Effect of enterocins against methicillin-resistant animal-derived staphylococci.

The occurence and spread of animal-derived methicillin resistant staphylococci (MRS) worldwide is a current problem, especially due to their increasing incidence in food animals and their products, with possible contamination of food consumers and handlers. Staphylococci isolated from animals (n = 123) were identified with MALDI-TOF mass spectrometry and screened for methicillin/oxacillin/cefoxitin resistance (MR) using the disk diffusion method. Twenty-three phenotypically MRS strains were analysed using PBP2' Latex Agglutination Test Kit to confirm the phenotypic MR and PCR was performed for mecA gene detection; mecA gene positive strains were furtherly confirmed by means of sequencing. The susceptibility of MRS to 11 partially-purified enterocins (Ent) produced by E. faecium, E. durans and E. mundtii strains of animal, feed/food and environmental origin was checked using agar spot tests. Out of 23 MRS, PBP testing confirmed MR in 17 strains. Three Staphylococcus epidermidis and one S. vitulinus were mecA positive. The majority of MRS, including two mecA gene-positive strains S. epidermidis R44/1 and P3/Tr2a, were susceptible to the tested enterocins, mainly to Ent7420, EntA(P)/EK13, Ent412, Ent55 and Ent9296 (in the range 100 - 12,800 AU/mL). The most susceptible strains appeared to be the mecA gene-positive S. epidermidis SE R44/1 and SE P3/Tr2a strains, inhibited by eight enterocins out of 11 tested (100-200 AU/mL). Only four strains (including mecA gene positive S. epidermidis SE P3/Tr1 and S. vitulinus SV K12PL/1) were resistant to the tested antimicrobial substances. These results indicate that the enterocins used offer a promising option for prevention and treatment of bacterial infection caused by MRS in animals.

In vitro and in silico approach for characterization of antimicrobial peptides from potential probiotic cultures against Staphylococcus aureus and Escherichia coli.

The focus of the present study was to characterize antimicrobial peptide produced by potential probiotic cultures of Enterococcus durans DB-1aa (MCC4243), Lactiplantibacillus plantarum Cu2-PM7 (MCC4246) and Limosilactobacillus fermentum Cu3-PM8 (MCC4233) against Staphylococus aureus MTCC 96 and Escherichia coli MTCC118. The growth kinetic assay revealed 24 h of incubation to be optimum for bacteriocin production. The partially purified compound of all the three selected cultures after ion-exchange chromatography was found to be thermoresistant and stable under a wide range of pH. The compound was sensitive to proteinase-K, but resistant to trypsin, α-amylase and lipase. Comparatively, bacteriocins from L. fermentum Cu3-PM8 and L. plantarum Cu2-PM7 showed higher stability under studied parameter, hence was taken up for further investigation. The apparent molecular weight of bacteriocin from L. fermentum MCC4233 and L. plantarum MCC4246 was found to be 3.5 kDa. Further, plantaricin gene from MCC4246 was characterized in silico. The translated partial amino acid sequence of the plnA gene in MCC4246 displayed 48 amino acids showing 100 % similarity with plantaricin A of Lactobacillus plantarum (WP_0036419). The sequence revealed 7 ß sheets, 6 α sheets, 6 predicted coils and 9 predicted turns. The predicted properties of the peptide included an isoelectric point of 10.82 and a hydrophobicity of 48.6 %. The molecular approach of using Geneious Prime software and protein prediction data base for characterization of bacteriocin is novel and predicts "KSSAYSLQMGATAIKQVKKLFKKWGW" to be a peptide responsible for antimicrobial activity. The study provides information about a broad spectrum bacteriocin in native probiotic culture and paves a way towards its application in functional foods as a biopreservative agent.

Isolation and Identification of Dominant Bacteria from Raw Donkey Milk Produced in a Region of Morocco by QIIME 2 and Evaluation of Their Antibacterial Activity.

Recently, the interest in donkey milk has increased considerably because it proved high nutritive and functional values of their ingredients. Its chemical composition is widely studied, but its microbiota, especially lactic acid bacteria, remains less studied. This study focuses on analyzing, isolating, and identifying lactic acid bacteria and evaluating their capacity to produce biomolecules with antibacterial activity. Among 44 strains identified, 43 are Gram-positive, and most are catalase-negative and cocci-shaped. Five strains were selected to evaluate their antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli. Different induction methods allowed to amplify the antibacterial effects against these pathogenic strains.

