Meningitis por Listeria: serie de casos en un hospital de tercer nivel y utilidad de las nuevas técnicas de diagnóstico microbiológico

Introducción: La meningitis por Listeria monocytogenes (MLM) es una entidad grave con complicaciones a corto plazo. La reacción de polimerasa en cadena (RPC) puede ayudar a mejorar su diagnóstico y pronóstico. Objetivos: Conocer las características de los pacientes diagnosticados de meningitis por L. monocytogenes en los últimos años, a través de diferentes métodos microbiológicos. Pacientes y Métodos: Serie de casos de pacientes adultos ingresados con MLM en el Hospital Clínico San Carlos, Madrid, España, durante doce años (2009-2021). Se describieron variables epidemiológicas, clínicas, microbiológicas, radiológicas y terapéuticas. Resultados: Se registraron doce pacientes con MLM (edad media 67,5 años, 75% varones). En ocho se obtuvo un cultivo positivo a L. monocytogenes. La RPC en líquido cefalorraquídeo (LCR) fue positiva en los dos casos en los que se realizó la prueba. El tratamiento dirigido en todos los casos fue ampicilina durante 21 días. Se registraron complicaciones en un cuarto de los casos. Del total de pacientes uno falleció. Conclusiones: La MLM es una enfermedad poco frecuente y de difícil diagnóstico. En nuestra serie de casos los dos pacientes diagnosticados por RPC tuvieron resultado de cultivo de LCR negativo, y presentaron buena evolución. La determinación de RPC podría permitir diagnosticar un mayor número de casos y con mayor precocidad.

Background: Listeria monocytogenes meningitis (LMM) is a serious entity with short-term complications. Polymerase chain reaction (PCR) can help to improve its diagnosis and prognosis. Aim: To know the characteristics of patients diagnosed with meningitis by L. monocytogenes in recent years, through different microbiological methods. Methods: Case series of adult patients admitted with LMM at the Hospital Clínico San Carlos of Madrid, Spain, during twelve years (2009-2021). Epidemiological, clinical, microbiological, radiological and therapeutic variables were described. Results: Twelve patients with LMM were recorded (mean age 67.5 years, 75% male). Eight had a positive culture for L. monocytogenes. cerebrospinal fluid (CSF) PCR was positive in the two cases in which the test was performed. Treatment in all cases was ampicillin for 21 days. Complications were recorded in a quarter of the cases. One patient died. Conclusions: LMM is a rare and difficult to diagnose disease. In our series of cases, the two patients diagnosed by PCR had negative CSF culture results, and presented good evolution. PCR determination could allow a greater number of cases to be diagnosed earlier.

Listeriosis diseminada: a propósito de un caso

La listeriosis es una enfermedad infecto contagiosa, transmitida por los alimentos, prevenible, y potencialmente grave. Las formas clínicas de presentación pueden ser muy variadas, desde una gastroenterocolitis hasta sepsis grave y compromiso multisistémico. Se discute el caso de una mujer joven que se presenta con manifestaciones neuropsiquiátricas y sistémicas subagudas, en contexto febril en la que a través de hemocultivos se llega al diagnóstico de Listeriosis invasiva. Se destaca el compromiso profundo parenquimatoso a forma de abscesos múltiples, como presentación menos frecuente. Se realiza tratamiento médico, antibioticoterapia prolongada, con franca mejoría clínica imagenológica. El diagnóstico de esta enfermedad requiere un alto índice de sospecha, optimizar las herramientas diagnósticas para un correcto relevo bacteriológico y así poder instaurar precozmente la antibioticoterapia.

Listeriosis is an infectious, contagious, foodborne, preventable, and potentially serious disease. The clinical forms of presentation can be very varied, from gastroenterocolitis to severe sepsis and multisystem involvement. We discuss the case of a young woman with subacute neuropsychiatric and systemic manifestations, in a febrile context in which the diagnosis of invasive Listeriosis is reached through blood cultures. Deep parenchymal involvement in the form of multiple abscesses stands out as a less frequent presentation. Medical treatment, prolonged antibiotic therapy, with clear clinical imaging improvement is performed. The diagnosis of this disease requires a high index of suspicion, optimization of diagnostic tools for a correct bacteriological relief and thus early initiation of antibiotic therapy.

A listeriose é uma doença infecciosa, contagiosa, transmitida por alimentos, evitável e potencialmente grave. As formas clínicas de apresentação podem ser muito variadas, desde gastroenterocolite até sepse grave e envolvimento multissistêmico. Discutimos o caso de uma jovem que apresenta manifestações neuropsiquiátricas e sistêmicas subagudas, em um contexto febril em que o diagnóstico de Listeriose invasiva é alcançado por meio de hemoculturas. O envolvimento do parênquima profundo na forma de múltiplos abscessos destaca-se como uma apresentação menos frequente. Realiza-se tratamento médico, antibioticoterapia prolongada, com nítida melhora da imagem clínica. O diagnóstico desta doença requer um alto índice de suspeição, otimização das ferramentas diagnósticas para um correto alívio bacteriológico e, assim, início precoce da antibioticoterapia.

Analysis of 50 cases of bloodstream infection with Listeria monocytogenes / 中国热带医学

@#Abstract: Objective　To analyze the characteristics of bloodstream infection of Listeria monocytogenes and provide basis for the diagnosis and treatment of the disease. Methods　We retrospectively analyzed the cases of Listeria monomyrhosi bloodstream infection in Peking Union Medical College Hospital (PUMCH) from April 2012 to April 2022. The age, sex, onset time, underlying disease, symptoms, diagnosis, treatment and prognosis of the patients were analyzed, as well as the changes of white blood cells (WBC), neutrophils, lymphocytes, and C-reactive protein (CRP) before and after anti-infection treatment. Results　Fifty cases of Listeria monocytogenes bloodstream infection confirmed by blood culture were involved. The age of patients ranged from 0 to 82 (43.7±20.0) years old, among whom 20.0% were over 60 years old. The onset time of patients was the highest in spring (44.0%), followed by winter (24.0%), and relatively fewer in summer and autumn (14.0%-18.0%). The median diagnosis time was 3 days (1-60 days). After the etiological diagnosis, 45 patients (90.0%) had underlying diseases or pregnancy status, and 45 patients were adjusted to the target antibacterial treatment mainly with carbapenems (48.9%) and penicillins (44.4%). The level of WBC, neutrophils, lymphocytes, monocytes, and CRP after treatment were significantly lower than those pre-treatments (P<0.05). Among all patients, 36 cases (72.0%) were treated according to the Antimicrobial Treatment Guidelines for Fever Sanford, of which 26 cases (72.2%) were discharged from the hospital, two cases died, one case was transferred to other hospitals, and 7 cases had a poor prognosis. Conclusions　Autoimmune diseases, tumor diseases, pregnant patients are susceptible to Listeria monocytogenes infection. Penicillins are the first choice for effective empiric therapy. For the patients allergic to penicillins, trimethoprim/sulfamethoxazole or meropenem could be used.

