Roughness Evolution Induced by Third-Body Wear.

Surface roughness is a key factor when it comes to friction and wear, as well as to other physical properties. These phenomena are controlled by mechanisms acting at small scales, in which the topography of apparently flat surfaces is revealed. Roughness in natural surfaces has been reported to conform to self-affine statistics in a wide variety of settings (ranging from earthquake physics to micro-electro-mechanical devices), meaning that the height profile can be described using a spectrum where the amplitude is proportional to its wavelength raised to a constant power, which is related to a statistical parameter named Hurst exponent. We analyze the roughness evolution in atomistic surfaces during molecular dynamics simulations of wear. Both pairs of initially flat and initially rough surfaces in contact are worn by a third body formed by particles trapped between them during relative sliding. During the first sliding stages, the particles trapped between the first bodies scratch the surfaces. Once the former becomes coated with atoms from the latter, the wear process slows down and becomes "adhesive like." The initial particle sizes are consistent with the minimum size to be expected for the debris, but tend to grow by material removal from the surfaces and to agglomerate. We show that, for the particular configurations under consideration, the surface roughness seems to converge to a steady state characterized by Hurst exponent close to 0.8, independently of the initial conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s11249-024-01833-9.

[The pathogenicity of Cronobacter in the light of bacterial genomics]. / La patogenicidad de Cronobacter a la luz de la genómica bacteriana.

Introduction: Cronobacter spp. is a genus of Gram-negative bacteria belonging to the family Enterobacteriaceae. Species of the genus Cronobacter, particularly C. sakazakii, are implicated in the development of severe disease in newborns, which occurs with necrotizing enterocolitis, sepsis and meningitis. The disease has been frequently associated with powdered infant formula (PIF) and can therefore occur in the form of outbreaks. The genus Cronobacter has undergone extensive diversification in the course of its evolution, with some species being clearly pathogenic to humans while the impact of other species on human health is uncertain or unknown. Whole genome sequencing is used both in population genetic studies to identify the limited number of genotypes associated with the disease and to detect genes associated with antibiotic resistance or virulence, ultimately allowing more precise epidemiological links to be established between pediatric disease and infant foods.

Introducción: Cronobacter es un género de bacterias gramnegativas perteneciente a la familia Enterobacteriaceae. Algunas especies del género Cronobacter, en particular C. sakazakii, están implicadas en el desarrollo de infecciones neonatales graves, incluyendo meningitis, sepsis y enterocolitis necrotizante. La enfermedad se ha relacionado frecuentemente con los preparados en polvo para lactantes (PPL) y se puede presentar, por tanto, en forma de brotes. El género Cronobacter ha experimentado una amplia diversificación en el curso de su evolución, siendo algunas especies claramente patógenas para los humanos mientras que el impacto de otras especies sobre la salud humana es incierto o desconocido. La secuenciación genómica se utiliza en los estudios de genética de poblaciones tanto para identificar el limitado número de genotipos asociados a la enfermedad como para detectar los genes asociados a la virulencia, la adaptación al estrés o la resistencia a antibióticos, lo que permite, en definitiva, establecer vínculos epidemiológicos más precisos entre la enfermedad pediátrica y los alimentos infantiles.

Prevalence and Population Diversity of Listeria monocytogenes Isolated from Dairy Cattle Farms in the Cantabria Region of Spain.

Listeria monocytogenes is an opportunistic pathogen that is widely distributed in the environment. Here we show the prevalence and transmission of L. monocytogenes in dairy farms in the Cantabria region, on the northern coast of Spain. A total of 424 samples was collected from 14 dairy farms (5 organic and 9 conventional) and 211 L. monocytogenes isolates were recovered following conventional microbiological methods. There were no statistically significant differences in antimicrobial resistance ratios between organic and conventional farms. A clonal relationship among the isolates was assessed by pulsed field gel electrophoresis (PFGE) analysis and 64 different pulsotypes were obtained. Most isolates (89%, n = 187) were classified as PCR serogroup IVb by using a multiplex PCR assay. In this case, 45 isolates of PCR serogroup IVb were whole genome-sequenced to perform a further analysis at genomic level. In silico MLST analysis showed the presence of 12 sequence types (ST), of which ST1, ST54 and ST666 were the most common. Our data indicate that the environment of cattle farms retains a high incidence of L. monocytogenes, including subtypes involved in human listeriosis reports and outbreaks. This pathogen is shed in the feces and could easily colonize dairy products, as a result of fecal contamination. Effective herd and manure management are needed in order to prevent possible outbreaks.

