Predicting ICU Mortality in Acute Respiratory Distress Syndrome Patients Using Machine Learning: The Predicting Outcome and STratifiCation of severity in ARDS (POSTCARDS) Study.

OBJECTIVES: To assess the value of machine learning approaches in the development of a multivariable model for early prediction of ICU death in patients with acute respiratory distress syndrome (ARDS). DESIGN: A development, testing, and external validation study using clinical data from four prospective, multicenter, observational cohorts. SETTING: A network of multidisciplinary ICUs. PATIENTS: A total of 1,303 patients with moderate-to-severe ARDS managed with lung-protective ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We developed and tested prediction models in 1,000 ARDS patients. We performed logistic regression analysis following variable selection by a genetic algorithm, random forest and extreme gradient boosting machine learning techniques. Potential predictors included demographics, comorbidities, ventilatory and oxygenation descriptors, and extrapulmonary organ failures. Risk modeling identified some major prognostic factors for ICU mortality, including age, cancer, immunosuppression, Pa o2 /F io2 , inspiratory plateau pressure, and number of extrapulmonary organ failures. Together, these characteristics contained most of the prognostic information in the first 24 hours to predict ICU mortality. Performance with machine learning methods was similar to logistic regression (area under the receiver operating characteristic curve [AUC], 0.87; 95% CI, 0.82-0.91). External validation in an independent cohort of 303 ARDS patients confirmed that the performance of the model was similar to a logistic regression model (AUC, 0.91; 95% CI, 0.87-0.94). CONCLUSIONS: Both machine learning and traditional methods lead to promising models to predict ICU death in moderate/severe ARDS patients. More research is needed to identify markers for severity beyond clinical determinants, such as demographics, comorbidities, lung mechanics, oxygenation, and extrapulmonary organ failure to guide patient management.

Stratification for Identification of Prognostic Categories In the Acute RESpiratory Distress Syndrome (SPIRES) Score.

OBJECTIVES: To develop a scoring model for stratifying patients with acute respiratory distress syndrome into risk categories (Stratification for identification of Prognostic categories In the acute RESpiratory distress syndrome score) for early prediction of death in the ICU, independent of the underlying disease and cause of death. DESIGN: A development and validation study using clinical data from four prospective, multicenter, observational cohorts. SETTING: A network of multidisciplinary ICUs. PATIENTS: One-thousand three-hundred one patients with moderate-to-severe acute respiratory distress syndrome managed with lung-protective ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The study followed Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis guidelines for prediction models. We performed logistic regression analysis, bootstrapping, and internal-external validation of prediction models with variables collected within 24 hours of acute respiratory distress syndrome diagnosis in 1,000 patients for model development. Primary outcome was ICU death. The Stratification for identification of Prognostic categories In the acute RESpiratory distress syndrome score was based on patient's age, number of extrapulmonary organ failures, values of end-inspiratory plateau pressure, and ratio of Pao2 to Fio2 assessed at 24 hours of acute respiratory distress syndrome diagnosis. The pooled area under the receiver operating characteristic curve across internal-external validations was 0.860 (95% CI, 0.831-0.890). External validation in a new cohort of 301 acute respiratory distress syndrome patients confirmed the accuracy and robustness of the scoring model (area under the receiver operating characteristic curve = 0.870; 95% CI, 0.829-0.911). The Stratification for identification of Prognostic categories In the acute RESpiratory distress syndrome score stratified patients in three distinct prognostic classes and achieved better prediction of ICU death than ratio of Pao2 to Fio2 at acute respiratory distress syndrome onset or at 24 hours, Acute Physiology and Chronic Health Evaluation II score, or Sequential Organ Failure Assessment scale. CONCLUSIONS: The Stratification for identification of Prognostic categories In the acute RESpiratory distress syndrome score represents a novel strategy for early stratification of acute respiratory distress syndrome patients into prognostic categories and for selecting patients for therapeutic trials.

Genomic diversity and characterization of Listeria monocytogenes from dry-cured ham processing plants.