IL-17B regulates Listeria monocytogenes infection by inhibiting macrophage infiltration / 中华微生物学和免疫学杂志

Objective:To investigate the related mechanism of IL-17B in regulating host immune response by studying the role and mechanism of IL-17B in the infection of Listeria monocytogenes in mice. Methods:Eighteen male C57BL/6 mice were randomly divided into three groups with six in each group: control group, PBS group and wild-type (WT) group. The control group was not given any treatment. The mice in the PBS group were injected with 100 μl of sterile PBS, while C57BL/6 mice in the WT group and IL-17B deficient (IL-17B -/-) male mice were injected intravenously with 100 μl of Listeria monocytogenes 19115 (2×10 4 colony forming unit). The mice were sacrificed 48 h after infection and then peripheral blood, spleen and liver samples were collected. Bacterial colonization in mouse spleen and liver was detected by plate count method; HE staining was used to evaluate histopathological damages; flow cytometry was used to detect the immune cells in different tissues. ELISA and qRT-PCR were used to detect the levels of IL-1β, IL-6, IL-12p40, TNF-α, IFN-γ and iNOS in serum and spleen. qRT-PCR were used to detect the expression of IL-17B and IL-17RB. Results:Bacterial colonization in mouse spleen was reduced in the IL-17B -/- group as compared with that in the WT group ( P<0.05). Compared with the PBS group, Listeria monocytogenes infection increased the expression of IL-17B and IL-17RB in mouse spleen ( P<0.05, P<0.01). There was no significant difference in the pathological damages in spleen between WT and IL-17B -/- groups. Moreover, compared with the WT group, the IL-17B -/- group showed increased macrophages, M1 macrophages ( P<0.01) and NK cells ( P<0.05) in spleen, up-regulated macrophages ( P<0.05) and M1 macrophages ( P<0.01) in the peripheral blood, enhanced expression of IL-6 in serum and spleen ( P<0.05), and promoted expression of IL-6, IL-12, IL-1β, TNF-α, IFN-γ and iNOS in spleen. Conclusions:IL-17B might inhibit Listeria monocytogenes clearance by inhibiting macrophage infiltration and the secretion of IL-6.

Actividad antibacterial de nanopartículas de óxido de zinc sobre Listeria monocytogenes ATCC 7644 / Antibacterial activity of zinc oxide nanoparticles against Listeria monocytogenes ATCC 7644

Introducción: Las nanopartículas de óxido de zinc (Np-ZnO) presentan diferentes comportamientos; permitiendo su aplicación en diversas áreas. Objetivos: Determinar cuál es la concentración mínima inhibitoria de nanopartículas de óxido de zinc sobre el crecimiento de Listeria monocytogenes ATCC 7644. El estudio: Se utilizaron nanopartículas de ZnO con un tamaño promedio de 90 nm, a diferentes concentraciones de 4; 2; 1; 0,5; 0,25; 0,12; 0,06; 0,03; 0,01; 0,007 mg/mL de Np-ZnO, preparadas en solución acuosa. Se incubó en un tiempo correspondiente al de generación de la bacteria, evaluando el crecimiento con la aparición de turbidez. Hallazgos: Listeria monocytogenes ATCC 7644 presentó una CMI de 0,06 mg/mL. Conclusión: La concentración mínima inhibitoria (CMI) resultante para las nanopartículas de óxido de zinc (Np-ZnO) de 90 nm de tamaño promedio fue de 0,06 mg/mL, suficiente para controlar significativamente el crecimiento contra Listeria monocytogenes ATCC 7644.

background:Zinc oxide nanoparticles (Np-ZnO) have different behaviors which allows its application in various areas. : To determine the Objectivesminimum inhibitory concentration (MIC) of Zinc oxide nanoparticles for Listeria monocytogenes ATCC 7644. Zinc oxide nanoparticles with an The study:average size of 90nm and different concentrations of 4; 2; 1; 0,5; 0,25; 0,12; 0,06; 0,03; 0,01; 0,007 mg/mLprepared in aqueous solution were used. It was incubated at a time corresponding to generation time of the bacteria, evaluating the growth with the presence of turbidity. : The MIC for FindingsListeriamonocytogenesATCC7644was0,06mg/mL.The Conclusion:minimum inhibitory concentration (MIC) of Zinc oxide nanoparticles (Np-ZnO) with an average size of 90nm for Listeria monocytogenes ATCC 7644 was 0,06 mg/mL, enough value to significantly control the growth of for Listeria monocytogenes ATCC 7644.

Cobalamin cbiP mutant shows decreased tolerance to low temperature and copper stress in Listeria monocytogenes

BACKGROUND: Listeria monocytogenes is a foodborne pathogen that causes listeriosis in humans. This pathogen activates multiple regulatory mechanisms in response to stress, and cobalamin biosynthesis might have a potential role in bacterial protection. Low temperature is a strategy used in the food industry to control bacteria proliferation; however, L. monocytogenes can grow in cold temperatures and overcome different stress conditions. In this study we selected L. monocytogenes List2-2, a strain with high tolerance to the combination of low temperature +copper, to understand whether the cobalamin biosynthesis pathway is part of the tolerance mechanism to this stress condition. For this, we characterized the transcription level of three cobalamin biosynthesis related genes ( cbiP , cbiB, and cysG ) and the eutV gene, a transcriptional regulator encoding gene involved in ethanolamine metabolism, in L. monocytogenes strain List2-2 growing simultaneously under two environmental stressors: low temperature (8 °C) +copper (0.5 mM of CuSO4 ×5H2O). In addition, the gene cbiP , which encodes an essential cobyric acid synthase required in the cobalamin pathway, was deleted by homologous recombination to evaluate the impact of this gene in L. monocytogenes tolerance to a low temperature (8 °C) +different copper concentrations. RESULTS: By analyzing the KEGG pathway database, twenty-two genes were involved in the cobalamin biosynthesis pathway in L. monocytogenes List2-2. The expression of genes cbiP , cbiB, and cysG, and eutV increased 6 h after the exposure to low temperature +copper. The cobalamin cbiP mutant strain List2-2Δ cbiP showed less tolerance to low temperature +copper (3 mM) than the wild type L. monocytogenes List2-2. The addition of cyanocobalamin (5 nM) to the medium reverted the phenotype observed in List2-2Δ cbiP . CONCLUSION: These results indicate that cobalamin biosynthesis is necessary for L. monocytogenes growth under stress and that the cbiP gene may play a role in the survival and growth of L. monocytogenes List2-2 at low temperature +copper.

