Biologically synthesized silver nanoparticles as potent antibacterial effective against multidrug-resistant Pseudomonas aeruginosa.

Pseudomonas aeruginosa is one of the most worrisome infectious bacteria due to its intrinsic and acquired resistance against several antibiotics and the recalcitrance of its infections; hence, the development of novel antimicrobials effective against multidrug-resistant P. aeruginosa is mandatory. In this work, silver nanoparticles obtained by green synthesis using a leaf extract and fungi were tested against a battery of clinical strains from cystic fibrosis, pneumonia and burnt patients, some of them with multidrug resistance. Both nanoparticles showed a potent antibacterial effect, causing severe damage to the cell wall, membrane and DNA, and inducing the production of reactive oxygen species. Moreover, the nanoparticles derived from fungi showed synergistic antibacterial effects with the antibiotics meropenem and levofloxacin for some clinical strains and both kinds of nanoparticles were nontoxic for larvae of the moth Galleria mellonella, encouraging further research for their implementation in the treatment of P. aeruginosa infections.

Decreased levels of cathepsin Z mRNA expressed by immune blood cells: diagnostic and prognostic implications in prostate cancer.

Cathepsin Z (CTSZ) is a cysteine protease responsible for the adhesion and migration of both immune and tumor cells. Due to its dual role, we hypothesized that the site of CTSZ expression could be determinant of the pro- or anti-tumorigenic effects of this enzyme. To test this hypothesis, we analyzed CTSZ expression data in healthy and tumor tissues by bioinformatics and evaluated the expression levels of CTSZ mRNA in the blood cells of prostate cancer (PCa) patients by qRT-PCR compared with healthy subjects, evaluating its diagnostic and prognostic implications for this type of cancer. Immune cells present in the blood of healthy patients overexpress CTSZ. In PCa, we found decreased CTSZ mRNA levels in blood cells, 75% lower than in healthy subjects, that diminished even more during biochemical relapse. CTSZ mRNA in the blood cells had an area under the curve for PCa diagnosis of 0.832, with a 93.3% specificity, and a positive likelihood ratio of 9.4. The site of CTSZ mRNA expression is fundamental to determine its final role as a protective determinant in PCa, such as CTSZ mRNA in the blood cells, or a malignant determinant, such as found for CTSZ expressed in high levels by different types of primary and metastatic tumors. Low CTSZ mRNA expression in the total blood is a possible PCa marker complementary to prostate-specific antigen (PSA) for biopsy decisions, with the potential to eliminate unnecessary biopsies.

Decreased levels of cathepsin Z mRNA expressed by immune blood cells: diagnostic and prognostic implications in prostate cancer

Cathepsin Z (CTSZ) is a cysteine protease responsible for the adhesion and migration of both immune and tumor cells. Due to its dual role, we hypothesized that the site of CTSZ expression could be determinant of the pro- or anti-tumorigenic effects of this enzyme. To test this hypothesis, we analyzed CTSZ expression data in healthy and tumor tissues by bioinformatics and evaluated the expression levels of CTSZ mRNA in the blood cells of prostate cancer (PCa) patients by qRT-PCR compared with healthy subjects, evaluating its diagnostic and prognostic implications for this type of cancer. Immune cells present in the blood of healthy patients overexpress CTSZ. In PCa, we found decreased CTSZ mRNA levels in blood cells, 75% lower than in healthy subjects, that diminished even more during biochemical relapse. CTSZ mRNA in the blood cells had an area under the curve for PCa diagnosis of 0.832, with a 93.3% specificity, and a positive likelihood ratio of 9.4. The site of CTSZ mRNA expression is fundamental to determine its final role as a protective determinant in PCa, such as CTSZ mRNA in the blood cells, or a malignant determinant, such as found for CTSZ expressed in high levels by different types of primary and metastatic tumors. Low CTSZ mRNA expression in the total blood is a possible PCa marker complementary to prostate-specific antigen (PSA) for biopsy decisions, with the potential to eliminate unnecessary biopsies.