Genomic diversity of Listeria monocytogenes isolates from the deboning and slicing areas of three dry-cured ham processing plants was analysed. L. monocytogenes was detected in 58 out of 491 samples from the environment and equipment surfaces, all from the deboning area, with differences in prevalence among facilities. The most frequent PCR-serogroup was IIa (74.1%) followed by IIb and IIc, and only one isolate was serogroup IVb. Twenty different pulsotypes and 11 sequence types (STs) grouped into 10 clonal complexes (CCs) were determined. ST121 (CC121) and ST9 (CC9) were the most abundant. Premature stop codons (PMSC6 and PMSC19) associated with attenuated virulence were found in the inlA sequence in 7 out of 12 selected strains. CC121 strains were strong biofilm formers and some harboured the transposon Tn6188, related with increased tolerance to quaternary ammonium compounds. L. monocytogenes clones considered hypovirulent resulted predominant in the deboning areas. The clonal structure and potential virulence of the isolates could help to establish adequate control measures and cleaning protocols for the comprehensive elimination of the pathogen in dry-cured ham processing environment.

Is Overall Mortality the Right Composite Endpoint in Clinical Trials of Acute Respiratory Distress Syndrome?

OBJECTIVES: Overall mortality in patients with acute respiratory distress syndrome is a composite endpoint because it includes death from multiple causes. In most acute respiratory distress syndrome trials, it is unknown whether reported deaths are due to acute respiratory distress syndrome or the underlying disease, unrelated to the specific intervention tested. We investigated the causes of death after contracting acute respiratory distress syndrome in a large cohort. DESIGN: A secondary analysis from three prospective, multicenter, observational studies. SETTING: A network of multidisciplinary ICUs. PATIENTS: We studied 778 patients with moderate-to-severe acute respiratory distress syndrome treated with lung-protective ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We examined death in the ICU from individual causes. Overall ICU mortality was 38.8% (95% CI, 35.4-42.3). Causes of acute respiratory distress syndrome modified the risk of death. Twenty-three percent of deaths occurred from refractory hypoxemia due to nonresolving acute respiratory distress syndrome. Most patients died from causes unrelated to acute respiratory distress syndrome: 48.7% of nonsurvivors died from multisystem organ failure, and cancer or brain injury was involved in 37.1% of deaths. When quantifying the true burden of acute respiratory distress syndrome outcome, we identified 506 patients (65.0%) with one or more exclusion criteria for enrollment into current interventional trials. Overall ICU mortality of the "trial cohort" (21.3%) was markedly lower than the parent cohort (relative risk, 0.55; 95% CI, 0.43-0.70; p < 0.000001). CONCLUSIONS: Most deaths in acute respiratory distress syndrome patients are not directly related to lung damage but to extrapulmonary multisystem organ failure. It would be challenging to prove that specific lung-directed therapies have an effect on overall survival.

Open Lung Approach for the Acute Respiratory Distress Syndrome: A Pilot, Randomized Controlled Trial.

OBJECTIVE: The open lung approach is a mechanical ventilation strategy involving lung recruitment and a decremental positive end-expiratory pressure trial. We compared the Acute Respiratory Distress Syndrome network protocol using low levels of positive end-expiratory pressure with open lung approach resulting in moderate to high levels of positive end-expiratory pressure for the management of established moderate/severe acute respiratory distress syndrome. DESIGN: A prospective, multicenter, pilot, randomized controlled trial. SETTING: A network of 20 multidisciplinary ICUs. PATIENTS: Patients meeting the American-European Consensus Conference definition for acute respiratory distress syndrome were considered for the study. INTERVENTIONS: At 12-36 hours after acute respiratory distress syndrome onset, patients were assessed under standardized ventilator settings (FIO2≥0.5, positive end-expiratory pressure ≥10 cm H2O). If Pao2/FIO2 ratio remained less than or equal to 200 mm Hg, patients were randomized to open lung approach or Acute Respiratory Distress Syndrome network protocol. All patients were ventilated with a tidal volume of 4 to 8 ml/kg predicted body weight. MEASUREMENTS AND MAIN RESULTS: From 1,874 screened patients with acute respiratory distress syndrome, 200 were randomized: 99 to open lung approach and 101 to Acute Respiratory Distress Syndrome network protocol. Main outcome measures were 60-day and ICU mortalities, and ventilator-free days. Mortality at day-60 (29% open lung approach vs. 33% Acute Respiratory Distress Syndrome Network protocol, p = 0.18, log rank test), ICU mortality (25% open lung approach vs. 30% Acute Respiratory Distress Syndrome network protocol, p = 0.53 Fisher's exact test), and ventilator-free days (8 [0-20] open lung approach vs. 7 [0-20] d Acute Respiratory Distress Syndrome network protocol, p = 0.53 Wilcoxon rank test) were not significantly different. Airway driving pressure (plateau pressure - positive end-expiratory pressure) and PaO2/FIO2 improved significantly at 24, 48 and 72 hours in patients in open lung approach compared with patients in Acute Respiratory Distress Syndrome network protocol. Barotrauma rate was similar in both groups. CONCLUSIONS: In patients with established acute respiratory distress syndrome, open lung approach improved oxygenation and driving pressure, without detrimental effects on mortality, ventilator-free days, or barotrauma. This pilot study supports the need for a large, multicenter trial using recruitment maneuvers and a decremental positive end-expiratory pressure trial in persistent acute respiratory distress syndrome.

