Transcriptome analysis of severely active chronic spontaneous urticaria shows an overall immunological skin involvement.

BACKGROUND: The knowledge about chronic spontaneous urticaria (CSU) phenotypes is based on its clinical characteristics, associated comorbidities, course of the disease, and its response to the available effective drugs. Genotype expression and its further correlation with CSU phenotypes are still unknown. We describe the cutaneous transcriptome of patients suffering a severely active CSU refractory to antihistamine treatment. METHODS: Through the bioinformatic analysis of the whole Human Genome with Oligo Microarrays and quantitative real-time polymerase chain reaction (qPCR), relevant genes expressed in nonlesional (NLS-CSU) and lesional skin (LS-CSU) and peripheral blood were identified in 20 patients suffering from severely active CSU and 10 healthy controls (HCs). RESULTS: From 39 genes differentially expressed in NLS-CSU when compared with HCs, 31 (79.48%) were confirmed by qPCR corresponding to genes involved in epidermal homeostasis and dermal repair. From the analysis comparing LS-CSU with NLS-CSU, a selection of 142 genes was studied with qPCR, and 103 (72.53%) were confirmed. Differentially expressed genes in the phenomenon of wheal development are involved in a variety of biological functions as, epidermal differentiation, intracellular signal function, transcriptional factors cell cycle differentiation, inflammation, or coagulation. Differentially expressed genes that uniformly increase or decrease along the skin worsening until the wheal appearance is shown. CONCLUSION: The skin of CSU patients with a severely active disease shows an overall immunological skin involvement showing a peculiar gene profile.

Characteristics and outcomes of patients admitted to Spanish ICU: A prospective observational study from the ENVIN-HELICS registry (2006-2011).

OBJECTIVE: To describe the case-mix of patients admitted to intensive care units (ICUs) in Spain during the period 2006-2011 and to assess changes in ICU mortality according to severity level. DESIGN: Secondary analysis of data obtained from the ENVN-HELICS registry. Observational prospective study. SETTING: Spanish ICU. PATIENTS: Patients admitted for over 24h. INTERVENTIONS: None. VARIABLES: Data for each of the participating hospitals and ICUs were recorded, as well as data that allowed to knowing the case-mix and the individual outcome of each patient. The study period was divided into two intervals, from 2006 to 2008 (period 1) and from 2009 to 2011 (period 2). Multilevel and multivariate models were used for the analysis of mortality and were performed in each stratum of severity level. RESULTS: The study population included 142,859 patients admitted to 188 adult ICUs. There was an increase in the mean age of the patients and in the percentage of patients >79 years (11.2% vs. 12.7%, P<0.001). Also, the mean APACHE II score increased from 14.35±8.29 to 14.72±8.43 (P<0.001). The crude overall intra-UCI mortality remained unchanged (11.4%) but adjusted mortality rate in patients with APACHE II score between 11 and 25 decreased modestly in recent years (12.3% vs. 11.6%, odds ratio=0.931, 95% CI 0.883-0.982; P=0.008). CONCLUSION: This study provides observational longitudinal data on case-mix of patients admitted to Spanish ICUs. A slight reduction in ICU mortality rate was observed among patients with intermediate severity level.

Intensive care practices in brain death diagnosis and organ donation.

We conducted a multicentre study of 1844 patients from 42 Spanish intensive care units, and analysed the clinical characteristics of brain death, the use of ancillary testing, and the clinical decisions taken after the diagnosis of brain death. The main cause of brain death was intracerebral haemorrhage (769/1844, 42%), followed by traumatic brain injury (343/1844, 19%) and subarachnoid haemorrhage (257/1844, 14%). The diagnosis of brain death was made rapidly (50% in the first 24 h). Of those patients who went on to die, the Glasgow Coma Scale on admission was ≤ 8/15 in 1146/1261 (91%) of patients with intracerebral haemorrhage, traumatic brain injury or anoxic encephalopathy; the Hunt and Hess Scale was 4-5 in 207/251 (83%) of patients following subarachnoid haemorrhage; and the National Institutes of Health Stroke Scale was ≥ 15 in 114/129 (89%) of patients with strokes. Brain death was diagnosed exclusively by clinical examination in 92/1844 (5%) of cases. Electroencephalography was the most frequently used ancillary test (1303/1752, 70.7%), followed by transcranial Doppler (652/1752, 37%). Organ donation took place in 70% of patients (1291/1844), with medical unsuitability (267/553, 48%) and family refusal (244/553, 13%) the main reasons for loss of potential donors. All life-sustaining measures were withdrawn in 413/553 of non-donors (75%).