Lactobacillus plantarum in Dual-Species Biofilms With Listeria monocytogenes Enhanced the Anti-Listeria Activity of a Commercial Disinfectant Based on Hydrogen Peroxide and Peracetic Acid.

The aim of this work was to investigate the effect of dual-species biofilms of Listeria monocytogenes with Lactobacillus plantarum on the anti-Listeria activity of a hydrogen peroxide/peracetic acid based commercial disinfectant (P3, Oxonia) when using conditions approaching the food industry environment. Nine strains of L. monocytogenes, including eight persistent strains collected from the meat industry and one laboratory control strain, were used in mono and in dual-species biofilms with a strain of L. plantarum. Biofilms were produced on stainless steel coupons (SSCs), at 11°C (low temperature) or at 25°C (control temperature), in TSB-YE (control rich medium) or in 1/10 diluted TSB-YE (mimicking the situation of biofilm formation after a deficient industrial cleaning procedure). The biofilm forming ability of the strains was evaluated by enumeration of viable cells, and the antibiofilm activity of P3 was assessed by the log reduction of viable cells on SSC. In both nutrient conditions and at low temperature, there was no significant difference (p > 0.05) between L. monocytogenes biofilm forming ability in mono- and in dual-species biofilms. In dual-species biofilms, L. monocytogenes was the dominant species. However, it was generally more susceptible to the lower concentration of P3 0.5% (v/v) than in pure culture biofilms. The presence of L. plantarum, although without significant interference in the number of viable cells of L. monocytogenes, enhanced the efficacy of the anti-Listeria activity of P3, since dual-species biofilms were easier to control. The results presented here reinforce the importance of the investigation into co-culture biofilms produced in food industry conditions, namely at low temperatures, when susceptibility to sanitizers is being assessed.

Analysis of Benzalkonium Chloride Resistance and Potential Virulence of Listeria monocytogenes Isolates Obtained from Different Stages of a Poultry Production Chain in Spain.

ABSTRACT: Listeria monocytogenes can survive in food production facilities and can be transmitted via contamination of food during the various stages of food production. This study was conducted to compile the results of three independent previous studies on the genetic diversity of L. monocytogenes in a poultry production company in Spain and to determine the potential virulence and sanitizer resistance of the strains by using both genotype and phenotype analyses. L. monocytogenes was detected at three production stages: a broiler abattoir, a processing plant, and retail stores marketing fresh poultry products from the same company. These three stages spanned three locations in three provinces of Spain. A set of 347 L. monocytogenes isolates representing 39 subtypes was obtained using pulsed-field gel electrophoresis (PFGE). A total of 28 subtypes (68%) had a full-length internalin A gene, and two subtypes had a phenotype with low potential for virulence because of a mutation in the prfA gene. A total of 32 subtypes (82%) were classified as benzalkonium chloride resistant (BAC-R) and contained the resistance determinant bcrABC (21 subtypes, 54%) or the resistance gene qacH (11 subtypes, 28%). A total of 13 persistent BAC-R subtypes (minimum of 3 months between the first and last sample from with the isolate was recovered) were identified at the abattoir and processing plant. The three production stages shared a unique subtype (PFGE type 1), which had the mutation in the prfA gene and the bcrABC resistance determinant. Whole genome sequencing revealed this subtype to be sequence type 31. Limited genetic diversity was noted in the isolates studied, including some subtypes that were persistent in the environment of the investigated facilities. Given the high prevalence of BAC-R subtypes, these results support the association between resistance to biocides and persistence of L. monocytogenes.

New insights to study the accumulation and erosion processes of fine-grained organic sediments in combined sewer systems from a laboratory scale model.

