Alginate coatings applied on apple cubes as a vehicle for Lacticaseibacillus casei: probiotic viability and overall quality of a new functional product.

BACKGROUND: Worldwide, vegan and vegetarian lifestyles, as well as food allergies and intolerance (e.g. lactose intolerance and milk protein allergy) demand the development of alternatives to dairy-based probiotic foods. In the present study, probiotic Lacticaseibacillus casei CECT 9104 was added to alginate-based edible coatings enriched with inulin and oligofructose and applied to fresh-cut apple. Microbiological, physicochemical and sensory quality parameters of the apple cubes were monitored during 8 days of refrigerated storage. Lacticaseibacillus casei was tested for its antagonistic effect against inoculated Listeria innocua and Escherichia coli O157:H7. The viability of the probiotic strain during refrigerated storage and after simulated gastrointestinal digestion (GID) was evaluated. RESULTS: After 8 days of storage, 9.52-9.64 log colony-forming units (CFU) g-1 of L. casei were detected in apple samples. The functional apple cubes retained 8.31-8.43 log CFU g-1 of the probiotic after GID, without a significant effect of prebiotic addition. The microbiological quality and nutritional properties were maintained by the use of active coatings, whereas the sensory quality decreased after 8 days of storage. A bactericidal effect was exerted by the probiotic strain loaded in the coating against L. innocua artificially inoculated on apple cubes. Escherichia coli O157:H7 counts were reduced by 2.5 log after 8 days. CONCLUSION: This study has demonstrated the suitability of apple cubes as an alternative matrix to milk for carrying probiotic L. casei CECT 9104 and prebiotics, offering a promising alternative for the development of plant-based functional foods. © 2024 Society of Chemical Industry.

Impairment of Listeria monocytogenes biofilm developed on industrial surfaces by Latilactobacillus curvatus CRL1579 bacteriocin.

The effect of lactocin AL705, bacteriocin produced by Latilactobacillus (Lat.) curvatus CRL1579 against Listeria biofilms on stainless steel (SS) and polytetrafluoroethylene (PTFE) coupons at 10 °C was investigated. L. monocytogenes FBUNT showed the greatest adhesion on both surfaces associated to the hydrophobicity of cell surface. Partially purified bacteriocin (800 UA/mL) effectively inhibited L. monocytogenes preformed biofilm through displacement strategy, reducing the pathogen by 5.54 ± 0.26 and 4.74 ± 0.05 log cycles at 3 and 6 days, respectively. The bacteriocin-producer decreased the pathogen biofilm by ∼2.84 log cycles. Control and Bac- treated samples reached cell counts of 7.05 ± 0.18 and 6.79 ± 0.06 log CFU/cm2 after 6 days of incubation. Confocal scanning laser microscopy (CLSM) allowed visualizing the inhibitory effect of lactocin AL705 on L. monocytogenes preformed biofilms under static and hydrodynamic flow conditions. A greater effect of the bacteriocin was found at 3 days independently of the surface matrix and pathogen growth conditions at 10 °C. As a more realistic approach, biofilm displacement strategy under continuous flow conditions showed a significant loss of biomass, mean thickness and substratum coverage of pathogen biofilm. These findings highlight the anti-biofilm capacity of lactocin AL705 and their potential application in food industries.

Investigating processing practices and microbiological quality of minimally processed vegetables in Brazil.

Minimally processed vegetables (MPVs) are marketed as convenient and healthy choices for consumers. However, the absence of post-commercialization treatments raises concerns about their microbiological safety. This study investigated the processing practices of 28 Brazilian MPV plants and compared the microbiological quality of these products with fresh counterparts in the city of Sao Paulo, Brazil. Through cluster analysis, the processing plants were categorized into two groups: group 1 (nineteen plants) primarily uses chemical substances in the washing step, while group 2 (nine plants) avoids chemical use but employs similar rinsing practices. Microbiological analysis of 100 samples (49 unprocessed and 51 MPVs) revealed no significant differences in microbial group counts (Enterobacteriaceae, coliforms, and E. coli) between the in natura (unprocessed) and MPV products. However, the prevalence of E. coli was higher in natura vegetables than in MPVs. The results indicated the presence of Salmonella DNA (from either dead or live cells or residual DNA) in 4 samples (3 in natura and 1 MPV) using conventional PCR, suggesting the presence of the pathogen in these samples. Listeria monocytogenes was absent, but Listeria innocua was found in two unprocessed products. The study suggests that certain MPVs have microbial loads similar to unprocessed vegetables, potentially serving as carriers for pathogen transmission. These findings emphasize the importance of understanding practices in Brazilian MPV processing plants, informing the implementation of control measures to improve MPV safety and shelf-life, thus ensuring microbiological safety.

