Linking intraspecies variability of Salmonella enterica isolates under acidic conditions to genotype.

There is a lack of information about Salmonella enterica strains under acidic conditions and their association with their genome. This study characterized intraspecies variability in the growth of 167 S. enterica isolates under two acid conditions (pH 4 and 5) and linked to the whole genome sequencing (WGS) data. A total of 1002 curves for each condition were obtained using turbidimetry measurements, and Baranyi and Roberts model was used to estimate the maximum rate of change (rcmax; OD600 nm h-1). Strains were categorized into slow, intermediate, and fast; and associations with their WGS data were performed. Huge variability in r c max ¯ $\overline {{\mathrm{r}}{{{\mathrm{c}}}_{{\mathrm{max}}}}} $ was observed at both conditions (pH 5 = 0.016-0.066 OD600nm h-1 and pH 4 = 0.003-0.028 OD600nm h-1). The majority of isolates was classified as intermediate r c max ¯ $\overline {{\mathrm{r}}{{{\mathrm{c}}}_{{\mathrm{max}}}}} $ (59.5% at pH 5 and 46.1% at pH 4). Strains classified as fast had a low frequency of allABCD genes at both pHs, and any of them having the presence of pefABCD, spvBCR, aadA2, dfrA12, and gyrA_D87G genes were linked to virulence or antimicrobial resistance. This study suggests that strains with fast capacity for growth under acidic conditions could have a fitness cost in their virulence or resistance potential. PRACTICAL APPLICATION: Data presented in this study could be used to select representative strains to evaluate the exposure assessment in different food items, mainly the growth and survival in acidic foods.

Genomic diversity of Salmonella enterica isolated from raw chicken at retail establishments in Mexico.

The genomic diversity of circulating non-typhoidal Salmonella in raw chicken was investigated in three states of central Mexico. A total of 192 S. enterica strains from chicken meat samples collected at supermarkets, fresh markets, and butcher shops were analyzed by whole-genome sequencing. The serovar distribution, occurrence of genes encoding for antimicrobial resistance, metal resistance, biocide resistance, plasmids and virulence factors, and clonal relatedness based on single nucleotide polymorphism (SNP) analysis were investigated. Serovars Infantis, Schwarzengrund and Enteritidis predominated among twenty identified. The distribution of serovars and proportion of AMR genes was different according to the state, year, season, and retail establishment (p < 0.001). Genes encoding metals resistance were identified in all the strains. A total of 145 virulence genes were identified and strains were classified into 32 virulotypes; serovars Infantis, Typhimurium, and Enteritidis showed the highest number of virulence genes. The strains matched 34 SNP clusters in the NCBI Pathogen Detection server and 59 %, which corresponded to Infantis, Schwarzengrund, Saintpaul, and Enteritidis, were associated with five major clusters and matched with chicken, environmental and clinical isolates from at least three countries. These results provide useful information to understand the epidemiology of Salmonella, conduct microbial risk assessment, and design risk-based control measures.

Clavulanic Acid Is a Leading Culprit Beta-Lactam in Immediate Allergic Reactions to Penicillins.

PURPOSE: Clavulanate, a beta-lactam associated with amoxicillin, is frequently prescribed in patients at all ages. Recent data implicate amoxicillin-clavulanate in up to 80% of beta-lactam allergy cases. We assessed clavulanate's role in inducing allergic reactions to this combination treatment, with a focus on selective immediate reactions. METHODS: Adults (≥ 16 years) reporting a history of immediate reactions to amoxicillin-clavulanate were evaluated through a beta-lactam allergological workup, using modified European Academy of Allergy and Clinical Immunology guidelines. Patients first underwent skin testing, and if negative, drug provocation tests. Expected outcomes were: Group A, subjects with immediate reaction to classical penicillin group determinants (penicilloyl polylysine, minor determinants mixture, and/or penicillin G); Group B, subjects with selective immediate reaction to amoxicillin; Group C, subjects with selective immediate reaction to clavulanate and Group D, those immediate reactions with co-sensitization to clavulanate plus penicillin group determinants or amoxicillin. RESULTS: Of 1,170 included patients, 104 had immediate reactions: 36.5% to penicillin group determinants (Group A), 26.9% to amoxicillin (Group B), 32.7% to clavulanate (Group C), and 3.8% to clavulanate plus penicillin determinants or amoxicillin (Group D). Diagnosis was made by skin testing in 79%, 75% and 47% of the patients, respectively, in the first 3 groups (P < 0.001). Drug provocation tests were necessary to establish most other diagnoses. Anaphylaxis predominated over urticaria/angioedema in all groups. CONCLUSIONS: Selective immediate reactions to clavulanate accounted for over a third of cases with confirmed reactions after amoxicillin-clavulanate intake, with more than half experiencing anaphylaxis. Within this group, skin test sensitivity was below 50%. People taking amoxicillin-clavulanate may also be co-sensitized to both drugs.