The deposition and resuspension of sediments are issues of considerable concern in combined sewer systems management. Sediments can produce the loss of hydraulic capacity and odour generation in sewers, and are also considered the main source of pollution due to their occasional uncontrolled discharges into the environment via Combined Sewer Overflows (CSO). Sewer sediments contain granular and cohesive organic fractions that can have a significant influence on bed resistance. In order to address the relationship between sewer sediment composition and its erodibility, accumulation and erosion experiments were performed in a flume test facility fed with wastewater. The flume was placed in a Wastewater Treatment Plant (WWTP), in which different circular pipe geometries were set. Wastewater flow inlet conditions and bed structures were monitored during the experiments. The photogrammetric technique Structure from Motion (SfM) was applied to record the bed deposit structures, providing accurate measurements of the accumulation rates. The SfM was also used to assess sediment transport and the characteristics of the bed forms after the erosion tests. In addition, velocity distributions and shear stress profiles were measured during the erosion tests to characterize flow resistance and sediment erosion. During both accumulation and erosion tests, sediments were sampled in order to analyse their physicochemical properties, thus highlighting the study of the biodegradability of the organic matter. Different deposition periods showed biological transformations in the bed deposit structure, which were seen to affect its cohesion, and in consequence, its erosion threshold. Tests with significant erosion rates agreed in broad terms with dimensionless sediment transport models derived from previous experimental studies performed with partly cohesive and organic materials in sewer pipes.

Hydraulic, wash-off and sediment transport experiments in a full-scale urban drainage physical model.

This paper presents a dataset obtained from hydraulic and sediment transport experiments performed in a full-scale urban drainage physical model of 36 m2. The study seeks to accurately measure sediment mobilization through the different parts of the model (surface, gully pots and pipe system), also obtaining a precise characterization of water flow and using realistic rainfall simulator to ensure the transferability of the results. Three different rain intensities and five sediment granulometries were tested in 6 hydraulic and 23 wash-off and sediment transport experiments. The following experimental data were produced: surface elevations and 2D runoff velocities measured by visualization techniques; surface and in-pipe water depths; flow discharges, total suspended solids concentrations and particle size distribution at the entrance of the gully pots and at the pipe system outlet; and sediment mass balances. This data is optimal for developing and validating wash-off and sediment transport formulations in urban drainage models, towards better treatment and management techniques for minimizing the impact of urban surface pollutants on the environments of towns and cities.

Inactivation of Listeria monocytogenes during dry-cured ham processing.

The effect of Serrano and Iberian dry-cured ham processing and ripening on Listeria monocytogenes inactivation at the surface of whole hams was investigated. Salted hams were surface inoculated (6.5 log CFU) with a cocktail of 4 L. monocytogenes strains isolated from environment and products of a meat industry. Serrano and Iberian hams were ripened for 16 and 24 months, respectively. A decrease of at least 4.6 log units on the surface of Serrano ham was recorded after 4 months for L. monocytogenes counts, which remained under the detection limit thereafter. L. monocytogenes declined by >5 log units on the surface of Iberian ham during the first 9 months and was not detected afterwards. The higher nitrite content of Serrano ham might have accelerated the decrease of the pathogen. This study validates the inactivation of L. monocytogenes on the surface of whole dry-hams during extended ripening.

Impacto socioeconómico del manejo actual de la pancreatitis aguda de origen biliar severa: estudio comparativo / Socioeconomic impact of the current management of severe biliary acute pancreatitis: comparative study

RESUMEN Objetivo La pancreatitis aguda de origen biliar es una patología gastrointestinal común, en donde el tratamiento oportuno es el pilar más importante a pesar de sus discrepancias. El objetivo del estudio es establecer el impacto socioeconómico en el manejo actual de esta patología, comparando dos hospitales de tercer nivel de estrato socioeconómico alto y bajo de la ciudad de Bogotá, Colombia. Materiales y Métodos Se realizó un estudio retrospectivo, comparativo de corte transversal entre enero de 2012 y diciembre de 2017, en dos hospitales de Bogotá D. C. Se evaluaron sus características socioeconómicas, género, tiempo de evolución al momento de la consulta, Marshall score, estancia en UCI, estancia hospitalaria, complicaciones, manejo quirúrgico y mortalidad. Resultados Se analizaron 101 pacientes de dos estratos socioeconómicos diferentes (alto y bajo). Se encontró que los pacientes de estrato bajo tienen un riesgo diez veces mayor de requerir un procedimiento quirúrgico. Asimismo, registraron una mayor mortalidad en comparación con pacientes de estrato alto (11,3% vs. 4,2%). También se evidenciaron más complicaciones en el grupo de nivel socioeconómico bajo con respecto al alto, como en la falla exocrina (81,1% vs. 31,3%) y el síndrome compartimental (35,8% vs. 4,2%). Conclusión Se encuentra mayor morbimortalidad en los pacientes de bajo nivel socioeconómico en el contexto de esta patología. Este estudio puede guiar a nuevas investigaciones acerca del impacto socioeconómico en los desenlaces de pancreatitis aguda severa.(AU)