COVID-19 with and without pneumonia: clinical outcomes in the internal medicine ward / COVID-19 con y sin neumonía: resultados en la sala de medicina interna

Abstract The clinical features of COVID-19 differ substantially upon the presence (or absence) of viral pneumonia. The aim of this article was to describe the clinical characteristics of COVID-19 patients admitted to the Internal Medicine ward, as divided into those with and without pneumonia. This single-center prospective cohort study was conducted in a tertiary teaching public hospital in Buenos Aires City named Hospital General de Agudos Carlos G. Durand. Baseline data collection was performed within 48 hours of admission and patients were followed until discharge or in-hospital death. Epidemiological, clinical, laboratory, and radiological characteristics together with treatment data were obtained from the medical records. Of the 417 included, 243 (58.3%) had pneumonia. Median age was 43 years (IQR:32-57) and 222 (53.2%) were female. The overall crude case-fatality rate was 3.8%. None of the COVID-19 patients without pneumonia developed critical disease, required invasive mechanical ventilation nor died during hospitalization. However, 7 (4%) developed severe disease during follow-up. Among patients with COVID-19 pneumonia, in-hospital mortality rate was 6.6%, severe disease developed in 81 (33.3%), critical disease in 23 (9.5%), and 22 (9.1%) were admitted to the intensive care unit. A largely good prognosis was observed among COVID-19 patients without pneumonia, still, even among this group, unfavorable clinical progression can develop and should be properly monitored. Critical illness among patients with COVID-19 pneumonia was frequent and observed rates from this cohort provide a sound characterization of COVID-19 clinical features in a major city from South America.

Resumen Las características clínicas del COVID-19 difieren sustancialmente según la presencia (o ausencia) de neumonía viral. El objetivo de este artículo fue describir las características clínicas de los pacientes con COVID-19 internados en el servicio de Clínica Médica, divididos en pacientes con y sin neumonía. Fue un estudio de cohorte prospectivo, con base en un único centro, realizado en un hospital público de la ciudad de Buenos Aires: Hospital General de Agudos Carlos G. Durand. La recolección basal de datos se realizó dentro de las 48 horas del ingreso y los pacientes fueron seguidos hasta el alta o la muerte hospitalaria. Las características epidemiológicas, clínicas, de laboratorio y radiológicas junto con los datos del tratamiento se obtuvieron de la historia clínica. De los 417 incluidos, 243 (58.3%) tenían neumonía. La mediana de edad fue de 43 años (RIC: 32-57) y 222 (53.2%) eran mujeres. La tasa global de letalidad fue del 3.8%. Ninguno de los pacientes con COVID-19 sin neumonía desarrolló enfermedad crítica, requirió ventilación mecánica invasiva ni falleció durante la hospitalización. Sin embargo, 7 (4%) desarrollaron enfermedad grave durante el seguimiento. Entre aquellos con neumonía COVID-19, la tasa de mortalidad hospitalaria fue del 6.6%, se desarrolló enfermedad grave en 81 (33.3%), enfermedad crítica en 23 (9.5%) y 22 (9.1%) fueron trasladados a la unidad de cuidados intensivos. Los pacientes con COVID-19 sin neumonía presentaron buen pronóstico; sin embargo, incluso en este grupo, se observaron algunos con progresión clínica desfavorable, por lo que se requirió seguimiento adecuado. En los pacientes con neumonía por COVID-19, el desarrollo de enfermedad crítica fue frecuente y las tasas observadas en esta cohorte proporcionan una caracterización sólida de las características clínicas de los pacientes con COVID-19 en una importante ciudad de América del Sur.

Estudio de cohorte prospectivo de pacientes con COVID-19 hospitalizados en servicio de clínica médica del Hospital Durand Protocolo de estudio / Prospective cohort study of patients with COVID-19 hospitalized in the Internal Medicine ward of Hospital Durand: study protocol

INTRODUCCIÓN: Conocer los predictores de mala evolución en pacientes con Enfermedad por Coronavirus 2019 (COVID-19) permite identificar de forma temprana a los pacientes con peor pronóstico, aportando mejores herramientas a la hora de tomar decisiones clínicas. Se presenta el protocolo de un estudio de cohorte cuyo objetivo principal es identificar factores de riesgo de infección severa, critica y mortalidad en pacientes con COVID-19 internados en el Servicio de Clínica Médica del Hospital Durand (Buenos Aires, Argentina). MÉTODOS: Estudio de cohorte prospectivo con base en un único centro. Se incluirá a todos los pacientes que ingresen al servicio de Clínica Médica con diagnóstico de COVID-19 durante el periodo de estudio. Se recolectarán las características epidemiológicas, clínicas, de laboratorio, radiológicas y los datos de tratamiento, al ingreso y al momento del alta o muerte hospitalaria. El evento final primario es la muerte en la internación; los eventos secundarios son el desarrollo de enfermedad grave y enfermedad crítica, la internación en unidad cerrada y el requerimiento de asistencia respiratoria mecánica.