Genotyping of Listeria monocytogenes isolates by high-resolution melting curve (HRM) analysis of tandem repeat locus

Abstract Listeria monocytogenes is responsible for causing listeriosis, a type of food poisoning with high mortality. This bacterium is mainly transmitted to humans through the consumption of contaminated foods. Detection of L. monocytogenes through molecular methods is crucial for food safety and clinical diagnosis. Present techniques are characterized by low discrimination power and high cost, as well as being time-consuming and taking several days to give the final result. In our study, MLVA-HRM (Multiple-Locus Variable-number tandem repeats Analysis ‒ High-Resolution Melting) was investigated as an alternative method for a fast and precise method for the genotyping of L. monocytogenes isolates. Forty-eight isolates of L. monocytogenes obtained from the microbial bank of Department of Microbiology, Iran University of Medical Sciences, were typed by MLVA-HRM analysis using five Variable Numbers of Tandem Repeat (VNTR) loci. A total of 43 different types were obtained. This research demonstrated the usefulness of the MLVA-HRMA method and its ability to discriminate L. monocytogenes isolates. Since this method is easier and more efficient than existing methods, it can be widely used in food processing plants and diagnostic laboratories as a fast and accurate method.

Distribución y caracterización fenotípica y genotípica de Listeria monocytogenes en aislamientos de alimentos, Colombia, 2010-2018 / Distribution and phenotypic and genotypic characterization of Listeria monocytogenes isolated from food, Colombia, 2010-2018

Resumen | Introducción. Listeria monocytogenes es un patógeno transmitido por alimentos que causa infecciones en humanos, entre ellas, meningitis, meningoencefalitis y septicemias, así como abortos. Con la tipificación serológica se han identificado 13 serotipos, siendo el 4b el causante de la mayoría de los brotes en el mundo. Objetivo. Determinar la frecuencia y la distribución de los serotipos y subtipos moleculares de L. monocytogenes aislados de alimentos en Colombia entre el 2010 y el 2018. Materiales y métodos. Se hizo un estudio descriptivo y retrospectivo a partir del análisis de 2.420 aislamientos que fueron identificados como L. monocytogenes y otras especies, por medio de pruebas bioquímicas, serológicas y de subtipificación molecular mediante electroforesis en gel de campo pulsado (PFGE). Resultados. De los 2.420 aislamientos recibidos, 2.326 fueron confirmados como L. monocytogenes. Los serotipos encontrados fueron: 4b (52%), 4d-4e (14,5%), 1/2a (11%), 1/2c (9,4%), 1/2b (9 %), y 3a, 3b, 3c, 4c, 4d, 4e y 7 (menos de 2%). Procedían de Bogotá (43%), Antioquia (25%), Valle (10%), Nariño (9%) y otros departamentos (7%). La caracterización genotípica agrupó los aislamientos evaluados en 167 patrones de PFGE; los perfiles más frecuentes se presentaron en productos lácteos, cárnicos y alimentos preparados. Conclusión. El 96,1 % de los aislamientos correspondieron a L. monocytogenes, con una buena concordancia entre el aislamiento y la identificación; el serotipo 4b, extremadamente virulento, fue el más frecuente. El análisis molecular evidenció la posible diseminación y permanencia en el tiempo de varios serotipos, lo que resalta la importancia de incluir este patógeno en los programas de vigilancia epidemiológica en alimentos.

Abstract | Introduction: Listeria monocytogenes is a food-borne pathogen that may cause infections in humans such as meningitis, meningoencephalitis, and septicemia, as well as abortions. By serological typing 13 serotypes have been identified of which 4b is responsible for most of the outbreaks in the world. Objective: To determine the frequency and distribution of serotypes and molecular subtypes of L. monocytogenes isolated in Colombia from food from 2010 to 2018. Materials and methods: We conducted a retrospective and descriptive study based on the analysis of 2,420 isolates confirmed as L. monocytogenes and other species using biochemical and serological tests, and pulsed-field gel electrophoresis (PFGE) for molecular subtyping. Results: Of the 2,420 isolates received, 2,326 were confirmed as L. monocytogenes. The serotypes found were 4b (52%), 4d-4e (14.5%), 1/2a (11%), 1/2c (9.4%), 1/2b (9%), and 3a, 3b, 3c, 4c, 4d, 4e and 7 (less than 2%). The isolates came from Bogotá (43%), Antioquia (25%), Valle (10%), Nariño (9%), and other departments (7%). The genotypic characterization grouped the isolates in 167 PFGE patterns. The most frequent patterns were identified in various dairy and meat products, and in prepared foods. Conclusion: A 96.1% of the isolates corresponded to L. monocytogenes showing good agreement between isolates and identification. Serotype 4b, highly virulent, was the most frequent. The molecular analysis showed the possible dissemination and permanence over time of several serotypes, which highlights the importance of including this pathogen in epidemiological food surveillance programs.

Muerte perinatal por listeriosis

Mujer de 35 años, con 22 semanas de gestación, presentó fiebre sin origen determinado y disminución de los movimientos fetales, evolucionando con muerte fetal por infección por Listeria monocytogenes, evidenciada por hemocultivos y el estudio anatomo- patológico del feto y la placenta.

Caracterización de bacterias ácido lácticas con actividad antimicrobiana aisladas del queso crema de Chiapas, México / Characterization of lactic acid bacteria with antimicrobial activity isolated from cream cheese from Chiapas, Mexico

Resumen El queso crema de Chiapas es un producto artesanal fabricado en diferentes regiones de México. La capacidad de las bacterias lácticas, de producir grandes cantidades de ácido láctico y acético, tiene como efecto la disminución del pH, considerado uno de los factores primarios en la inhibición de microorganismos indeseables, como patógenos y bacterias coliformes, en alimentos lácteos. El objetivo de este trabajo fue aislar bacterias ácido lácticas y evaluar su efecto antagónico contra bacterias patógenas in vitro y contra patógenos presentes en la leche cuando se adicionan durante la elaboración del queso crema. Se aislaron cepas de bacterias lácticas del queso crema de Chiapas, México. Los aislados fueron identificados mediante pruebas bioquímicas API 50CH y secuencias del gen ribosomal 16S. Las bacterias de interés se usaron en pruebas de inhibición del crecimiento con cepas patógenas. Se cuantificó la producción de ácido acético y láctico por cromatografía de gases acoplado a masas en los quesos, al inicio y a los 10 d posteriores a su elabo ración. Se aislaron 203 cepas bacterianas, de las cuales 82 tuvieron la capacidad de inhibir el crecimiento de 7 cepas bacterianas patógenas. Las cepas fueron identificadas por la secuencia parcial del gen ribosomal 16S como pertenecientes al género Lactobacillus; la adición de estas cepas en la elaboración del queso crema redujo o eliminó coliformes, Staphylococcus aureus, mohos y levaduras, mientras que en el queso elaborado con leche pasteurizada se detectaron 290 UFC/mL de mohos y levaduras. Estos resultados sugieren que las cepas de Lactobacillus aisladas del queso crema artesanal de Chiapas tienen potencial para su uso como cultivo iniciador con actividad de bioconservación en este y productos similares.

