Contamination Of Milk Research Articles

Characterization of dual-species biofilms formed by bacteria isolated from milk

This study evaluated biofilm formation of bacteria isolated from raw milk and investigated the composition of extracellular polymeric substances (EPS) using Raman spectroscopy. Biofilms were formed from six isolates on a 96-well microplate at 7 and 25 °C in 1 and 10% reconstituted whole milk. Biofilms were then formed on stainless steel coupons at 7 °C from two isolates identified as strong biofilm producers. Pseudomonas fluorescens, a frequent contaminant of raw milk, forms single or dual-species biofilms with Staphylococcus aureus; however, the sessile cell number of S. aureus remained constant over ten days. Raman spectroscopy identified that EPS composition varied with carbohydrate and protein substrates, the predominant components in P. fluorescens single or dual-species biofilms. Understanding the formation and composition of biofilms at different temperatures and in milk concentrations that simulate the equipment used in the dairy industry is a significant subsidy for establishing adequate sanitary protocols for their mitigation.

Dairy Farmers' Knowledge, Attitudes, and Practices (KAP) Towards Aflatoxin Contamination in Milk and Feeds in Bahir Dar, Ethiopia.

Aflatoxins, primary foodborne mycotoxins, come from Aspergillus flavus and Aspergillus parasiticus fungi. They pose significant health risks to humans and animals, creating a major challenge in the dairy sector. The objective of this study is to evaluate the knowledge, attitudes, and practices (KAP) of dairy farmers regarding aflatoxin contamination in milk and feeds. Conducted as a cross-sectional study in Bahir Dar city between November 2019 and February 2020, this investigation randomly selected 106 dairy farms for data collection. Face-to-face interviews, facilitated by a semistructured questionnaire, were employed. Findings indicate that 59.4% of respondents displayed good knowledge, while a substantial 94.3% exhibited a favorable attitude. Intriguingly, only 1.9% implemented good practices. Notably, the educational background of dairy farmers emerged as a significant factor influencing their KAP (p < 0.05). Conversely, various sociodemographic factors did not yield a significant impact on the KAP of dairy farmers. Despite a robust knowledge base and favorable attitudes towards aflatoxin among dairy farmers, the study highlights a significant gap in the implementation of recommended practices. This finding emphasizes the necessity for increased efforts to cultivate and reinforce good practices. Collaborative initiatives involving diverse stakeholders are crucial to reducing aflatoxin contamination in the dairy industry.

Lead contamination in human milk affects infants' language trajectory: results from a prospective cohort study.

Infants growing up in low- and middle-income countries are at increased risk of suffering adverse childhood experiences, including exposure to environmental pollution and lack of cognitive stimulation. In this study, we aimed to examine the levels of metals in the human milk of women living in São Paulo City, Brazil, and determine the effects on infants' neurodevelopment. For such, a total of 185 human milk samples were analyzed for arsenic (As), lead (Pb), mercury (Hg), and cadmium (Cd) using inductively coupled plasma mass spectrometry (ICP-MS). We applied the Bayley scales of infant and toddler development Third Edition (Bayley-III) to assess developmental milestones. In our analysis, we found a mean (standard deviation) concentration of As in human milk equal to 2.76 (4.09) μg L-1, followed by Pb 2.09 (5.36) and Hg 1.96 (6.68). Cd was not detected. We observed that infants exposed to Pb presented language trajectories lower than non-exposed infants (β = -0.413; 95% CI -0.653, -0.173) after adjustment for infant age, maternal education, socioeconomic status, infant sex, and sample weights. Our results report As, Pb, and Hg contamination in human milk, and that infant exposure to Pb decreased infants' language development. These results evidence maternal-child environmental exposure and its detrimental impact on infants' health.

Assessment of some chemical residues in Egyptian raw milk and traditional cheese.