Natural antimicrobials and high-pressure treatments on the inactivation of Salmonella Enteritidis and Escherichia coli O157:H7 in cold-smoked salmon.

BACKGROUND: High hydrostatic pressure (HHP) combined with reuterin and lactoperoxidase system (LPS) has exerted antimicrobial activity against Listeria monocytogenes in cold-smoked salmon at chilled temperatures. Therefore the purpose of this work was to evaluate the effect of HHP combined with reuterin, LPS and lactoferrin (LF) on the survival of Salmonella enterica subsp. enterica serovar Enteritidis and Escherichia coli O157:H7 in cold-smoked salmon stored at 4 and 10 °C. RESULTS: Salmonella Enteritidis and E. coli O157:H7 were reduced more than 3 log colony-forming units (CFU) g(-1) by the pressure treatment (450 MPa/5 min). LPS slightly diminished pathogen levels throughout storage, whereas no effect was recorded when reuterin or LF was added. The Salmonella population was below the detection limit (<1 log CFU g(-1) ) during the storage of HHP-treated smoked salmon at 4 and 10 °C. The antimicrobial activity of HHP against E. coli O157:H7 was increased when 450 MPa was applied in combination with LPS in cold-smoked salmon at 4 and 10 °C. CONCLUSION: HHP at 450 MPa/5 min inactivated S. Enteritidis in cold-smoked salmon and in combination with LPS would be useful as a hurdle technology approach against E. coli O157:H7, even under mild temperature abuse conditions. © 2015 Society of Chemical Industry.

Enterocins Produced by Enterococci Isolated from Breast-Fed Infants: Antilisterial Potential.

Enterocins are bacteriocins synthesized by Enterococcus strains that show an interesting antimicrobial effectiveness against foodborne pathogens such as Listeria monocytogenes. The objectives of this study were to identify and analyze the expression of enterocin genes of Enterococcus isolated from breast-fed infants and evaluate their ability to inhibit three human isolates of virulent L. monocytogenes, as well as some probiotic bacteria. The susceptibility of the strains of L. monocytogenes to fifteen antibiotics was tested, detecting their resistance to cefoxitin (constitutively resistant), oxacillin, and clindamycin. The production of enterocins A, B, and P was observed in Enterococcus faecium isolates, while enterocin AS-48 was detected in an Enterococcus faecalis isolate. AS-48 showed antilisterial activity by itself, while the joint action of enterocins A and B or B and P was necessary for inhibiting L. monocytogenes, demonstrating the synergistic effect of those combinations. The presence of multiple enterocin genes does not assure the inhibition of L. monocytogenes strains. However, the expression of multiple enterocin genes showed a good correlation with the inhibition capacity of these strains. Furthermore, the potential beneficial strains of lactobacilli and bifidobacteria examined were not inhibited by any of the enterocins produced individually or in combination, with the exception of Bifidobacterium longum BB536, which was inhibited by enterocin AS-48 and the joint production of enterocins A and B or B and P. The enterocins studied here could be candidates for developing alternative treatments against antibiotic-resistant bacterial infections. Moreover, these selected enterocin-producing E. faecium strains isolated from breast-fed infants could be used as probiotic strains due to their antilisterial effect, as well as the absence of virulence factors.

Clinical relevance of timing of assessment of ICU mortality in patients with moderate-to-severe Acute Respiratory Distress Syndrome.