Abstract Chiapas cream cheese is an artisanal product manufactured in different regions of Mexico. The ability of lactic bacteria to produce large amounts of lactic and acetic acid has the effect of decreasing the pH, considered one of the primary factors in the inhibition of undesirable microorganisms such as pathogens and coliform bacteria, in dairy foods. The objective of this work was to isolate lactic acid bacteria and evaluate their antagonistic effect against pathogenic bacteria in vitro, as well as their effect against pathogens that are present in milk when they are added in the preparation of cream cheese. Strains of lactic bacteria were isolated from cream cheese from Chiapas, Mexico. Isolates were identified by API 50CH biochemical tests and 16S ribosomal gene sequences. The bacteria under study were used in pathogen growth inhibition tests. The production of acetic and lactic acid was quantified by gas chromatography coupled to masses in the cheeses at the beginning and 10 d after its elaboration. 203 bacterial strains were isolated, 82 of which had the ability to inhibit the growth of 7 pathogenic bacterial strains. The strains were identified by the partial sequence of the 16S ribosomal gene as belonging to the genus Lactobacillus; The addition of these strains in the elaboration of cream cheese reduces or eliminates coliforms, Staphylococcus aureus, molds and yeasts, while in the cheese made with pasteurized milk 290 CFU/mL of molds and yeasts were detected. These results suggest that Lactobacillus strains isolated from Chiapas artisanal cream cheese has the potential to be used as a starter culture with bioconservation activity in this and similar products.

Infección por listeria monocytogenes en el embarazo, asociado a desprendimiento de placenta y complicaciones perinatales: reporte de un caso / Listeria monocytogenes infection in pregnancy, associated with placental abruption and perinatal complications: case report

INTRODUCCIÓN la listeriosis, aunque es una infección infrecuente, debe ser considerada en pacientes inmunocomprometidos y gestantes, especialmente en aquellos que consumen alimentos crudos o productos lácteos no pasteurizados, lo que pone en riesgo a un gran número de mujeres embarazadas en países de habla hispana. Es importante que el médico considere su inclusión en los posibles diagnósticos diferenciales cuando la sospecha clínica lo amerite, lo que permitirá hacer un diagnóstico temprano y por lo tanto un tratamiento oportuno, evitando así las posibles complicaciones en el binomio madre-hijo. CASO CLÍNICO clínico multigestante, con embarazo de 33 + 5 semanas, que ingresó a una institución de alto nivel de complejidad en la ciudad de Medellín, Colombia, por síndrome febril asociado a sepsis obstétrica debido a infección intraamniótica por Listeria monocytogenes, que requirió cesárea de urgencia, en donde se evidenció un desprendimiento placentario del 100 % secundario al proceso infeccioso y asociado a complicaciones neonatales. CONCLUSIONES: el diagnóstico de listeriosis gestacional supone un reto clínico por su presentación inespecífica y baja incidencia. Sin embargo, las consecuencias obstétricas arrastran una gran morbilidad de la madre y morbi-mortalidad neonatal, lo que hace de suma importancia que el clínico lo tenga presente en su arsenal diagnóstico, ya que una vez diagnosticado, el tratamiento oportuno tiene desenlaces clínicos favorables.

INTRODUCTION: although listeriosis is a rare infection, it should be considered in immunocompromised patients and pregnancy, especially in those who consume raw food or unpasteurized dairy, which puts a large number of pregnant women in Hispanic countries at risk. It is of special importance for physicians to include listeriosis among possible diagnoses when clinical suspicion arises in order to timely treat it and thus avoid the complications that may occur in the mother-child binomial. CLINICAL CASE: a pregnant woman (33 + 5 weeks) with multiple gestations, was admitted to a high level of complexity institution in the city of Medellín, Colombia, presenting a febrile syndrome associated with obstetric sepsis due to intra-amniotic infection by Listeria monocytogenes, which required emergency cesarean section where a 100 % placental abruption was evidenced secondary to the infectious process and associated with neonatal complications. CONCLUSIONS: The diagnosis of gestational listeriosis is a clinical challenge due to its nonspecific presentation and low incidence. However, the obstetric consequences drag a great maternal morbidity and neonatal morbidity and mortality, which is why it is important for physicians to consider this in the diagnostic arsenal because once diagnosed, the appropriate treatment has favorable clinical outcomes.

Listeriose em pacientes nefropatas imunossuprimidos - relato de dois casos / Listeriosis in patients immunosuppressed nephropaths - report of two cases

Contexto: A Listeria monocytogenes é um bacilo gram-positivo de baixa patogenicidade na população geral, mas importante causa de mortalidade por sepse e meningite em pacientes imunocomprometidos. Receptores de órgãos sólidos e candidatos em tratamento de dessensibilização são suscetíveis à infecção pela Listeria monocytogenes, embora sua apresentação clínica seja pouco reconhecida. Descrição dos casos: Paciente do sexo masculino, 43 anos, internado devido a rejeição aguda de enxerto pós-transplante renal, apresenta pico febril matutino e cefaleia. Paciente do sexo feminino, 59 anos, com doença renal crônica e em terapia de dessensibilização devido reatividade a painel antígeno leucocitário humano, busca pronto-socorro com febre, cefaleia e diarreia. A infecção por Listeria monocytogenes foi confirmada por hemocultura em ambos os casos. Discussão: A ocorrência de listeriose é esporádica e associada ao consumo de alimentos altamente contaminados, como laticínios, produtos frescos e carnes processadas. A redução da imunocompetência é o principal fator de risco para o desenvolvimento da doença em não gestantes, bem como para o aumento da mortalidade. O diagnóstico é estabelecido majoritariamente por hemocultura e o exame do líquido cefalorraquidiano é imprescindível para acessar o acometimento do sistema nervoso central, uma vez que os sinais meníngeos podem estar ausentes. O tratamento é realizado com beta-lactâmicos ou aminoglicosídeos. A ampicilina foi utilizada nos casos relatados e promoveu boa resposta clínica. Conclusão: Os profissionais devem atentar para a gravidade da infecção por Listeria monocytogenes e considerar sua ocorrência em pacientes imunocomprometidos, fornecendo orientações profiláticas a todos os candidatos a transplante de órgãos sólidos e tratamento empírico nos casos suspeitos.

