Possible Sources Of Contamination Research Articles

Interventions Implemented to Remediate Mold Identified in Neonatal Intensive Care Unit (NICU) Incubators, 2022-2023

IntroductionNeonatal Intensive Care Units (NICUs) utilize incubators to sustain core temperatures associated with transepidermial water loss. High relative humidity in incubators provide an environment for fungi to grow. In August 2022, mold was identified growing in eleven (85%) NICU incubators. MethodsA team assembled to address mold in incubators. The environment was addressed as a possible source of contamination by consulting an environmental specialist. The air handler, ducts, and environment were terminally cleaned. Specimens were collected from the contaminated incubators and the manufacturer reviewed cleaning practices. Experimental trials were conducted using the incubators to replicate mold growth after interventions. ResultsThe environmental consultant approved when the space could be reoccupied. Incubators introduced to the clean environment did not grow mold. Various fungi and/or yeast were identified in the contaminated incubators. Opportunities to improve cleaning and replacement of parts were identified by the manufacturer. September 2022-February 2023, seven experimental trials were completed after cleaning the incubators. Four (36%) of the eleven contaminated incubators were placed back in use due to no fungal growth. No patient illnesses occurred. ConclusionThe interventions implemented stopped ongoing contamination of incubators and use of previously contaminated incubators.

Chemical profiling of paper recycling grades using GC-MS and LC-MS: An exploration of contaminants and their possible sources

Paper packaging made with recycled paperboard is used to pack various consumer goods that can include amongst others, electronics, toys, food, cosmetics, and stationery. Chemical profiling of the various paper recycling grades used in the manufacture of recycled paperboard was undertaken to investigate possible sources of contaminants and their propagation in the paper recycling chain. Pre-consumer, retail and post-consumer paper-based materials were collected at papermills, corrugators, grocery stores, household waste, solid waste disposal sites and recycling facilities. In the GC-MS analysis, phthalates, long-chain aliphatic compounds, and fatty acids were the most commonly detected compounds whilst phthalates and bisphenols featured most prevalently in the LC-MS analysis. The factors that were identified as likely contributors to the detection of the different chemical compounds included the presence of wood derivatives, the use of certain chemical additives during manufacturing, and exposure of paper to contaminants from consumers, other goods and the environment. Waste mingling, recovery, sorting and reprocessing into recycled paper were also shown to influence the chemical profile of paper materials. Sparse partial least squares-discriminate analysis indicated that newspaper and office paper had unique chemical constituents, whilst cartons were shown to have higher variability. By looking at key stages of paper recycling, this study showed that the possible persistence and transformation of chemical compounds in additives must be evaluated when considering the recyclability of paper-based materials. Further, it highlighted that different separation approaches may be required to reduce contaminant exposure opportunities in post-consumer paper materials.

Assessment of Heavy Metal Contamination of Groundwater in Rural Areas of Duhok City, Iraq

This study investigates the quality of groundwater sources in the rural areas of Duhok City, Iraq, with a particular focus on heavy metal contamination, chemical composition, and properties of water. Water samples from 14 wells, serving as the main water source for the surrounding areas, were collected and analyzed. Water quality parameters including calcium (Ca²⁺), magnesium (Mg²⁺), chloride (Cl⁻), potassium (K⁺), and sulfate (SO₄²⁻) values ranged from 24 to 105.6 mg/L, 6.832 to 50.752 mg/L, 18 to 34 mg/L, 1 to 7 mg/L, and 3.4 to 38 mg/L respectively. Common heavy metals like manganese (Mn), lead (Pb), copper (Cu), and cobalt (Co) exhibited varying concentrations. Most parameters meet the WHO standards, except for the elevated potassium in one sample, requiring attention. Additionally, 50% of the sampled wells showed elevated cadmium (Cd) levels. Possible sources of contamination include industrial activities, agricultural runoff, and geological factors, highlighting the importance of ongoing monitoring and targeted interventions to ensure access to clean and safe water.