The assessment of risks related to food safety is becoming a challenge in developing countries with its consequent health hazards. Chemical risk assessment in dairy products is important to maintain consumer health locally and internationally. Since milk and dairy products are essential foods for a wide range of customers, mostly children, patients, and pregnant women, it is very important to estimate the risks of some chemical residues, such as pesticides, some heavy metals, and aflatoxins. This work aims to determine the levels of chemical contamination in milk and traditional Egyptian cheese. Heavy metals were determined in samples by atomic absorption spectrometry. GC-mass spectrometry (MS)/MS and LC-MS/MS were also used for measuring pesticide residues. The Aflatoxin M1 was determined by enzyme-linked immune-sorbent assay. Raw milk samples were tested and showed elevated concentrations of lead and cadmium, (46% and 4%, respectively). The heavy metals detected in the Egyptian cheese samples were variable depending on the type of cheese. Moreover, p.p.-DDE phenofose was present in 45% and 29% of raw milk and Ras cheese samples, respectively. For Aflatoxin M1, only 7% of milk samples and 2.9% of Ras cheese samples exceeded the acceptable limits. More surveying and risk assessment of chemical residues in milk and milk products are essential for controlling health risks to consumers.

MAIN TECHNOLOGICAL CHARACTERISTICS OF COW’S MILK IN ACCORDANCE WITH EU REQUIREMENTS

The study is focused on considering the issues of harmonization of domestic standards in accordance with EU requirements, the importance of studies of the quality of cow’s milk in relation to microbial contamination, and the informational capabilities of the indicator of the number of somatic cells in milk. It is outlined that the production of milk in Ukraine has decreased over the last decade, nevertheless, an increase in the average annual milk yield per cow is being monitored, which indicates improvement in the genetic material. The normative documents establishing requirements for the quality of milk and dairy products in accordance with European standards, in particular, for indicators of total bacterial insemination, number of somatic cells, freezing point, fat and protein percentage, were considered. The mentioned indicators in the leading countries for the production of dairy products and the peculiarities of determining its quality were analyzed, in particular, in relation to psychrotrophic microflora. In this sense, the temperature range of contamination of milk by bacteria of various types is given. The main sources and the share of their impact on milk contamination, which spreads through the internal and external environment, are established in the study, as well as the means of their avoidance are indicated. The sanitary condition of milking equipment, the speed and quality of milk cooling after milking (in general, about 70%) have the greatest influence on the contamination of dairy products. Important influencing factors are proper care of the udder, the condition of the floor, the sanitary and hygienic condition of the location of the animals, feed, water, air in the premises, as well as the labour hygiene of the workers on the dairy farm. The important indicator of milk quality is the content of somatic cells, which is the main indicator of infection in the animal’s body and makes it possible to identify cows with mastitis in time. Regular control of the content of somatic cells in milk is especially important during the subclinical course of mastitis. In this sense, it is promising to use express methods of mastitis diagnosis, to establish relationships between the synthesis of milk components and the physiological state of the cow, to determine the genetic determinant of the sensitivity of cows to mastitis pathogens, and therefore to prevent mastitis by targeted selection of animals.

Trend of High Microbial Contamination in Livestock Milk in Indonesia and Distribution Mapping

Milk is a food ingredient that is considered main source of nutrition for humans because contains essential substances for the body. Microbial contamination of milk can pose various health hazards to humans. Information regarding trends in microbial contamination and mapping its distribution is still limited. Research continues to develop rapidly with methods of analyzing bibliographic linkages with scientific communication models, data that is increasingly interesting to explore. The data were analyzed using bibliometric methods related to milk contamination in Indonesia. After sorting, 108 suitable articles were obtained. The results of the analysis show the peak of article production. After 2021, there was a decrease in the number of publications, indicating a shift in research direction. International collaboration between countries also looks significant. Key themes such as “probiotics,” “milk yield,” and “lactic acid bacteria (lab)” emerged as dominant focuses in this study. Meanwhile, the theme in the ‘Emerging or Declining Themes’ area, has not yet become main focus, but there is potential for development, and challenges that require further research and innovation. Overall, this review provides insight into research trends, international collaborations, and theme dynamics, eflecting the need for future research to continue to explore and reassess research focus.