ABSTRACT Objetive Acute pancreatitis of biliary origin is a common gastrointestinal pathology, in which timely management still is the most important. The aims of this research is establish the socioeconomic impact in the current management of severe acute pancreatitis of biliary origin comparing two centers of the third level, one of high socioeconomic population and another of low in Bogotá, Colombia. Materials and Methods A retrospective, cross-sectional comparative study was conducted between January 2012 and December 2017, in two hospitals of Bogotá DC. We evaluated their socioeconomic characteristics, gender, time of evolution at the time of consultation, Marshall score, ICU stay, hospital stay, complications, surgical management and mortality. Results 101 patients from two different socioeconomic strata (high and low) were analyzed, where a 10 times higher risk of requiring a surgical procedure in the group of patients with low stratum was found, as well as a higher mortality compared with those of high stratum. (11.3% Vs 4.2%). There were also more complications in the low socioeconomic group with respect to the high, as in the exocrine failure (81.1% vs 31.3%) and the compartment syndrome (35.8% vs 4.2%). Conclusion There is greater morbidity and mortality in patients of low socioeconomic status in the context of this pathology. This study can guide new research that increases the clarity of the socioeconomic impact on the outcomes of severe acute pancreatitis.(AU)

Whole-Genome Sequences of Seven Listeria monocytogenes Strains from Different Stages of a Poultry Meat Production Chain.

Here, we present the draft genome sequences of seven Listeria monocytogenes strains isolated during three independent studies carried out in three stages of a poultry meat production chain. The genome sequences of these strains obtained from different stages can help to understand the possible transmission of L. monocytogenes.

[Socioeconomic impact of the current management of severe biliary acute pancreatitis: comparative study]. / Impacto socioeconómico del manejo actual de la pancreatitis aguda de origen biliar severa: estudio comparativo.

OBJETIVE: Acute pancreatitis of biliary origin is a common gastrointestinal pathology, in which timely management still is the most important. The aims of this research is establish the socioeconomic impact in the current management of severe acute pancreatitis of biliary origin comparing two centers of the third level, one of high socioeconomic population and another of low in Bogotá, Colombia. MATERIALS AND METHODS: A retrospective, cross-sectional comparative study was conducted between January 2012 and December 2017, in two hospitals of Bogotá DC. We evaluated their socioeconomic characteristics, gender, time of evolution at the time of consultation, Marshall score, ICU stay, hospital stay, complications, surgical management and mortality. RESULTS: 101 patients from two different socioeconomic strata (high and low) were analyzed, where a 10 times higher risk of requiring a surgical procedure in the group of patients with low stratum was found, as well as a higher mortality compared with those of high stratum. (11.3% Vs 4.2%). There were also more complications in the low socioeconomic group with respect to the high, as in the exocrine failure (81.1% vs 31.3%) and the compartment syndrome (35.8% vs 4.2%). CONCLUSION: There is greater morbidity and mortality in patients of low socioeconomic status in the context of this pathology. This study can guide new research that increases the clarity of the socioeconomic impact on the outcomes of severe acute pancreatitis.