Effect of storage temperature and time on the behavior of Salmonella, Listeria monocytogenes, and background microbiota on whole fresh avocados (Persea americana var Hass).

Avocados are popular fruits; however, contamination of whole fresh avocados and avocado products with foodborne pathogens has raised concern about their safety. Recalls and import alerts of avocado products due to contamination with Listeria monocytogenes cause important economic losses. The behavior of Salmonella, L. monocytogenes, and background microbiota on whole fresh avocados at 5 and 25 °C as affected by temperature and time of storage was investigated. Whole fresh avocados were inoculated by immersion in suspensions containing six rifampicin-resistant strains of Salmonella or L. monocytogenes, and stored at 5 °C for 48 d, or at 25 °C for 11 d. At selected sampling times, avocados were removed from storage and pathogens enumerated. The log counts of both pathogens at each temperature were fitted to the Weibull distribution nonlinear model to estimate kinetic parameters including the time for the first 1-log reduction (δ), the shape of the curve (ρ), and the time for two (2-D) and three (3-D) log reductions. Salmonella and L. monocytogenes initial populations (approx. 7 log CFU/avocado) decreased during storage at 5 and 25 °C; L. monocytogenes mean counts were higher than those observed for Salmonella (P < 0.05). L. monocytogenes showed a lower rate of decline at 5 °C when compared to Salmonella. In general, the ability of both pathogens to survive on the surface of avocados stored at room temperature was similar. Salmonella and L. monocytogenes counts decline over time on the epicarp of whole avocados; however, if the initial number of cells is large enough, the pathogens could be present for large periods of time. Simultaneously, psychrotrophic microorganisms (PM), aerobic plate count (APC), coliforms (C) and yeasts/molds (Y/M) were enumerated from non-inoculated avocados stored at 5 and 25 °C. Initial mean counts for PM, APC, C and Y/M ranged from 6.1 to 6.6 log CFU/avocado and showed no change (P > 0.05) during storage at both temperatures. Good agricultural and handling practices from farm to fork are crucial to prevent or minimize contamination of whole avocados; otherwise, if large numbers of pathogens contaminate the fruit, they could survive and be transferred to the pulp, or to other ready to eat foods, representing a risk for consumers.

Clinical impact and immunological alterations in asthmatic patients allergic to grass pollen subjected to high urban pollution in Madrid.

BACKGROUND: The prevalence of asthma has increased in recent decades. Among the reasons for this increase is environmental pollution. Pollutants cause bronchial inflammation and introduce modifications in the pollen, making it more allergenic. OBJECTIVE: Assess symptoms and medication requirements of asthmatic patients with grass allergies in Madrid (high urban pollution) and Ciudad Real (low pollution), and simultaneously evaluate the in vitro effects that pollen collected in both areas has on the immune cells of patients. METHODS: During two pollen seasons, patients from both cities were included. The patients recorded their symptoms and the asthma medication they took daily. In both cities, pollen data, pollutants and meteorological variables were evaluated. The response to different cell populations from patients in both areas were analysed after "in vitro" stimulation with pollen from both cities. RESULTS: The symptoms and medication use of the patients in Madrid was 29.94% higher. The NO2 concentration in Madrid was triple that of Ciudad Real (33.4 vs. 9.1 µg/m3 of air). All other pollutants had very similar concentrations during the study period. Pollen from the high pollution area caused a significant enhancement of T-CD8+ and NK cells proliferation compared with pollen of low pollution area, independently of the patient's origin. CONCLUSION: Asthmatic patients from Madrid have a worse clinical evolution than those from Ciudad Real because of higher levels of urban pollution, and this could be driven by the higher capacity of pollen of Madrid to activate T-CD8+ and NK cells.

Detection, quantification, and characterization of Salmonella enterica in mango, tomato, and raw chicken purchased in the central region of Mexico.