Identification of lactic acid bacteria with anti-listeria activity. Characterization and application of a bacteriocinogenic strain in the control of Listeria monocytogenes in cheese.

The purpose of the research paper was firstly to identify bacteriocin-producing lactic acid bacteria characterizing strains with anti-listeria activity and, secondly, to characterize bacteriocin evaluating its in vitro efficiency as a natural preservative and, thirdly, to evaluate the anti-listeria effect of the bacteriocinogenic strain of Lactiplantibacillus plantarum in cheeses and produce an edible film with anti-listerial effect. Of 355 lactic acid bacteria strains tested, two were able to produce bacteriocin against Listeria monocytogenes and were identified as Lactiplantibacillus plantarum and Lactiplantibacillus pentosus. A bactericidal effect of strain QS494 (Lactiplantibacillus plantarum) was observed in the first 8 h, with a reduction of 1.7 log, using cell-free supernatant with Listeria monocytogenes, where viable cells were counted on listeria selective agar. Both strains showed good technological characteristics and were without production of virulence factors. Changes in the pH of the cell-free supernatant obtained from Lactiplantibacillus plantarum did not affect its antimicrobial activity, which remained stable after heat treatments for up to 15 min at 121°C. Inhibitory activity was also observed after 12 weeks of storage at -20°C. In the evaluation of the anti-listeria effect in cheeses, a 3 log reduction in the Listeria monocytogenes count was observed in 120 h in cheeses produced with bacteriocinogenic lactic acid bacteria, while in cheeses produced with non-bacteriocinogenic culture, we observed a 2 log increase in the count. Edible films produced with the addition of precipitate from the cell free supernatant showed an antimicrobial effect against Listeria monocytogenes. Thus, the two strains studied have technological and biosafety potential.

Genomic Insights into Listeria monocytogenes: Organic Acid Interventions for Biofilm Prevention and Control.

Listeria monocytogenes is an important pathogen that has been implicated in foodborne illness. The aim of the present study was to investigate the diversity of virulence factors associated with the mechanisms of pathogenicity, persistence, and formation of biofilm L. monocytogenes by tandem analysis of whole-genome sequencing. The lineages that presented L. monocytogenes (LmAV-2, LmAV-3, and LmAV-6) from Hass avocados were lineages I and II. Listeria pathogenicity island 1 (LIPI-1) and LIPI-2 were found in the isolates, while LIPI-3 and Listeria genomic island (LGI-2) only was in IIb. Stress survival island (SSI-1) was identified in lineage I and II. In the in silico analysis, resistance genes belonging to several groups of antibiotics were detected, but the bcrABC and transposon Tn6188 related to resistance to quaternary ammonium salts (QACs) were not detected in L. monocytogenes. Subsequently, the anti-L. monocytogenes planktonic cell effect showed for QACs (MIC = 6.25 ppm/MBC = 100 ppm), lactic acid (MBC = 1 mg/mL), citric acid (MBC = 0.5 mg/mL) and gallic acid (MBC = 2 mg/mL). The anti-biofilm effect with organic acids (22 °C) caused a reduction of 4-5 log10 cfu/cm2 after 10 min against control biofilm L. monocytogenes formed on PP than SS. This study is an important contribution to understanding the genomic diversity and epidemiology of L. monocytogenes to establish a control measure to reduce the impact on the environment and the consumer.

Antimicrobial activity of Tetradenia riparialeaf essential oil / Actividad antimicrobiana del aceite esencial de hoja de Tetradenia riparia

Food spoilage is a widely neglected problem and the constant use of synthetic fungicides could develop resistant fungi. The objective of this study was to evaluate the chemical composition and antimicrobial activity of Tetradenia riparialeaf essential oil against foodborne disease microorganisms. Leaf essential oil was obtained by hydrodistillation and identified by gas chromatography coupled to mass spectrometry. The antimicrobial activity was studied by broth microdilution. The major compounds identified were oxygenated sesquiterpenes (43.6%): 14-hydroxy-9-epi-(E)-cariophylene (20.8%) and τ-cadinol (18.4%); followed by oxygenated diterpenes (24.6%): 6,7-dehydroroyleanone (12.6%) and 9ß, 13ß-epoxy-7-abiethene (10.6%); sesquiterpenic hydrocarbons (17.1%) and oxygenated monoterpenes (7.4%): fenchone (5.6%). The essential oil had broad antibacterial and antifungal activity, mainly against A. versicolor and P. ochrochloron with fungistatic and fungicidal activities and B. cereus, L. monocytogenes, and S. aureuswith bacteriostatic and bactericidal activities. T. riparialeaf essential oil is a potential alternative to control microorganisms-

