultry farms on the environment, make this solution an attractive alternative to mineral fertilizers, in line with the assumptions of the circular economy.

Characterization of Aspergillus section Flavi associated with stored grains

Increased frequencies of Aspergillus section Flavi and aflatoxins in cereal grains have been seen in recent years due to changes in climate circumstances, such as high temperatures and drought. To assess the microbiological risks of contamination, it is critical to have a reliable and accurate means of identifying the fungi. The main goal of this study was to characterize Aspergillus species from section Flavi obtained from twenty-three samples of barley and maize grains, gathered from different markets in Qena, Egypt, using morphological and molecular techniques. Twenty-three isolates were chosen, one isolate from each sample; they were identified as A. aflatoxiformans (4 isolates), A. flavus (18), and A. parasiticus (1). The existence of four aflatoxin biosynthesis genes was also investigated in relation to the strains’ ability to produce total aflatoxins and aflatoxin B1, focusing on the regulatory gene aflR and the structural genes aflD and aflM. All strains producing aflatoxins were linked to the presence of aflR1 and/or aflR2, except two isolates that exhibited aflatoxins but from which aflR1 or aflR2 were not detected, which may be due to one or more missing or unstudied additional genes involved in aflatoxin production. AflD and aflM genes were amplified by 10 and 9 isolates, respectively. Five samples of barley and maize were contaminated by aflatoxins. Fifteen isolates were positive for producing total aflatoxins in the range of 0.1–240 ppm. Antagonistic activity of Trichoderma viride against A. flavus (F5) was assessed at 31.3%. Trichoderma reduced total aflatoxins in all treated seeds, particularly those subjected to Trichoderma formulation.

Rainwater treatment system efficiency: Household slow sand filter combined with UVC lamp disinfection

A household system to treat rainwater composed of a Household Slow Sand Filter (HSSF) and a commercial ultraviolet lamp reactor was evaluated. Rainwater was collected in the southeast of Brazil (São Carlos, São Paulo) and inoculated with Escherichia coli to simulate contamination. The system was evaluated for 100 consecutive days under real-scale conditions, aiming to remove microbiological and physical-chemical parameters. Results indicated that HSSF removed 1.10 ± 0.33 log of E. coli even with the schmutzdecke in slow formation due to the low concentration of organic matter concentration and scarcity and low diversity of microorganisms in the rainwater. On the other hand, the UV disinfection (UV dose of 30 mJ/cm2) presented an average removal of 4.60 ± 0.58 log, with 87.5 % of the samples presenting absence of microbiological risk. No significant improvement in physical-chemical water quality after the household treatment was observed due to the high quality of raw rainwater. Therefore, it was recognised that rainwater quality was not substantially improved by the HSSF (i.e., filtration could be dispensed) and only UVC lamp disinfection would be enough to produce drinking water. Recontamination was observed during the tests, as weather events and monitored parameters were capable of highlighting the importance of safe storage practices.

Prevalence and phylogenetic traits of nitrite-producing bacteria in raw ingredients and processed baby foods: Potential sources of foodborne infant methemoglobinemia

Nitrite, which has been mainly regarded as a chemical hazard, can induce infant methemoglobinemia. As for nitrite as a product of microbial metabolism, the contribution of the oral or gut microbiome has mostly received attention, whereas the role of nitrite-producing bacteria (NPBs) in food has been less elucidated. In this study, mesophilic NPBs were isolated from food samples (n = 320) composed of raw ingredients for weaning foods (n = 160; beetroot, broccoli, carrot, lettuce, rice powder, spinach, sweet potato, and honey) and processed baby foods (n = 160; cereal snack, cheese, yogurt, powdered infant formula, sorghum syrup, vegetable fruit juice, and weaning food). The phylogenetic diversity of the NPB strains was analyzed via 16S rRNA sequencing. All 15 food items harbored NPBs, with a prevalence of 71.9 % and 34.4 % for the raw ingredients and processed foods, respectively. The NPBs isolated from the foods were identified as Actinomycetota (Actinomycetes), Bacteroidota (Flavobacteriia, Sphingobacteriia), Bacillota (Bacilli), or Pseudomonadota (Alpha-, Beta-, and Gammaproteobacteria). Among the raw and processed foods, beetroot (85.0 %) and powdered infant formula (70.0 %) showed had the highest NPB prevalence (P > 0.05). Bacillota predominated in both types of food. The contamination source of Pseudomonadota, which was another major phylum present in the raw ingredients, was presumed to be the soil and endophytes in the seeds, whereas that of Bacillota was the manufacturing equipment used with the raw ingredients. Common species for probiotics, such as Lacticaseibacillus, Leuconostoc, Enterococcus, and Bacillus, were isolated and identified as NPBs. To our knowledge, this is the first study to reveal the taxonomical diversity and omnipresence of NPBs in food for babies. The results of this study highlight the importance of food-mediated microbiological risks of infant methemoglobinemia which are yet underrecognized.