[Comparative analysis of patients admitted to Spanish Intensive Care Units due to medical and surgical disease]. / Análisis comparativo de pacientes ingresados en Unidades de Cuidados Intensivos españolas por causa médica y quirúrgica.

OBJECTIVE: To describe the characteristics of the patients case-mix admitted to ICUs due to medical and surgical disease, and to compare both groups. DESIGN: Analysis of data covering the period 2006-2011 in the ENVIN-HELICS registry. An observational, prospective, multicenter and voluntary participation study. SETTING: A total of 188 Spanish ICUs. PATIENTS: All patients admitted for more than 24 hours. MAIN VARIABLES: Demographic data, cause of admission, severity scores, length of stay, mortality. RESULTS: A total of 138,999 patients were analyzed. Of these, 65,467 (47.1%) were admitted due to a non-coronary medical cause, 27,785 (20,0%) due to coronary-related illness, 28,044 (20,2%) after elective surgery and 17,613 (12.7%) after urgent surgery. Use of devices, nosocomial infections and isolation of multirresistant organisms were more prevalent in urgent surgery patients. Longer length of stay (median 5 days; interquartile range 2-11) as well as higher severity scale values (APACHE II and SAPS II) corresponded to this same group of patients. Mortality was higher in non-coronay medical patients. On categorizing the patients according to the APACHE II score, mortality was seen to be higher in urgent surgery cases than in elective surgery patients in all groups. The largest difference was observed in the APACHE II score 6-10 group (3% vs. 0.9%) (OR: 2.14, 95% CI 1.825-2.513; p<0.001). CONCLUSIONS: The mortality rate is higher in non-coronary medical patients, though resource use per patient is greater in the urgent surgery cases. The APACHE II scale underestimates mortality in emergency surgery patients.

Modelling survival kinetics of Staphylococcus aureus and Escherichia coli O157:H7 on stainless steel surfaces soiled with different substrates under static conditions of temperature and relative humidity.

The survival of Escherichia coli O157:H7 and Staphylococcus aureus on stainless steel surfaces with Saline Solution (SS), Tryptone Soy Broth (TSB) and meat purge was studied, and based on results, mathematical models describing survival of pathogens as a function of time were proposed. Results indicated that S. aureus was able to survive longer than E. coli O157:H7 in all substrates. The type of substrate had a greater impact on the survival of E. coli O157:H7. This microorganism only remained viable for 8 and 50 h (hours) on surfaces with SS and TSB, respectively while on meat purge, the microorganism could be recovered after 200 h. For S. aureus, SS and TSB led to similar survival times (250 h) whereas on meat purge, survival capacity increased to 800 h. Survival data for S. aureus could be well described by a log-linear model or a Weibull model depending on the type of substrate (R(2) > 0.85). E. coli O157:H7 displayed an evident tail zone which made the Weibull model more appropriate (R(2) > 0.94). These survival models may be used in quantitative risk assessment to produce more accurate risk estimates. Finally, the results highlight the importance of performing effective cleaning procedures to prevent cross contamination.

Urethral catheter-related urinary infection in critical patients admitted to the ICU. Descriptive data of the ENVIN-UCI study.