El deterioro de los alimentos es un problema ampliamente desatendido y el uso constante de fungicidas sintéticos podría desarrollar hongos resistentes. El objetivo de este estudio fue evaluar la composición química y la actividad antimicrobiana del aceite esencial de hoja de Tetradenia riparia contra microorganismos patógenos transmitidos por los alimentos. El aceite esencial de hoja se obtuvo por hidrodestilación y se identificó mediante cromatografía de gases acoplada a espectrometría de masas. La actividad antimicrobiana estudiada fue por microdilución en caldo. Los compuestos principales del aceite esencial se identificaron como sesquiterpenos oxigenados (43,6%): 14-hidroxi-9-epi-(E)-cariofileno (20,8%) y τ-cadinol (18,4%); seguido de diterpenos oxigenados (24,6%): 6-7-deshidroroileanona (12,6%) y 9ß, 13ß-epoxi-7-abieteno (10,6%); hidrocarburos sesquiterpénicos (17,1%) y monoterpenos oxigenados (7,4%): fenchona (5,6%). Tenía amplia actividad antibacteriana y antifúngica, principalmente contra A. versicolor y P. ochrochloron con actividades fungistáticas y fungicidas, y principalmente contra B. cereus, L. monocytogenes y S. aureus con actividades bacteriostáticas y bactericidas. El aceite esencial de hoja de T. riparia es una alternativa potencial para controlar microorganismos.

Modeling of Listeria innocua, Escherichia coli, and Salmonella Enteritidis inactivation in milk treated by gamma irradiation.

Measuring microbial inactivation in food is useful for food technology as it allows for predicting the growth or death of microorganisms. This study aimed to investigate the effect of gamma irradiation on the lethality of microorganisms inoculated in milk, estimate the mathematical model of inactivation of each microorganism, and evaluate kinetic indices to determine the efficient dose in the treatment of milk. Raw milk samples were inoculated with cultures of Salmonella enterica subsp. enterica serovar Enteritidis (ATCC 13076), Escherichia coli (ATCC 8739), and Listeria innocua (ATCC 3309), irradiated at doses of 0, 0.5, 1, 1.5, 2, 2.5, and 3 kGy. The fitting of the models to the microbial inactivation data was performed using the GinaFIT software. The results demonstrated a significant effect of irradiation doses on the population of microorganisms, with the application of a dose of 3 kGy, a reduction of approximately 6 logarithmic cycles is observed for L. innocua and 5 for S. Enteritidis and E. coli. The model with the best fit was different for each microorganism studied: for L. innocua, the model was log-linear + shoulder; for S. Enteritidis and E. coli, the model that showed the best fit was the biphasic. The studied model fitted well (R2 ≥ 0.9; R2 adj. ≥ 0.9 and smallest RMSE values) for the inactivation kinetics. The lethality of the treatment, considering a reduction in the 4D value, was achieved with the predicted dose of doses of ±2.22, ±2.10, and ±1.77 kGy, for L. innocua, S. Enteritidis, and E. coli, respectively.

Functionality of the bacteriocin sakacin G produced by Lactobacillus curvatus ACU-1 on cooked sausages under industrial conditions.

Biopreservation is an alternative to prevent the growth of pathogens and reduce microbial spoilage in food based on the use of microorganisms and/or their metabolic products. The objective of this study was to determine the optimal mode of application and the effectiveness of cell-free supernatant (CFS) from Lactobacillus curvatus ACU-1, containing sakacin G, in Vienna-type sausages to control Listeria and spoilage flora. The functionality and the optimal dosage form between CFS, producing bacteria, a combination or concentrate of bacteriocin applied on Vienna-type sausages before and after stuffing the casings on an industrial scale were determined. Sakacin G was effective for the control of Listeria applied to the casing both before and after stuffing. The application of the antimicrobial on the ready sausages inhibits both lactic acid bacteria and mesophilic microorganisms from zero sampling time. The heat resistance of the bacteriocin in the food was verified under industrial manufacturing conditions. The antimicrobial activity of sakacin G was maintained throughout the period studied in all the conditions tested. In conclusion, the application of CFS containing bacteriocin is useful given both before and after casing stuffing; but the application prior to the stuffing is more practical for the process of elaboration.

