"Antibacterial effect and possible mechanism of action of 1,3,4-oxadiazole in Staphylococcus aureus".

Staphylococcus aureus is one of the main etiological agents causing foodborne diseases, and the development of new antibacterial agents is urgent. This study evaluated the antibacterial activity and the possible mechanism of action of the 1,3,4-oxadiazole LMM6 against S. aureus. The minimum inhibitory concentration (MIC) of LMM6 ranged from 1.95 to 7.81 µg ml-1. The time-kill assay showed that 48-h treatment at 1× to 8× MIC reduced S. aureus by 4 log colony forming unit (CFU), indicating a bacteriostatic effect. Regarding the possible mechanism of action of LMM6, there was accumulation of reactive oxygen species (ROS) and an increase in the absorption of crystal violet (∼50%) by the cells treated with LMM6 at 1× and 2× MIC for 6-12 h. In addition, there was increased propidium iodide uptake (∼84%) after exposure to LMM6 for 12 h at 2× MIC. After 48 h of treatment, 100% of bacteria had been injured. Scanning electron microscopy observations demonstrated that LMM6-treated cells were smaller compared with the untreated group. LMM6 exhibited bacteriostatic activity and its mechanism of action involves increase of intracellular ROS and disturbance of the cell membrane, which can be considered a key target for controlling the growth of S. aureus.

Optimization of the Erythrosine-mediated photodynamic therapy against Escherichia coli using response surface methodology.

BACKGROUND: The efficacy of photodynamic therapy (PDT) depends on the combination of light and a photosensitizer for inactivation of microorganisms. However, finding the ideal conditions for the factors involved in this technique is time and cost-consuming. The rotational composite central design (RCCD) is a tool that can be allied with PDT to achieve precise results within a shorter working time. METHODS: This study used the response surface methodology to optimize the parameters of PDT mediated by Erythrosine (ERY) and green light-emitting diodes (LED) in different Escherichia coli strains by applying RCCD. RESULTS: The RCCD predicted optimum values of ERY and light exposure on PDT. According to the experimental results, the light exposure time showed the most significant influence on the inactivation of the evaluated bacteria. The optimized operating conditions were validated in laboratory tests, and no viable cells were recovered with ERY at 116 µmol L-1 and 30 min of light (33.34 J cm2) for E. coli ATCC 25922, 108 µmol L-1 and 40 min (44.38 J cm2) for E. coli ATCC 35218, and 108 µmol L-1 and 29.3 min (32.5 J cm2) for E. coli O157:H7 EDL 933. CONCLUSION: The adjusted polynomial models provided accurate information on the combined effects of ERY and lighting time with green LED on PDT. The application of the RCCD, in addition to reducing the number of experiments, also allows for increased quantity and quality of the results. Therefore, surface response methodology combined with PDT is a promising approach to inactivate E. coli.

Comportamento da população em relação aos cuidados com os alimentos durante a pandemia da COVID-19 / Population behavior in relation to food care during the COVID-19 pandemic

Este estudo analisou o conhecimento e comportamento em relação aos cuidados e higiene alimentar antes e durante a pandemia da COVID-19 no Brasil. Os participantes foram recrutados pelas redes sociais para responder um questionário sobre aspectos sociodemográficos, conhecimento sobre coronavírus, isolamento social e recebimento de informações sobre higienização de alimentos e suas embalagens. Participaram da pesquisa 1.061 indivíduos, sendo a maioria do sexo feminino (87%), com até 35 anos (69,9%); 82,8% tinham ou estavam a concluir o ensino superior; e a renda mensal de 63,2% era de até 6 salários mínimos. Sobre a higiene de frutas e hortaliças, 56,59% dos participantes passaram a usar água e sabão durante a pandemia. Quanto a limpeza das embalagens dos alimentos recebidos por delivery, 71,85% dos participantes passaram a limpar as embalagens durante a pandemia. De forma geral, pode-se observar modificações significativas nos cuidados com os alimentos durante a pandemia da COVID-19.

This study during knowledge and behavior in food care and hygiene before and that of COVID-19 in Brazil. Participants were recruited through social networks for respondents on the sociodemographic aspects of the population's knowledge about coronavirus, social isolation and receiving information on hygiene of food and its packaging. A total of 1,061 participated in the survey, the majority being female (87%), aged up to 35 years (69.9%); 8.8% had or 2.8% had higher education; and 63.6% monthly income was up to 6% monthly. Regarding the hygiene of fruits and vegetables, 56.59% of the participants chose soap and water during the. As for cleaning packages received by delivery, 71% of patients choose to clean packages during the pandemic. In general, the pandemic can be considered in the care with food of COVID-19.

Insight about cell wall remodulation triggered by rifampicin in Mycobacterium tuberculosis.

Rifampicin plays an important role during the treatment of tuberculosis, which makes it to be recommended throughout the regimen. The molecular target for rifampicin activity and resistance is the bacterial RNA polymerase coded by rpoB. However, it has been observed that Mycobacterium tuberculosis could use different metabolic pathways contributing to drug activity/resistance. In this sense, Proteomics analysis has been a key aspect towards the understanding of the dynamic genome expression triggered by drugs and other M. tuberculosis hostile stimuli. Herein, we aimed to report the changes in the M. tuberculosis protein profile triggered by rifampicin. The M. tuberculosis H37Rv strain was submitted to 12, 24 and 48 h of rifampicin challenge, at the minimal inhibitory concentration (0.03 µg mL-1), and proteins were extracted. The protein identification was carried out by liquid chromatography coupled to mass spectrometry (LC-MS). Four proteins, Ino1 (Rv0046c), FabD (Rv2243), EsxK (Rv1197) and PPE60 (Rv3478) were statistically underexpressed over 48 h of rifampicin exposure, indicating that in addition to the known activity of rifampin in transcriptional machinery in M. tuberculosis, processes related to disturbance in cell wall synthesis and lipid metabolism in the bacillus are also triggered by rifampicin contributing to bacillus death.