Benzotriazole Ultraviolet Absorber Contamination in Breast Milk and the Infant Health Risk

Benzotriazole Ultraviolet Absorber Contamination in Breast Milk and the Infant Health Risk

CURRENT STATE OF THE 137CS MILK POLLUTION IN SETTLEMENTS OF RIVNE REGION AND VILLAGE NARODYCHI ZHYTOMYR REGION

The article analyses the results of selective monitoring of 137Cs content in milk from private households in the village of Narodychi, Zhytomyr region, and 14 settlements of Rivne region. A total of 213 milk samples were collected and analysed in 2023 in the Rivne region and about 30 in Narodychi. The analysis of the milk samples for 137Cs content showed that the contamination of this livestock product with 137Cs has complex dynamics. In most settlements of the monitoring network, the average values of 137Cs contamination in whole milk exceed the hygienic standards (PL-2006 - 100 Bq/l). 70% of milk samples recorded an exceedance of the permissible level. The highest activity concentration of this radionuclide (350 Bq/l) was observed in Stare Selo. Seasonal changes in the activity concentration of the radionuclide in milk were also observed. During the stall period, the activity concentration of milk with 137Cs ranged from less than 2 to 88 Bq/l. However, during the grazing period, the level of milk contamination with 137Cs increased to 100-350 Bq/l. Recent studies have shown a steady decrease in milk radioactivity. Nevertheless, without countermeasures, the reduction of 137Cs accumulation and transfer to milk will be mainly due to the physical decay of the radionuclide. The mineral part has likely exhausted its absorption capabilities for the natural processes, and therefore, it will not affect the reduction of milk contamination.

Tracking the microbial communities from the farm to the processing facility of a washed-rind cheese operation.

Milk residue and the accompanying biofilm accumulation in milking systems can compromise the microbial quality of milk and the downstream processes of cheese production. Over a six-month study, the microbial ecosystems of milk (n = 24), tap water (n = 24) and environmental swabs (n = 384) were cultured by plating decimal dilutions to obtain viable counts of total aerobic mesophilic lactose-utilizing bacteria (lactose-M17), lactic acid bacteria (MRS), yeasts and molds (Yeast, Glucose, Chloramphenicol (YGC) medium). Viable aerobic lactose-M17 plate counts of milk remained well below 4.7 log CFU/ml over five of the months, except for 1 week in November where milk at the facility exceeded 5 log CFU/ml. Swab samples of the farm milking equipment showed consistent viable counts after sanitation, while the bulk tank swabs contained the lowest counts. Viable counts from swabs of the facility were generally below the detection limit in the majority of samples with occasional residual contamination on some food contact surfaces. Extracted DNA was amplified using primers targeting the V3-V4 region of the 16S rRNA gene, and the amplicons were sequenced by MiSeq to determine the shared microbiota between the farm and the processing facility (8 genera). Culture independent analysis of bacterial taxa in milk, water and residual contamination after sanitation with swab samples revealed the shared and distinct microbiota between the sample types of both facilities. Amplicon sequence variants (ASVs) of the V3-V4 region of the 16S rRNA gene revealed that the microbiota of milk samples had lower diversity than water or environmental swabs (279 ASVs compared to 3,444 in water and 8,747 in environmental swabs). Brevibacterium and Yaniella (both Actinomycetota) were observed in all sampling types. Further studies will include whole genome sequencing of Brevibacterium spp. isolates to determine their functionality and diversity within the system.

Alarming multidrug resistance in Staphylococcus aureus isolated from raw milk of cows with subclinical mastitis: Antibiotic resistance patterns and occurrence of selected resistance genes.