Listeria innocua and serotypes of Listeria monocytogenes isolated from clinical cases in small ruminants in the northwest of Uruguay / Listeria innocua e serotipos do Listeria monocytogenes isoladas dos casos clínicos em pequenos ruminantes no noroeste do Uruguai

Listeriosis is an infectious disease caused by bacteria of the genus Listeria, the neurological form being more common in ruminants. There are many reports of listeriosis in small ruminants in the region that includes Brazil, Argentina and Uruguay. However, these diagnoses were mainly based on histological lesions in the central nervous system (CNS) without the isolation and characterization of the involved Listeria strains. The aim of this study was to report sheep and goats listeriosis cases from 2016 to 2021 in northwestern Uruguay. The diagnosis was made according to lesions observed at histopathology, plus Listeria isolation in CNS, identifying it at specie and serotype level. Nine animals (n=9) of three outbreaks and five sporadic cases of listeriosis were studied. Sheep was the species with more cases in relation to goats, and adults were the category most affected. Cases occurred in spring and less frequently in winter. All presented neurological clinical signs and the lesions in the CNS were consistent with suppurative meningoencephalitis and micro-abscesses in the brainstem. In eight of nine CNS samples, Listeria strains were isolated (seven L. monocytogenes and one L. innocua). All the L. monocytogenes isolates carried the inlA gene; serotyping showed that four strains belonged to serotype 1/2b, two isolates belonged to serotype 4b, and one to serotype 1/2a. Considering that listeriosis is a common disease in this region and the fact that isolates are scarcely recovered from small ruminants, it would be important to emphasize the need for Listeria isolation to better characterize the strains that affect animals. Not only to improve knowledge about the epidemiology of disease but also with the objective of developing serotype specific vaccines for animal use.

Listeriose uma doença bacteriana causada pelo gênero Listeria, a forma nervosa é a mais comum em ruminantes. No Brasil, Argentina e Uruguai há vários relatos de listeriose em pequenos ruminantes com diagnóstico baseado na histopatologia do sistema nervoso central (SNC), sem o isolamento e a caracterização do agente. O objetivo deste trabalho foi relatar uma série de casos diagnosticados em ovinos e caprinos no período 2016-2021 no noroeste do Uruguai. O diagnóstico foi feito basado nas lesões observadas na histopatologia, e caracterização das cepas de Listeria recuperadas do SNC quanto à espécie e sorotipo. Nove animais (n=9) do três surtos e cinco casos isolados de listeriose foram estudados. Os ovinos foram a espécie com o maior número de casos em relação aos caprinos, sendo os animais adultos a categoria mais afetada em ambas espécies. A doença ocorreu principalmente na primavera com alguns casos observados no inverno. Todos os casos apresentavam sinais clínicos nervosos e as lesões no SNC caracterizavam-se por meningoencefalite supurativa com presença de microabscessos no tronco encefálico. Em oito de nove amostras do SNC foram isoladas cepas de Listeria (sete L. monocytogenes e uma L. innocua). Todos os isolados de L. monocytogenes continham o gene inlA; a sorotipagem apresentou quatro cepas do serotipo 1/2b, duas cepas serotipo 4b e uma cepa 1/2a. Levando em consideração que nesta região a listeriose é uma doença frequente e que existem poucos isolados recuperados de casos clínicos em pequeño ruminantes, torna-se relevante o isolamento deste agente para caracterização das cepas que afetam os animais. Não só para melhorar o conhecimento sobre a epidemiologia da doença, mas também com o objetivo de desenvolver vacinas sorotipo-especificas para uso animal.

Listeria monocytogenes and Pseudomonas spp. Distribution in a Processing Facility of Spotted Sorubim (Pseudoplatystoma corruscans) in Brazil.

ABSTRACT: The ecology of Listeria monocytogenes and Pseudomonas spp. during the slaughtering of spotted sorubim (Pseudoplatystoma corruscans) in a fish processing facility was assessed. Fish samples (n = 28) were obtained in different points of slaughtering (A, arrival; B, washing; C, gutting; and D, cooling) and subjected to detection of L. monocytogenes and enumeration of Pseudomonas spp. High frequencies of Listeria spp. (17 of 28 to 22 of 28) and L. monocytogenes (6 of 28 to 9 of 28) were identified in all slaughtering points but were not significantly different (P ≥ 0.05). All L. monocytogenes isolates (n = 33) were identified as belonging to serogroup IVb (serotype 4b) and subjected to macrorestriction with ApaI and AscI. The results indicated a continuous entry of L. monocytogenes in the facility, as well as a temporary persistence of a specific pulsotype. Pseudomonas spp. counts significantly decreased between points A and D (P < 0.05), but the mean counts in the end products (D) remained higher than 3 log CFU/g, suggesting the potential for fast spoilage. The obtained results show that L. monocytogenes and Pseudomonas spp. are widely distributed during spotted sorubim slaughtering, indicating the need for proper hygienic procedures to control these bacteria in the processing facility.