Mortality is a frequently reported outcome in clinical studies of acute respiratory distress syndrome (ARDS). However, timing of mortality assessment has not been well characterized. We aimed to identify a crossing-point between cumulative survival and death in the intensive care unit (ICU) of patients with moderate-to-severe ARDS, beyond which the number of survivors would exceed the number of deaths. We hypothesized that this intersection would occur earlier in a successful clinical trial vs. observational studies of moderate/severe ARDS and predict treatment response. We conducted an ancillary study of 1580 patients with moderate-to-severe ARDS managed with lung-protective ventilation to assess the relevance and timing of measuring ICU mortality rates at different time-points during ICU stay. First, we analyzed 1303 patients from four multicenter, observational cohorts enrolling consecutive patients with moderate/severe ARDS. We assessed cumulative ICU survival from the time of moderate/severe ARDS diagnosis to ventilatory support discontinuation within 7-days, 28-days, 60-days, and at ICU discharge. Then, we compared these findings to those of a successful randomized trial of 277 moderate/severe ARDS patients. In the observational cohorts, ICU mortality (487/1303, 37.4%) and 28-day mortality (425/1102, 38.6%) were similar (p = 0.549). Cumulative proportion of ICU survivors and non-survivors crossed at day-7; after day-7, the number of ICU survivors was progressively higher compared to non-survivors. Measures of oxygenation, lung mechanics, and severity scores were different between survivors and non-survivors at each point-in-time (p < 0.001). In the trial cohort, the cumulative proportion of survivors and non-survivors in the treatment group crossed before day-3 after diagnosis of moderate/severe ARDS. In clinical ARDS studies, 28-day mortality closely approximates and may be used as a surrogate for ICU mortality. For patients with moderate-to-severe ARDS, ICU mortality assessment within the first week of a trial might be an early predictor of treatment response.

The PANDORA Study: Prevalence and Outcome of Acute Hypoxemic Respiratory Failure in the Pre-COVID-19 Era.

OBJECTIVES: To establish the epidemiological characteristics, ventilator management, and outcomes in patients with acute hypoxemic respiratory failure (AHRF), with or without acute respiratory distress syndrome (ARDS), in the era of lung-protective mechanical ventilation (MV). DESIGN: A 6-month prospective, epidemiological, observational study. SETTING: A network of 22 multidisciplinary ICUs in Spain. PATIENTS: Consecutive mechanically ventilated patients with AHRF (defined as Pao2/Fio2 ≤ 300 mm Hg on positive end-expiratory pressure [PEEP] ≥ 5 cm H2O and Fio2 ≥ 0.3) and followed-up until hospital discharge. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Primary outcomes were prevalence of AHRF and ICU mortality. Secondary outcomes included prevalence of ARDS, ventilatory management, and use of adjunctive therapies. During the study period, 9,803 patients were admitted: 4,456 (45.5%) received MV, 1,271 (13%) met AHRF criteria (1,241 were included into the study: 333 [26.8%] met Berlin ARDS criteria and 908 [73.2%] did not). At baseline, tidal volume was 6.9 ± 1.1 mL/kg predicted body weight, PEEP 8.4 ± 3.1 cm H2O, Fio2 0.63 ± 0.22, and plateau pressure 21.5 ± 5.4 cm H2O. ARDS patients received higher Fio2 and PEEP than non-ARDS (0.75 ± 0.22 vs 0.59 ± 0.20 cm H2O and 10.3 ± 3.4 vs 7.7 ± 2.6 cm H2O, respectively [p < 0.0001]). Adjunctive therapies were rarely used in non-ARDS patients. Patients without ARDS had higher ventilator-free days than ARDS (12.2 ± 11.6 vs 9.3 ± 9.7 d; p < 0.001). All-cause ICU mortality was similar in AHRF with or without ARDS (34.8% [95% CI, 29.7-40.2] vs 35.5% [95% CI, 32.3-38.7]; p = 0.837). CONCLUSIONS: AHRF without ARDS is a very common syndrome in the ICU with a high mortality that requires specific studies into its epidemiology and ventilatory management. We found that the prevalence of ARDS was much lower than reported in recent observational studies.

[Subcapsular hepatic hematoma: an uncommon complication of endoscopic retrograde cholangiopancreatography]. / Hematoma hepático subcapsular. Una rara complicación de la CPRE.

This report describes the case of a patient who developed a subcapsular hepatic hematoma 48 hours after endoscopic retrograde cholangiopancreatography. She was treated by embolizing the sites of bleeding and by surgically resecting the area. We review the literature and discuss the potential mechanisms that cause this complication.

Listeria monocytogenes inactivation in deboned dry-cured hams by high pressure processing.