OBJECTIVE: To describe trends in national catheter-related urinary tract infection (CRUTI) rates, as well as etiologies and multiresistance markers. DESIGN: An observational, prospective, multicenter voluntary participation study was conducted from 1 April to 30 June in the period between 2005 and 2010. SETTING: Intensive Care Units (ICUs) that participated in the ENVIN-ICU registry during the study period. PATIENTS: We included all patients admitted to the participating ICUs and patients with urinary catheter placement for more than 24 hours (78,863 patients). INTERVENTION: Patient monitoring was continued until discharge from the ICU or up to 60 days. VARIABLES OF INTEREST: CRUTIs were defined according to the CDC system, and frequency is expressed as incidence density (ID) in relation to the number of urinary catheter-patients days. RESULTS: A total of 2329 patients (2.95%) developed one or more CRUTI. The ID decreased from 6.69 to 4.18 episodes per 1000 days of urinary catheter between 2005 and 2010 (p<0.001). In relation to the underlying etiology, gramnegative bacilli predominated (55.6 to 61.6%), followed by fungi (18.7 to 25.2%) and grampositive cocci (17.1 to 25.9%). In 2010, ciprofloxacin-resistant E. coli strains (37.1%) increased, as well as imipenem-resistant (36.4%) and ciprofloxacin-resistant (37.1%) strains of P. aeruginosa. CONCLUSIONS: A decrease was observed in CRUTI rates, maintaining the same etiological distribution and showing increased resistances in gramnegative pathogens, especially E. coli and P. aeruginosa.

Acute Horner syndrome secondary to glandular fever due to Epstein Barr virus infection.

We present a clinical situation where a 47-year old female patient consulted with left partial ptosis and miosis that started, two weeks before, with an episode of glandular fever secondary to Epstein-Barr infection. Apraclonidine 0.5% and Phenylephrine 1% drop testing was performed with results consistent with suspected left Horner Syndrome (HS), with a probable postganglionic location. Magnetic Resonance Angiography (MRA) at the moment of the acute presentation did not show any image suggesting carotid arterial dissection but showed irregular narrowing of the left internal carotid artery on its paravertebral extracranial way, consistent to enlarged intra-carotid sheath lymphoid tissue. A week later, a Doppler ultrasound was performed, showing bilateral images compatible with internal carotid arterial dissection. When Postganglionar HS is suspected, the first aetiology to rule out is a carotid arterial dissection because of its potentially fatal outcome and for being a more described entity as postganglionic HS aetiology. However, it is also evidenced that a certain diagnose is not always possible. Furthermore, we describe the enlarged internal carotid artery sheath lymphoid tissue as a possible cause of sympathetic nerve disruption causing a Postganglionar HS, although not common.

Acceptance and validity of the methods used to implement a competency based medical education programme in an Intensive Care Department of a teaching referral center.

OBJECTIVES: 1. To determine the satisfaction of tutors and residents with a specific methodology used to implement CoBaTrICE. 2. To determine the reliability and validity of the global rating scales designed ad hoc to assess the performance of the residents for training purposes. DESIGN: Prospective cohort study. PARTICIPANTS: All the residents and tutors of the ICU Department of the Hospital Universitario y Politécnico la Fe de Valencia. INTERVENTION: CoBaTrICE implementation started in March 2016, it was based on: (1) Training the tutors in feedback techniques; (2) Performing multiple objective and structured work based assessments to achieve the competences of the program; and (3) The use of an electronic portfolio to promote learning reflection and to collect the evidence that learning was taking place. METHODS: The acceptance of CoBaTrICE was explored through a satisfaction survey conducted after 9 months of implementation of the training program. The 15 residents and 5 tutors of the ICU Department were asked about the methodology of the formative assessments, the quality of the feedback, self-learning regulation and the electronic portfolio usefulness. The validity of the global rating scales was assessed through the tests alfa de Cronbach, reliability and generalizability indexes, and intraclass correlation coefficient. RESULTS: The implementation of CoBaTrICE was satisfactory in all the dimensions studied. The global rating scales used for formative purposes showed reliability and validity. CONCLUSIONS: The methodology used to implement CoBaTrICE was highly valued by tutors and residents. The global rating scales used for formative purposes showed reliability and validity.

Differential regulation of constitutive major histocompatibility complex class I expression in T and B lymphocytes.

Major histocompatibility complex (MHC) class I antigens are constitutively expressed yet highly induced by interferon (IFN) during inflammation. We found that not only IFN-induced but also normal basal expression of MHC I required IFN receptors and signal transducer and activator of transcription (STAT)1, providing genetic evidence for continuous IFN signaling. Surprisingly, an IFN-independent requirement for STAT1 was also found, specifically in T lymphocytes, where MHC class I expression was not fully accounted for by IFN signaling. This IFN-independent pathway maintained tyrosine phosphorylation of STAT1 in T but not B lymphocytes even in the absence of IFN receptors. Interestingly, interleukin (IL)-7 selectively activated STAT1 and induced MHC class I in mature T but not B cells. These loss of function studies demonstrate an essential role of endogenous IFN and activated STAT1 for constitutive MHC class I expression in normal mice and define IL-7-dependent but IFN-independent regulation of STAT1 restricted to T lymphocytes.

Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements.

The presence of Escherichia coli in contaminated food products is commonly attributed to faecal contamination when they are improperly handled and/or when inactivation treatments fail. Adaptation of E. coli at low pH and a(w) levels can vary at different temperatures depending on the serotype, thus more detailed studies are needed. In this work, a screening to assess the growth of four pathogenic serotypes of E. coli (O55:H6; O59:H21; O158:H23 and O157:H7) was performed. Subsequently, boundary models were elaborated with the fastest serotype selected at different temperatures (8, 12 and 16 degrees C), and inoculum levels (2, 3 and 4log cfu/mL) as function of pH (7.00-5.00) and a(w) (0.999-0.960). Finally, the growth kinetics of E. coli was described in the conditions that allowed growth. Results obtained showed that the serotypes O157:H7 and O59:H21 did not grow at more stringent conditions (8 degrees C; pH 5.50), while the E. coli O158:H23 was the best adapted, resulting in faster growth. The logistic regression models presented a good adjustment to data observed since more than 96.7% of cases were correctly classified. The growth interface was shifted to more limited conditions as the inoculum size was higher. Detection times (t(d), h) and their variability were higher at low levels of the environmental factors studied. This work provides insight on the growth kinetics of E. coli at various environmental conditions.

Changes of resistance rates in Pseudomonas aeruginosa strains are unrelated to antimicrobial consumption in ICU populations with invasive device-related infection.

OBJECTIVE: To evaluate the relationship between antipseudomonal antibiotic consumption and each individual drug resistance rate in Pseudomonas aeruginosa strains causing ICU acquired invasive device-related infections (IDRI). DESIGN: A post hoc analysis was made of the data collected prospectively from the ENVIN-HELICS registry. SETTING: Intensive Care Units participating in the ENVIN-UCI registry between the years 2007 and 2016 (3-month registry each year). PATIENTS: Patients admitted for over 24h. MAIN VARIABLES: Annual linear and nonlinear trends of resistance rates of P. aeruginosa strains identified in IDRI and days of treatment of each antipseudomonal antibiotic family per 1000 occupied ICU bed days (DOT) were calculated. RESULTS: A total of 15,095 episodes of IDRI were diagnosed in 11,652 patients (6.2% out of a total of 187,100). Pseudomonas aeruginosa was identified in 2095 (13.6%) of 15,432 pathogens causing IDRI. Resistance increased significantly over the study period for piperacillin-tazobactam (P<0.001), imipenem (P=0.016), meropenem (P=0.004), ceftazidime (P=0.005) and cefepime (P=0.015), while variations in resistance rates for amikacin, ciprofloxacin, levofloxacin and colistin proved nonsignificant. A significant DOT decrease was observed for aminoglycosides (P<0.001), cephalosporins (P<0.001), quinolones (P<0.001) and carbapenems (P<0.001). CONCLUSIONS: No significant association was observed between consumption of each antipseudomonal antibiotic family and the respective resistance rates for P. aeruginosa strains identified in IDRI.

SED4 encodes a yeast endoplasmic reticulum protein that binds Sec16p and participates in vesicle formation.