Bovine mastitis is a widespread and costly disease that affects dairy farming globally, characterized by mammary gland inflammation. Bovine intramammary gland infection has been associated with more than 135 different pathogens of which Staphylococcus aureus is the main etiology of sub-clinical mastitis (SCM). The current study was designed to investigate the prevalence, antibiotic resistance pattern, and the presence of antibiotic resistance genes (mecA, tetK, aacA-aphD and blaZ) in S. aureus isolated from the raw milk of cows with subclinical mastitis. A total of 543 milk samples were collected from lactating cows such as Holstein Friesian (n = 79), Sahiwal (n = 175), Cholistani (n = 107), and Red Sindhi (n = 182) from different dairy farms in Pakistan. From the milk samples microscopic slides were prepared and the somatic cell count was assessed to find SCM. To isolate and identify S. aureus, milk was streaked on mannitol salt agar (MSA) plates. Further confirmation was done based on biochemical assays, including gram staining (+ coccus), catalase test (+), and coagulase test (+). All the biochemically confirmed S. aureus isolates were molecularly identified using the thermonuclease (nuc) gene. The antibiotic resistance pattern of all the S. aureus isolates was evaluated through the disc diffusion method. Out of 543 milk samples, 310 (57.09%) were positive for SCM. Among the SCM-positive samples, S. aureus was detected in 30.32% (94/310) samples. Out of 94 isolates, 47 (50%) were determined to be multidrug resistant (MDR). Among these MDR isolates, 11 exhibited resistance to Cefoxitin, and hence were classified as methicillin-resistant Staphylococcus aureus (MRSA). The S. aureus isolates showed the highest resistance to Lincomycin (84.04%) followed by Ampicillin (45.74%), while the least resistance was shown to Sulfamethoxazole/Trimethoprim (3.19%) and Gentamycin (6.38%). Polymerase chain reaction (PCR) analysis revealed that 55.31% of the isolates carried blaZ gene, 46.80% carried tetK gene, 17.02% harbored the mecA gene, whereas, aacA-aphD gene was found in 13.82% samples. Our findings revealed a significant level of contamination of milk with S. aureus and half (50%) of the isolates were MDR. The isolated S. aureus harbored various antibiotic resistance genes responsible for the absorbed phenotypic resistance. The alarmingly high prevalence of MDR S. aureus isolates and MRSA strains in these cases possess a serious risk to public health, emphasizes the urgent need to address this issue to protect both human and animal health in Pakistan.

Experimental Protocol to Toxoplasma gondii Detection in Fresh Goat Milk.

Toxoplasma gondii is a zoonotic parasite with global distribution capable of infecting homeothermic animals. Transmission of protozoan to humans includes ingestion of water and raw food contaminated with sporulated oocysts, ingestion of raw or undercooked meat with tissue cysts, and tachyzoites' transplacental transmission. Fresh goat milk intake has already been linked to human toxoplasmosis outbreaks, but little is known about the infectious potential of this biological sample. Accordingly, the aim of the present study is to assess the survival and infectivity of T. gondii tachyzoites in fresh goat milk samples through an experimental protocol to detect this parasite via bioassay carried out with a murine model, DNA amplification, and serology. Swiss Webster mice were inoculated with fresh goat milk samples contaminated with different T. gondii RH strain tachyzoite concentrations per milliliter and stored for different refrigeration times. Animals showing clinical signs compatible to toxoplasmosis were euthanized. Milk samples contaminated with high parasitic loads and kept for a shorter refrigeration time were the most lethal ones. No significant differences were observed between mean death rates recorded for different goat milk contamination concentrations (p = 0.1888), and for the refrigeration time, contaminated milk samples were kept under (p = 0.9440). T. gondii DNA was amplified in all contaminated milk samples, but only one of the surviving mice was serologically positive. Results of the present study have shown T. gondii survival and infectivity in fresh goat milk samples, and it highlights its significant risk for public health. Therefore, molecular methods must be the tests of choice when milk samples are used to assess infection caused by protozoan in goats' dairy products.

Occurence of antimicrobial residues in milk and labneh consumed in Lebanon

ABSTRACT Antimicrobials are administered in livestock for different uses leading to milk contamination and several undesirable effects. Because there is a lack of surveillance of antimicrobial residues (AMRs) in milk and dairy products in Lebanon, this study aims to determine the occurrence of AMRs in 90 Lebanese samples of milk and labneh (concentrated yoghurt). Multi-residue screening methods with suitable sample preparations were applied to detect 71 AMRs in milk and labneh, respectively, using LC-MS/MS. Of the total number of samples, 71% was contaminated with AMRs and (fluoro)quinolones and macrolides were the most detected families. Additional confirmation tests proved that 6.7% of the milk samples were non-compliant for the macrolides tilmicosin, tulathromycin and spiramycin. Moreover, some labneh prepared from contaminated milk samples was analysed to determine the fate of AMRs during the manufacturing process. The results showed that some AMRs could be concentrated, eliminated or degraded, based on their physicochemical characteristics.