To estimate human exposure to Salmonella enterica, it is essential to understand the pathogen distribution and characteristics. Prevalence and concentration of S. enterica were determined in mango, tomato, and raw chicken samples purchased in three states (Aguascalientes, Querétaro, and Guadalajara) located in the central region of Mexico during two seasons. In addition, S. enterica isolates were characterized by absence/presence of 13 virulence genes (chromosomal, prophage, and plasmid) and resistance to 14 antibiotics. A total of 300 samples of mango, 272 of tomato, and 354 of raw chicken were analyzed. The mean of the prevalence (24.9%) and concentration (-0.61 Log MPN/g) of S. enterica in chicken was higher than in mango (1.3%, -1.7 Log MPN/g) and tomato (1.1%, -1.7 Log MPN). Among S. enterica isolates (284), there were 7 different virulotypes, belonging 68.7% of isolates to V2; there was high variability in the presence of mobile genetic elements. The occurrence of specific mobile elements ranged from 81.4% to 11.3% among isolates. Among the isolates, 91.5% were resistant to at least one antibiotic with ampicillin being the most frequent; 54.9% of isolates were multidrug resistant. Data from this study can be used for quantitative microbial risk assessment of S. enterica related to mango, tomato, and raw chicken consumption in the central region of Mexico. PRACTICAL APPLICATION: Data on the prevalence and concentration of Salmonella enterica obtained in this study can be used to estimate the exposure assessment for the consumption of mango, tomato, and chicken in the central region of Mexico. In addition, the characteristics of the S. enterica isolates could be used to select representative strains for future studies to evaluate the intraspecies variability.

Infección por SARS-CoV-2 COVID-19: seguimiento de casos sospechosos y contactos en la población pediátrica de un hospital de tercer nivel / SARS-CoV-2 COVID 19 infection: follow-up of suspected cases and contacts in the pediatric population of a tertiary care hospital / Infecção por SARS-CoV-2 COVID 19: monitoramento de casos suspeitos e contatos na população pediátrica de um hospital terciário

La Organización Mundial de la Salud (OMS) declaró la pandemia por SARS-CoV-2 COVID-19 el 11 de marzo de 2020. En Uruguay el 13 de marzo de 2020 se notificaron los primeros casos declarándose el estado de emergencia sanitaria. Desde el inicio de la epidemia hasta el 27 de abril de 2021 se reportaron 22.718 casos en menores de 15 años. Dada esta situación epidemiológica desde el Departamento de Pediatría se implementó el diagnóstico y seguimiento clínico telefónico de los niños y adolescentes (NNA) que consultaron en la Emergencia Pediátrica y constituyeran casos y/o contactos de enfermedad por coronavirus 2019 (COVID-19). Se analizan las características epidemiológicas y clínicas de NNA en seguimiento por sospecha de infección por SARS-CoV-2 en un hospital de tercer nivel entre el 1 de marzo de 2020 y el 28 de febrero de 2021. Se realizó un estudio observacional descriptivo retrospectivo en ese período. Se incluyeron pacientes de 0 a 14 años que consultaron en el Departamento de Emergencia Pediátrica con síntomas sugestivos de COVID-19 o por situación de contacto con un caso confirmado. Fuentes de datos: estadísticas de ingresos, historias clínicas y laboratorio. Variables: fecha de consulta, sexo, edad, procedencia, clínica, contacto COVID-19 confirmado, comorbilidad, resultado de test PCR para SARS-CoV-2, seguimiento y evolución. Análisis estadístico distribución de frecuencias, medidas de resumen y pruebas de significancia, considerando estadísticamente significativo un valor de p ≤0.05. Consideraciones éticas: no se realizó una intervención específica, se garantizó la privacidad y el anonimato de las personas involucradas. Se realizaron 657 consultas. 455 (69,3%) telefónicas, y 202 (30,7%) presenciales. 287 (43,7%) asintomáticos y 370 (56,3%) sintomáticos: rinorrea (27%), fiebre (23%), tos(22%), odinofagia (14%), gastrointestinales (4,8%), dificultad respiratoria (3,6%), entre otros. 394 pacientes (60%) fueron contactos, 254 (64,5%) intrafamiliar, 89 (22,6%) educativo entre otros. 467 (71,1%) tuvieron al menos un seguimiento, 451 (96,6%) telefónico y 16 (3,4%) presencial. 78 (11,9%) fueron positivos, 504 (76,7%) negativos y 75 (11,4%) no realizó test. 646 (98,3%) ambulatorios, uno ingresó a CTI. Ninguno falleció. A través de telemedicina se logró implementar un seguimiento adecuado de casos y contactos COVID-19 e identificar situaciones que requirieran atención presencial. La mayoría cursaron su enfermedad en forma ambulatoria. En los menores de 12 años hubo más infecciones asintomáticas y la fuente de contagio fue un conviviente con mayor frecuencia que en los mayores de 12 años, siendo estas diferencias estadísticamente significativas (p=0,006 y p=0,005). La presentación clínica en esta población fue similar a la reportada. El seguimiento telefónico y la orientación oportunas contribuyeron a la adopción de medidas para disminuir los contagios y la circulación viral y permitieron acompañar al paciente y su familia física y emocionalmente.