SEC16 is required for transport vesicle budding from the ER in Saccharomyces cerevisiae, and encodes a large hydrophilic protein found on the ER membrane and as part of the coat of transport vesicles. In a screen to find functionally related genes, we isolated SED4 as a dosage-dependent suppressor of temperature-sensitive SEC16 mutations. Sed4p is an integral ER membrane protein whose cytosolic domain binds to the COOH-terminal domain of Sec16p as shown by two-hybrid assay and coprecipitation. The interaction between Sed4p and Sec16p probably occurs before budding is complete, because Sed4p is not found in budded vesicles. Deletion of SED4 decreases the rate of ER to Golgi transport, and exacerbates mutations defective in vesicle formation, but not those that affect later steps in the secretory pathway. Thus, Sed4p is important, but not necessary, for vesicle formation at the ER. Sec12p, a close homologue of Sed4p, also acts early in the assembly of transport vesicles. However, SEC12 performs a different function than SED4 since Sec12p does not bind Sec16p, and genetic tests show that SEC12 and SED4 are not functionally interchangeable. The importance of Sed4p for vesicle formation is underlined by the isolation of a phenotypically silent mutation, sar1-5, that produces a strong ER to Golgi transport defect when combined with sed4 mutations. Extensive genetic interactions between SAR1, SED4, and SEC16 show close functional links between these proteins and imply that they might function together as a multisubunit complex on the ER membrane.

LST1 is a SEC24 homologue used for selective export of the plasma membrane ATPase from the endoplasmic reticulum.

In Saccharomyces cerevisiae, vesicles that carry proteins from the ER to the Golgi compartment are encapsulated by COPII coat proteins. We identified mutations in ten genes, designated LST (lethal with sec-thirteen), that were lethal in combination with the COPII mutation sec13-1. LST1 showed synthetic-lethal interactions with the complete set of COPII genes, indicating that LST1 encodes a new COPII function. LST1 codes for a protein similar in sequence to the COPII subunit Sec24p. Like Sec24p, Lst1p is a peripheral ER membrane protein that binds to the COPII subunit Sec23p. Chromosomal deletion of LST1 is not lethal, but inhibits transport of the plasma membrane proton-ATPase (Pma1p) to the cell surface, causing poor growth on media of low pH. Localization by both immunofluorescence microscopy and cell fractionation shows that the export of Pma1p from the ER is impaired in lst1Delta mutants. Transport of other proteins from the ER was not affected by lst1Delta, nor was Pma1p transport found to be particularly sensitive to other COPII defects. Together, these findings suggest that a specialized form of the COPII coat subunit, with Lst1p in place of Sec24p, is used for the efficient packaging of Pma1p into vesicles derived from the ER.

Yeast SEC16 gene encodes a multidomain vesicle coat protein that interacts with Sec23p.

Temperature-sensitive mutations in the SEC16 gene of Saccharomyces cerevisiae block budding of transport vesicles from the ER. SEC16 was cloned by complementation of the sec16-1 mutation and encodes a 240-kD protein located in the insoluble, particulate component of cell lysates. Sec16p is released from this particulate fraction by high salt, but not by nonionic detergents or urea. Some Sec16p is localized to the ER by immunofluorescence microscopy. Membrane-associated Sec16p is incorporated into transport vesicles derived from the ER that are formed in an in vitro vesicle budding reaction. Sec16p binds to Sec23p, a COPII vesicle coat protein, as shown by the two-hybrid interaction assay and affinity studies in cell extracts. These findings indicate that Sec16p associates with Sec23p as part of the transport vesicle coat structure. Genetic analysis of SEC16 identifies three functionally distinguishable domains. One domain is defined by the five temperature-sensitive mutations clustered in the middle of SEC16. Each of these mutations can be complemented by the central domain of SEC16 expressed alone. The stoichiometry of Sec16p is critical for secretory function since overexpression of Sec16p causes a lethal secretion defect. This lethal function maps to the NH2-terminus of the protein, defining a second functional domain. A separate function for the COOH-terminal domain of Sec16p is shown by its ability to bind Sec23p. Together, these results suggest that Sec16p engages in multiple protein-protein interactions both on the ER membrane and as part of the coat of a completed vesicle.

Is a project needed to prevent urinary tract infection in patients admitted to spanish ICUs? / ¿Es necesario un proyecto para prevenir las infecciones del tracto urinario en los pacientes ingresados en unidades de cuidados intensivos españolas?