The effect of high pressure processing (HPP) on Listeria monocytogenes inactivation on the surface and in the interior of deboned dry-cured ham was investigated. Whole deboned hams were pressurized at 450 MPa for 10 min or 600 MPa for 5 min and stored for 60 d at 4 and 12 °C. In control non-pressurized dry-cured hams, L. monocytogenes counts decreased on the surface throughout refrigerated storage, whereas remained unchanged in the interior of the product. Treatments at 600 MPa reduced L. monocytogenes population by 2 logs on the surface and by 3 logs in the interior of hams. Minor changes in the physicochemical characteristics were found. High water activity in the interior of dry-cured ham might enhance the pathogen inhibition by HPP. Treatment at 600 MPa for 5 min in whole dry-cured ham allowed to reach the Food Safety Objective for L. monocytogenes according to the European and the USDA criteria in case of contamination during deboning.

Impact of Water Activity on the Inactivation and Gene Expression of Listeria monocytogenes during Refrigerated Storage of Pressurized Dry-Cured Ham.

Listeria monocytogenes population and the expression patterns of three virulence (plcA, hly, and iap) and one stress-related (sigB) genes in dry-cured ham with different water activity (aw) values (0.92, 0.88, and 0.84) and treated with high pressure processing (HPP, 450 MPa/10 min and 600 MPa/5 min) were monitored throughout 30 days (d) at 4 °C. The antimicrobial effect of HPP at 600 MPa against L. monocytogenes S4-2 (serotype 1/2b) and S12-1 (serotype 1/2c) was greater in dry-cured ham with aw values of 0.92, with reductions of 2.5 and 2.8 log units, respectively. The efficacy of HPP treatments decreased at lower aw values. Regarding gene expression, L. monocytogenes strains responded differently to HPP. For strain S4-2, the four target genes were generally overexpressed in dry-cured ham immediately after HPP treatments at the three aw values investigated, although the extent of this induction was lower in the samples pressurized at 600 MPa and with aw values of 0.84. For strain S12-1, the expression of all target genes was repressed at the three aw values investigated. The antimicrobial efficacy of HPP against L. monocytogenes could be compromised by low aw values in food products. However, no growth of HPP-survival cells was observed during refrigerated storage in low-aw dry-cured ham, and the overexpression of virulence and stress-related genes decreased.

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.

Neurally adjusted ventilatory assist in acute respiratory failure: a randomized controlled trial.

PURPOSE: We hypothesized that neurally adjusted ventilatory assist (NAVA) compared to conventional lung-protective mechanical ventilation (MV) decreases duration of MV and mortality in patients with acute respiratory failure (ARF). METHODS: We carried out a multicenter, randomized, controlled trial in patients with ARF from several etiologies. Intubated patients ventilated for ≤ 5 days expected to require MV for ≥ 72 h and able to breathe spontaneously were eligible for enrollment. Eligible patients were randomly assigned based on balanced treatment assignments with a computerized randomization allocation sequence to two ventilatory strategies: (1) lung-protective MV (control group), and (2) lung-protective MV with NAVA (NAVA group). Allocation concealment was maintained at all sites during the trial. Primary outcome was the number of ventilator-free days (VFDs) at 28 days. Secondary outcome was all-cause hospital mortality. All analyses were done according to the intention-to-treat principle. RESULTS: Between March 2014 and October 2019, we enrolled 306 patients and randomly assigned 153 patients to the NAVA group and 153 to the control group. Median VFDs were higher in the NAVA than in the control group (22 vs. 18 days; between-group difference 4 days; 95% confidence interval [CI] 0 to 8 days; p = 0.016). At hospital discharge, 39 (25.5%) patients in the NAVA group and 47 (30.7%) patients in the control group had died (between-group difference - 5.2%, 95% CI - 15.2 to 4.8, p = 0.31). Other clinical, physiological or safety outcomes did not differ significantly between the trial groups. CONCLUSION: NAVA decreased duration of MV although it did not improve survival in ventilated patients with ARF.

Antilisterial Effect and Influence on Listeria monocytogenes Gene Expression of Enterocin or Enterococcus faecalis in Sliced Dry-Cured Ham Stored at 7°C.

In this study, we focused on the effect of an enterocin or an Enterococcus faecalis strain added onto sliced dry-cured ham that was artificially inoculated with Listeria monocytogenes and stored at 7°C. The population of L. monocytogenes and the expression of five genes were monitored throughout the storage period. A persistent and a nonpersistent strain were tested, and both were influenced by the presence of the enterocin; both populations were reduced by more than 2 Log CFU/g after 14 days compared with the control, noninoculated ham. The presence of E. faecalis, a bacteriocin-producing lactic acid bacterium, had a less pronounced effect on the viable counts for both strains. Concerning gene expression, a common trend observed for both strains in the presence of enterocin was the down-regulation of genes tested after 30 min of storage at 7°C. For the remainder of the storage period, the expression fluctuated but was mostly reduced. Similarly, the presence of E. faecalis led to an overall down-regulation of genes. The effect on gene expression of both enterocin and E. faecalis was more pronounced on the nonpersistent L. monocytogenes strain. Although the potential of a bacteriocin and a bacteriocin-producing microorganism to control L. monocytogenes was confirmed, this study highlights that gene expression may be influenced and needs to be evaluated when considering such biopreservation interventions.