Attenuated Total Reflection Fourier Transform Infrared Spectroscopy combined with chemometric modelling for the classification of clinically relevant Enterococci.

AIMS: Attenuated Total Reflection Fourier Transform Infrared (ATR-FT-IR) Spectroscopy and chemometric modelling, including soft independent modelling by class analogy (SIMCA), partial least squares discriminant analysis (PLS-DA) and support vector machine (SVM), were applied to attempt to discriminate 60 clinical isolates of Enterococcus faecium and Enterococcus faecalis and hence evaluate the performance of the spectroscopic approach in identifying enterococci infections. METHODS AND RESULTS: The bacterial samples were identified by polymerize chain reaction (PCR) amplification and their ATR-FT-IR spectra acquired. Spectra were processed to the second derivative using the Savitzky-Golay algorithm and normalized using extended multiplicative signal correction employing the UnscramblerX (CAMO, Norway) software package. Multivariate classification models and their performance were evaluated using Cohen's Kappa coefficient. Principal component analysis (PCA) score plots showed separate clusters of spectra related to membership to E. faecium and E. faecalis, with this explained by bands assigned to PO2 (1230 cm-1 ), P-O-C (1114 cm-1 ), monosubstituted alkene (997, 987 cm-1 ) and C-O (1070, 1055, 1036 cm-1 ) corresponding to teichoic acids, polysaccharides and peptidoglycan from the cell wall in PCA and PLS-DA loading plots. The best classification model for E. faecium and E. faecalis is SVM, indicating via highest Kappa score. The classification coefficient between SIMCA, PLS-DA, SVM and PCR as reference method were 0·59, 0·9 and 1, respectively, shown as the Kappa scores. CONCLUSIONS: The main spectral differences observed between the two clinically relevant enterococci species were associated with changes in the teichoic acid content of cell walls. With regard to the binary classification method, SVM was found to be the best performing classification model, providing the highest correlation with the PCR results. SIGNIFICANCE AND IMPACT OF THE STUDY: The study shows that ATR-FT-IR spectroscopy in combination with chemometric modelling can be applied for the phenotypic identification and discrimination of clinically relevant and similar enterococcal species.

Photoinactivation results of Enterococcus moraviensis with blue and violet light suggest the involvement of an unconsidered photosensitizer.

Microorganisms can be photoinactivated with 405 and 450 nm irradiation, due to endogenous photosensitizers, which absorb light of these wavelengths and generate reactive oxygen species that destroy the cells from within. The photosensitizers assumed to be responsible are porphyrins in the spectral region around 405 nm and flavins at about 450 nm. The aim of this study was to investigate this hypothesis on enterococci, considering that they do not contain porphyrins. In photoinactivation experiments with Enterococcus moraviensis, 405 nm and 450 nm irradiation both led to a reduction of the bacterial concentration by several orders of magnitude with 405 nm irradiation being much more efficient. The measurement and analysis of the fluorescence spectra revealed no signs of porphyrins whereas flavins seemed to be rapidly converted to lumichrome by 405 nm radiation. Therefore, probably none of the usual suspects, porphyrins and flavins, was responsible for the photoinactivation of Enterococcus moraviensis during 405 nm irradiation. Fluorescence experiments revealed the spectra of lumichrome and NADH, which are both known photosensitizers. Presumably, one of them or both were actually involved here. As NADH and flavins (and therefore their photodegradation product lumichrome) are abundant in all microorganisms, they are probably also involved in 405 nm photoinactivation processes of other species.

Bacteriophage-receptor binding proteins for multiplex detection of Staphylococcus and Enterococcus in blood.