OBJETIVO: La pancreatitis aguda de origen biliar es una patología gastrointestinal común, en donde el tratamiento oportuno es el pilar más importante a pesar de sus discrepancias. El objetivo del estudio es establecer el impacto socioeconómico en el manejo actual de esta patología, comparando dos hospitales de tercer nivel de estrato socioeconómico alto y bajo de la ciudad de Bogotá, Colombia. MATERIALES Y MÉTODOS: Se realizó un estudio retrospectivo, comparativo de corte transversal entre enero de 2012 y diciembre de 2017, en dos hospitales de Bogotá D. C. Se evaluaron sus características socioeconómicas, género, tiempo de evolución al momento de la consulta, Marshall score, estancia en UCI, estancia hospitalaria, complicaciones, manejo quirúrgico y mortalidad. RESULTADOS: Se analizaron 101 pacientes de dos estratos socioeconómicos diferentes (alto y bajo). Se encontró que los pacientes de estrato bajo tienen un riesgo diez veces mayor de requerir un procedimiento quirúrgico. Asimismo, registraron una mayor mortalidad en comparación con pacientes de estrato alto (11,3% vs. 4,2%). También se evidenciaron más complicaciones en el grupo de nivel socioeconómico bajo con respecto al alto, como en la falla exocrina (81,1% vs. 31,3%) y el síndrome compartimental (35,8% vs. 4,2%). CONCLUSIÓN: Se encuentra mayor morbimortalidad en los pacientes de bajo nivel socioeconómico en el contexto de esta patología. Este estudio puede guiar a nuevas investigaciones acerca del impacto socioeconómico en los desenlaces de pancreatitis aguda severa.

Effect of Low Doses of Disinfectants on the Biofilm-Forming Ability of Listeria monocytogenes.

This study was intended to investigate the effect of contact with concentrations close to the minimum inhibitory concentration (MIC) (0.5, 1, and 1.5 MIC; MIC of planktonic cells was determined using a microdilution broth method) of sodium hypochlorite (SHY) or benzalkonium chloride (BZK) during the process of formation of biofilm (24 h), upon the architecture and viability of the biofilms formed by four L. monocytogenes isolates of molecular serotype 1/2a: S2-1 (BZK-susceptible strain; MICBZK = 3.0 ppm), S2-2 (BZK-resistant strain qacH positive; MICBZK = 13 ppm), CDL 69 (BZK-resistant strain bcrABC positive; MICBZK = 10 ppm), and S2BAC (BZK-resistant laboratory mutant of S2-1, with multidrug resistance phenotype; MICBZK = 9 ppm). Images were examined through confocal laser scanning microscopy after staining with SYTO 9 and Propidium Iodide. Biovolume values in the observation field (14,161 µm2) in the absence of biocides ranged from 103,928.3 ± 6,730.2 µm3 (S2BAC) to 276,030.9 ± 42,291.9 µm3 (S2-1). Exposure to SHY at 0.5 MIC reduced (p < 0.05) the biovolume of biofilms formed by S2-1 and S2BAC and did not modify (p > 0.05) the biovolume of biofilms by S2-2 and CDL 69. Exposure to sub-MICs of BZK decreased (p < 0.05; S2-1) or enhanced (p < 0.05; S2-2, CDL 69 and S2BAC) biofilm development. Exposure to biocides at 1 or 1.5 MIC inhibited biofilm formation. This study provides clear evidence that BZK at sub-MICs can enhance the biofilm-forming ability of BZK-resistant L. monocytogenes strains. Because biofilms contribute to the persistence of bacteria throughout the food chain and represent a major source of food contamination, our findings suggest the importance of avoiding sub-MICs of disinfectants in food-handling environments.

Experimental study of pollutant washoff on a full-scale street section physical model.

This study analyses the mobilization of total suspended solids (TSS) for different spatial distributions of sediment load located over the roadway surface of a full-scale street section physical model. At the sewer network outlet, flow discharges were measured and TSS pollutographs were determined with manual grab samples and inferred from turbidity records. In all the tests, the rain duration was 5 min and its averaged intensity was 101 mm/h. In addition, solids that were not washed off at the end of the experiments were collected from the street surface, gully pots and pipes and the mass balance error was checked. The experiments were configured to assess the influence of the initial load, spatial distribution method, distance from gully pot and distribution area dimensions on the TSS washoff. The study showed that sediment initial load and distribution cannot explain completely pollutant washoff processes because other variables such as the spatial rainfall distribution or the runoff depth also affect to the outlet pollutographs and system mass balances.

Monitoring accumulation sediment characteristics in full scale sewer physical model with urban wastewater.