Potentially pathogenic Staphylococcus aureus and Listeria spp. in Brazilian unpasteurized cheese production / Staphylococcus aureus e Listeria spp. potencialmente patogênicos na produção de queijos não pasteurizados

This study aimed to identify potentially pathogenic microorganisms (Listeria innocua, L. seeligeri, L. ivanovii, L. monocytogenes, Staphylococcus aureus, and several virulence genes) in unpasteurized cheese production in the northeastern region of the state of São Paulo, Brazil. Listeria species were detected in 68 (64.14%) out of 106 samples of bovine feces, swabs from milkers' and cheese handlers' hands, milking buckets, raw milk, whey, water, cheese processing surface,s and utensils. All the samples collected at one farm were contaminated with Listeria spp. L. innocua, L. seeligeri, L. ivanovii, or L. monocytogenes were not detected in the samples collected in this study. A set of 391 Staphylococcus spp. isolates were obtained in these samples, from which 60 (15.31%) were identified as S. aureus using PCR (Polymerase Chain Reaction). S. aureus carrying virulence genes (eta, hlg, seg, seh, sei) were detected in milk, in swabs from cheese handler's hands, whey, milk, sieves, buckets, and cheese. The hlg gene (encodes gamma hemolysin) was detected in all the S. aureus isolates. These findings show that poor hygienic practice is associated with a higher risk of pathogenic bacteria in milk or cheese, providing useful information for public health authorities to increase food safety surveillance and prevent the dissemination of pathogens.

O objetivo desse estudo foi identificar microrganismos potencialmente patogênicos (Listeria innocua, L. seeligeri, L. ivanovii, L. monocytogenes, Staphylococcus aureus e diversos genes de virulência) na produção de queijos de leite cru na região noroeste do Estado de São Paulo, Brasil. Listeria foram detectadas em 68 (64,14%) das 106 amostras obtidas de fezes bovinas, suabes das mãos de ordenhadores e queijeiros, baldes, leite cru, soro, água, superfícies e utensílios da produção de queijos. Todas as amostras coletadas em uma fazenda estavam contaminadas com Listeria spp. L. innocua, L. seeligeri, L. ivanovii, e L. monocytogenes não foram detectadas nas amostras coletadas nesse estudo. Um conjunto de 391 isolados de Staphylococcus spp. foram obtidos das amostras, e desses 60 (15,31%) foram identificados como S. aureus pela PCR (Polymerase Chain Reaction). S. aureus contendo genes de virulência (eta, hlg, seg, seh, sei) foram detectados em leite, mãos dos ordenhadores, soro, utensílios e queijos. O gene hlg (gama-hemolisina)foi detectado em todos os isolados de S. aureus.Esses resultados demonstram que práticas inadequadas de higiene estão associadas com um maior risco da presença de bactérias patogênicas no leite e queijos crus, fornecendo informações para as autoridades de saúde pública para incrementarem a vigilância e prevenirem a disseminação de patógenos.

Influence of the food matrix on dual-species biofilm of Listeria monocytogenes and Pseudomonas fluorescens

In the food industry, the formation of biofilms results in serious microbial recontamination problem. This work aimed to study Listeria sp. obtained from sliced products and food handling surfaces, for the preparation of food of animal origin to be consumed cold. Listeria monocytogenes, Listeria innocua and Listeria seeligeri were detected. In the evaluation of antibiotic susceptibility, the isolates were sensitive to ampicillin and penicillin, which were the main antibiotics used in treatment. The isolates showed the ability to form biofilm in microplate, in stainless steel and polypropylene surfaces, with a variation of sessile cells between 4.29±0.23 and 7.03±0.01 log10 CFU cm-2 in TSBYE. This ability was also observed in food matrix composed of UHT whole milk in mono-species cultivation and in associated cultivation of L. monocytogenes with Pseudomonas fluorescens. The application of sanitizers peracetic acid and sodium hypochlorite revealed efficiency in the eradication of adhered cells and biofilms formed in stainless steel surfaces. Therefore, Listeria sp. showed to be persistent and able to form biofilm in mono-species cultivation or associated with P. fluorescens, under different conditions. Taking these aspects into account, the need for proper hygiene in the food production process is highlighted in order to avoid risks to the consumers health.(AU)

Evaluation of VITEK® 2 and MALDI-TOF/MS automated methodologies in the identification of atypical Listeria spp. isolated from food in different regions of Brazil.