Investigation of the Effectiveness of Barrier Layers to Inhibit Mutagenic Effects of Recycled LDPE Films, Using a Miniaturized Ames Test and GC-MS Analysis

To fulfil the European Green Deal targets and implement a circular economy, there is an urgent need to increase recycling rates of packaging materials. However, before recycled materials can be used in food contact applications, they must meet high safety standards. According to the European Food Safety Authority (EFSA), a worst-case scenario must be applied and unknown substances must be evaluated as being potentially genotoxic. The Ames test, which detects direct DNA-reactive effects, together with chromatographic analysis is very promising to complement risk assessment. This study aims to evaluate the effectiveness of functional barriers in ten different samples, including virgin and recycled LDPE foils. FT-IR analysis did not show major differences between virgin and recycled films. Light microscopy revealed differences in quality and an increased number of particles. GC-MS analysis detected and quantified 35 substances, including eight unknowns. Using a miniaturized version of the Ames test, four of ten samples tested positive in two individual migrates up to a dilution of 12.5%. All virgin LDPE materials tested negative; however, recycled material F showed an increased mutagenic activity, with an n-fold induction up to 28. Samples with functional barriers lowered migration and reduced mutagenicity. Nonetheless, further investigations are needed to identify possible sources of contamination.

SEPARACIÓN DE PARTÍCULAS INCLUIDAS EN HIELOS NATURALES PORSUBLIMACIÓN ADAPTADA

Non-soluble particles trapped in natural ice (glaciers, permafrost, hail) provide valuable information about the environments in which they were formed. The extraction of the particles is usually carried out through the melting of ice and subsequent filtering of the water obtained. Here, a novel methodology for extracting ice particles from the solid phase is presented, which is efficient, low cost in infrastructure, and minimizes possible sources of contamination. This methodology of adapted sublimation particle separation allows to determine the spatial distribution and concentration of non-soluble particles, as well as their sizes (without the limitations of filtration), their shape, structure and elementalchemical composition. The method is in this case applied to hail collected during the program COSECHEROS, which has a medium-sized particle of 40μm at its center.

Comparative analysis of the effects of different purification methods on the yield and purity of cow milk extracellular vesicles

AbstractIsolation of extracellular vesicles (EV) has been developing rapidly in parallel with the interest in EVs. However, commonly utilized protocols may not suit more challenging sample matrixes and could potentially yield suboptimal results. Knowing and assessing the pitfalls of isolation procedure to be used, should be involved to some extent for EV analytics. EVs in cow milk are of great interest due to their abundancy and large‐scale availability as well as their cross‐species bioavailability and possible use as drug carriers. However, the characteristics of milk EVs overlap with those of other milk components. This makes it difficult to isolate and study EVs individually. There exists also a lack of consensus for isolation methods. In this study, we demonstrated the differences between various differential centrifugation‐based approaches for isolation of large quantities of EVs from cow milk. Samples were further purified with gradient centrifugation and size exclusion chromatography (SEC) and differences were analyzed. Quality measurements were conducted on multiple independent platforms. Particle analysis, electron microscopy and RNA analysis were used, to comprehensively characterize the isolated samples and to identify the limitations and possible sources of contamination in the EV isolation protocols. Vesicle concentration to protein ratio and RNA to protein ratios were observed to increase as samples were purified, suggesting co‐isolation with major milk proteins in direct differential centrifugation protocols. We demonstrated a novel size assessment of vesicles using a particle mobility analyzer that matched the sizing using electron microscopy in contrast to commonly utilized nanoparticle tracking analysis. Based on the standards of the International Society for Extracellular Vesicles and the quick checklist of EV‐Track.org for EV isolation, we emphasize the need for complete characterization and validation of the isolation protocol with all EV‐related work to ensure the accuracy of results and allow further analytics and experiments.

Mycoplasmas detection in milk samples ¿are the techniques reliable?