COVID-19 with and without pneumonia: clinical outcomes in the internal medicine ward.

The clinical features of COVID-19 differ substantially upon the presence (or absence) of viral pneumonia. The aim of this article was to describe the clinical characteristics of COVID-19 patients admitted to the Internal Medicine ward, as divided into those with and without pneumonia. This single-center prospective cohort study was conducted in a tertiary teaching public hospital in Buenos Aires City named Hospital General de Agudos Carlos G. Durand. Baseline data collection was performed within 48 hours of admission and patients were followed until discharge or in-hospital death. Epidemiological, clinical, laboratory, and radiological characteristics together with treatment data were obtained from the medical records. Of the 417 included, 243 (58.3%) had pneumonia. Median age was 43 years (IQR:32-57) and 222 (53.2%) were female. The overall crude case-fatality rate was 3.8%. None of the COVID-19 patients without pneumonia developed critical disease, required invasive mechanical ventilation nor died during hospitalization. However, 7 (4%) developed severe disease during follow-up. Among patients with COVID-19 pneumonia, in-hospital mortality rate was 6.6%, severe disease developed in 81 (33.3%), critical disease in 23 (9.5%), and 22 (9.1%) were admitted to the intensive care unit. A largely good prognosis was observed among COVID-19 patients without pneumonia, still, even among this group, unfavorable clinical progression can develop and should be properly monitored. Critical illness among patients with COVID-19 pneumonia was frequent and observed rates from this cohort provide a sound characterization of COVID-19 clinical features in a major city from South America.

Las características clínicas del COVID-19 difieren sustancialmente según la presencia (o ausencia) de neumonía viral. El objetivo de este artículo fue describir las características clínicas de los pacientes con COVID-19 internados en el servicio de Clínica Médica, divididos en pacientes con y sin neumonía. Fue un estudio de cohorte prospectivo, con base en un único centro, realizado en un hospital público de la ciudad de Buenos Aires: Hospital General de Agudos Carlos G. Durand. La recolección basal de datos se realizó dentro de las 48 horas del ingreso y los pacientes fueron seguidos hasta el alta o la muerte hospitalaria. Las características epidemiológicas, clínicas, de laboratorio y radiológicas junto con los datos del tratamiento se obtuvieron de la historia clínica. De los 417 incluidos, 243 (58.3%) tenían neumonía. La mediana de edad fue de 43 años (RIC: 32-57) y 222 (53.2%) eran mujeres. La tasa global de letalidad fue del 3.8%. Ninguno de los pacientes con COVID-19 sin neumonía desarrolló enfermedad crítica, requirió ventilación mecánica invasiva ni falleció durante la hospitalización. Sin embargo, 7 (4%) desarrollaron enfermedad grave durante el seguimiento. Entre aquellos con neumonía COVID-19, la tasa de mortalidad hospitalaria fue del 6.6%, se desarrolló enfermedad grave en 81 (33.3%), enfermedad crítica en 23 (9.5%) y 22 (9.1%) fueron trasladados a la unidad de cuidados intensivos. Los pacientes con COVID-19 sin neumonía presentaron buen pronóstico; sin embargo, incluso en este grupo, se observaron algunos con progresión clínica desfavorable, por lo que se requirió seguimiento adecuado. En los pacientes con neumonía por COVID-19, el desarrollo de enfermedad crítica fue frecuente y las tasas observadas en esta cohorte proporcionan una caracterización sólida de las características clínicas de los pacientes con COVID-19 en una importante ciudad de América del Sur.

Assessing the relationship between organic farming practices and microbiological characteristics of organic lettuce varieties (Lactuca sativa L.) grown in Sao Paulo, Brazil.

AIMS: This study aimed to gather information on farming practices employed in organic lettuce fields in Sao Paulo, Brazil and associate these practices with the microbiological characteristics of the products. METHODS AND RESULTS: Practices were surveyed using a questionnaire applied in ten farms, where 200 heads of lettuce were collected and submitted to enumeration of total coliforms and generic Escherichia coli and tested for Salmonella spp. using culture and molecular (qPCR) methods. Based on the responses, the farms could be clustered in two groups: group 1, comprised by six farms, where chicken manure was used as fertilizer in most of them and the composting process was not performed on site; and group 2, comprised by four farms, where other types of fertilizer were used, and the composting process was performed on site. Generic E. coli was detected in 56 (28%) samples, with an average of 1·1 ± 0·7 log MPN per g. Salmonella DNA was detected in two (1%) samples by qPCR. CONCLUSIONS: The prevalence and bacterial loads of generic E. coli, and the occurrence of Salmonella, even at low populations undetectable by conventional culture methods, highlight the need for control measures during farming practices to reduce microbial contamination and risks of foodborne illnesses. These measures include the use of properly composted manure and appropriate washing procedures for leafy vegetables before consumption. SIGNIFICANCE AND IMPACT OF THE STUDY: The obtained data contribute to a better understanding of the farming practices of organically grown lettuces in Sao Paulo, Brazil.