Chemical characterization and antimicrobial activity of Campomanesia aurea against three strains of Listeria monocytogenes / Caracterização química e atividade antimicrobiana de Campomanesia aurea contra três cepas de Listeria monocytogenes

Abstract The essential oil (EO) composition of leaves of Campomanesia aurea was analyzed by GC-MS. The plant was collected in April (EOA) and October (EOO) in São Francisco de Assis/RS. The essential oils were obtained by hydrodistillation in a modified Clevenger apparatus. The yields were 4.44% in April, and 6.15%, in October. Thirty-one compounds were identified in EOA, accounting for 96.87% of the total, and twenty-eight compounds were identified in EOO, accounting for 99.46% of the total. For EOA, the major identified monoterpene was p-cymene (8.33%) and the major identified sesquiterpene was α-cadinol (10.72%), while regarding EOO the major identified monoterpene was repeatedly Terpinolene (3.43%), whereas the major identified sesquiterpene was α-cadinol (12.79%). The antibacterial activity of the essential oil was evaluated against the three Listeria monocytogenes from the American Type Culture Collection (strains ATCC 7644, 19114 and 13932). The essential oil showed a MIC of 10 mg/mL against the strains ATCC 7644 and 19114, with bacteriostatic effect of 20 mg/mL and a MIC of 20 mg/mL for ATCC 13932. Regarding the antibiofilm activity, o EOO showed the best results with an inhibition of 90% in the sessile growth with an applied concentration of 4.0 mg/mL.

Resumo O óleo essencial (EO) das folhas de Campomanesia aurea foi analisado por CG-EM. O A planta foi coletada em abril (OEA) e outubro (OEO) em São Francisco de Assis/RS. Os óleos essenciais foram obtidos por hidrodestilação em aparelho Clevenger modificado. Os rendimentos foram de 4,44% em abril e 6,15% em outubro. Trinta e um compostos foram identificados no EOA, representando 96,87% do total, e vinte e oito compostos foram identificados no EOO, representando 99,46% do total. Para EOA, o principal monoterpeno identificado foi o p-cimeno (8,33%) e o principal sesquiterpeno identificado foi o α-candinol (10,72%), enquanto o EOO o maior monoterpeno identificado foi repetidamente Terpinolene (3,43%), enquanto o sesquiterpeno principal identificado foi α-cadinol (12,79%). A atividade antibacteriana do óleo essencial foi avaliada contra as três cepas de Listeria monocytogenes obtidas a partir da American Type Culture Collection (isolados ATCC 7644, 19114 and 13932). O óleo essencial apresentou uma CIM de 10 mg/mL contra as cepas ATCC 7644. e 19114, com efeito bacteriostático de 20 mg/mL e MIC de 20 mg/mL para ATCC 13932. Quanto à atividade antibiofilme, o EOO apresentou os melhores resultados com uma inibição de 90% no crescimento séssil com uma concentração aplicada de 4,0 mg/mL.

Adesão, internalização e sobrevivência de Salmonella spp. e Listeria monocytogenes em mangas (Mangifera indica), variedade 'Tommy Atkins' / Adhesion, internalization and survival of Salmonella spp. and Listeria monocytogenes in mangoes (Mangifera indica), variety 'Tommy Atkins'

Surtos de salmonelose e listeriose associados ao consumo de frutas inteiras ou minimamente processadas ocorrem com frequência. O objetivo deste estudo foi investigar a capacidade de adesão e internalização de Salmonella spp. e Listeria monocytogenes em mangas (Mangifera indica) variedade Tommy Atkins, em diferentes condições de contaminação experimental e tratamento hidrotérmico, bem como avaliar a multiplicação dos patógenos internalizados na polpa das frutas durante armazenamento em refrigeração (8oC ) e temperatura ambiente (25oC). O estudo foi conduzido com as cepas S. Enteritidis ATCC 13076, S. Thyphimurium ATCC 14028, L. monocytogenes ATCC 7644 e L. monocytogenes Scott A. Inicialmente as cepas foram avaliadas segundo o índice de hidrofobicidade e capacidade de formação de biofilme em poliestireno. A adesão à superfície da manga foi avaliada por técnicas microbiológicas e também pela técnica de microscopia eletrônica de varredura. A internalização foi avaliada a partir de inoculação na cicatriz do pedúnculo (6 log UFC/mL) e após tratamento hidrotérmico e imersão em solução contaminada (6 log UFC/mL), mantidas a 8 °C e a 25 °C por 24h, 5 e 10 dias. A sobrevivência foi avaliada através da inoculação em região demarcada, em cenário de baixo (2 log UFC/mL) e alto nível de contaminação (6 log UFC/mL), a 8 °C e 25 °C, nos tempos 0, 1, 2, 3, 5 e 10 dias. A adesão foi observada nos dois patógenos, mesmo após sucessivas lavagens, com diferença significativa (p<0,05) após 1h de exposição e observou-se presença de estruturas exopolissacarídicas em diferentes tempos e condições de temperatura. A internalização ocorreu em todas as amostras avaliadas e a região do pedúnculo foi a mais afetada pela contaminação, diferindo significativamente na comparação com a região blossom end (p<0,05) a 8 °C e 25 °C. A sobrevivência foi observada nas duas temperaturas até o décimo dia. A multiplicação a 8°C foi significativamente mais baixa (p<0,05). Os resultados demonstraram que a Salmonella spp e L. monocytogenes são capazes de aderir à superfície, de internalizar e se alastrar pela polpa e ainda sobreviverem por períodos consideráveis, em 8 °C e 25 °C. Esses dados poderão auxiliar produtores e órgãos de saúde no desenvolvimento de avaliações quantitativas de risco e no estabelecimento de medidas adequadas para evitar surtos

Outbreaks of salmonellosis and listeriosis associated with the consumption of whole or minimally processed fruits occur frequently. The aim of this study was to investigate the ability of spp. and Listeria monocytogenes to adhere and internalize in mangoes (Mangifera indica) variety Tommy Atkins, under different conditions of experimental contamination and hydrothermal treatment, as well as evaluate the multiplication of the internalized pathogens in the fruit pulp during storage under refrigeration (8oC) and room temperature (25oC). The study was conducted with the strains S. Enteritidis ATCC 13076, S. Thyphimurium ATCC 14028, L. monocytogenes ATCC 7644 and L. monocytogenes Scott A. Initially the strains were evaluated according to the hydrophobicity index and capability to form biofilms on polystyrene surface. Adhesion to the mango surface was evaluated by microbiological techniques and also by scanning electron microscopy. Internalization was evaluated by inoculating the peduncle scar (6 log CFU / mL) and immersion of the fruits in contaminated solution (6 log CFU / mL) after hydrothermal treatment, during storage at 8 °C and 25 °C for 24h, 5 and 10 days. Survival was assessed by inoculation in a demarcated region, using low (2 log CFU / mL) and high level of contamination (6 log CFU / mL), and storage at 8 °C and 25 °C during 0, 1, 2, 3, 5 and 10 days. Adhesion was observed for both pathogens, even after successive washes, with a significant difference (p <0.05) after 1 h of exposure. Adhesion was mediated by exopolysaccharide structures, observed at different times and temperature conditions. Internalization occurred in all samples and the peduncle region was the most affected by the contamination, differing significantly in comparison with the blossom end region (p <0.05) at 8 °C and 25 oC. Survival was observed at both temperatures until the tenth day. The multiplication at 8 °C was significantly lower than at 25 oC (p <0.05). The results showed that Salmonella spp and L. monocytogenes were able to adhere to the surface, to internalize and spread through the pulp and still survive for considerable periods, at 8 °C and 25 °C. This data may help producers and health agencies to develop quantitative risk assessments and to establish appropriate measures to prevent outbreaks