Listeria monocytogenes is a pathogen responsible for listeriosis, a foodborne disease with high mortality rates (20-30%). It mainly affects the elderly, pregnant women, and immunocompromised people. Although not pathogenic, the isolation and identification of Listeria innocua are critical since they can indicate L. monocytogenes' presence as they are closely related and widely distributed in the environment and food processing plants. The objective of this study was to evaluate the effectiveness of the automated methods VITEK® 2 and MALDI-TOF/MS in identifying 94 strains of the genus Listeria with atypical identification profile. The resulting identification by Polymerase Chain Reaction (PCR), using specific primers for the most common species of Listeria, was considered the correct identification and presented a total of 31 strains identified as Listeria innocua (LI), 54 as L. monocytogenes (LM), 8 as Listeria welshimeri (LW) and 1 as Listeria grayi (LG). The VITEK® 2 automated system correctly identified, on average, 79% of the LI strains, 16% of the LM strains, and 88.0% of the LW strains. In the analysis by MALDI-TOF/MS, on average, 73% of LM strains were correctly identified, few LW strains were correctly identified, and all LI strains were incorrectly identified. Both VITEK® 2 and MALDI-TOF/MS correctly identified the LG strain in both analyzes. The results demonstrate that automated methodologies could not discriminate atypical strains of the Listeria genus and point to the need for the use of complementary tests, such as PCR and chromogenic media, for the correct identification of these strains.

Listeria innocua isolated from diseased ruminants harbour minor virulence genes of L. monocytogenes.

Listeriosis is one of the most common nervous diseases in ruminants, and is caused almost exclusively by the Gram-positive bacterium, Listeria monocytogenes. However, there are few reports of listeriosis associated with L. innocua, which is genetically closely related to L. monocytogenes, but considered non-pathogenic. In this work, we report two cases of suppurative meningoencephalitis in apparently previously healthy ruminants from different farms, in which two strains of L. innocua were recovered. The whole genomes from both isolates were sequenced, allowing phylogenetic analyses to be performed, which indicated that the two strains were very closely related. Virulence determinants were searched, especially genes coding for the main L. monocytogenes virulence factors which have been previously described in L. innocua. Surprisingly, the two isolates do not possess such virulence determinants. Instead, both strains carried a set of genes that encode for other virulence factors of the genus Listeria detected  using the Virulence Factor Database (VFDB): iap (division and invasion of host cells), lpeA (entry into non-professional phagocytes cells), fbpA (multifunctional virulence factor, including adherence to host cells), lspA (surface protein anchoring), lap (adhesion to enterocytes and trans epithelial translocation), pdgA (resistance to lysozyme), oatA (resistance to different antimicrobial compounds and also required for growth inside macrophages), lplA1 (use of host-metabolites for in vivo growth), gtcA (catalyses teichoic acid of bacterial wall), prsA2 (cell invasion, vacuole lysis and intracellular growth), clpC, clpE and clpP (survival under several stress conditions). These genes among others detected, could be involved in the ability of L. innocua to produce damage in animal and human hosts. These results highlight the multifactorial profile of Listeria pathogenesis and the need for comprehensive scientific research that address microbiological, environmental and veterinary aspects of listeriosis.

Prevalence of Listeria monocytogenes fecal carriers in HIV-infected and -uninfected pregnant women from Brazil.

OBJECTIVE: The aim of this study is to describe the prevalence of Listeria spp. in feces of HIV-infected and -uninfected pregnant women in Brazil. METHODS: Cross-sectional study. Women on their second or third trimester of pregnancy were submitted to a clinical questionnaire and feces collection. The feces were inoculated on selective media and identification by biochemical tests combined with PCR. RESULTS: A total of 213 pregnant women were enrolled: 73 (34%) HIV-infected and 140 (66%) -non-infected. The prevalence of Listeria spp. and L. monocytogenes in feces of HIV-infected women were 8.2% and 2.7%. In the HIV-uninfected were 8.6% and 2.9% (p-values = 0.98 and 0.66, respectively). CONCLUSION: The prevalence of fecal carriers of Listeria spp. and L. monocytogenes was not associated with HIV infection during pregnancy.

Listeria bacteremia in patients from a peruvian oncologic institute, 2005-2015. / Bacteriemia por listeria en pacientes de un instituto oncológico peruano, 2005-2015.

Listeriosis infection is a severe disease, with high morbidity and mortality in the immunocompromised patient, especially with disseminated and fatal presentations in cancer patients. A descriptive study was developed to describe the clinical and epidemiologic characteristics in oncologic patients with listeriosis in the Instituto Nacional de Enfermedades Neoplásicas between the years 2005-2015. A total of 29 patients were included; 23 (79.3%) of the listeriosis cases showed up in patients with hematological neoplasia, of which 52.1% was acute lymphatic leukemia and 39.1% non-Hodgkin's lymphoma. The 72.4% of the isolated species correspond to Listeria monocytogenes. Twenty-seven (93.1%) patients met sepsis criteria and twenty-four (82.7%) had neurologic affection. Bacteremia was the most common presentation, followed by meningoencephalitis (20.6%). Global mortality was 75.8%. In conclusion in cancer patients, listeriosis implies high morbidity and mortality. Therefore, the suspicion of this entity is mandatory in onco-hematologic patients with sepsis and acute neurologic symptoms.