Bacteriocins of Gram-positive bacteria having activity spectra extending beyond closely-related species.

Bacteriocins are bacterially-produced antimicrobial peptides that have killing activity principally against other relatively closely-related bacteria. Some bacteriocins of the lactic acid bacteria (LAB) have for many years been extensively applied in food biopreservation. However, especially during the last decade, a number of reports have appeared about unanticipated extensions to the generally rather narrow anti-bacterial activity spectrum of some of the LAB bacteriocins and novel applications have been proposed for bacteriocins ranging from controlling the growth of an increasingly-heterogeneous variety of pathogens, including Gram-negative multidrug resistant bacteria, viruses, yeasts, and in particular, difficult to control Mycobacterium spp., to their potential application as anticancer agents. How best can we assess this now rapidly-accumulating stream of reports on potential future applications of bacteriocins? Where is the line between realistic, science-based proposals and highly-speculative fiction and what are the 'critical points' that might help us to draw this line? In this review, we have attempted to analyse a selection of the presently-available data concerning relatively 'unorthodox' (i.e. beyond food preservation) applications of bacteriocins, and, by utilising our set of 'critical points', we endeavour to identify essential or/and missing information that appear crucial for success of the proposed applications.

Development of an oxidative stress sensor in live bacteria using the optimized HyPer2 protein.

Oxidative stress is a key regulator in many cellular processes but also an important burden for living organisms. The source of oxidative damage usually is difficult to measure and assess with analytical tools or chemical indicators. One major limitation is to discriminate the presence of secondary oxidant molecules derived from the cellular metabolism after exposure to the oxidant or the scavenging capacity of reactive oxygen species by cells. Using a whole-cell reporter system based on an optimized HyPer2 protein for Escherichia coli expression, we demonstrate that, as previously shown for eukaryotic organisms, the effect at the transcriptional level of hydrogen peroxide can be monitored in vivo using flow cytometry of bacterial cells without the need of a direct analytical measurement. In this approach, we generated two different HyPer2 expression systems, one that is induced by IPTG and a second one that is induced by oxidative stress responsive promoters to control the expression of the HyPer2 protein and the exposure of higher H2O2 concentrations that has been shown to activate oxidative response genes. Both systems showed that the pathway that leads to the generation of H2O2 in vivo can be traced from H2O2 exposure. Our results indicate that hydrogen peroxide pulses can be readily detected in E. coli cells by a defined fluorescence signature that is H2O2 concentration-dependent. Our findings indicate that although less sensitive than purified protein or expressed in eukaryotic cells, HyPer2 is a good bacterial sensor for H2O2. As proof of concept, this system was used to trace the oxidative capacity of Toluidine Blue O showing that oxidative stress and redox imbalance is generated inside the cell. This system is expanding the repertoire of whole cell probes available for tracing cellular stress in bacteria.

Brazilian artisanal ripened cheeses as sources of proteolytic lactic acid bacteria capable of reducing cow milk allergy.

AIM: The objective was to obtain lactic acid bacteria (LAB) capable of hydrolysing immunoreactive proteins in milk, to optimize the hydrolysis, to determine the proteolysis kinetics and to test the safety of the best hydrolytic strain. METHODS AND RESULTS: Brazilian cheese was used as source of LAB capable of hydrolysing main milk allergens. Proteolytic isolates were submitted to RAPD-PCR for the characterization of clonal diversity. Optimized hydrolysis was strain and protein fraction dependent. 16S rDNA sequencing identified three proteolytic strains: Enterococcus faecalis VB43, that hydrolysed αS1 -, αS2 - and ß-caseins, α-lactalbumin and ß-lactoglobulin (partial hydrolysis), and Pediococcus acidilactici VB90 and Weissella viridescens VB111, that caused partial hydrolysis of αS1 - and αS2 -caseins. Enterococcus faecalis VB43 tested negative for virulence genes asa1, agg, efaA, hyl, esp, cylLL and cylLS but positive for genes ace and gelE. Ethylenediamine tetra-acetic acid inhibited the proteolysis, indicating that the main proteases of E. faecalis VB43 are metalloproteases. CONCLUSION: Brazilian artisanal cheese is a good source of LAB capable of hydrolysing allergenic proteins in milk. One isolate (E. faecalis VB43) presented outstanding activity against these proteins and lacked most of the tested virulence genes. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterococcus faecalis VB43 presents good potential for the manufacture of hypoallergenic dairy products.