Isolation and characterization of Lactobacillus brevis C23 with ability to secrete antimicrobial substance for the inhibition of a foodborne pathogen Listeria monocytogenes ATCC 7644

Aims@#This study aims to isolate lactic acid bacteria (LAB) from various food sources to obtain a potent strain against Listeria monocytogenes. @*Methodology and results@#A total of 68 LAB isolates were selected to evaluate their antimicrobial activity against L. monocytogenes, a foodborne pathogen and a causative agent of listeriosis. The selected isolate was identified and characterized. The isolate C23 from cabbage showed the highest antimicrobial activity against L. monocytogenes ATCC 7644 with inhibition ability of 73.94%. The isolate was closely related to Lactobacillus brevis by 16S rRNA sequencing and subsequently deposited in GenBank with an accession number of MN880215, named as L. brevis C23. The cell free supernatant (CFS) of L. brevis C23 had high tolerance in low pH and was able to withstand up to 60 °C. The proteinaceous nature of the antimicrobial agent was also confirmed through the enzymatic test. The CFS was stable on different detergents as well as bile salts. Under transmission electron microscopy (TEM), the inhibitory effect of CFS against L. monocytogenes was proven by causing cell lysis.@*Conclusion, significance and impact of study@#Bacteriocin-like inhibitory substances (BLIS) of L. brevis C23 showed very promising potential in food industrial application.

Advances on the mechanisms regulating the formation of the biofilm of Listeria monocytogenes / 生物工程学报

Listeria monocytogenes is an important food-borne pathogen. The distribution and survival of L. monocytogenes are related to its ability to form biofilms. Biofilms are resistant to adverse environments, and bacteria separated from the biofilms may lead to persistent food contaminations. The formation, maturation and structure of biofilms depend on a variety of external and internal factors, among which a variety of regulatory mechanisms play important roles. This review summarizes the regulatory mechanisms (including intracellular, intercellular and interspecific interactions) involved in the biofilm formation of L. monocytogenes in order to control the biofilm formation in food processing environments, thus providing new intervention strategy for food safety.

The semi-quantitative risk assessment of Listeria monocytogenes contamination in cooked meat products in bulk in Zhejiang Province / 预防医学

Objective@#To investigate the contamination status and assess the potential consumption risk of Listeria monocytogenes ( L. monocytogenes ) in cooked meat products in bulk in Zhejiang Province, so as to provide strategy for food safety supervision and management.@*Methods@#A total of 2 320 cooked meat products were sampled from eleven cities in Zhejiang Province during 2018-2020. The detection of L. monocytogenes was carried out in accordance with the national standard GB/T 4789.30-2016. Risk Ranger software was used for the semi-quantitative risk assessment on the whole population and pregnant women.@*Results@#The total detection rate of L. monocytogenes in cooked meat products in bulk in Zhejiang Province was 2.97% ( 69/2 320 ). The detection rates in stewed, smoked/roasted, fried, dried products and others were 3.85%, 1.81%, 0.59%, 0% and 0.94%, which were significantly different ( P<0.05 ). There were 28 positive samples in 1 069 samples collected in 2020, with the concentration ranging from 5 to 590 CFU/g and averaging 6.8 CFU/g. The estimated number of listeriosis cases each year caused by consumption of cooked meat products in bulk was 131 in the whole population with a risk score of 42, and 1.44 in pregnant women with a risk score of 54. The risk coefficient could reduce to approximate zero after sufficient heating before intake.@*Conclusion@#The prevalence of L. monocytogenes in cooked meat products in bulk in Zhejiang Province during 2018-2020 poses a potential risk in food safety. Pregnant women should avoid eating.

Investigation of Listeria monocytogenes, Salmonella enterica and Yersinia enterocolitica in pig carcasses in Southern Brazil / Pesquisa de Listeria monocytogenes, Salmonella enterica and Yersinia enterocolitica em carcaças de suínos no sul do Brasil

The intensification of pig production and advances in the sanitary control of herds profoundly changed the profile of risk attributed to pork consumption. In the actual scenario, most microorganisms related to macroscopic lesions observed in the post mortem inspection are not transmitted by food, while foodborne bacteria of importance to consumer health do not cause macroscopic lesions. In Brazil, the "Ministério da Agricultura, Pecuária e Abastecimento" requested a scientific opinion on the prioritizing of pathogens potentially transmitted by unprocessed pork. After conducting a qualitative risk assessment, only Salmonella enterica was classified as of high risk to consumers. The present study was part of the validation step of the risk assessment and aimed to investigate the frequency of S. enterica, Yersinia enterocolitica and Listeria monocytogenes and hygienic-sanitary indicators in pig carcasses of pigs rose under intensive production and slaughtered under the Federal Inspection System in three slaughterhouses located in Southern Brazil. Additionally, the antimicrobial resistance profile of the isolated pathogens was also investigated. A total of 378 carcasses were sampled by superficial sponges before the chilling step in three slaughterhouses. Samples were investigated for the presence of the three aforementioned pathogens and subjected to enumeration of Colony Formation Units (log CFU.cm-1) of total aerobic mesophiles (TAM) and Enterobacteriaceae. Salmonella strains were tested by disc diffusion test for resistance to eleven antimicrobials. There were significantly statistical differences (p<0.0001) on the median counts of both indicators between the slaughterhouses. The median of TAM was very close for Slaughterhouses A and B: 1.573 log CFU.cm-1 and 1.6014 log CFU.cm-1, respectively. While in Slaughterhouse C, a higher TAM median was detected (2.216 log CFU.cm-1). A similar profile was observed regarding to Enterobacteriaceae, and medians were calculated as follow: -0.426 log CFU.cm-1 in Slaughterhouse A; 0.2163 log CFU.cm-1 in B; and 0.633 log CFU.cm-1 in C. Regarding the pathogens investigated, L. monocytogenes was not detected and only one carcass from Slaughterhouse C was positive for Y. enterocolitica. Thus, the results suggest a very low prevalence of L. monocytogenes and Y. enterocolitica in the sampled population. A total of 65 (17.2%) carcasses were positive for S. enterica, with a difference in frequencies between slaughterhouses and slaughter days. The prevalence of Salmonella positive carcasses was higher in the Slaughterhouse C (25.4%; CI 95% 19-32%) in comparison with A (9.5%; CI 95% 9-14%) and B (18.3%; CI 95% 12-24%). There was no significantly statistical association between Enterobacteriaceae counts and Salmonella isolation on carcass surface (p=0.69). The slaughtering day, nested within the slaughterhouse, explains 31.3% of Salmonella prevalence variability. S. Typhimurium (38.1%) was the most prevalent, followed by S. Infantis (30.1%). Among the 61 Salmonella strains tested for resistance to antimicrobials, 18 (31.6%) were full-susceptible. No strain displayed resistance to azithromycin, ceftazidime, cefotaxime and meropenem. The highest resistance frequency was displayed to tetracycline (54.1%), followed by ampicillin (50.82%), nalidixic acid (42.62%) and chloramphenicol (42.62). Multi-resistance was detected in 52.54% of the, strains. In conclusion, S. enterica is more prevalent in pre-chill pig carcasses than Y. enterocolitica and L. monocytogenes and thus should be prioritized in monitoring and control programs at slaughter. Salmonella serovars varied among slaughterhouses and present significant differences in their resistance to antimicrobials. Slaughterhouses that present higher medians of TAM or Enterobacteriaceae in a monitoring period may have higher S. enterica prevalences as well. However, there is a high variation of S. enterica prevalence among slaughter days, which cannot be always related to the hygienic indicators counts observed on a given day.(AU)