La listeriosis es una infección severa de elevada morbimortalidad en el paciente inmunocomprometido, existen formas diseminadas y fatales en el paciente oncológico. Se realizó un estudio descriptivo de las características clínico-epidemiológicas de los pacientes oncológicos con listeriosis atendidos en el Instituto Nacional de Enfermedades Neoplásicas entre 2005 y 2015. Se incluyeron 29 pacientes, 23 (79,3%) casos de listeriosis se presentaron en pacientes con neoplasia hematológica, de los cuales el 52,3% fueron leucemia linfática aguda y 39,1% linfoma no Hodgkin. Listeria monocytogenes representó el 72,4% de las especies aisladas. Veintisiete (93,1%) tuvieron criterios de sepsis y veinticuatro (82,7%) compromiso neurológico al ingreso. La presentación más común fue la bacteriemia, seguida de la meningoencefalitis (20,6%). La mortalidad global fue del 75,8%. Se concluye que la listeriosis conlleva elevada morbimortalidad en el paciente oncohematológico, por lo que debe sospecharse en el paciente admitido con sepsis y/o compromiso neurológico agudo.

Presence of Listeria monocytogenes in Ready-to-Eat Meat Products Sold at Retail Stores in Costa Rica and Analysis of Contributing Factors.

ABSTRACT: Listeria monocytogenes is a pathogenic bacterium associated with ready-to-eat (RTE) meat products sold at the retail level. The objective of this research was to determine the prevalence of L. monocytogenes in RTE meat products sold at retail in Costa Rica and to study the factors associated with the levels of contamination; analyzed factors include hygienic practices within stores (cutting techniques and microbial contamination of products) and the behavior of the isolates (persistence against antimicrobials and transfer potential). A total of 190 samples of RTE meat products were collected and analyzed for the presence of coliforms and Listeria spp. Isolates of L. monocytogenes were then evaluated in terms of resistance to disinfectants (quaternary ammonium compound [QAC] and chlorine) and their transfer potential from food contact surfaces (knife and cutting boards). Overall Listeria spp. prevalence was 37.4% (71 of 190); Listeria innocua was present in 32.1% (61 of 190) of the products, and L. monocytogenes was found in just 2.6% (5 of 190) of the samples. Most contaminated samples were cut with a knife at the moment of purchase (44.2%). When analyzing practices within the stores, it was observed that L. monocytogenes transfer from inoculated knife to salchichón was higher for samples cut at the beginning of the experiment. In addition, L. monocytogenes transfer from inoculated cutting boards was independent of the number of slices but contamination from plastic was higher than wood. Regarding L. monocytogenes resistance to disinfectants, average reductions of 2.6 ± 1.1 log CFU/mL were detected after 6 min of exposure to 200 ppm of chlorine; however, chlorine resistance varied among the strains. Prevalence of L. monocytogenes in RTE meat products sold at retail could be associated with handling practices within the stores; further studies are necessary to estimate the impact of these practices on the overall risk for consumers.

Bacteriemia por listeria en pacientes de un instituto oncológico peruano, 2005-2015 / Listeria bacteremia in patients from a peruvian oncologic institute, 2005-2015

RESUMEN La listeriosis es una infección severa de elevada morbimortalidad en el paciente inmunocomprometido, existen formas diseminadas y fatales en el paciente oncológico. Se realizó un estudio descriptivo de las características clínico-epidemiológicas de los pacientes oncológicos con listeriosis atendidos en el Instituto Nacional de Enfermedades Neoplásicas entre 2005 y 2015. Se incluyeron 29 pacientes, 23 (79,3%) casos de listeriosis se presentaron en pacientes con neoplasia hematológica, de los cuales el 52,3% fueron leucemia linfática aguda y 39,1% linfoma no Hodgkin. Listeria monocytogenes representó el 72,4% de las especies aisladas. Veintisiete (93,1%) tuvieron criterios de sepsis y veinticuatro (82,7%) compromiso neurológico al ingreso. La presentación más común fue la bacteriemia, seguida de la meningoencefalitis (20,6%). La mortalidad global fue del 75,8%. Se concluye que la listeriosis conlleva elevada morbimortalidad en el paciente oncohematológico, por lo que debe sospecharse en el paciente admitido con sepsis y/o compromiso neurológico agudo.