Rubella Seropositivity in Pregnant Women After Vaccination Campaign in Brazil's Federal District.

Rubella is an acute viral disease that usually does not generate sequels; however, in pregnant women the infection can cause serious abnormalities to fetuses, which are collectively called congenital rubella syndrome. In Brazil, population immunization was started in 1992, but few epidemiological studies have been conducted to assess vaccination coverage and seroconversion since then. The aim of this work is to evaluate the seropositivity of pregnant women to rubella virus after vaccination campaign was carried out in 2008. Serological tests for rubella diagnosis were performed in 87 pregnant women who attended the University of Brasilia Hospital, Federal District, Brazil. Antirubella IgG antibodies were detected in 83 out of 87 pregnant women (95.4%), with an age-independent seroprevalence. Only one woman was positive in IgM serological tests. Our data suggest high levels of vaccination coverage and antirubella immunization in the Brazil Federal District population.

Soymilk fermentation by Enterococcus faecalis VB43 leads to reduction in the immunoreactivity of allergenic proteins ß-conglycinin (7S) and glycinin (11S).

Food allergies represent a serious problem affecting human health and soy proteins rank among the most allergenic proteins from food origin. The proteolytic enzymes produced by lactic acid bacteria (LAB) can hydrolyse the major allergens present in soybean, reducing their immunoreactivity. Many studies have reported the ability of LAB to ferment soy-based products; while the majority of them focus on the improvement of the sensory characteristics and functionality of soy proteins, a lack of information about the role of lactic fermentation in the reduction of immunoreactivity of these proteins exists. The aim of the present study was to evaluate the capability of the proteolytic strain Enterococcus faecalis VB43 to hydrolyse the main allergenic proteins present in soymilk and to determine the immunoreactivity of the obtained hydrolysates. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) results of fermented soymilk demonstrated complete hydrolysis of the ß-subunit from ß-conglycinin and the acidic polypeptide from glycinin. Reversed phase high performance liquid chromatography (RP-HPLC) analysis of the peptides released after hydrolysis revealed the appearance of new peptides and the disappearance of non-hydrolysed proteins, indicating extensive hydrolysis of the substrate. Results from competitive enzyme-linked immunosorbent assay (ELISA) tests clearly indicated a reduction in the immunoreactivity (more than one logarithmic unit) in the fermented sample as compared to the non-fermented control. Our results suggest that the soymilk fermented by E. faecalis VB43 may induce lower allergic responses in sensitive individuals. The strain E. faecalis VB43 may be considered as an excellent candidate to efficiently reduce the immunoreactivity of soymilk proteins.

Características de los casos de violencia contra la mujer de Asunción y Gran Asunción, Paraguay (2008-2012) / Characteristics of cases of violence against women from Asunción and Gran Asunción, Paraguay (2008-2012)

La violencia contra la mujer constituye"todo acto de violencia basado en el género que tiene como resultado posible o real un daño físico, sexual o psicológico", constituyendo un problema de violación de los derechos humanos y de salud pública. El objetivo fuedescribir las características de los casos de violencia contra las mujeres provenientes de Asunción y Gran Asunción, registrados en el Museo de la Justicia, desde el 1 de enero del 2008 al 30 de junio del 2012. Fueron analizadas 1.722 fichas de los juzgados de paz de Asunción y Gran Asunción, remitidos al Museo de la Justicia.Elpromedio de edad de la víctima fue de 35 ± 11,5 años (rango 15 a 87); victimarios 37 ± 10,6 años (rango 14 a 87).Tanto las víctimas como los agresores eran de Asunción, casados, estudios primarios. Las víctimas eran amas de casa 55,1%, (949) y los agresores dependientes (44,9%, 773). El 56,1% (966) tenían hijos y de estos 39,7% (683) sufrieron algún tipo de agresión. El 63,4%(1.092) recibió más de un tipo de violencia, siendo la psíquica las más frecuente (25%, 430). El 50,3%(867) recibió agresiones con una frecuencia de 1 a 5 veces en el último año, 50,2% (864) realizó denuncias previas. Otros factores fueron el alcohol 24,9% (428) y factores culturales como los celos, el machismo, etc. Se encontraron diferencias estadísticamente significativas con la profesión y la violencia. La violencia contra la mujer constituye un grave problema que debe ser visualizado para su prevención. Palabras claves: Violencia contra la mujer; Violencia; mujer; Asunción; Gran Asunción.