A intensificação da produção de suínos e os avanços no controle sanitário dos rebanhos alterou de forma importante o perfil de risco do consumo de carne suína. No cenário atual, a maioria dos microrganismos causadores de lesões macroscópicas detectáveis na inspeção post mortem não são transmissíveis por alimentos, enquanto bactérias de importância como causadoras de doenças transmitidas por alimentos não causam lesões macroscópicas. No Brasil, o Ministério da Agricultura, Pecuária e Abastecimento solicitou uma opinião científica sobre a priorização de patógenos potencialmente transmitidos pela carne suína in natura. Após conduzir uma avaliação de risco qualitativa, apenas Salmonella enterica foi classificada como de alto risco para o consumidor. O presente estudo foi parte da etapa de validação da avaliação de risco e objetivou: investigar a frequência de S. enterica, Yersinia enterocolitica e Listeria. monocytogenes; e enumerar indicadores higiênico-sanitários em carcaças de suínos abatidos sob inspeção federal em frigoríficos dedicados ao abate de suínos sob sistema intensivo de criação no sul do Brasil. Além disso, o perfil de resistência a antimicrobianos dos patógenos isolados foi investigado. A superfície de um total de 378 carcaças foi amostrada por esponjas, na etapa de pré-resfriamento em três matadouros frigoríficos (A, B, C). As amostras foram investigadas quanto à presença dos três patógenos acima mencionados e quanto à enumeração de Unidades Formadoras de Colônia (log UFC.cm-1) de mesófilos aeróbios totais (MAT) e Enterobacteriaceae. As cepas isoladas de Salmonella foram testadas quanto à resistência a onze antimicrobianos pela técnica de disco difusão. As medianas de contagem de ambos os indicadores apresentaram diferença significativa (p<0,0001) entre matadouros-frigoríficos. A mediana de MAT foi bastante próxima para A e B (1,573 log UFC.cm-1 e 1,6014 log UFC.cm-1, respectivamente), enquanto em C uma mediana de MAT mais elevada foi determinada (2,216 log CFU.cm-1). Um perfil semelhante foi observado em relação a Enterobacteriaceae, sendo as medianas calculadas para A, B e C, respectivamente: -0,426 log CFU.cm-1; 0,2163 log UFC.cm-1; e 0,633 log UFC.cm-1. Em relação aos patógenos investigados, L. monocytogenes não foi detectada e apenas uma carcaça, do Matadouro C, foi positiva para Y. enterocolitica. Portanto, os resultados sugerem uma prevalência muito baixa desses patógenos na população amostrada. Em um total de 65 (17,2%) carcaças houve isolamento de S. enterica, com diferença nas frequências observadas entre matadouros e dias de abate. A prevalência de carcaças positivas para S. enterica foi maior no Matadouro C (25,4%; IC95% 19-32%) em comparação com A (9,5%; IC95% 9-14%) e B (18,3%; IC95% 12-24%). Não houve associação estatística entre o número de Enterobacteriaceae e o isolamento de S. enterica na superfície das carcaças (p=0,69). O dia de abate agrupado por frigorífico explica 31,3% da variação na prevalência de Salmonella. O sorovar mais frequente de S. enterica foi Typhimurium (38,1%) seguido de S. Infantis (30,1%). Entre as 61 cepas de S. enterica testadas quanto à resistência a antimicrobianos, 18 (31,6%) foram totalmente suscetíveis aos antimicrobianos testados. Nenhuma cepa apresentou resistência a azitromicina, ceftazidima, cefotaxima e meropenem. As maiores frequências de resistência foram demonstradas contra tetraciclina (54,1%), ampicilina (50,8%), ácido nalidíxico (42,62%) e cloranfenicol (42,62%). Em 52,54% das cepas foi detectada multi-resistência. Em conclusão, S. enterica é mais prevalente em carcaças suínas no pré-resfriamento do que Y. enterocolitica e L. monocytogenes. Portanto, S. enterica deve ser priorizada em programas de monitoramento e controle ao abate. Os sorovares de Salmonella variam entre matadouros e apresentam diferenças significativas na resistência a antimicrobianos. Matadouros de suínos que apresentam medianas de MAT e Enterobacteriaceae num período de monitoramento podem apresentar também prevalências mais de altas de presença de S. enterica. Entretanto, há uma alta variabilidade na frequência de S. enterica entre dias de abate, e nem sempre há relação entre essa frequência e a contagem de indicadores higiênico-sanitários determinados num determinado dia.(AU)

Listeria monocytogenes meningoencephalitis in a patient with Systemic Lupus Erythematosus / Meningoencefalite por Listeria monocytogenes em paciente com Lúpus Eritematoso Sistêmico

Abstract Introduction: Infectious complications are common in systemic lupus erythematosus. Although uncommon, central nervous system infections do occur and have significant lethality, with several etiological agents. Methods: We report on the case of a 29-year-old woman recently diagnosed with systemic lupus erythematosus with hematological, cutaneous, serous and renal manifestations (class IV lupus nephritis), who underwent corticosteroid pulse therapy and mycophenolate induction therapy. After 3 months of evolution, she developed headache and altered mental status. Computed tomography showed an area of hypoattenuation in the left frontal white matter and her cerebrospinal fluid examination showed pleocytosis and hyperproteinorrhachia. Peripheral blood and CSF culture identified Listeria monocytogenes. The patient presented deterioration of her neurological status, requiring invasive mechanical ventilation, monitoring of intracranial pressure and, despite all the intensive support, persisted in a comatose state and developed multiple organ failure, evolving to death due to nosocomial bloodstream infection. Discussion: Infection from L. monocytogenes usually occurs after eating contaminated food, manifesting itself with diarrhea and, occasionally, invasively, such as neurolisteriosis. Further investigation with CSF analysis and MRI is necessary, and the diagnosis consists of isolating the bacteria in sterile body fluid. Conclusion: The case presents a patient whose diagnosis of meningoencephalitis became an important differential with neuropsychiatric disorder. The poor outcome reinforces the need to remember this infectious condition as a serious complication in the natural history of SLE.