Introduction: the World Health Organization (WHO) declared the SARS-CoV2 COVID 19 pandemic on March 11, 2020. In Uruguay, on March 13, 2020, the first cases were reported, and a state of health emergency was set up. From the beginning of the epidemic until April 27, 2021, 22,718 cases were reported in children under 15 years of age. Given this epidemiological situation, the Department of Pediatrics implemented the telephone consultations and clinical follow-up of children and adolescents (CHA) who consulted in the Pediatric Emergency and became cases and/or contacts of coronavirus disease 2019 (COVID 19). Objective: to analyze the epidemiological and clinical characteristics of children under follow-up for suspected SARS-CoV-2 infection in a tertiary care hospital between March 1, 2020 and February 28, 2021. Material and methods: a retrospective descriptive observational study was carried out in the period mentioned above. Patients from 0 to 14 years old who consulted in the Pediatric Emergency Department with symptoms of COVID 19 or because of a contact with a confirmed case were included. Data sources: admission statistics, medical records and laboratory. Variables: consultation date, sex, age, origin, clinic, confirmed COVID 19 contact, comorbidity, PCR test result for SARS-CoV-2, follow-up and evolution. Statistical analysis frequency distribution, summary measures and significance tests, a value of p≤0.05 was regarded as statistically significant. Ethical considerations: no specific intervention was performed, the privacy and anonymity of the people involved were guaranteed. 657 consultations were made. 455 (69.3%) by telephone, and 202 (30.7%) in person. 287 (43.7%) asymptomatic and 370 (56.3%) symptomatic: runny nose (27%), fever (23%), cough (22%), sore throat (14%), gastrointestinal (4.8%), respiratory distress (3.6%) among others. 394 patients (60%) were contacts, 254 (64.5%) intrafamily, 89 (22.6%) at school, among others. 467 (71.1%) had at least 1 follow-up, 451 (96.6%) by telephone and 16 (3.4%) in person. 78 (11.9%) were positive, 504 (76.7%) negative and 75 (11.4%) did not perform the test. 646 (98.3%) outpatients, 1 admitted to ICU. None died. Conclusions: through telemedicine, we could implement an adequate follow-up of COVID 19 cases and contacts and identify situations that required in-person care. In most cases, the disease was resolved in an outpatient manner. Patients under 12 were more asymptomatic and the source of infection was a cohabitant more frequently than in those over 12 years of age, these differences being statistically significant (p=0.006 and p=0.005). The clinical presentation in this population was similar to reported data. The timely telephone follow-up and orientation contributed to the adoption of measures to reduce infections and viral circulation and enabled patients and families to feel physically and emotionally accompanied.