Healthcare-associated infections (HCAIs) affect hundreds of millions of patients, representing a significant burden for public health. They are usually associated to multidrug resistant bacteria, which increases their incidence and severity. Bloodstream infections are among the most frequent and life-threatening HCAIs, with Enterococcus and Staphylococcus among the most common isolated pathogens. The correct and fast identification of the etiological agents is crucial for clinical decision-making, allowing to rapidly select the appropriate antimicrobial and to prevent from overuse and misuse of antibiotics and the consequent increase in antimicrobial resistance. Conventional culture methods are still the gold standard to identify these pathogens, however, are time-consuming and may lead to erroneous diagnosis, which compromises an efficient treatment. (Bacterio)phage receptor binding proteins (RBPs) are the structures responsible for the high specificity conferred to phages against bacteria and thus are very attractive biorecognition elements with high potential for specific detection and identification of pathogens. Taking into account all these facts, we have designed and developed a new, fast, accurate, reliable and unskilled diagnostic method based on newly identified phage RBPs and spectrofluorometric techniques that allows the multiplex detection of Enterococcus and Staphylococcus in blood samples in less than 1.5 hr after an enrichment step.

Species identification of Enterococcus spp: Whole genome sequencing compared to three biochemical test-based systems and two Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) systems.

AIM: Here, we evaluated the performance of two commercial MALDI-TOF MS systems and three biochemical-based systems and compared them to WGS as the gold standard for identifying isolates of vancomycin-resistant enterococci (VRE). METHODS: A total of 87 VRE clinical isolates were included. The mass spectrometers were the Microflex system with Biotyper software 3.1 and the Vitek MS system. The biochemical-based systems included the Vitek 2, Phoenix, and MicroScan WalkAway systems. WGS was performed on an Illumina MiSeq instrument using the MiSeq v3 reagent kit. Vancomycin resistance was determined according to CLSI criteria. RESULTS: Among the 87 VRE, 71 and 16 were identified as Enterococcus faecium and Enterococcus faecalis by WGS. All 71 E faecium were correctly identified by both mass spectrometers, as well as the Vitek 2 and Phoenix instruments. However, only 51 E faecium isolates were correctly identified by the MicroScan system. The most frequent misidentification was Enterococcus casseliflavus (n = 20). For vancomycin-resistant E faecium, the Microflex Biotyper system had the highest sensitivity (85.54%), and all instruments (except for the Microscan) had a 100% specificity and PPV. Up to 87% of E faecalis isolates were misidentified by VITEK MS and VITEK2, 81% by Microscan and Phoenix, and 75% by Bruker biotyper. CONCLUSION: As the coverage of type strain-genome sequence database continues to grow and the cost of DNA sequencing continues to decrease, genome-based identification can be a useful tool for diagnostic laboratories, with its superior accuracy even over MALDI-TOF and database-driven operations.

An eco-friendly synthesis of Enterococcus sp.-mediated gold nanoparticle induces cytotoxicity in human colorectal cancer cells.

Gold nanoparticles (AuNPs) have become frequently used materials in biotechnological and biomedical applications including cancer. They can be commonly synthesized by biological and chemical methods. In the present study, we synthesized Enterococcus-mediated AuNPs and evaluated their cytotoxicity in human colorectal cancer cell line (HT-29). AuNPs are synthesized intracellularly using Enterococcus sp. RMAA. Characterization of AuNPs has done using UV spectrophotometry and transmission electron microscope. Cytotoxicity was evaluated by MTT assay. Intercellular reactive oxygen species (ROS) expression and apoptosis-related morphology were evaluated by dichlorodihydrofluorescein diacetate and acridine orange/ethidium bromide staining via fluorescence microscopy. JC-1 staining and caspase 3 immunofluorescence expression were analyzed by confocal microscopy. Enterococcus sp. RMAA-mediated AuNPs are spherical and induced concentration-dependent cytotoxicity in HT-29 cells. AuNP treatments also induced ROS and caspase-3 expressions and reduced the mitochondrial membrane potential. Morphology related to apoptotic changes was also noticed after AuNP treatments in HT-29 cells. The present study revealed that Enterococcus-derived AuNPs induced apoptotic cell death in HT-29 cells and suggests that AuNPs could be used as a pro apoptotic agent for colon cancer treatment.

Temporal stability of E. coli and Enterococci concentrations in a Pennsylvania creek.

