The Effect of Previous Life Cycle Phase on the Growth Kinetics, Morphology, and Antibiotic Resistance of Salmonella Typhimurium DT104 in Brain Heart Infusion and Ground Chicken Extract

Growth models are predominately used in the food industry to estimate the potential growth of selected microorganisms under environmental conditions. The growth kinetics, cellular morphology, and antibiotic resistance were studied throughout the life cycle of Salmonella Typhimurium. The effect of the previous life cycle phase [late log phase (LLP), early stationary phase (ESP), late stationary phase (LSP), and early death phase (EDP)] of Salmonella after reinoculation in brain heart infusion broth (BHI), ground chicken extract (GCE), and BHI at pH 5, 7, and 9 and salt concentrations 2, 3, and 4% was investigated. The growth media and previous life cycle phase had significant effects on the lag time (λ), specific growth rate (μmax), and maximum population density (Ymax). At 2 and 4% salt concentration, the LLP had the significantly (p < 0.05) fastest μmax (1.07 and 0.69 log CFU/ml/h, respectively). As the cells transitioned from the late log phase (LLP) to the early death phase (EDP), the λ significantly (p < 0.05) increased. At pH 5 and 9, the EDP had a significantly (p < 0.05) lower Ymax than the LLP, ESP, and LSP. As the cells transitioned from a rod shape to a coccoid shape in the EDP, the cells were more susceptible to antibiotics. The cells regained their resistance as they transitioned back to a rod shape from the EDP to the log and stationary phase. Our results revealed that growth kinetics, cell’s length, shape, and antibiotic resistance were significantly affected by the previous life cycle phase. The results of this study also demonstrate that the previous life cycle should be considered when developing growth models of foodborne pathogens to better ensure the safety of poultry and poultry products

Nitroheterocyclic drugs cure experimental <i>Trypanosoma cruzi</i> infections more effectively in the chronic stage than in the acute stage

The insect-transmitted protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, and infects 5-8 million people in Latin America. Chagas disease is characterised by an acute phase, which is partially resolved by the immune system, but then develops as a chronic life-long infection. There is a consensus that the front-line drugs benznidazole and nifurtimox are more effective against the acute stage in both clinical and experimental settings. However, confirmative studies have been restricted by difficulties in demonstrating sterile parasitological cure. Here, we describe a systematic study of nitroheterocyclic drug efficacy using highly sensitive bioluminescence imaging of murine infections. Unexpectedly, we find both drugs are more effective at curing chronic infections, judged by treatment duration and therapeutic dose. This was not associated with factors that differentially influence plasma drug concentrations in the two disease stages. We also observed that fexinidazole and fexinidazole sulfone are more effective than benznidazole and nifurtimox as curative treatments, particularly for acute stage infections, most likely as a result of the higher and more prolonged exposure of the sulfone derivative. If these findings are translatable to human patients, they will have important implications for treatment strategies

Evaluation of safety management in an Appliances manufacturing company

Introduction: Prevention of accidents and work related diseases, are not allowed regardless of the safety of employees, customers, contractors and other persons. Assessment of individual safety management activities could reduce many losses. Present study aimed to evaluate the safety management of a household appliance manufacturing company.  .Material and Method: This study has done in a household appliance manufacturing company in Damavand city. Two questionnaires were firstly designed based on the weighted scores. The questionnaire 1 consisted of 4 indicators: Safety of machinery, Electrical safety, Risk assessment and Fire safety. Questionnaire 2 consisted of 11 sub indicators. Both questionnaires were completed by 30 HSE experts and supervisors. Reliability of questionnaires was based on cronbachs alpha coefficient. the safety status of each unit was determined and scored using information acquired by the questionnaires. Lastly, the safety of the entire company was determined.  .Result: Results showed that in safety management: the pressing and store house were in a good range of 66.66 and 60.12 points. Powder painting, enameling, laboratory were in a average range of 56.25, 55.92 and 54.15 points. Assembling and door storage were in a week range of 46.06 points.  .Conclusion: The findings showed that the safety status in the studied appliances company is in average range with 55.45 points. Therefore, it is recommended that the safety indicators should be improved for the betterment of the safety management in the company