Microbiological and parasitological risk analysis of novel food sources obtained with the use of insects

The problem of food safety being an important component of the country's food security, provides not only for continuous improvement of the methodology of hygienic standardization, but also for the formation of requirements for novel food, in particular, those obtained from non-traditional sources. The accumulated practical and theoretical competence in the food hygiene area, as well as knowledge of current trends of the food base broadening, allow us to analyze the risks associated with novel food obtained of insects. The purpose of the research was to analyze the microbiological and parasitological risk of novel food sources obtained with the use of insects, suggest the effective risk management measures. Material and methods. The analytical part of the work included literature search, collection of information and statistical materials published in domestic and foreign scientific editions. The search was carried out using the Google Academy retrieval system and electronic databases (PubMed, MEDLINE, EMBASE, Scopus, Web of Science, eLIBRARY), mainly in the last 25 years, using the keywords: Hermetia illucens, Tenebrio molitor, Acheta domesticus, insects, parasite, nematode, pathogen, cysts. Results. Based on the published materials' analysis, a systematization of microbiological and parasitological factors potentially capable of colonizing edible insects has been carried out. There were identified representatives of 24 groups of pathogenic and 18 opportunistic microorganisms and helminths related to microbial and parasitic pathogens, the spread of which is significantly influenced by inappropriate conditions of feeding and keeping insects. As there are currently no veterinary requirements for insect breeding and farming conditions, contamination of end products with infectious and parasitic pathogens can vary over a very wide range. Conclusion. The use of native insect biomass carries certain risks associated with its microbial and parasitic contamination, and the development of measures to prevent them requires significant resources. The possibility of deep processing of such raw materials can be considered as one of the solutions to mitigate these risks. For use in the food industry, insects should be subjected to processing similar to that currently used for soybean seeds, which includes separation of protein (entomoprotein), fat and chitin fractions, each of which would have an independent use. Thus, at present, insects should be considered as a source of novel food ingredients, first of all, complete protein of animal origin.

Microbiological Distribution, Antimicrobial Susceptibility and Risk Factors of Polymicrobial Infections in Diabetic Foot.

Diabetic foot infection (DFI) leads to poor prognosis and polymicrobial infections are usually the main cause. The study is to explore the microbiological distribution, antimicrobial drug susceptibility, and risk factors of polymicrobial infections in hospitalized patients with DFI. This retrospective study included 160 patients with DFI in Wagner's grades 2, 3, and 4. Deep necrotic tissue was used to acquire specimens for microbiological culture. VITEK-2 system and MALDI-TOF mass spectrometry were used to identify the bacterial isolates. The Kirby Bauer method was used for drug susceptibility tests. A total of 202 pathogens were isolated. The proportion of gram-negative bacilli (GNB, 62.4%, 126 of 202) was higher than that of gram-positive cocci (GPC, 37.6%, 76 of 202). The most prevalent GPC was Staphylococcus aureus in every Wagner grade, while the most common GNB varied in different Wagner grades. Linezolid was the most effective antibiotic for GPC in different Wagner grades. Imipenem was the most effective antibiotic for GNB in Wagner grade 2. Amikacin was the most effective antibiotic for GNB in Wagner grades 3 and 4. Polymicrobial infections existed only in Wagner grades 3 and 4 and increased the risk of amputation (p < 0.01). History of antibiotics, duration of diabetic foot, CRP, and lower extremity arterial disease were the independent risk factors of polymicrobial infections (p < 0.05). Clinicians should adjust the antibiotic as needed based on the results of drug susceptibility and clinical treatment effect among different Wagner grades. Particular attention should be given to the treatment of polymicrobial infections.