Microbial quality of irrigation waters is a substantial food safety factor. Escherichia coli (E. coli) and Enterococci are used as the fecal indicator bacteria (FIB) to assess microbial water quality. Analysis of temporally stable patterns of FIB can facilitate effective monitoring of microbial water quality. The objectives of this study were (1) to investigate the spatiotemporal variation of E. coli and Enterococci concentrations in a large creek traversing diverse land use areas and (2) to explore the presence of temporally stable FIB concentration patterns along the creek. Concentrations of both FIB were measured weekly at five water monitoring locations along the 20-km long creek reach in Pennsylvania at baseflow for three years. The temporal stability was assessed using mean relative deviations of logarithms of FIB concentration from the average across the reach measured at the same time. The Spearman rank correlation coefficients between logarithms of FIB concentrations on consecutive sampling times was another metric used to assess the temporal stability of FIB concentration patterns. Logarithms of FIB concentrations had sinusoidal dependence on time and significantly correlated with temperature at all locations Both FIB exhibited temporal stability of concentrations. The two most downstream locations in urbanized areas tended to have logarithms of concentrations higher than the average along the observation reach. The location in the upstream forested area had mostly lower concentrations (log E. coli 1.59, log Enterococci 1.69) than average (log E. coli 2.07, log Enterococci 2.20). concentrations in colony-forming units (CFU) (100 mL)-1. Two locations in the agricultural and sparsely urbanized area had these logarithm values close to the average. The temporal stability was more pronounced in cold seasons than in warm seasons. No significant difference was found between pattern determined for each of three observation years and for the entire three-year observation period. The Spearman rank correlations between observations on consecutive dates showed moderate to very strong relationships in most cases. Existence of the temporal stability of FIB concentrations in the creek indicates locations that inform about the average logarithm of concentrations or the geometric mean concentrations along the entire observation reach.

Structural enterocin gene profiles and mode of antilisterial activity in synthetic liquid media and skim milk of autochthonous Enterococcus spp. isolates from artisan Greek Graviera and Galotyri cheeses.

The presence of eight common structural enterocin genes, singly or in varying combinations, in the genome of 15 antagonistic Enterococcus spp. previously isolated from artisan Greek Graviera and Galotyri retail cheeses was tested and associated with the mode of enterocin (Ent+) antilisterial activity of each isolate in three liquid culture media. The isolates were assigned to nine distinct strain genotypes of E. faecium (4 strains), E. durans (2) and E. faecalis (3). All strains were non-hemolytic, except for a cyl-positive E. faecalis genotype isolated from Galotyri cheese, which was strongly listericidal. All other strains varied from being listeriostatic to weakly listericidal in MRS and M17 broth, whereas all failed to inhibit listerial growth in skim milk. Two E. faecium strains retained strong Ent+ activity following neutralization and filter-sterilization of their MRS or M17 co-culture supernatants, whereas, all others required contact or proximity of their viable cells with L. monocytogenes cells in order to display activity. Additional studies to evaluate safety and potential synergistic effects of each strain genotype with starter LAB species in real milk environments will reveal the most active and truly harmless Enterococcus genotypes to be applied as co-starter or bioprotective adjunct cultures in traditional Greek cheese technologies.

Rapid identification of pathogenic bacteria using Raman spectroscopy and deep learning.

Raman optical spectroscopy promises label-free bacterial detection, identification, and antibiotic susceptibility testing in a single step. However, achieving clinically relevant speeds and accuracies remains challenging due to weak Raman signal from bacterial cells and numerous bacterial species and phenotypes. Here we generate an extensive dataset of bacterial Raman spectra and apply deep learning approaches to accurately identify 30 common bacterial pathogens. Even on low signal-to-noise spectra, we achieve average isolate-level accuracies exceeding 82% and antibiotic treatment identification accuracies of 97.0±0.3%. We also show that this approach distinguishes between methicillin-resistant and -susceptible isolates of Staphylococcus aureus (MRSA and MSSA) with 89±0.1% accuracy. We validate our results on clinical isolates from 50 patients. Using just 10 bacterial spectra from each patient isolate, we achieve treatment identification accuracies of 99.7%. Our approach has potential for culture-free pathogen identification and antibiotic susceptibility testing, and could be readily extended for diagnostics on blood, urine, and sputum.

Characterization of Anti-Listeria monocytogenes Properties of two Bacteriocin-Producing Enterococcus mundtii Isolated from Fresh Fish and Seafood.