Implementation of Good Manufacturing Practices in Milk Processing Companies in Nairobi County and Microbial Contamination of Milk and Milk Products

Good manufacturing practice involves a series of measures to be adopted by the food industries in order to guarantee the safety and conformity of food products to specific regulations. Even though good manufacturing practices are vital systems in food safety and is associated with minimum sanitary and processing requirements for the food industry, only a few studies have reported GMP implementation by small milk processing companies. Therefore, the present study was undertaken in milk processing firms to evaluate the implementation of good manufacturing practices for control of microbial contamination in milk and milk products. Purposive, random and stratified sampling techniques was used to identify milk processing companies. Ten processing facilities were purposively sampled for the study. The representatives were interviewed, using a pretested questionnaire and data was collected and analyzed. All the processors had qualified personnel handling milk and milk products with a daily processing capacity of 20000-30000 litres. It was observed that the processors complied with all regulatory and licensing requirements and had in place critical process controls with majority indicating pasteurization at temperatures ranging from 80-90oC as the most common method. The processors had several food safety management systems such as ISO 22000, GMPs, and HACCP which were handled by trained and competent staff. It was observed that all the processors tested for total viable counts (TVC), and E. coli while only 50% and 33.3% of the processors tested for S. aureus and L. monocytogenes respectively. Furthermore, the processors (33.3%) reported E. coli as the main contaminant while L. monocytogenes were not detected. A majority (83.3%) had well-documented cleaning programs and had a system of controlling cross contamination which was enforced through different colour codes (66.7%), memos and notices (16.7%) and through colour coding of processing equipment (16.7%). In conclusion, the present study discovered that milk processors had implemented good manufacturing practices (GMP) and conformed to good processing practices.

Psychrophilic phage phiGM22-3 efficiently controls Pseudomonas fluorescens contamination in cold-stored milk

Pseudomonas fluorescens is a common spoilage causing microbe found in milk. Antibiotic preservatives may cause emergence of multidrug resistance, posing food safety related risks to public health. Phage treatment may be used as an alternative to antibiotics in controlling P. fluorescens contaminations. Here we reported that P. fluorescens phage phiGM22-3 reproduced rapidly over a broad temperature range of 4 through 30°C, and the optimum growth of phiGM22-3 occurred at 10°C, indicating that it was a psychrophilic virus. Genome analysis revealed that phiGM22-3 has a genome of 42,662 bp with an identical terminal direct repeat sequence of 328 bp and encodes 58 predicted proteins. Evidence revealed that phiGM22-3 recognized lipopolysaccharides (LPS) as receptor for infection. Additionally, two phage mutants phiMX2 and phiMX8 with different host ranges were identified in the phiGM22-3 population. Phage killing efficiency of P. fluorescens cells artificially inoculated in milk was evaluated. Phage phiGM22-3 and the cocktails containing phiMX2 and phiMX8 can lyse almost 100% bacterial cells at 4°C within 24 h. Taken together, our data indicated that the psychrophilic virus phiGM22-3 and its two mutants can efficiently inhibit bacteria growth at 4°C, showing a great potential to be used as alternatives to conventional antibiotics against P. fluorescens in refrigerated foods.