A series of experiments were carried out with real wastewater in a pilot flume located at A Coruña wastewater treatment plant (WWTP) (Spain). A full scale model was developed to test a circular (300 mm inner diameter) and an equivalent area egg-shaped plastic pipe under controlled experimental conditions (pipe slope 2-5‰, averaged discharge Q = 4 L/s). Velocity profiles and sediment accumulation in the pipe invert was daily measured. Within the 7-11 days, the average sediment accumulation rate found in the circular pipe was between 1.4 and 3.8 mm/d. The sediment height depended on the input wastewater sediment distribution and organic content. The egg-shaped pipe presented no sediment deposit for the same downstream boundary conditions, although biofilms were attached to the walls of both pipes. Besides, wastewater quality was monitored continuously and sediment composition was studied at the end of experiments. Two types of sediment were recorded: a granular bed deposit (ρ = 1,460 kg/m3, d50 = 202 µm) and wall biofilms (ρ = 1,190 kg/m3, d50 = 76 µm).

A simplified method for determining potential heavy metal loads washed-off by stormwater runoff from road-deposited sediments.

A simplified method is proposed for determining the potential load of heavy metals (HMs) derived from the wash-off caused by surface runoff on road-deposited sediment (RDS). The method consists of three phases: (i) characterization of RDS load wash-off, (ii) assessment of HM load in dry weather, and (iii) application of a wash-off equation. Two processes were included in the wash-off equation: HM transport (solid fraction) and HM leaching (dissolved fraction). The average wash-off of HMs ranges from 16.6 to 46.3%, relative to the total mass of HMs associated with dry-weather RDS (Pb, Zn, Cu, Cr, Ni, Cd, Fe, Mn, Co, and Ba). Cd, Mn, and Zn presented the highest wash-off in the areas studied. The size fraction below 250µm contributed an average of 86.7% of potential HM load washed-off from RDS. Based on the phenomena included in the wash-off equation, it was observed the following order of precedence: transport of RDS<250µm, leaching of RDS<250µm, and leaching of RDS≥250µm. Solid and dissolved fractions contributed 70.7 and 29.3% of the potential HM load washed-off by runoff from RDS, respectively. The proposed method serves as a management tool for road HM pollution during rain.

Characterisation of sediments during transport of solids in circular sewer pipes.

This research is focused in the monitoring of sediments in circular sewer pipes with different diameters at a flume facility fed with urban wastewater. For this purpose, sediment physical and chemical characteristics, and sediment mobility were recorded. The Structure from Motion photogrammetric technique was used for the measurement of sediment bed evolution. In addition, sediment properties were determined in order to study the cohesiveness of the bed deposits. In particular, the chemical oxygen demand and the oxygen uptake rate of the sediment samples were analysed after different accumulation periods on the pipe inverts, resulting in a relation between these parameters and the mobility processes of solids.

Potential Impact of the Resistance to Quaternary Ammonium Disinfectants on the Persistence of Listeria monocytogenes in Food Processing Environments.

The persistence of certain strains of Listeria monocytogenes, even after the food processing environment has been cleaned and disinfected, suggests that this may be related to phenomena that reduce the concentration of the disinfectants to subinhibitory levels. This includes (i) the existence of environmental niches or reservoirs that are difficult for disinfectants to reach, (ii) microorganisms that form biofilms and create microenvironments in which adequate concentrations of disinfectants cannot be attained, and (iii) the acquisition of resistance mechanisms in L. monocytogenes, including those that lead to a reduction in the intracellular concentration of the disinfectants. The only available data with regard to the resistance of L. monocytogenes to disinfectants applied in food production environments refer to genotypic resistance to quaternary ammonium compounds (QACs). Although there are several well-characterized efflux pumps that confer resistance to QACs, it is a low-level resistance that does not generate resistance to QACs at the concentrations applied in the food industry. However, dilution in the environment and biodegradation result in QAC concentration gradients. As a result, the microorganisms are frequently exposed to subinhibitory concentrations of QACs. Therefore, the low-level resistance to QACs in L. monocytogenes may contribute to its environmental adaptation and persistence. In fact, in certain cases, the relationship between low-level resistance and the environmental persistence of L. monocytogenes in different food production chains has been previously established. The resistant strains would have survival advantages in these environments over sensitive strains, such as the ability to form biofilms in the presence of increased biocide concentrations.