Neurally adjusted ventilatory assist in patients with acute respiratory failure: study protocol for a randomized controlled trial.

BACKGROUND: Patient-ventilator asynchrony is a common problem in mechanically ventilated patients with acute respiratory failure. It is assumed that asynchronies worsen lung function and prolong the duration of mechanical ventilation (MV). Neurally Adjusted Ventilatory Assist (NAVA) is a novel approach to MV based on neural respiratory center output that is able to trigger, cycle, and regulate the ventilatory cycle. We hypothesized that the use of NAVA compared to conventional lung-protective MV will result in a reduction of the duration of MV. It is further hypothesized that NAVA compared to conventional lung-protective MV will result in a decrease in the length of ICU and hospital stay, and mortality. METHODS/DESIGN: This is a prospective, multicenter, randomized controlled trial in 306 mechanically ventilated patients with acute respiratory failure from several etiologies. Only patients ventilated for less than 5 days, and who are expected to require prolonged MV for an additional 72 h or more and are able to breathe spontaneously, will be considered for enrollment. Eligible patients will be randomly allocated to two ventilatory arms: (1) conventional lung-protective MV (n = 153) and conventional lung-protective MV with NAVA (n = 153). Primary outcome is the number of ventilator-free days, defined as days alive and free from MV at day 28 after endotracheal intubation. Secondary outcomes are total length of MV, and ICU and hospital mortality. DISCUSSION: This is the first randomized clinical trial examining, on a multicenter scale, the beneficial effects of NAVA in reducing the dependency on MV of patients with acute respiratory failure. TRIAL REGISTRATION: ClinicalTrials.gov website ( NCT01730794 ). Registered on 15 November 2012.

Commercial biopreservatives combined with salt and sugar to control Listeria monocytogenes during smoked salmon processing.

Three commercial antimicrobials, applied during the salting stage in the preparation of cold-smoked salmon, were investigated for their effect on the behavior of Listeria monocytogenes. Fresh salmon inoculated with L. monocytogenes INIA 2530 was treated with three bacteriocin-based commercial biopreservatives, which were applied in combination with a salt-sugar mix. The product was kept at 8°C for 7 days. L. monocytogenes grew by approximately 3 log CFU/g in control salmon (without the salt-sugar mix or biopreservatives). Pathogen levels were reduced by the three biopreservatives investigated. After 7 days at 8°C, L. monocytogenes counts in salmon treated with biopreservatives combined with the salt-sugar mix were significantly lower than those observed in salmon treated with only salt and sugar. At the end of storage, salmon treated with biopreservative derived from Pediococcus acidilactici had pathogen levels 3.6 log CFU/g lower than in control salmon (without the salt-sugar mix) and 1.5 log CFU/g lower than in the samples treated with only salt and sugar. The application of commercial biopreservatives to fresh salmon during the dry-salting stage might help control L. monocytogenes growth, thus enhancing the safety of cold-smoked salmon during refrigerated storage.

High pressure treatments on the inactivation of Salmonella Enteritidis and the physicochemical, rheological and color characteristics of sliced vacuum-packaged dry-cured ham.

The effect of high pressure (HP) on Salmonella Enteritidis in sliced dry-cured ham stored under temperature abuse (8°C) during 60d was investigated. After treatment, reductions of S. Enteritidis were 1.06, 2.54 and 4.32 log units in ham treated at 400, 500 and 600MPa for 5min at 12°C, compared to non-pressurized samples. After 60d, counts of S. Enteritidis in ham treated at 400 and 500MPa were 2.56 and 2.66 log units lower than in non-treated ham, whereas the pathogen was only detected after enrichment in ham treated at 600MPa. Lipid oxidation increased with storage and pressurization, whereas total free amino acid contents were similar in HP and control samples after 60d. Dry-cured ham treated at the highest pressures exhibited lower shear resistance, whereas the maximum force to compress the sample was slightly changed. Color (L*, a* and b*) varied with pressurization and storage. Changes induced by HP in dry-cured ham were attenuated during storage.