Violence against women constitutes in "any genderbased act of violence that results in physical, sexual or psychological harm" resulting in the violation of human rights and public health. The objective was to describe the characteristics of cases of violence against women from Asunción and Gran Asunción, registered in the Museum of Justice, from January 1, 2008 to June 30, 2012. 1,722 files sent to the Museum of Justice were analyzed from Asuncion and Gran Asunción's peace courts. The average age of the victims was between 35 ± 11.5 years (range 15-87); perpetrators 37 ± 10.6 years (range 14 to 87). Both the victims and the perpetrators were of Asunción, married, primary studies. The victims were housewives (55.1%, 949) and the dependent aggressors (44.9%, 773). 56.1% (966) had children and of these, 39.7% (683) suffered some form of aggression. 63.4% (1,092) received more than one type of violence, being the psychic the most frequent one (25%, 430). 50.3% (867) received assaults with a frequency of 15 times in the last year, 50.2% (864) made previous complaints. Other factors were alcohol 24.9% (428) and cultural factors such as jealousy, male chauvinism, etc. Statistically significant differences were found with the profession and violence. Violence against women is a serious problem that must be visualized for its prevention. Key words: Violence against women; violence; woman; Asuncion; Gran Asunción.

Assessing the effect of sodium dichloroisocyanurate concentration on transfer of Salmonella enterica serotype Typhimurium in wash water for production of minimally processed iceberg lettuce (Lactuca sativa L.).

UNLABELLED: This study evaluated the impact of sodium dichloroisocyanurate (5, 10, 20, 30, 40, 50 and 250 mg l(-1) ) in wash water on transfer of Salmonella Typhimurium from contaminated lettuce to wash water and then to other noncontaminated lettuces washed sequentially in the same water. Experiments were designed mimicking the conditions commonly seen in minimally processed vegetable (MPV) processing plants in Brazil. The scenarios were as follows: (1) Washing one inoculated lettuce portion in nonchlorinated water, followed by washing 10 noninoculated portions sequentially. (2) Washing one inoculated lettuce portion in chlorinated water followed by washing five noninoculated portions sequentially. (3) Washing five inoculated lettuce portions in chlorinated water sequentially, followed by washing five noninoculated portions sequentially. (4) Washing five noninoculated lettuce portions in chlorinated water sequentially, followed by washing five inoculated portions sequentially and then by washing five noninoculated portions sequentially in the same water. Salm. Typhimurium transfer from inoculated lettuce to wash water and further dissemination to noninoculated lettuces occurred when nonchlorinated water was used (scenario 1). When chlorinated water was used (scenarios 2, 3 and 4), no measurable Salm. Typhimurium transfer occurred if the sanitizer was ≥10 mg l(-1) . Use of sanitizers in correct concentrations is important to minimize the risk of microbial transfer during MPV washing. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, the impact of sodium dichloroisocyanurate in the wash water on transfer of Salmonella Typhimurium from inoculated lettuce to wash water and then to other noninoculated lettuces washed sequentially in the same water was evaluated. The use of chlorinated water, at concentration above 10 mg l(-1) , effectively prevented Salm. Typhimurium transfer under several different washing scenarios. Conversely, when nonchlorinated water was used, Salm. Typhimurium transfer occurred in up to at least 10 noninoculated batches of lettuce washed sequentially in the same water.

In vitro fermentation of prebiotic carbohydrates by intestinal microbiota in the presence of Lactobacillus amylovorus DSM 16998.