Food microbiology is an important aspect that must be considered during food manufacturing, which is, considering the possible sources of contamination, including operators. Highlighting that the group of mycoplasmas are little studied and therefore their presence in foods is not considered. Different mollicutes, particularly mycoplasmas, have been associated with economic losses in the poultry and dairy industries. The objective of this work was to determine the presence of the mycoplasma genus in milk samples through specific microbiological culture and to complement the diagnosis with the PCR technique. Two hundred milk samples were analyzed in Puebla city-Mexico. The samples obtained were centrifuge and reseeded in triplicate on SP4 agar, incubating and analyzed by stereoscopic microscopy. From each milk sample, DNA extraction was carried out with Zymo Research Quick-DNA™ Mini prep kit and primers AR1 and AR2 were used. The microbiological study showed positivity for mycoplasmas of 17% and 39%, in the liquid and solid phase, respectively. With the PCR technique, 53% positivity for mycoplasmas was obtained, which allows us to consider the presence of factors associated with samples of animal origin and that may be interfering with the sensitivity of the technique. Analyzing the viability of techniques to detect microorganisms, particularly mycoplasma, in foods is a practice that is recommended for the well-being of consumers.

Multiple potentially toxic elements in urban gardens from a Brazilian industrialized city.

Urban agriculture should be promoted as long as the food produced is safe for consumption. Located in the metropolitan region of São Paulo-Brazil, Santo André has intense industrial activities and more recently an increasing stimulus to urban gardening. One of the potential risks associated to this activity is the presence of potentially toxic elements (PTEs). In this study, the concentration of PTEs (As, Ba, Cd, Co, Cu, Cr, Ni, Mo, Pb, Sb, Se, V and Zn) was evaluated by soil (n = 85) and soil amendments (n = 19) in urban gardens from this municipality. Only barium was above regulatory limits in agricultural soil ranging from 20 to 112mgkg-1. Geochemical indexes (Igeo, Cf and Er) revealed moderate to severe pollution for As, Ba, Cr, Cu, Pb Se and Zn, especialy in Capuava petrochemical complex gardens. A multivariate statistical approach discriminated Capuava gardens from the others and correlated As, Cr and V as main factors of pollution. However, carcinogenic and non-carcinogenic risks were below the acceptable range for regulatory purposes of 10-6-10-4 for adults. Soil amendments were identified as a possible source of contamination for Ba, Zn and Pb which ranged from 37 to 4137mgkg-1, 20 to 701mgkg-1 and 0.7 to 73mgkg-1, respectively. The results also indicated the presence of six pathogenic bacteria in these amendments. Besides that, the occurrence of antimicrobial resistance for Shigella, Enterobacter and Citrobacter isolates suggests that soil management practices improvement is necessary.

Evaluating groundwater contamination: An examination of a municipal solid waste dump yard in southern India's Manchester City

Groundwater is a critical resource that is utilized for a variety of reasons, but over-extraction can lead to a number of environmental and socioeconomic issues such as diminished water supply, land subsidence, and pollution. To manage groundwater resources in a sustainable manner, proper monitoring, regulation, and conservation strategies are required. Groundwater contamination in India is growing as a result of population increase and industrialisation, which can have serious health and environmental consequences. To avoid groundwater pollution, it is critical to monitor and control possible sources of contamination, as well as to promote sustainable farming practices and the use of less hazardous pesticides and fertilizers. To get a better knowledge of groundwater pollution, the current study attempted to analyse the quality of groundwater in the neighbourhood of the Vellalore dump yard (located in Coimbatore, India), encompassing an area of 161.87 hectares. To examine the quality of groundwater in the contaminated region, several physical and chemical properties such as pH, dissolved oxygen, total dissolved solids, and water quality index were measured. The majority of the water samples from the region are classed as low quality and unsafe for drinking. The plume appears to be migrating northerly and northwest from the landfill location, most likely due to the natural slope of the dump site towards the northwestern direction. The bulk of the gathered samples have low water quality, making the water unfit for even basic residential use. These findings highlight the need of local governments taking proactive efforts to protect the groundwater in this area, pushing for a comprehensive approach to prevent additional pollution. The report emphasizes the critical need for local governments to take prompt action to prevent additional groundwater pollution by establishing a comprehensive strategy.