ABSTRACT Listeriosis infection is a severe disease, with high morbidity and mortality in the immunocompromised patient, especially with disseminated and fatal presentations in cancer patients. A descriptive study was developed to describe the clinical and epidemiologic characteristics in oncologic patients with listeriosis in the Instituto Nacional de Enfermedades Neoplásicas between the years 2005-2015. A total of 29 patients were included; 23 (79.3%) of the listeriosis cases showed up in patients with hematological neoplasia, of which 52.1% was acute lymphatic leukemia and 39.1% non-Hodgkin's lymphoma. The 72.4% of the isolated species correspond to Listeria monocytogenes. Twenty-seven (93.1%) patients met sepsis criteria and twenty-four (82.7%) had neurologic affection. Bacteremia was the most common presentation, followed by meningoencephalitis (20.6%). Global mortality was 75.8%. In conclusion in cancer patients, listeriosis implies high morbidity and mortality. Therefore, the suspicion of this entity is mandatory in onco-hematologic patients with sepsis and acute neurologic symptoms.

Bacteriemia por listeria en pacientes de un instituto oncológico peruano, 2005-2015 / Listeria bacteremia in patients from a peruvian oncologic institute, 2005-2015

RESUMEN La listeriosis es una infección severa de elevada morbimortalidad en el paciente inmunocomprometido, existen formas diseminadas y fatales en el paciente oncológico. Se realizó un estudio descriptivo de las características clínico-epidemiológicas de los pacientes oncológicos con listeriosis atendidos en el Instituto Nacional de Enfermedades Neoplásicas entre 2005 y 2015. Se incluyeron 29 pacientes, 23 (79,3%) casos de listeriosis se presentaron en pacientes con neoplasia hematológica, de los cuales el 52,3% fueron leucemia linfática aguda y 39,1% linfoma no Hodgkin. Listeria monocytogenes representó el 72,4% de las especies aisladas. Veintisiete (93,1%) tuvieron criterios de sepsis y veinticuatro (82,7%) compromiso neurológico al ingreso. La presentación más común fue la bacteriemia, seguida de la meningoencefalitis (20,6%). La mortalidad global fue del 75,8%. Se concluye que la listeriosis conlleva elevada morbimortalidad en el paciente oncohematológico, por lo que debe sospecharse en el paciente admitido con sepsis y/o compromiso neurológico agudo.

ABSTRACT Listeriosis infection is a severe disease, with high morbidity and mortality in the immunocompromised patient, especially with disseminated and fatal presentations in cancer patients. A descriptive study was developed to describe the clinical and epidemiologic characteristics in oncologic patients with listeriosis in the Instituto Nacional de Enfermedades Neoplásicas between the years 2005-2015. A total of 29 patients were included; 23 (79.3%) of the listeriosis cases showed up in patients with hematological neoplasia, of which 52.1% was acute lymphatic leukemia and 39.1% non-Hodgkin's lymphoma. The 72.4% of the isolated species correspond to Listeria monocytogenes. Twenty-seven (93.1%) patients met sepsis criteria and twenty-four (82.7%) had neurologic affection. Bacteremia was the most common presentation, followed by meningoencephalitis (20.6%). Global mortality was 75.8%. In conclusion in cancer patients, listeriosis implies high morbidity and mortality. Therefore, the suspicion of this entity is mandatory in onco-hematologic patients with sepsis and acute neurologic symptoms.

Bovine Lactoferrin can Decrease the In Vitro Biofilm Production and Show Synergy with Antibiotics Against Listeria and Escherichia coli Isolates.

BACKGROUND: Bovine Lactoferrin (bLf) has been reported as antimicrobial, antiviral, immunomodulatory and anticancer protein. Escherichia coli and Listeria spp. are food-borne bacteria that can produce illness in human being and mammals, the emergent antimicrobial drug resistance has been reported in these pathogens. OBJECTIVE: The aim for this study was to evaluate the bLf effect on in vitro biofilm production and the synergic effect of antibiotics on E. coli and Listeria isolates. METHODS: E. coli and Listeria specimens were isolated from bovine carcasses and slaughterhouses surfaces, respectively. Biofilm formation was analyzed with or without bLf, incubated for 48 h and spectrophotometry, cell viability was analyzed by colony-forming unit (CFU) and the synergistic effect of bLf with ampicillin, oxytetracycline, and streptomycin was evaluated through the fractional concentration index (FCI). RESULTS: Our results show that a low bLf concentration (0.8 µM) can diminish the in vitro biofilm production in Listeria isolates; also improves the in vitro oxytetracycline and streptomycin activity against E. coli, and ampicillin activity against Listeria isolates. CONCLUSION: bLf can affect the biofilm production in Listeria isolates from slaughterhouses surfaces and shown synergic effect with ampicillin. Also has a synergic effect with oxytetracycline and streptomycin against E. coli isolates from bovine carcasses.