The aim of this study was to evaluate the assimilation of the prebiotics fructooligosaccharides (FOS), galactooligosaccharides (GOS), and Konjac glucomannan oligosaccharides (KGMO) by three human (H1, H2 and H3) and pig (P1, P2 and P3) faecal microbiotas in the presence of the potentially probiotic strain Lactobacillus amylovorus DSM 16698, using an in vitro batch fermentation model. Total bacteria and L. amylovorus populations were quantified using qPCR and biochemical features (pH, production of short chain fatty acids (SCFA), lactate, ammonia, and carbohydrate assimilation) were determined. L. amylovorus did not have a competitive advantage under in vitro conditions, reflected by its reduced relative abundance during fermentation despite the carbohydrate sources added. Pig microbiota sustained more stable probiotic counts. Intermittently produced lactate was possibly assimilated by the microbiota and converted to other SCFA as the carbohydrates were assimilated, with H3 probably having a methanogenic metabolism with high lactate and acetate consumption except in the presence of FOS, which assimilation resulted in the highest total SCFA for this volunteer. Addition of FOS also resulted in lower pH and ammonia, which might have been used as nitrogen source by pig microbiota. KGMO needed longer fermentation periods to be completely assimilated by both human and porcine faecal microbiotas. Overall, our results reinforce the notion that care must be taken when generalising the effects claimed for a given probiotic or potentially probiotic strain, including the combination with different prebiotic substrates, since they may vary considerably among individuals, which is important when studying potentially pro- and prebiotic combinations for application as functional foods and feed ingredients.

Purification and characterization of the bacteriocin produced by Lactobacillus sakei MBSa1 isolated from Brazilian salami.

AIMS: The study aimed at determining the biochemical characteristics of the bacteriocin produced by Lactobacillus sakei MBSa1, isolated from salami, correlating the results with the genetic features of the producer strain. METHODS AND RESULTS: Identification of strain MBSa1 was performed by 16S rDNA sequencing. The bacteriocin was tested for spectrum of activity, heat and pH stability, mechanism of action, molecular mass and amino acid sequence when purified by cation-exchange and reversed-phase HPLC. Genomic DNA was tested for bacteriocin genes commonly present in Lact. sakei. Bacteriocin MBSa1 was heat-stable, unaffected by pH 2·0 to 6·0 and active against all tested Listeria monocytogenes strains. Maximal production of bacteriocin MBSa1 (1600 AU ml(-1)) in MRS broth occurred after 20 h at 25°C. The molecular mass of produced bacteriocin was 4303·3 Da, and the molecule contained the SIIGGMISGWAASGLAG sequence, also present in sakacin A. The strain contained the sakacin A and curvacin A genes but was negative for other tested sakacin genes (sakacins T-α, T-ß, X, P, G and Q). CONCLUSIONS: In the studied conditions, Lact. sakei MBSa1 produced sakacin A, a class II bacteriocin, with anti-Listeria activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The study covers the purification and characterization of the bacteriocin produced by a lactic acid bacteria isolated from salami (Lact. sakei MBSa1), linking genetic and expression information. Its heat-resistance, pH stability in acid conditions (pH 2·0-6·0) and activity against L. monocytogenes food isolates bring up a potential technological application to improve food safety.

In vitro study of beneficial properties and safety of lactic acid bacteria isolated from Portuguese fermented meat products.

Many lactic acid bacteria produce bacteriocins with a rather broad spectrum of inhibition, which could offer potential applications in food preservation. Bacteriocin production by starter cultures may bring advantage to these strains in competitive interactions with pathogenic bacteria from the food matrix. The objective of this study was to determine the safety of beneficial strains (Lactobacillus plantarum ST202Ch and ST216Ch, Enterococcus faecium ST211Ch, and Lactobacillus sakei ST22Ch, ST153Ch and ST154Ch) previously isolated from fermented meat products and characterised as bacteriocin producers. Auto-aggregation was strain-specific, and values of 28.97, 27.86 and 28.56% were recorded for L. sakei ST22Ch, ST153Ch and ST154Ch, respectively, 16.95 and 14.58% for L. plantarum ST202Ch and ST216Ch, respectively, and 12.77% for E. faecium ST211Ch. Various degrees of co-aggregation between 28.85 and 44.76% for Listeria monocytogenes 211 and 409, and between 23.60 to 34.96% for E. faecium ATCC 19443 were observed. According to the results of the diffusion method, the studied strains demonstrated susceptibility to penicillin G, ampicillin, amoxicillin, amoxicillin/clavulonic acid, imipenem, linezolid, and tetracycline. In addition, the susceptibility of the six strains to various non-antibiotic commercial drugs was examined. Production of ß-galactosidase by L. sakei ST22Ch, ST153Ch and ST154Ch, L. plantarum ST202Ch and ST216Ch, and E. faecium ST211Ch was confirmed by employing sterile filter paper discs impregnated with o-nitrophenyl-ß-D-galactopyranose. A statistically significant (P<0.001) inhibition of Mycobacterium tuberculosis growth by bacteriocins produced by L. plantarum ST202Ch (38.3%) and ST216Ch (48.6%), L. sakei ST153Ch (16.2%) and ST154Ch (16.1%), and E. faecium ST211Ch (21.7%) was observed. As determined by the polymerase chain reaction, the tested strains showed a low virulence gene profile.