Introdução: a Organização Mundial da Saúde (OMS) declarou a pandemia de SARS-CoV2 COVID 19 eno dia 11 de março de 2020. No Uruguai, em 13 de março de 2020, foram notificados os primeiros casos e foi declarado o estado de emergência sanitária. Desde o início da epidemia até 27 de abril de 2021, foram notificados 22.718 casos em menores de 15 anos. Perante esta situação epidemiológica, o Departamento de Pediatria implementou o diagnóstico telefónico e o acompanhamento clínico das crianças e adolescentes (CA) que consultaram na Emergência Pediátrica e constituíram casos e/ou contatos de doença por coronavírus 2019 (COVID 19). Objetivo: analisar as características epidemiológicas e clínicas de crianças em acompanhamento por suspeita de infecção por SARS-CoV-2 em um hospital terciário entre 1º de março de 2020 e 28 de fevereiro de 2021. Materiais e métodos: foi realizado um estudo observacional descritivo retrospectivo no período mencionado acima. Foram incluídos pacientes de 0 a 14 anos que consultaram no pronto-socorro pediátrico com sintomas sugestivos de COVID 19 ou devido ao contato com um caso confirmado. Fontes de dados: estatísticas de admissão, prontuários e laboratório. Variáveis: data da consulta, sexo, idade, procedência, clínica, contato confirmado de COVID 19, comorbidade, resultado do teste PCR para SARS-CoV-2, acompanhamento e evolução. Distribuição de frequência da análise estatística, medidas sumárias e testes de significância, considerando-se um valor de p≤0,05 como estatisticamente significativo. Considerações éticas: não foi realizada nenhuma intervenção específica, foi garantida a privacidade e o anonimato das pessoas envolvidas. Foram feitas 657 consultas. 455 (69,3%) por telefone e 202 (30,7%) pessoalmente. 287 (43.7%) assintomáticos y 370 (56.3%) sintomáticos: rinorreia (27%), febre(23%), tosse(22%), odinofagia (14%), gastrointestinal (4.8%), dificuldade respiratória (3.6%) entre outros. 394 pacientes (60%) foram contatos, 254 (64,5%) intrafamiliares, 89 (22,6%) na escola, entre outros. 467 (71,1%) tiveram pelo menos 1 acompanhamento, 451 (96,6%) por telefone e 16 (3,4%) pessoalmente. 78 (11,9%) foram positivos, 504 (76,7%) negativos e 75 (11,4%) não realizaram o teste. 646 (98,3%) pacientes ambulatoriais, 1 internado na UTI. Nenhum deles morreu. Conclusões: por meio da telemedicina, foi possível implementar um acompanhamento adequado dos casos e contatos da COVID 19 e identificar situações que exigiram atendimento presencial. A maioria atendeu sua doença de forma ambulatorial. Nos menores de 12 anos houve mais infecções assintomáticas e a fonte de infecção foi um coabitante mais do que nos maiores de 12 anos, sendo essas diferenças estatisticamente significativas (p=0,006 p=0,005). Essa população foi semelhante aos dados registrados. O acompanhamento e orientação oportuna por telefone contribuíram para a adoção de medidas de redução de infecções e circulação viral e permitiram que o paciente e sua família se sentissem acompanhados física e emocionalmente.

Patterns of response and drugs involved in hypersensitivity reactions to beta-lactams in children.

BACKGROUND: Beta-lactams generate different allergenic determinants that induce selective or cross-reactive drug hypersensitivity reactions (DHRs). We aimed to identify the drugs involved, the selectivity of the response, the mechanism, and the value of the different diagnostic tests for establishing a diagnosis in children evaluated for DHRs to beta-lactams. METHODS: Prospective study evaluating children aged under 16 years reporting DHRs to beta-lactams. Reactions were classified as immediate and non-immediate reactions. The workup included sIgE, skin testing, and drug provocation tests (DPTs) for immediate reactions and patch testing and DPTs for non-immediate ones. RESULTS: Of the 510 children included, 133 were evaluated for immediate reactions and confirmed in 8.3%. Skin test/in vitro IgE contributed to diagnosing half of the cases. Selective reactions occurred with amoxicillin (63%), followed by common penicillin determinants (27%) and cephalosporins (0.9%). Among non-immediate reactions (11.4% of the 377 children evaluated), most required DPTs, 52.7% of which were positive at 6-7 days of drug challenge. Selective reactions were identified with amoxicillin (80%), penicillin G (7.5%), cephalosporins (7.5%), and clavulanic acid (5%). Urticaria and maculopapular exanthema were the most frequent entities. CONCLUSIONS: There were few confirmed cases of either type of reaction. Skin testing proved less valuable in non-immediate reactions, over half of which would also have been lost in a short DPT protocol. Selective responders to amoxicillin were more likely to have non-immediate reactions, while clavulanic acid selectivity was exclusive to the non-immediate typology. Over half the cases with DPTs required 6-7 days of treatment for DHR confirmation.

Stronger impulse capture and impaired inhibition of prepotent action in children with ADHD performing a Simon task: An electromyographic study.

