RESUMO
Control of Listeria monocytogenes in food processing facilities is a difficult issue because of the ability of this microorganism to form biofilms and adapt to adverse environmental conditions. Survival at high concentrations of sodium chloride and growth at refrigeration temperatures are two other important characteristics of L. monocytogenes isolates. The aim of this study was to compare the growth characteristics under stress conditions at different temperatures of L. monocytogenes serotypes responsible for the majority of clinical cases from different sources. Twenty-two L. monocytogenes isolates, 12 from clinical cases (8 serotype 4b and 4 serotype 1/2a) and 10 from food (6 serotype 4b and 4 serotype 1/2a), and an L. monocytogenes Scott A (serotype 4b) reference strain were analyzed for the ability to grow in brain heart infusion broth plus 1.9 M NaCl (11%) at 4, 10, and 25°C for 73, 42, and 15 days, respectively. The majority of L. monocytogenes strains was viable or even grew at 4°C and under the high osmotic conditions usually used to control pathogens in the food industry. At 10°C, most strains could adapt and grow; however, no significant difference (P > 0.05) was found for lag-phase duration, maximum growth rate, and maximum cell density. At 25°C, all strains were able to grow, and populations increased by up 5 log CFU/ml. Clinical strains had a significantly longer lag phase and lower maximum cell density (P < 0.05) than did food strains. Regarding virulence potential, no significant differences in hemolytic activity were found among serotypes; however, serotype 4b strains were more invasive in Caco-2 cells than were serotype 1/2a strains (P < 0.05). The global tendency of decreasing NaCl concentrations in processed foods for health reasons may facilitate L. monocytogenes survival and growth in these products. Therefore, food companies must consider additional microbial growth barriers to assure product safety.
Assuntos
Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/metabolismo , Listeriose/microbiologia , Carne/microbiologia , Cloreto de Sódio/metabolismo , Animais , Células CACO-2 , Galinhas , Temperatura Baixa , Meios de Cultura/química , Meios de Cultura/metabolismo , Armazenamento de Alimentos , Humanos , Listeria monocytogenes/isolamento & purificação , Listeria monocytogenes/patogenicidade , Viabilidade Microbiana , Refrigeração , Sorotipagem , VirulênciaRESUMO
PURPOSE: This study was designed to compare the efficacy of polymyxin B with other antimicrobials in the treatment of ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT) by Pseudomonas aeruginosa or Acinetobacter baumannii. METHODS: A prospective cohort study was performed. Patients >18 years of age with the diagnosis of VAP or VAT who received appropriate therapy for >48 h were analyzed. The primary outcome was 30-day mortality. Clinical covariates were assessed and compared between the groups. RESULTS: A total of 67 episodes were analyzed: 45 (67 %) treated with polymyxin B and 22 (33 %) with comparators. The crude 30-day mortality was 53 % (24 of 45) in the polymyxin B group and 27 % (6 of 22) in the comparator group (P = 0.08). Multivariable analysis using Cox regression models indicated that polymyxin B treatment was independently associated with increased mortality. CONCLUSIONS: Polymyxin B treatment in the currently recommended dosage may be inferior to other drugs in the treatment of VAP and VAT caused by organisms tested as susceptible in vitro to this agent.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Bronquite/tratamento farmacológico , Pneumonia Bacteriana/tratamento farmacológico , Pneumonia Associada à Ventilação Mecânica/tratamento farmacológico , Polimixina B/uso terapêutico , Pseudomonas aeruginosa/efeitos dos fármacos , Traqueíte/tratamento farmacológico , APACHE , Infecções por Acinetobacter/tratamento farmacológico , Adulto , Idoso , Antibacterianos/administração & dosagem , Antibacterianos/uso terapêutico , Bronquite/microbiologia , Bronquite/mortalidade , Creatina/análise , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Avaliação de Medicamentos/métodos , Feminino , Humanos , Unidades de Terapia Intensiva , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Pneumonia Bacteriana/mortalidade , Pneumonia Associada à Ventilação Mecânica/microbiologia , Pneumonia Associada à Ventilação Mecânica/mortalidade , Polimixina B/administração & dosagem , Modelos de Riscos Proporcionais , Estudos Prospectivos , Infecções por Pseudomonas/tratamento farmacológico , Traqueíte/microbiologia , Traqueíte/mortalidade , Resultado do TratamentoRESUMO
We propose and experimentally demonstrate a hardware-efficient, feed-forward, wide-range frequency offset estimator for DSP-based optical coherent receivers. Using a simple relationship of signal spectrum, this estimator is capable to estimate offsets in a range compliant with OIF requirements. Obtained results show that this estimator has a high tolerance to spectrum asymmetry caused by electrical and optical signal filtering, even when using return-to-zero pulse shaping.
RESUMO
Interpro is a widely used tool for protein annotation in genome sequencing projects, demanding a large amount of computation and representing a huge time-consuming step. We present a strategy to execute programs using databases Pfam, PROSITE and ProDom of Interpro in a distributed environment using a Java-based messaging system. We developed a two-layer scheduling architecture of the distributed infrastructure. Then, we made experiments and analyzed the results. Our distributed system gave much better results than Interpro Pfam, PROSITE and ProDom running in a centralized platform. This approach seems to be appropriate and promising for highly demanding computational tools used for biological applications.