Tolerance variations and mechanisms of Salmonella enterica serovar Newport in response to long-term hypertonic stress

Abstract Objectives To assess the variations in hypertonic tolerance among Salmonella enterica serovar Newport (S. Newport) strains isolated from diverse sources and investigate the mechanism underlying the tolerance differences between the sensitive and tolerant strain. Materials and Methods In this work, various S. Newport strains were cultured in 5% and 10% NaCl solutions (hypertonic stress), and the most sensitive and tolerant strains were selected using a Weibull model. The regulatory mechanisms underlying the hypertonic tolerance differences of S. Newport were preliminarily investigated in the aspects of cell phenotype, intracellular solute concentration, and gene expression level. Results With prolonged hypertonic stress time, the leakage of nucleic acids and proteins of S. Newport increased gradually, and the membrane potential of S. Newport declined after increasing. Compared with the sensitive strain, the tolerant counterpart exhibited the ability to maintain the integrity of the cell membrane and sustain a high membrane potential level. The expression levels of the upstream genes proV and otsB in the tolerant strain were significantly lower than those in the sensitive strain; but the Kdp and Trk systems and downstream genes proX, proW, and otsA were highly expressed in the tolerant strain compared with the sensitive strain, leading to higher concentrations of intracellular K+ and trehalose, enabling better survival in a hypertonic environment. Conclusions The findings of this work offer valuable insights into pathogen survival mechanisms under hypertonic stress and contribute to the development of strategies for mitigating microbiological risks during long-term processing and storage in the cured food industry.

Physicochemical Properties, Bioactive Compounds Degradation Kinetics, and Microbiological Counts of Fortified Pomegranate Gummy Candy (GC) during Ambient Storage

This study explored the potential of fortified pomegranate gummy candies (GC) as a solution for insufficient vitamin C and phenol intake. It entailed two objectives: assessing the impact of ambient storage (20±2 ℃) on various GC properties and developing kinetic models to predict vitamin C and phenol degradation during storage. The study involved the preparation of GC using a modified formulation and examined moisture content, water activity, texture, vitamin C, total phenolic content, and microbiological counts during 15-day-storage. Findings revealed that the moisture content decreased from 21.82% to 13.41%, potentially affecting texture. Water activity remained high (0.84-0.86), posing potential microbiological risks. The textural analysis indicated high hardness, springiness, gumminess, and chewiness, which may impact consumer acceptance. Adhesiveness remained minimal. Vitamin C decreased from 2,176.90 mg AA/100g to 1,419.10 mg AA/100g, possibly influenced by moisture and oxygen. Phenolic content decreased from 2,845.97 mg GAE/100g to 2,183.70 mg GAE/100g, remaining remarkably high. Kinetic modeling revealed that zero-order kinetics best described degradation, with constant degradation rates. In conclusion, fortified pomegranate GC demonstrate potential as functional food. However, further research is necessary to optimize texture properties, improve formulation and understand complex interactions between gelatin and phenolic compounds for enhanced consumer acceptance and health benefits.

Impact of low-dose gamma irradiation treatment on microbial and chemical properties of raw milk white cheese

Using raw milk in cheese-making has microbiological risks, however a considerable number of artisan cheese makers around the world prefer raw milk, as heat treatment damages natural microbiota and alters the characteristic taste and flavor of the cheese. The potential of the gamma irradiation process to make the raw milk cheese microbiologically safe was investigated in this study. A total of 5 groups of cheese were produced, including control groups (control pasteurized milk cheese and control non-irradiated raw milk cheese). After the white cheese samples were kept in brine for 1 night, they were vacuum-packaged and each group was subjected to gamma irradiation at doses of 1, 2, and 3 kGy, respectively. Chemical composition, pH, acidity, Urea-PAGE images, total aerobic mesophilic bacteria (TAMB), coliform group bacteria, E. coli, yeasts and molds, Lactobacillus and Lactococcus counts of cheese samples were determined during 60 days of storage at 4°C. All analyzes were performed on days 1, 30, and 60 of production. We found that irradiation reduced the microbiological load of the cheeses and slowed down the degradation of αs1-CN and β-CN especially at 3 kGy. Irradiation at 3 kGy successfully inhibited the coliforms and E. coli, however yeast and mold counts were still high due to initial high levels. Our study showed that irradiation of the raw milk cheese is a promising method to reduce the microbial counts to acceptable limits which could reduce the required ripening periods for the microbial safety of raw milk cheeses.