Resumo Introdução: As complicações infecciosas são frequentes no lúpus eritematoso sistêmico. Apesar de incomum, infecções do sistema nervoso central ocorrem e têm significativa letalidade, apresentando diversos agentes etiológicos. Métodos: Descrevemos aqui o caso de uma mulher de 29 anos recentemente diagnosticada com lúpus eritematoso sistêmico com manifestações hematológica, cutânea, serosa e renal (nefrite lúpica classe IV), submetida a pulsoterapia com corticoide e terapia de indução com micofenolato. Após 3 meses de evolução, apresentou quadro de cefaleia e alteração de estado mental. Tomografia computadorizada evidenciou área de hipoatenuação em substância branca frontal esquerda e exame de líquido cefalorraquidiano mostrava pleocitose e hiperproteinorraquia. Cultura de sangue periférico e do liquor identificaram Listeria monocytogenes. Paciente apresentou deterioração do quadro neurológico, necessitando de ventilação mecânica invasiva, monitorização de pressão intracraniana e, apesar de todo o suporte intensivo, persistiu em estado comatoso e disfunção de múltiplos órgãos, evoluindo a óbito por infecção de corrente sanguínea nosocomial. Discussão: Infecção por L. monocytogenes ocorre geralmente após ingestão de alimentos contaminados, manifestando-se por diarreia e, eventualmente, de forma invasiva como a neurolisteriose. Investigação complementar com análise de liquor e ressonância magnética faz-se necessária, sendo o diagnóstico confirmado por isolamento da bactéria em líquido corporal estéril. Conclusão: O caso representa uma paciente cujo diagnóstico de meningoencefalite tornou-se importante diferencial com atividade de doença neuropsiquiátrica. A evolução insatisfatória reforça a necessidade de se lembrar desta condição infecciosa como complicação grave na história natural do LES.

Detecção de listeria monocytogenes em produtos lácteos e produtos cárneos à base de frango / Detection of listeria monocytogenes in dairy products and chicken meat / Detección de listeria monocytogenes en productos lácteos y en productos cárnicos a base de pollo

Listeria monocytogenes é um patógeno de origem alimentar que frequentemente causa infecções, podendo até ser fatal. Trata-se de um microrganismo ubiquitário, transmitido ao ser humano principalmente por meio dos alimentos, como os produtos prontos para o consumo. O objetivo deste estudo foi verificar os índices de positividade para L. monocytogenes em queijos e produtos cárneos à base de frango, analisados em um laboratório de microbiologia de alimentos do Rio Grande do Sul. A triagem inicial das amostras seguiu o protocolo AOAC, método n° 2004.02, 2004. A confirmação dos resultados positivos foi realizada conforme Instrução Normativa nº 62/2003 (Mapa) e ISO 11290-1:1996, Amd.1:2004. Foram analisadas 666 amostras de queijos de baixa umidade, 3.897 de média umidade e 826 de alta umidade. Dos produtos à base de frango foram analisadas 547 amostras de salsicha, 172 de mortadela e 24 de linguiça. O estudo verificou que os queijos de baixa umidade estão significativamente associados ao resultado positivo (p=0,002) para L. monocytogenes e os queijos de alta umidade associaram-se ao resultado negativo (p=0,002). Com relação aos produtos à base de frango, a salsicha esteve significativamente associada ao resultado negativo para L. monocytogenes (p≤0,01), e a mortadela significativamente associada ao resultado positivo (p≤0,01). Visto que de modo geral esses produtos são consumidos diretamente, sem o emprego de calor, sugere-se reforçar tanto o controle sobre as boas práticas de fabricação quanto o monitoramento dos produtos.

Listeria monocytogenes is a foodborne pathogen that often causes infections and may even be fatal. It is an ubiquitous microorganism, transmitted to humans mainly through food such as ready-to-eat products. This study sought to verify the positivity indexes for L. monocytogenes in cheese and chicken meat products, analyzed in a food microbiology laboratory in Rio Grande do Sul, Brazil. The initial sample screening followed the AOAC protocol, Method No. 2004.02, 2004. Confirmation of positive results was performed according to Normative Instruction 62/2003 (MAPA) and ISO 11290-1: 1996, Amd.1: 2004. A total of 666 low moisture, 3897 medium moisture and 826 high moisture cheese samples were analyzed. Of the chicken meat products, 547 wiener, 172 mortadella and 24 sausage samples were analyzed. Results showed that low moisture cheeses were significantly associated with a positive result (p=0.002) for L. monocytogenes, while high moisture cheeses were associated with a negative result (p= 0.002). As for chicken meat products, the wiener was significantly associated with the negative result for L. monocytogenes (p≤0.01) and the mortadella significantly associated with the positive result (p≤0.01). Since most of these products are consumed directly, without the use of heat, it is suggested to reinforce both the control over Good Manufacturing Practices and the monitoring of the products.

Listeria monocytogenes es un patógeno de origen alimentario causante muchas veces de infecciones, incluso fatales. Es un microorganismo ubiquitario, que se transmite al hombre principalmente a través de los alimentos, generalmente por productos listos para el consumo. El objetivo de este estudio fue verificar los índices de positividad para L. monocytogenes en quesos y productos cárnicos a base de pollo, analizados en un laboratorio de microbiología de alimentos de Rio Grande do Sul (Brasil). El tamizaje inicial de las muestras siguió el protocolo AOAC, método 2004.02, 2004. La confirmación de los resultados positivos fue realizada conforme a la Instrucción Normativa 62/2003 (Mapa) e ISO 11290-1:1996, Amd.1:2004. Se analizaron 666 muestras de quesos de baja humedad, 3.897 de media humedad y 826 de alta humedad. De los productos a base de pollo se analizaron 547 muestras de salchichas, 172 de mortadela y 24 de chorizos. Este estudio verificó que los quesos de baja humedad fueron significativamente asociados al resultado positivo (p=0,002) para L. monocytogenes, y los quesos de alta humedad al resultado negativo (p=0,002). En cuanto a los productos a base de pollo, las salchichas estuvieron significativamente asociadas al resultado negativo para L. monocytogenes (p≤0,01), y la mortadela fue significativamente asociada al resultado positivo (p≤0,01). Dado que la mayoría de estos productos son consumidos directamente, sin cocción, se sugiere un mayor control de las buenas prácticas de fabricación y de monitoreo de los mismos.