OBJECTIVE: To analyze epidemiological data of catheter-associated urinary tract infection (CAUTI) in critically ill patients admitted to Spanish ICUs in order to assess the need of implementing a nationwide intervention program to reduce these infections. DESIGN: Non-intervention retrospective annual period prevalence analysis. SETTING: Participating ICUs in the ENVIN-UCI multicenter registry between the years 2007-2016. PATIENTS: Critically ill patients admitted to the ICU with catheter-associated urinary tract infection (CAUTI). MAIN VARIABLES: Incidence rates per 1,000 catheter-days; urinary catheter utilization ratio; proportion of CAUTIs in relation to total health care-associated infections (HAIs). RESULTS: A total of 187,100 patients, 137,654 (73.6%) of whom had a urinary catheter in place during 1,215,673 days (84% of days of ICU stay) were included. In 4,539 (3.3%) patients with urinary catheter, 4,977 CAUTIs were diagnosed (3.6 episodes per 100 patients with urinary catheter). The CAUTI incidence rate showed a 19% decrease between 2007 and 2016 (4.69 to 3.8 episodes per 1,000 catheter-days), although a sustained urinary catheter utilization ratio was observed (0.84 [0.82-0.86]). The proportion of CAUTI increased from 23.3% to 31.9% of all HAIs controlled in the ICU. CONCLUSIONS: Although CAUTI rates have declined in recent years, these infections have become proportionally the first HAIs in the ICU. The urinary catheter utilization ratio remains high in Spanish ICUs. There is room for improvement, so that a CAUTI-ZERO project in our country could be useful.

Invasive device-associated infections caused by Pseudomonas aeruginosa in critically ill patients: evolution over 10 years.

Invasive device-associated infections caused by Pseudomonas aeruginosa over 10 years (2007-2016) were assessed based on data from the ENVIN-HELICS registry (200 Spanish intensive care units). P. aeruginosa was the leading pathogen except in the last two years in which there was a slight decrease, with Escherichia coli as the leading aetiology. The rate of infections caused by P. aeruginosa remained between 12.0% and 14.6% throughout the study period. There was a significant increase of isolates resistant to imipenem, meropenem, ceftazidime, cefepime, and piperacillin-tazobactam. Multidrug-resistant and the sum of extensively drug- and pandrug-resistant strains also increased. Resistance to anti-pseudomonal antimicrobials remains a matter of concern.

Management of microbiological safety of ready-to-eat meat products by mathematical modelling: Listeria monocytogenes as an example.

The recent Commission Regulation (EC) No 2073/2005 establishes microbiological criteria in foods. For the pathogen Listeria monocytogenes in the category ready-to-eat foods able to support its growth, other than those intended for infants and for special medical purposes, two different microbiological criteria are proposed: (i) L. monocytogenes levels should be <100 cfu/g throughout the shelf-life of the product, (ii) absence in 25 g of the product at the stage before the food has left the immediate control of the food business operator, who has produced it. The application of either the first or the second of these criteria depends on whether or not the manufacturer is able to demonstrate that the level of L. monocytogenes in the food product will not exceed 100 cfu/g throughout its shelf-life. This demonstration should be based on physico-chemical characteristics of the target product and consultation of scientific literature, and, when necessary, on quantitative models and/or challenge tests. Once the characteristics of the product as well as scientific literature show that the pathogen has potential to grow on a specific food commodity, it seems adequate to use quantitative models and/or perform challenge tests to study the extent to which L. monocytogenes could grow. In this study, we aim to illustrate with an example in cooked ham the application of quantitative models as a tool to manage the compliance with these criteria. Two approaches were considered: deterministic and probabilistic, in three different commercial brands (A, B, and C). The deterministic approach showed that the limit 100 cfu/g was exceeded largely at the end of the shelf-life of all three; however, when reducing the storage time, the level of L. monocytogenes remained below 100 cfu/g in B. The probabilistic approach demonstrated very low percentiles corresponding to 100 cfu/g; when reducing the storage time, percentiles for three products increased, especially in products B and C (from 4.92% to 75.90%, and from 0.90% to 73.90%, respectively). This study shows how different storage times influence the level of L. monocytogenes at the end of the shelf-life of cooked ham, and, depending on the level reached, the microbiological criterion applied should be different, as stated above. Beside this, the choice of either point-estimate or probabilistic approach should be determined by the competent sanitary authority, and, in case of selecting the second approach, a certain percentile for the level 100 cfu/g should be established.

Survey of temperature and consumption patterns of fresh-cut leafy green salads: risk factors for listeriosis.