Spice-Induced Metal Contamination and Microbiological Risk Assessment of Instant Noodles Prepared for Human Consumption.

With the rising worries of potential metal contamination in cooked noodles, this study aimed at unravelling, for the first time, the possible source of metal contamination in cooked noodles. Noodles cooked with full spices (CWFS), cooked with half spices (CWHS), cooked with quarter spices (CWQS), and cooked with no spices (CWNS: control) and their spices were analysed for metals using inductively coupled plasma-atomic emission spectrometry. The microbiological quality of the noodles was also evaluated. Metal concentrations in cooked noodles varied with spice quantity. Noodles CWFS had the highest significant (p < 0.05) concentration of Pb (0.36 ± 0.12mg/kg), Ni (1.05 ± 0.01mg/kg), Cd (0.07 ± 0.04mg/kg), Co (0.02 ± 0.002mg/kg), and Na (9.45 ± 0.04mg/kg), compared to the control (CWNS). The mean Pb and Ni of spice and cooked noodles were above the WHO acceptable limits for food and could be harmful to consumers. Pearson's correlation and PCA showed that packed noodle spices introduced metals into the cooked noodles. Although the hazard indices (adults and children) in all noodle's groups were less than 1, children still had the potential to contract cancer from Ni exposure because the carcinogenic risk values of CWQS (2.87 × 10-4), CWHS (3.03 × 10-4), and CWFS (3.21 × 10-4) were greater than 10-4. Microbiological analysis revealed the presence of potential pathogens that showed multidrug resistance and the ability to elaborate protease and amylase enzymes. Given the impending chronic health risks inherent in processed noodles, consistent consumption should be avoided.

A review on the application of UV‐C treatment on food and food surfaces: association with food microbiology, predictive microbiology and quantitative microbial risk assessment

SummaryThe so‐called emerging technologies have gained prominence in the field of food processing, compared to conventional heat treatments, due to technological, sensorial and microbiological safety benefits. Ultraviolet radiation (UV), more specifically UV‐C radiation, is inexpensive and has been one of the most studied technologies. This work seeks to summarise the application of UV‐C treatment, contextualising its efficiency in the inactivation of microorganisms in different food matrices and surfaces associated with food handling and allowing the visualisation of trends in the combination of UV‐C radiation with other technologies. Still, the technology is related to quantitative tools associated with food microbiology. Factors related to processing parameters, characteristics of the microbial population and food properties have a direct influence on the effectiveness of UV‐C technology. The UV‐C treatment parameters must be rigorously defined, considering the particularities of each food matrix, so that undesirable identity or sensory changes do not occur. The application of mathematical tools, such as predictive microbiology and quantitative microbial risk assessment, is fundamental in the planning and definition of processing parameters for UV‐C radiation technology.

Mycobacterium chimaera Infections in a Unit of Cardio Surgery: Study at a General Hospital in Padua, Italy.

Mycobacterium chimaera is a slow-growing non-tuberculous mycobacterium already known for being able to colonize cardio surgery heater-cooler units (HCUs). This study aims to describe the real magnitude of the phenomenon, providing a methodological protocol and the results of a longitudinal survey. In the period 1 January 2017-23 May 2022, over 1191 samples were collected on 35 HCUs of two different manufacturers. Among them, we identified 118 (10.3%) positive results for M. chimaera. We propose our 4-year biosurveillance experience as a practical model to minimize microbiological patients' risk, suggesting the need for new procedures and interventions for a safer and more ecological cardio surgery.