The Connection between Persistent, Disinfectant-Resistant Listeria monocytogenes Strains from Two Geographically Separate Iberian Pork Processing Plants: Evidence from Comparative Genome Analysis.

The aim of this study was to investigate the basis of the putative persistence of Listeria monocytogenes in a new industrial facility dedicated to the processing of ready-to-eat (RTE) Iberian pork products. Quaternary ammonium compounds, which included benzalkonium chloride (BAC), were repeatedly used as surface disinfectants in the processing plant. Clean and disinfected surfaces were sampled to evaluate if resistance to disinfectants was associated with persistence. Of the 14 isolates obtained from product contact and non-product contact surfaces, only five different pulsed-field gel electrophoresis (PFGE) types were identified during the 27-month study period. Two of these PFGE types (S1 and S10-1) were previously identified to be persistent and BAC-resistant (BAC(r)) strains in a geographically separate slaughterhouse belonging to the same company. The remaining three PFGE types, which were first identified in this study, were also BAC(r). Whole-genome sequencing and in silico multilocus sequence typing (MLST) analysis of five BAC(r) isolates of the different PFGE types identified in this study showed that the isolate of the S1 PFGE type belonged to MLST sequence type 31 (ST31), a low-virulence type characterized by mutations in the inlA and prfA genes. The isolates of the remaining four PFGE types were found to belong to MLST ST121, a persistent type that has been isolated in several countries. The ST121 strains contained the BAC resistance transposon Tn6188. The disinfection-resistant L. monocytogenes population in this RTE pork product plant comprised two distinct genotypes with different multidrug resistance phenotypes. This work offers insight into the L. monocytogenes subtypes associated with persistence in food processing environments.

Perinatal infection and hypoxic-ischemic encephalopathy: a pilot study.

Recent studies suggest a synergic effect of infection and hypoxia-ischemia in the causation of perinatal brain damage. We conducted a prospective pilot study on the presence of infection in hypoxic-ischemic encephalopathy (HIE), focusing on neurotropic viruses. Sixteen newborns with HIE were included in the study. There were no confirmed cases of viral infection. There was a case of bacterial early onset sepsis and four cases of suspected sepsis due to clinical and/or analytical signs, but with negative cultures. Our results do not support universal screening for viral infection in cases of HIE.

Human parechovius and enterovirus in neonates: Distinct infections with overlapping features.

INTRODUCTION: Human parechoviruses (HPeVs) have recently been added to the family Picornaviridae, where Enteroviruses (HEV) belong. The specific characteristics of HPeV infection in the neonate are not clear, and their involvement in neonatal infection is believed to be largely underestimated. HPeV type 3 has been recently linked to sepsis-like illness and neurological involvement in the newborn. OBJECTIVE: To assess the involvement of HPeV in central nervous system (CNS) infections throughout the neonatal period in term newborns, describe their clinical, analytical and cerebrospinal fluid (CSF) characteristics, and compare them to HEV infections. METHODS: Term newborns admitted for neurological symptoms or a suspected infection, aged 0-30 days were prospectively recruited (September 2012-August 2014). Bacterial cultures were performed in all patients. Viral tests were performed in CSF including: RT-PCR for cytomegalovirus, Herpes simplex type 1 and 2, Epstein-Barr virus, HEV and HPeV. HEV and HPeV positive samples were genotyped. RESULTS: Fifty-seven newborns were diagnosed of sepsis-like illness and/or CNS alteration. HEV (8.7%) and HPeV-3 (3.5%) were the two most common viral agents involved during the study period. The most frequent symptom at admission was fever. Irritability was present in 1/2 of HPeV and 1/5 of HEV cases. There were no other neurological symptoms. Blood and CSF analysis were unremarkable in HPeV infections. All cases resolved favorably. CONCLUSIONS: HPeV infection was clinically very similar to that of HEV, while it featured normal blood and CSF analysis. PRACTICE IMPLICATIONS: HPeV should be considered by clinicians in the differential diagnosis of neonatal infection, particularly when blood and CSF analysis are unremarkable.