Evaluation of contamination of cow milk with various conditionally pathogenic microflora for mastitis: genera Staphylococcus

The food safety issue of livestock products concerning insemination by opportunistic and accompanying microflora has attracted increasing attention from specialists. The ever-increasing trade and export of dairy and meat products from Ukraine to the EU countries requires constant monitoring of inoculation with mesophilic-aerobic and facultatively anaerobic microorganisms and psychrophilic microorganisms, in particular the genera Listeria and Yersinia, which survive and multiply at low temperatures and in salted and fermented products and pose a threat to human health. Milk and lactic acid products make up a significant part of the diet of a modern person. Therefore, constant control of raw materials from dairy enterprises for the production of milk and directly at enterprises for its processing is a guarantee of food safety. At the stage of milk production, due to violations of technological cycles of production (mastitis and contamination with antibiotics) and the spread of several diseases in Ukraine (paratuberculosis, tuberculosis, leptospirosis, brucellosis), milk from a herd of dairy cows poses a significant threat to human health due to the danger of mastitis milk and milk containing the causative agents of tuberculosis, brucellosis, leptospirosis, and recently there are more and more reports about the association of bovine paratuberculosis and human short bowel syndrome (Crohn's disease) mainly among the young population of Europe, which may be due to extreme variability and adaptive capacity mycobacteria.

Milk Contamination and Regulatory Updates

The Article Abstract is not available.

Evaluating the UV-C sensitivity of Coxiella burnetii in skim milk using a bench-scale collimated beam system and comparative thermal sensitivity study by high-temperature short-time pasteurization

Introduction:Coxiella burnetii is a zoonotic Gram-negative obligate intracellular bacterial pathogen and the causative agent of query (Q) fever in humans. Contamination of milk by C. burnetii, as a consequence of livestock infection, is a significant public health concern. Effective methods to inactivate C. burnetii in milk are a critical aspect of food safety. Implementation of non-thermal UV-C processing technologies in the dairy industry can effectively preserve the sensory and nutritional quality of raw milk products while ensuring their safety, making them a viable alternative to traditional high-temperature short-time (HTST) pasteurization methods.Methods: Optical light attenuation factors, such as the absorption, scattering, and reflection by skim milk (SM) were evaluated using a spectrophotometer. SM inoculated with an avirulent strain of C. burnetii was irradiated using a collimated beam device equipped with a low-pressure UV-C 254 nm lamp at doses from 0 to 12 mJ/cm2. Optical properties were considered for the evaluation of the delivered UV-C dose. The pasteurization treatment was conducted using a lab scale HTST pasteurizer (72°C/15 s). The verification studies were conducted using Escherichia coli ATCC 25922 inoculated in a phosphate buffer (transparent fluid) and humic acid (opaque fluid). Salmonella enterica serovar Muenchen ATCC BAA 1674 inoculated in SM was tested for its suitability as a surrogate for C. burnetii, a bacterium that requires specialized equipment and expertise for experimentation.Results and Discussion: Absorption, reduced scattering coefficient, and the reflectance of SM at 254 nm were measured as 19 ± 0.3/cm, 26 ± 0.5/cm, and 10.6%, respectively. The UV-C results showed a log-linear inactivation of C. burnetii in SM with the UV-C sensitivity (D10) value of 4.1 ± 0.04 mJ/cm2. The results of HTST pasteurization revealed that C. burnetii was heat-sensitive with a D value of 1.75 min. Salmonella Muenchen showed similar UV inactivation kinetics and is, thereby, suggested as a suitable surrogate to C. burnetii for the pilot-scale UV-C processing studies of SM.

Identification and Characterisation of Spore-Forming Bacteria in Bovine Raw Milk Collected from Four Dairy Farms in New Zealand

Contamination of milk and dairy products with pathogenic and spoilage bacteria may result in huge economic loss due to recalls of products. This study aimed to identify spore-forming bacteria from raw milk and characterise those for toxin production and their spoilage ability. Bovine raw milk collected from dairy farms in the Manawatu region of the North Island of New Zealand was tested for the presence of both aerobic and anaerobic spore-forming bacteria using standard culture-based techniques, as well as genomic analysis. The spore-forming bacteria were investigated for the presence of toxin genes and their spoilage potential. A low number of aerobic spore-forming bacteria were detected in raw-milk samples collected from the four farms in summer and winter. The 16S rRNA sequence types similar to important food spoilage bacteria like C. beijerinckii, C. sporogenes, B. licheniformis and members of the Paenibacillus genus, as well as potentially toxigenic bacteria such as B. cereus and C. perfringens were isolated. Genes responsible for important toxin production were present in some of the tested spore-forming bacteria. This pilot study highlights the presence of various spoilage and pathogenic spore-forming bacteria in raw milk from these farms. A low number of spore-forming bacteria indicates the implementation of good hygienic farm practices and management to reduce the contamination of raw milk with spore-forming bacteria.