Soil Contamination by Metals/Metalloids around an Industrial Region and Associated Human Health Risk Assessment

Industrial, agricultural, transportation, and waste management activities cause soil contamination by metals/metalloids. Soil contamination is an essential global concern since it poses a significant risk to human health. Particularly in areas near heavy industry, people are more prone to exposure. This study aims to determine current metal/metalloid contamination levels in soil from Aliağa industrial region and assess associated health risks. Five surface soil samples were collected from the region, representing residential, agricultural areas, and downwind of possible sources. Pollution indices were calculated to determine the metal(loid)s with anthropogenic inputs, and a human health risk assessment was conducted. As a result, significant to extreme enrichment of arsenic (As), moderate to significant enrichment of zinc (Zn) and manganese (Mn), and very high enrichment of lead (Pb) and cadmium (Cd) were observed in soil samples. Possible sources of contamination were iron and steel facilities with electric arc furnaces and oil combustion. Non-carcinogenic risk assessment revealed acceptable risks of exposure to Aliağa soils, while exposure scenarios had a great impact on estimated risks. Arsenic, chromium (Cr), and Pb appeared to be significant contributors to non-carcinogenic risk. Carcinogenic risks associated with exposure to As, Pb, Cr, cobalt (Co), and Cd in soils were evaluated to be at an acceptable level. This study only considered soil exposure pathways; hence, a comprehensive risk assessment is deemed necessary not to underestimate the risk of living around an industrial region. Nevertheless, the study provided crucial information for the current hot spots for metal(loid)s in the region and human exposure level.

Compositional data analysis of heavy metal contamination and eco-environmental risks in Himalayan agricultural soils, northern Pakistan

The importance of soil as a critical environmental medium cannot be overstated, as it provides various ecosystem services while supporting agricultural activities. Regrettably, soil contamination can impair the utility of these services and productivity in agriculture, and may even create several health hazards. Therefore, this study aimed to envisage the levels of heavy metals (HM) contamination in agricultural soils and identify the possible sources of contamination. A total of 54 soil samples from the designated area were obtained and subjected to analysis for the presence of nine HM, i.e., Ni, Cd, Cr, Co, Fe, Mn, Cu, Zn, and Pb, using atomic absorption spectrometry. This study used several single and multi-parameter indices for pollution and ecological risk evaluation. Compositional data analysis (CoDa) was used to assess the associations and potential sources of the HM. The findings revealed that Fe demonstrated the highest concentration among the studied HM, while Cd exhibited the lowest. The ecological risks were primarily attributed to Mn and Cd, with a considerable (40%) number of samples indicating high ecological risks. Based on contamination indices, Cd was identified as the study area's primary concern for soil pollution. Nevertheless, the PLI and modified degree of contamination (mCdeg) values exhibited a minimal inclusive effect of HM on soil. Furthermore, it was determined that the source of origin for all HM except Cd and Pb was geogenic. The soils in the area are under lesser human influence and mostly suggest a natural state. However, the contamination risk posed by Cd and the ecological risk posed by Cd and Mn raise concerns. A comprehensive evaluation of the contamination status and the risks was obtained using multiple indices. This study highlights the need for monitoring and managing HM contamination and mitigating the potential risks from Cd and Mn contamination in the area.

Quantification of Microplastics in Plastic-Bottled Chinese Baijiu Using Micro-FTIR in Imaging Mode

Microplastics (MPs) are prevalent in our environment, being present in the air we breathe and in the food we consume. Due to the widespread use of plastic materials in everyday life, the amount of microplastics being released into the biosphere has become increasingly apparent in recent years. This study provides the first documentation of the presence of microplastics in Chinese baijiu, a popular alcoholic beverage in China, bottled in plastic. It is essential to note the significance of this discovery and potential implications for human health. Analysis of samples collected from the Chinese market showed the presence of microplastics in all six Chinese baijiu brands tested. Concentrations ranged from 172 MPs/500 mL to 944 MPs/500 mL with an average concentration of 436 MPs/500 mL. Cellulose and PA accounted for 70.4% and 17.8% of all microplastics detected, respectively. These were the most commonly detected types. Other types of microplastics were also found, including PET, PP, PVC, and PE. PET accounted for 2.7%, PP for 2.2%, PVC for 1.2%, and PE for 0.1% of all microplastics. The possible sources of contamination include raw materials, ambient air, and equipment and vessels that shed microplastics. Therefore, this study emphasizes the requirement for further research to mitigate the potential hazards associated with human exposure to microplastics. Additionally, it presents significant findings on the presence of microplastics in Chinese baijiu sold in plastic bottles.