This study addressed the bacteriocin production in 116 lactic acid bacteria isolated from 143 fish and seafood samples. The screening for the production of antibacterial substances allowed for the selection of 16 LAB isolates endowed with inhibitory capability. Bacteriocins (bacLP17 and bacLP18) of two strains, Enterococcus mundtii LP17 and Enterococcus mundtii LP18, respectively, isolated from red mullet and sardine samples, determined large inhibition zones against all the Listeria species. Virulence traits and antibiotic resistances of all producers were verified, and no isolates presented dangerous characteristics, including the two best bacteriocin producers E. mundtii LP17 and E. mundtii LP18, which were subsequently investigated for their potential use in fish and seafood products biopreservation. For both strains, the highest level of bacteriocin production (1280 AU/ml) was recorded when cells were grown at 30 °C in MRS broth at pH ranging from 6.0 to 9.0, and high levels of adsorption of bacteriocins, bacLP17 and bacLP18, to the target cells Listeria monocytogenes were also observed. The results obtained in this study revealed that two strains of E. mundtii originating from seafood exhibited a strong inhibitory activity against L. monocytogenes and may be useful in controlling the growth of this pathogen in the same food products.

Biotechnological Method of Preparation and Characterization of Recombinant Antimicrobial Peptide Avicin A from Enterococcus avium.

Avicin A is a bacteriocin from the gram-positive bacterium Enterococcus avium. It exhibits a high microbicidal activity against bacteria of the genus Listeria, a causative agent of the severe human infection listeriosis. We developed a biotechnological method for obtaining avicin A and characterized its structure and biological activity. We also proposed a possible mechanism of the antimicrobial action of avicin A.

Virulence profiles of vancomycin-resistant enterococci isolated from surface and ground water utilized by humans in the North West Province, South Africa: a public health perspective.

Vancomycin-resistant enterococci (VRE) have been responsible for numerous outbreaks of serious infections in humans worldwide. Enterococcus faecium and Enterococcus faecalis are the principal species that are frequently associated with vancomycin resistance determinants, thus usually implicated in hospital- and community-acquired infections in humans. The study aim was to determine the antibiotic resistance and virulence profiles of VREs isolated from surface and groundwater samples that are used by humans in the North West Province, South Africa. A total of 170 water samples were collected and analyzed. Eighty-one potential isolates were screened for characteristics of Enterococcus species using preliminary biochemical tests, PCR assays and sequence analysis. The antimicrobial resistance profiles of the isolates against nine antibiotics were determined and a dendrogram was generated to access the relatedness of the isolates. The isolates were screened for the presence of antibiotic resistance and virulence genes by multiplex PCR analysis. A total of 56 isolates were confirmed as Enterococcus species and the proportion of E. faecium (46.9%) was higher than E. faecalis (29%) and E. saccharolyticus (1.2%). Sequence data of E. faecium, E. faecalis, and E. saccharolyticus isolates revealed 97 to 98% similarities to clinical strains deposited in NCBI Genbank. Large proportions (44; 78.6%) of the isolates were resistant to vancomycin while 16 and 3.6% of the isolates possessed the vanA and vanB genes respectively. The MAR phenotype Vancomycin-Nalidixic Acid-Streptomycin-Chloramphenicol-Ampicillin-Oxytetracycline-Gentamycin-Nitrofurantoin-Sulphamethoxazole indicated that some isolates were resistant to all of the nine antibiotics tested. Cluster analysis of antibiotic resistance data revealed two major clusters. Sixteen (36.4%), 14 (27.3%), 3 (6.8%), and 2 (4.5%) of the VRE isolates possessed the gel, asa1, hyl, and esp virulence genes respectively while the cylA gene was not detected in the study. Multiple antibiotic-resistant enterococci were also resistant to vancomycin and possessed virulence determinants indicating that they can pose severe public health complications on individuals who consume contaminated water.

Bacteriocin production and adhesion properties as mechanisms for the anti-listerial activity of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA.