OBJECTIVE: A deficit in interference control is commonly reported in children with attention deficit hyperactivity disorder (ADHD). This has mainly been interpreted as a difficulty in inhibiting inappropriate responses. However, it could be due to at least two distinct and independent processes, which are often confounded: The activation or suppression of impulsive responses. The aim of the present study was to separate the contribution of these two processes. METHOD: We compared performance of 26 children with ADHD to that of 26 nonADHD children using a novel approach based on electromyographic activity (EMG) analysis. EMG allows two distinct indices to be computed: Incorrect activation rate, which is an index of the intensity of impulse capture and correction rate, which provides a direct measure of the ability to suppress automatic responses. RESULTS: Children with ADHD were slower, committed more errors, and had a larger interference effect than nonADHD children. Moreover, we observed a greater incorrect activation rate and a lower correction rate in the ADHD group. CONCLUSIONS: Our data suggest that the difficulties in interference control found in children with ADHD are explained by both impaired inhibitory processes and a greater propensity to activate automatic responses. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Recomendaciones en el manejo de pacientes de medicina reproductiva en tiempos de SARS-CoV-2: Un resumen de la literatura / Management recommendation of reproductive medicine patients in SARS-CoV-2 time: A literature summarize

La pandemia de SARS-CoV-2 es una emergencia sanitaria sin precedentes, que ha implicado un reordenamiento en la priorización de procedimientos médicos electivos, frente a un potencial colapso del sistema de salud a nivel mundial y riesgo de contagio del personal y pacientes. Al igual que en el resto del mundo, en Chile la mayoría de los centros de medicina reproductiva han debido suspender sus diferentes terapias de reproducción asistida (TRA). Sin embargo, a raiz de la disminución del número de contagios y mayor evidencia científica disponible, la Sociedad Europea de Reproducción Humana y Embriología (ESHRE) ha recomendado reiniciar los ciclos de medicina reproductiva de forma gradual, a través de sistemas de triage, priorizando pacientes por medio de la generación de distintos escenarios. Considerando esta recomendación, se realizó una revisión sobre la evidencia existente respecto a SARS-CoV-2 / COVID-19 en medicina reproductiva recopilando diferentes directrices de las principales sociedades internacionales, con el objetivo de generar una recomendación ajustada a la realidad nacional.

SARS-CoV-2 pandemic is an unprecedented health emergency, which involves a reorganization of elective procedures, facing a potential global health system collapse. In Chile, as in the rest of the world. most reproductive medicine centers have suspended their different assisted reproduction therapies (ART). However, due to the decrease in the number of infections and due to a greater collection of scientific evidence, the European Society for Human Reproduction and Embryology (ESHRE) have recommended restarting cycles gradually through triage systems, prioritizing patients through the generation of different scenarios. With this in mind, we carried out a review of the existing evidence so far regarding SARS-CoV-2 and reproductive medicine, and we tried to compile the different guidelines of the main international societies, to generate a recommendation adjusted to our local scenario.

How Is Temporal Processing Affected in Children with Attention-deficit/hyperactivity Disorder?

We compared the performance of children with ADHD and typically developing children on two temporal tasks, a bisection task and a reproduction task, in auditory and visual modalities. Children with ADHD presented a larger variability when performing auditory and visual temporal tasks. Moreover, they overestimated the durations in bisection tasks and underproduced duration intervals in the visual reproduction task. In the context of the pacemaker-accumulator model, these results suggest that temporal deficits might result from a dysfunction in the switch and/or memory impairment.

Thermal and Chemical Treatments To Reduce Salmonella on Alfalfa (Medicago sativa) and Broccoli (Brassica oleracea var. italica) Seeds before and during the Sprouting Process: A Hurdle Approach.

Sprouts are vehicles of foodborne diseases caused by pathogens such as Salmonella. The aim of this study was to evaluate thermal and chemical treatments applied as a hurdle approach to reduce Salmonella in alfalfa (Medicago sativa) and broccoli (Brassica oleracea var. italica) seeds before and during their germination. Seeds, inoculated and then dried at 55°C for 48 h, were subjected to a chemical treatment and a thermal shock with (i) 75 mM caprylic acid at 70°C for 5 s, (ii) 0.04% CaO at 70°C for 5 s, or (iii) 1% H2O2 at 70°C for 5 s. After each treatment, seeds were immersed in water at 3°C for 5 s. Next, the imbibition process was carried out with 0.016% H2O2 at pH 3.0. Finally, the seeds were transferred to a rotary drum-type germinator and were sprayed with the same chemical solution that was applied before the imbibition process, for 20 s at intervals of 5 min for 40 min at 3 rpm. All chemical treatments reduced Salmonella at least 5 log CFU/g on both seeds. Germination rates between 90 and 93% were obtained after application of thermal and chemical treatments. Salmonella was not detected after the imbibition stage when caprylic acid and H2O2 treatments were applied. However, during the germination process of both seeds, Salmonella counts of >6 log CFU/g were obtained despite all treatments being applied at different stages of the sprouting process. These results demonstrated that thermal and chemical treatments used as a hurdle approach to control Salmonella on alfalfa and broccoli seeds significantly reduced the pathogen concentration on seeds >5 log but were ineffective to eliminate Salmonella and to control its growth during the sprouting process. The production of safe sprouts continues to be a major challenge for industry.