Evaluation of Hygienic Practices and Microbiological Quality of Street Vended Fruit Salads in Morogoro, Tanzania

Street vended foods have gained popularity due to economic benefits. However, they have been recognized as a potential hazard to public health as a result of poor hygienic practices. The study was conducted to assess the hygienic practices and microbiological quality of street vended fruit salads vended in Morogoro Municipal, Tanzania. A total of 30 respondents were involved in the study to assess of quality of fruit salad vended by town street vendors (TSV), University cafeterias (UCV), and town restaurants vendors (TRV). The findings revealed that most vendors (86.3%) were unaware of food safety, 73.3% were unaware of food safety standards and laws, and every seller evaluated was unaware of food safety initiatives such as Good Manufacturing Practices (GMP) and Good Hygienic Practices (GHP) and had never implemented any of them. All vendors saw the doctor only when they were ill. Nevertheless, none of vendor had a quality registration certificate or had undergone training in food safety and hygiene. Most of the salad preparation settings (46.7%) did not adhere to the fundamental requirements of a food preparation facility, and the vending facilities were in disrepair. Piles of dirty were observed in the food salad preparation and vending premises and 80% of the vendors used uncovered waste bins that were observed to encourage pests such as flies and cockroaches in the premises. The total aerobic count (TAC) ranged from 3.92±0.31 to 4.29±0.21 log CFU/g. All fruit salad samples were contaminated with coliforms and the level of coliform count exceeded 1.4×104 MPN/g in fruit salad samples indicating poor hygiene and fecal contamination. Possible sources of contamination were found to be water quality, cross-contamination, food handling and preparation equipment, and environmental factors such as dust, pests, and air quality. According to the study's findings, the majority of fruit salad sellers in the study area did not adhere to hygienic practices, and the made fruit salads were of poor microbiological quality, putting consumers at risk for food safety.

Molecular Detection and Prevalence of Toxoplasma gondii in Ready-to-eat Vegetables and Oysters in Central Luzon, Philippines

Toxoplasmosis, a parasitic infection caused by T. gondii, may be considered as a neglected disease in the Philippines. Consumption of raw or undercooked cyst-containing meat and accidental ingestion of oocysts excreted in the environment are two of the main routes in acquiring the infection. In the Philippines, there is no comprehensive or updated information on the prevalence of T. gondii among human populations and as a food-borne pathogen. We detected T. gondii DNA in ready-to-eat (RTE) vegetables and oysters sold in markets in Central Luzon, Philippines using molecular method. Six (10%) out of the 60 collected vegetable samples tested positive through nested PCR amplification of B1 gene. As for the oyster samples, four (9.09%) out of the 44 collected pooled samples were positive for T. gondii. Phylogenetic analyses revealed all the DNA sequences retrieved from positive samples clustered with T. gondii with a virulent Type 1 genotype (accession no: KX270388). Further studies should be done to identify the exact genotypic profiles of the T. gondii detected in the vegetable and oyster samples to infer pathogenicity and possible sources of contamination. Our findings suggest possible transmission patterns of T. gondii oocysts as a potential health threat to consumers.

Mapping the impacts of the anthropogenic activities and seawater intrusion on the shallow coastal aquifer of Port Said, Egypt