Detection of Clostridium perfringens in donor milk at a human breast milk bank: a case report

BackgroundThe breast milk bank is a professional organization that collects donor human milk (DHM) for special medical needs by recruiting qualified breast milk donors. Such organizations are also responsible for the disinfection, processing, testing, storage, distribution, and use of breast milk. As DHM is a biological product, it may get contaminated. Microbiological testing is the final step to determine microbial contamination of DHM. However, a universal method for the microbiological analysis of DHM in breast milk banks globally is lacking.DHM without strict screening may become a potential carrier of pathogens and seriously threaten the health of infants. Clostridium perfringens, a gram-positive anaerobic bacterium, is capable of causing wound infections, including gas gangrene, enteritis/enterocolitis, and enterotoxemia. Here, the first case of C. perfringens detected in DHM has been reported to facilitate the identification of such contamination in breast milk banks.Case presentationA breastfeeding mother donated 3000 mL of milk to the breast milk bank of the First Affiliated Hospital of the Army Medical University(over 2900 beds and patient receiving capacity of over 132,000), Chongqing, China. The milk sample was subjected to microbiological screening using liquid enrichment, followed by anaerobic and aerobic culturing. The results revealed the growth of C. perfringens in the anaerobic culture medium, but no bacteria or yeast-like fungi were observed in the aerobic culture medium. The donor did not exhibit any clinical symptoms, and her routine blood results and body temperature were normal. However, the infant fed with her milk had recurrent bloody stools. Breast milk bank infection control emergency handling as well as environmental sampling and investigation revealed that the cause was contamination of the donor’s home-use breast pump with C. perfringens. The infant no longer experienced bloody stool once the donor changed the breast pump.ConclusionsC. perfringens can enter breast milk from contaminated pumping environments or devices, thus causing illness in infants. The microbiological testing of DHM in breast milk banks can be accomplished using liquid enrichment, along with anaerobic and aerobic culture, which is of immense significance in improving the standards for microbiological screening, DHM safety, and infant health.

Accumulation characteristics of metals in human breast milk and association with dietary intake in northeastern China

The trace elements present in breast milk play a vital role in the growth and development of infants. Nevertheless, numerous studies have reported the presence of toxic metal contamination in breast milk from various countries and regions, which poses potential risks to breastfed infants. This article aimed to investigate the characteristics of trace elements in breast milk and explore the relationship between breast milk and diet in Dalian, a coastal city in northeastern China. Breast milk samples and representative local food samples were collected from Dalian for research. The results revealed that 57 % of breast milk samples significantly exceeded the WHO safety limit (0.6 μg/L) for arsenic, with a measured mean value of 0.96 μg/L. Moreover, the levels of chromium (mean value: 2.63 μg/L) in 34 % of breast milk samples exceed the WHO recommended safety level (chromium: 1.5 μg/L). Aquatic foods accounted for 60 % to 90 % of the total intake of arsenic, cadmium, vanadium, mercury, and lead. The Spearman correlation analysis demonstrated strong positive correlations among breast milk metal elements, including copper-zinc (r = 0.68) and nickel‑chromium (r = 0.89). Furthermore, the food-to-milk accumulation factors (FMAF) of strontium, nickel, arsenic, vanadium, cadmium, and mercury were relatively low (median values <0.005). While the FMAF values for chromium and lead were higher, with median values of 0.038 and 0.07, respectively. The results indicated potential risks of the toxic metal arsenic in breast milk from Dalian, China for breastfed infants. Therefore, continuous monitoring of breast milk for toxic metals and foodborne contamination is necessary.