Probiotics play an important role in maintaining a healthy and stable intestinal microbiota, primarily by preventing infection. Probiotic lactic acid bacteria (LAB) are known to be inhibitory to many bacterial enteric pathogens, including antibiotic-resistant strains. Whilst the positive role that probiotics have on human physiology, specifically in the treatment or prevention of specific infectious diseases of the gastro-intestinal tract (GIT) is known, the precise mechanistic basis of these effects remains a major research goal. In this study, molecular evidence to underpin the protective and anti-listerial effect of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA against orally administered Listeria monocytogenes EGDe in the GIT of mice is provided. Bacteriocins plantaricin 423 and mundticin ST4SA, produced by L. plantarum 423 and E. mundtii ST4SA, respectively, inhibited the growth of L. monocytogenes in vitro and in vivo. Bacteriocin-negative mutants of L. plantarum 423 and E. mundtii ST4SA failed to exclude L. monocytogenes EGDe from the gastrointestinal tract (GIT) of mice. Furthermore, L. plantarum 423 and E. mundtii ST4SA failed to inhibit recombinant strains of L. monocytogenes EGDe in vivo that expressed the immunity proteins of the two bacteriocins. These results confirmed that bacteriocins plantaricin 423 and mundticin ST4SA acted as anti-infective mediators in vivo. Compared to wild type strains, mutants of L. plantarum 423 and E. mundtii ST4SA, in which the adhesion genes were knocked out, were less effective in the exclusion of L. monocytogenes EGDe from the GIT of mice. This work demonstrates the importance of bacteriocin and adhesion genes as probiotic anti-infective mechanisms.

Characterization of the bacteriocin produced by Enterococcus italicus ONU547 isolated from Thai fermented cabbage.

Seventy-eight isolates of lactic acid bacteria from Ukraine and Thailand were screened for bacteriocinogenic activity against indicator strain Lactobacillus sakei subsp. sakei JCM 1157. One isolate showed an antagonistic activity of cell-free supernatant eliminated after the treatment with Proteinase K. Based on 16S rRNA gene sequence, this isolate was identified as Enterococcus italicus. Bacteriocin produced by this strain showed antimicrobial activity against L. sakei subsp. sakei JCM 1157, Brochothrix thermosphacta DSMZ 20171, and Listeria ivanovii subsp. ivanovii DSMZ 20750 in agar well diffusion assay. This bacteriocin was cationic and hydrophobic. The partially purified bacteriocin was thermostable, while heating of cell-free supernatant increased its activity more than twofold. Molecular mass of the partially purified bacteriocin as determined by SDS-PAGE differed from enterocin A and B previously known for E. italicus. Concentrated bacteriocin decreased the level of biofilm formation in L. sakei subsp. sakei JCM 1157 and Pseudomonas aeruginosa PAO1 in 52.5 and 48.0%, respectively (p < 0.05). We suggest that the studied bacteriocin could be a perspective antibiofilm agent in food conservation and medicine.

Modelling of ultraviolet light inactivation kinetics of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, Clostridium difficile spores and murine norovirus on fomite surfaces.

AIMS: Quantitative data on the doses needed to inactivate micro-organisms on fomites are not available for ultraviolet applications. The goal of this study was to determine the doses of UV light needed to reduce bacteria and murine norovirus (MNV) on hard surface fomites through experimentation and to identify appropriate models for predicting targeted levels of reduction. METHODS AND RESULTS: Stainless steel and Formica laminate coupons were selected as they are common surfaces found in healthcare settings. Test organisms included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Clostridium difficile and MNV. The fomites were inoculated with 105 -107 bacteria or virus and exposed to a range of UV doses. The order of resistance to UV irradiation was virus, bacterial spore and vegetative cell. The best fitting inactivation curves suggested nonlinear responses to increasing doses after a 3-4 log reduction in the test organisms. The average UV doses required for a 3 log reduction in the C. difficile, MRSA and VRE were 16 000, 6164 and 11 228 (mJ-s cm-2 ) for stainless steel, respectively, and 16 000, 11 727 and 12 441 (mJ-s cm-2 ) for Formica laminate, respectively. CONCLUSIONS: Higher UV light doses are required to inactivate bacteria and viruses on hard surfaces than in suspension. Greater doses are needed to inactivate bacterial spores and MNV compared to vegetative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Quantitative data and models on UV light doses needed to inactivate bacteria and MNV on hard surfaces are now available. The generalizable results of this study can be used to estimate required UV dosages to achieve targeted levels of inactivation based on estimated levels of contamination or to support quantitative microbial risk assessments.