Increasing demand for fresh-cut or ready-to-eat fruits and vegetables, developed to meet the consumer need for quick and convenient products, has prompted extensive research into their microbiological quality, safety, processing, and packaging. The microbial ecology of Listeria monocytogenes is recognized as a major safety concern for fresh-cut produce. A survey was performed to collect information on consumption patterns of fresh-cut leafy green salads and the temperature of domestic refrigerators. Salad consumption was low-moderate: 24.3% of respondents never purchased fresh-cut leafy green salads; of those who reported buying these products, 7.41% did so more than twice a week, 17.28% once or twice a week, 29.63% once or twice a month, and 45.68% occasionally. Saving time and convenience were the advantages most widely reported by consumers. A total of 9.9% of respondents did not always respect the "use-by" date of fresh-cut salads, a negative practice that could contribute to the risk of listeriosis. Temperatures reported in domestic refrigerators were compatible with the growth of L. monocytogenes on ready-to-eat salads. Variations in average temperature followed a normal distribution, N(6.62, 2.56), while the variability of temperature variance was described by a gamma distribution, G(2.00, 1.00). As expected, when a time of day-temperature profile was plotted over a 24-h period, changes corresponding to the transition between day and night were observed. Knowledge of consumption patterns and consumer hygiene practices is essential, first in assessing the risk of listeriosis (risk assessment) and second in taking measures to manage that risk (risk management).

Extracting additional risk managers information from a risk assessment of Listeria monocytogenes in deli meats.

The risk assessment study of Listeria monocytogenes in ready-to-eat foods conducted by the U.S. Food and Drug Administration is an example of an extensive quantitative microbiological risk assessment that could be used by risk analysts and other scientists to obtain information and by managers and stakeholders to make decisions on food safety management. The present study was conducted to investigate how detailed sensitivity analysis can be used by assessors to extract more information on risk factors and how results can be communicated to managers and stakeholders in an understandable way. The extended sensitivity analysis revealed that the extremes at the right side of the dose distribution (at consumption, 9 to 11.5 log CFU per serving) were responsible for most of the cases of listeriosis simulated. For concentration at retail, values below the detection limit of 0.04 CFU/g and the often used limit for L. monocytogenes of 100 CFU/g (also at retail) were associated with a high number of annual cases of listeriosis (about 29 and 82%, respectively). This association can be explained by growth of L. monocytogenes at both average and extreme values of temperature and time, indicating that a wide distribution can lead to high risk levels. Another finding is the importance of the maximal population density (i.e., the maximum concentration of L. monocytogenes assumed at a certain temperature) for accurately estimating the risk of infection by opportunistic pathogens such as L. monocytogenes. According to the obtained results, mainly concentrations corresponding to the highest maximal population densities caused risk in the simulation. However, sensitivity analysis applied to the uncertainty parameters revealed that prevalence at retail was the most important source of uncertainty in the model.

Modeling the growth of Listeria monocytogenes in pasteurized white asparagus.

Growth of Listeria monocytogenes in pasteurized white asparagus was monitored at different storage temperatures (4, 10, 20, and 30 degrees C). Among the main microbial kinetic parameters, growth rate (mu) per hour was calculated at each temperature using the Baranyi-Roberts model. L. monocytogenes was able to grow at all temperatures, although at 4 degrees C only a slight increment of the microbial population was observed (approximately 1 log CFU/g) after 300 h of storage. Subsequently, two different secondary modeling approaches were proposed to study the relationship between mu and storage temperature: the Arrhenius and Ratkowsky models. Although both models properly described the data observed, smaller values of root mean square error (RMSE) and standard error of prediction (SEP) were obtained with the Ratkowsky model, providing a better goodness of fit (Ratkowsky model: RMSE = 0.010, SEP = 21.23%; Arrhenius model: RMSE = 0.026, SEP = 54.37%). The maximum population density (MPD) was calculated at each temperature studied. A clear dependence between MPD and temperature was found; lower temperatures produced lower values of MPD. This finding confirmed the Jameson effect, indicating that multiple hurdles in the food-processing chain plus lower temperatures reduced L. monocytogenes growth. Predicting the growth of L. monocytogenes along the food chain will help to reduce microbial risks associated with consumption of pasteurized white asparagus.