The quality and quantity of groundwater resources have been continuously deteriorating as a result of anthropogenic activities and their excessive usage. This has intensified seawater intrusion, particularly in the coastal area of Egypt. The management of this issue and preventing ongoing groundwater contamination are crucial responsibilities. Thus, an integrated strategy using remote sensing, geophysical technique, and hydrogeochemical analysis is used in this work to identify the causes of degradation and evaluate their impacts on the groundwater quality in East Port Said, Egypt. The following points were identified: 1) Remote sensing analysis between 1984 and 2015 showed an increase in anthropogenic activities, such as the construction of fish farms and vegetation, which became their areas of 12.5 and 37.8 km2 respectively. 2) Field observations demonstrated that the groundwater resources are being overexploited and it is expected that these human activities could have an impact on the groundwater quality. 3) The results of the resistivity approach indicated that sand and clay constitute the underlying layers and the shallow subsurface strata contain a high concentration of saline water. As a result, the aquifer is vulnerable to seawater intrusion due to its homogeneity. 4) Nineteen samples of groundwater were collected from the shallow Quaternary aquifer and the hydrochemical characteristic of the samples was identified. The hydrochemical analysis showed that the groundwater across the research area is of the Na-Cl water type and is highly saline (from 7,558 to 23,218 mg/L). By integrating the aforementioned techniques, it is evident that the research region is affected by anthropogenic activities as well as seawater intrusion on groundwater quality. These results serve as a solid base for further research on groundwater-surface water interactions and the evaluation of possible sources of contamination in the shallow aquifers under stress from anthropogenic activity in such environments.

Groundwater quality assessment in the alluvial region of upper yamuna basin, India

The study is undertaken to assess the groundwater quality in the alluvial region of the Yamuna basin, mainly comprising unconsolidated sand, silt and clays. A total of 14 and 13 water samples were collected in pre- and post-monsoon seasons, respectively, from handpumps, tubewells, ponds and irrigated fields to assess the water quality for human consumption and identify possible sources of contaminants in water. According to the Gibbs diagram, the ionic composition of water is mainly dominated by the rock weathering processes. The major hydrochemical facies is Ca–Mg–HCO3 type. The scatter plots between Ca+Mg:SO4+HCO3 and Na:Cl indicate the occurrence of silicate weathering which is supported by HCO3/HCO3+SO4 ratio <1. Manganese (Mn) concentration in 57% and 54% water samples in pre- and post-monsoon season exceeds the permissible limit i.e. 0.3 mg/L. Further, high iron (Fe) concentration (up to 33.5 mg/L) is also detected mainly in the shallow groundwater. The presence of higher Mn and Fe concentrations in the water samples is generally associated with the regions having low or negative redox values. Additionally, their positive correlation with sulphate and chloride ions indicates their occurrence as sulfates and chlorides. The results signify the role of regional geology in the presence of these ions in water along with the secondary influence of agricultural and anthropogenic activities (human and animal waste) on the quality of shallow groundwater. The Water Quality Index varies greatly, from excellent to unsuitable category in both seasons mainly due to the presence of high Fe and Mn content in shallow handpumps, village pond and a few tubewells located in the agricultural fields. Leaching of fertilizers and fungicides in the agricultural fields may further contribute in deteriorating shallow groundwater quality.

Use of X-Ray Photoelectron Spectroscopy as an analytical tool for the study of contamination by Teflon in the synthesis of Mo(VI)Cl2O2Bipy/TiO2 catalysts

The preparation of catalysts can involve various sources of contamination, which can seriously affect the quality of the prepared materials. In the present work, a case of fluorine contamination in a set of catalyst samples was studied, in which using the X-Ray Photoelectron Spectroscopy (XPS) technique, it was evidenced by the F 1s signal that this element was present in the form of Teflon, since its binding energy corresponded mainly to the CF2 species. Furthermore, using the C 1s signal, it was also possible to corroborate the presence of the CF2 group, which is associated with the main component of the Teflon carbon chains. The use of this information made it possible to identify that the solvent dehydration procedure (previous step to obtaining the catalysts) could lead to contamination with Teflon since it involved various accessories with Teflon, organic solvents and high temperature; the Teflon tape and the magnetic stirrer being the possible sources of contamination.

Determination of Hyaluronic Acid Dermal Filler Impurities Using SEM/EDS Analysis.