Role of nicotine on cognitive and behavioral deficits in sepsis-surviving rats.

Sepsis and its complications are important causes of mortality in intensive care units and sepsis survivors may present long-term cognitive and emotional impairments, including memory deficits and anxiety symptoms. In the present study, we investigated whether repeated nicotine administration can affect the behavioral changes in sepsis-surviving rats. Male Wistar rats were divided in two groups: sham-operated and experimental sepsis induced by cecal ligation and puncture (CLP). The animals were injected subcutaneously with nicotine (0.1 mg/kg) or vehicle once a day during 1 week before and/or 1 week after sepsis induction. Thirty minutes after the last administration (i.e., 7 days after surgery), the animals were tested in the open field, elevated plus-maze and step-down inhibitory avoidance tasks. The repeated nicotine treatment did not affect the survival rate in the sepsis group (50%). Moreover, no significant changes on locomotor activity were observed in the sepsis group while the treatment with nicotine during 1 week after surgery reduced the locomotion of sepsis-surviving rats in the open field. It is important to note that both schedules of nicotine treatment (prior and/or after CLP) improved the sepsis-induced anxiogenic-like responses. Interestingly, nicotine was able to improve short- and long-term inhibitory avoidance memory impairments, observed in sepsis survivors, only when administered during 2 consecutive weeks (i.e., prior and after CLP). Taken together, these results indicate that repeated nicotine administration does not alter the survival rate in rats submitted to CLP and provide new evidence that nicotine can improve long-lasting memory impairments and anxiogenic-like responses in sepsis-surviving animals.

Isolation and characterization of a nisin-like bacteriocin produced by a Lactococcus lactis strain isolated from charqui, a Brazilian fermented, salted and dried meat product.

A Lactococcus lactis subsp. lactis strain (L. lactis 69) capable to produce a heat-stable bacteriocin was isolated from charqui, a Brazilian fermented, salted and sun-dried meat product. The bacteriocin inhibited, in vitro, Listeria monocytogenes, Staphylococcus aureus, several lactic acid bacteria isolated from foods and spoilage halotolerant bacteria isolated from charqui. The activity of the bacteriocin was not affected by pH (2.0-10.0), heating (100 °C), and chemical agents (1% w/v). Treatment of growing cells of L. monocytogenes ScottA with the cell-free supernatant of L. lactis 69 resulted in complete cell inactivation. L. lactis 69 harbored the gene for the production of a nisin-like bacteriocin, and the amino acid sequence of the active peptide was identical to sequences previously described for nisin Z. However, differences were observed regarding the leader peptide. Besides, the isolate was able to survive and produce bacteriocins in culture medium with NaCl content up to 20%, evidencing a potential application as an additional hurdle in the preservation of charqui.

Bacteriocinogenic and virulence potential of Enterococcus isolates obtained from raw milk and cheese.

AIMS: To provide molecular and phenotypical characterization of Enterococcus isolates obtained from raw milk and cheese, regarding their bacteriocinogenic and virulence activity. METHODS AND RESULTS: Forty-three bacteriocinogenic enterococci isolates were identified by 16s rDNA, fingerprinted by RAPD-PCR analysis and tested by PCR for the presence of genes for lantibiotics (lanM, lanB and lanC) and enterocins (entA, entB, entP, entL50AB and entAS48) and by phenotypical methods for bacteriocin production and inhibitory spectrum. Also, the virulence of the isolates was evaluated by PCR for genes gelE, hyl, asa1, esp, cylA, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc and by phenotypical tests for gelatinase, lipase, DNAse and α- and ß-haemolysis. Most isolates (93·0%) harboured at least one lantibiotic or enterocin gene and were positive for several tested virulence genes, mainly asa1 (100%), gelE (93·0%) and efaA (83.7%). 53.5% of the isolates presented ß-haemolysis [corrected]. CONCLUSIONS: Enterococcus spp. isolates presented an interesting potential application for food preservation because of bacteriocin production; however, virulence-related genes were identified in all RAPD profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrated the contradictory characteristics of the tested Enterococcus isolates: they presented a good potential for application in food biopreservation but contained several virulence factors.