Impact of short-incubation MALDI-TOF MS on empiric antibiotic therapy in bloodstream infections caused by Pseudomonas aeruginosa, Enterococcus spp. and AmpC-producing Enterobacteriaceae.

The impact of the short-incubation matrix-assisted laser desorption ionization time-of-flight (si-MALDI-TOF) mass spectrometry technique was evaluated in the treatment of bloodstream infections (BSIs) caused by Pseudomonas aeruginosa, Enterococcus spp., and Amp-C producing Enterobacteriaceae. A total of 124 bacteremia episodes were divided into 2 groups: i) si-MALDI-TOF group (n = 69) and ii) control group (n = 55). Identification by si-MALDI-TOF resulted in 12.8% increase in cases receiving appropriate antibiotic treatment within 48 h from blood culture draw. The importance of the rapid identification was emphasized in BSIs caused by enterococci (n = 62), where si-MALDI-TOF led to appropriate antibiotic treatment in 87.9% of cases (versus control group 65.5%, P = 0.036). Implementation of si-MALDI-TOF technology for microbial identification was associated with increased proportion of patients receiving effective antibiotic treatment within 48 h from blood culture draw. The effect was most significant in BSIs caused by enterococcal species and in a subgroup of immunosuppressed patients.

Increasing Antiradical Activity of Polyphenols from Lotus Seed Epicarp by Probiotic Bacteria Bioconversion.

Probiotic bacteria is able to metabolize polyphenols and produce functional compounds. In this study, we investigated the ability of probiotic bacteria including Lactobacillus, bifidobacteria and Enterococcus strains to increase the antioxidant capacity of polyphenols from lotus seed epicarp (PLSE) at full ripening stage. The results showed that the six selected strains of probiotic bacteria grew well in De Man, Rogosa and Sharpe (MRS) broth with PLSE, and their resistant extent to PLSE varied from strain to strain. The metabolized PLSE was found to have good antioxidant properties on 3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals in vitro. Five polyphenol compounds-chlorogenic acid, caffeic acid, catechin, epicatechin and hyperoside-were suggested as the major bioactive metabolism for the antiradical activity of PLSE metabolized by Lactobacillus reuteri DSM20016, Enterococcus faecalis M74 and Bifidobacterium breve ATCC 15701. Moreover, L. reuteri DSM20016 and E. faecalis M74 were found to have a high PLSE bioconversion rate. Our results suggested that both L. reuteri DSM20016 and E. faecalis M74 might have excellent potential for the bioconversion of PLSE to increase its antiradical activity.

Assessment of Coagulase-Negative Staphylococci and Lactic Acid Bacteria Isolated from Portuguese Dry Fermented Sausages as Potential Starters Based on Their Biogenic Amine Profile.

The aim of this study was to evaluate the decarboxylase activity of coagulase-negative staphylococci (CNS) and lactic acid bacteria (LAB) involved in meat products fermentation, in order to characterize and select the strains most suitable to be used as safe starter cultures. Isolates were obtained from traditional Portuguese dry fermented meat sausages, identified by PCR and characterized according to their technological properties. Lactobacilli and enterococci were assessed for their bacteriocinogenic potential. Biogenic amines (BA) were screened by culture method and analyzed by RP-HPLC/UV. The screening method, compared with chromatographic analysis, was not reliable for CNS and LAB strains selection. Tyramine decarboxylase activity was present in CNS strains, with a slight production of amines. No other hazardous BA were produced. Among lactobacilli, moderate production of tyramine was related only to Lactobacillus curvatus, with some strains producing putrescine or 2-phenylethylamine. Enterococci were high and moderate producers of tyramine and 2-phenylethylamine, respectively. Staphylococcus xylosus, Staphylococcus equorum, and Staphylococcus carnosus, independent of their genetic and technological profiles and BA production, were adequate for use in meat products, according to the data. Lactobacillus plantarum and Lactobacillus sakei strains could also be selected for starters. PRACTICAL APPLICATION: The selection of coagulase-negative staphylococci and lactic acid bacteria (LAB) isolates were based on their production of biogenic amines in order to avoid this potential hazard production in meat products. The most suitable isolates could be used as safe starter cultures in meat products industry. The staphylococci and LAB selected will achieve particular organoleptic characteristics in meat products and bioprotection from pathogens.