Although hyaluronic acid (HA) filler injections are associated with various non-vascular inflammatory complications, the underlying mode of action remains unclear. The hyaluronic acid filler may not be sufficiently pure, leading to an immune response. The present study attempted to identify any impurities in hyaluronic acid fillers available on the market. Particles were counted after degrading hyaluronic acid filler with hyaluronidase. Particulate matter was subsequently observed using scanning electron microscopy, and the particle components were evaluated using energy-dispersive X-ray spectroscopy. Different quantities of impurity particles (>10 and 25 μm) were detected microscopically. Silicon and aluminum isotopes were also detected. Hyaluronic acid fillers were contaminated with these particles. The degree of contamination varied substantially among the tested filler products. These contaminant particles may evoke reactions in the patient's body. Clinicians should be aware of this source of possible contamination and its effects.

Retrospective study on the prevalence of Yersinia enterocolitica in food collected in Umbria region (central Italy).

Yersinia enterocolitica represents one of the main foodborne pathogens in Europe and the evaluation of possible sources of contamination and its prevalence in food is of considerable interest for risk analysis approach. The results of the search for Yersinia enterocolitica in food samples taken in Umbria region (central Italy) were evaluated during the years 2015-2018. Different types of foods were considered, both ready-to-eat (meat products, dairy products, and raw vegetables) and meat preparations to be eaten after cooking. Samples were assayed by molecular screening for the species indicator gene ompF. Screening positives were subjected to isolation and characterization by searching for specific virulence marker genes, including the ail gene responsible for invasiveness and the ystB gene for the production of enterotoxin. The total prevalence of positive samples for Yersinia enterocolitica was 16.86% with a higher percentage of positive samples in meat preparations (19.35%), followed by ready-to-eat vegetables (11.76%). Poultry meat samples had a higher prevalence than pork and beef samples. Neither positive samples were found in meat products and dairy, nor seasonality in positivity was observed. All isolated strains of Yersinia enterocolitica were biotype 1A, with absence of the ail virulence gene but presence of ystB gene. Since the strains isolated from human patients appear to be primarily biotypes that possess the ail marker, future investigations would be needed regarding the real role of biotype 1A in human disease. In this context, attention should certainly be paid to ready-to-eat vegetables and to careful cooking of meat preparations.

Heat-resistant and biofilm-forming Escherichia coli in pasteurized milk from Brazil.

Escherichia coli harboring a transmissible locus of stress tolerance (tLST) and the ability to form biofilms represent a serious risk in dairy production. Thus, we aimed to evaluate the microbiological quality of pasteurized milk from two dairy producers in Mato Grosso, Brazil, with a focus on determining the possible presence of E. coli with heat resistance (60°C/6min), biofilm-forming potential phenotypes and genotypes, and antimicrobial susceptibility. For this, fifty pasteurized milk samples from producers named A and B were obtained for 5weeks to investigate the presence of Enterobacteriaceae members, coliforms, and E. coli. For heat resistance, E. coli isolates were exposed to a water bath at 60°C for 0 and 6min. In antibiogram analysis, eight antibiotics belonging to six antimicrobial classes were analyzed. The potential to form biofilms was quantified at 570nm, and curli expression by Congo Red was analyzed. To determine the genotypic profile, we performed PCR for the tLST and rpoS genes, and pulsed-field gel electrophoresis (PFGE) was used to investigate the clonal profile of the isolates. Thus, producer A presented unsatisfactory microbiological conditions regarding Enterobacteriaceae and coliforms for weeks 4 and 5, while all samples analyzed for producer B were contaminated at above-the-limit levels established by national and international legislation. These unsatisfactory conditions enabled us to isolate 31 E. coli from both producers (7 isolates from producer A and 24 isolates from producer B). In this way, 6 E. coli isolates (5 from producer A and 1 from producer B) were highly heat resistant. However, although only 6 E. coli showed a highly heat-resistant profile, 97% (30/31) of all E. coli were tLST-positive. In contrast, all isolates were sensitive to all antimicrobials tested. In addition, moderate or weak biofilm potential was verified in 51.6% (16/31), and the expression of curli and presence of rpoS was not always related to this biofilm potential. Therefore, the results emphasize the spreading of heat-resistant E. coli with tLST in both producers and indicate the biofilm as a possible source of contamination during milk pasteurization. However, the possibility of E. coli producing biofilm and surviving pasteurization temperatures cannot be ruled out, and this should be investigated.