Salmonella, Listeria monocytogenes, and Indicator Microorganisms on Hass Avocados Sold at Retail Markets in Guadalajara, Mexico.

Hass avocados may become contaminated with Salmonella and Listeria monocytogenes at the farm and the packing facility or later during transportation and at retail. In Mexico, avocados are frequently sold in bulk at retail markets, where they are stored at room temperature for several hours or days and exposed to potential sources of microorganisms. These conditions may favor the entry, adhesion, survival, and biofilm formation of Salmonella and L. monocytogenes. The aim of this study was to determine the occurrence of Salmonella, L. monocytogenes, and other Listeria species and the levels of indicator microorganisms on the surface of avocados sold at retail markets. A total of 450 samples (Persea americana var. Hass) were acquired from retail markets located in Guadalajara, Mexico. One group of 225 samples was evaluated for the presence of Salmonella and for enumeration of aerobic plate counts, yeasts and molds, Enterobacteriaceae, coliforms, and Escherichia coli. The other 225 samples were processed for isolation of L. monocytogenes and other Listeria species. Microbial counts (log CFU per avocado) were 4.3 to 9.0 for aerobic plate counts, 3.3 to 7.1 for yeasts and molds, 3.3 to 8.2 for Enterobacteriaceae, 3.3 to 8.4 for coliforms, and 3.3 to 6.2 for E. coli. Eight samples (3.5%) were positive for Salmonella. Listeria spp. and L. monocytogenes were detected in 31 (13.8%) and 18 (8.0%) of 225 samples, respectively. Listeria innocua, Listeria welshimeri, and Listeria grayi were isolated from 7.6, 1.3, and 0.9% of samples. These results indicate that avocados may carry countable levels of microorganisms and could be a vehicle for transmission of Salmonella and L. monocytogenes.

Genetic diversity and antimicrobial resistance of Salmonella serotypes recovered throughout the beef production chain and from patients with salmonellosis.

Salmonella is one of the major foodborne pathogens worldwide. The antimicrobial resistance (AMR) of this foodborne pathogen has raised a great concern in recent years. Studies on the frequency and characterization of Salmonella serotypes can help to improve our knowledge on the epidemiology of this pathogen. The purpose of this study was to compare the serotypes, AMR and genetic profiles of Salmonella isolates recovered from raw beef throughout the beef production chain and from human feces associated with clinical cases of salmonellosis. The serotype, AMR and pulsed-field gel electrophoresis profile of 243 Salmonella enterica isolates recovered from beef carcasses (n = 78), ground beef (n = 135), and human feces from clinical cases of salmonellosis (n = 30) were compared. Forty-three different Salmonella serotypes were identified and regardless of the source, the top five corresponded to Typhimurium, Give, Group B (partially serotyped), Infantis and Anatum. Twelve serotypes from beef carcasses were also found in ground beef, showing their presence throughout the beef production chain. Salmonella Typhimurium, Infantis, Anatum and Montevideo were the only serotypes identified in all sample types. Resistance to tetracyclines was the most frequent (41.2%) followed by resistance to aminoglycosides (37%), folate pathway inhibitors (21%), quinolones (20.2%), phenicols (17.1%), penicillins (15.6%) and cephems (7%). Multidrug resistance was observed in 28.8% of the isolates, and those from human feces showed resistance to a larger number of antimicrobials. Great concern arises from the resistance and reduced susceptibility observed to quinolones and cephalosporins because these drugs are the first line of treatment for invasive Salmonella infections. Twenty-seven distinct pulse-types were detected among 238 isolates. Clustering analysis for the most frequent serotypes identified groups of isolates with similar AMR profiles. Multidrug resistance spreading throughout the food production chain should be continually monitored and its importance emphasized.