Survival and predictive modeling of Listeria monocytogenes under simulated human gastric conditions in the presence of bovine milk products.

Listeria monocytogenes is an opportunistic foodborne pathogen which has been implicated in many outbreaks of foodborne diseases. This study evaluated the effects of gastric acidity and gastric digestion time of adults, L. monocytogenes strain and food type on the survival of L. monocytogenes under simulated stomach conditions of adults in in vitro gastric models with dynamic pH changes occurring throughout the exposure. Individual strains as well as a cocktail of L. monocytogenes, inoculated at 8 log CFU/mL in filtered bovine milk products, 0 % milk, 2 % milk, 2 % chocolate milk and 3.25 % milk, were introduced to the gastric models for 2 h. The survival of L. monocytogenes depended on a combination of factors, including gastric acidity and gastric digestion time of adults, L. monocytogenes strain, food type and recovery method (P < 0.05). The survival rates of L. monocytogenes inoculated in 2 % milk after a 2-h exposure to simulated gastric fluids with pH values of 1.5, 2.0 and 3.0 were 0.003 to 0.040 %, 22.7 to 43.4 % and 16.6 to 27.2 %, respectively. Fluid milk containing a higher milk fat content (3.25 % vs 0 % milk) protected L. monocytogenes from being inactivated when they were exposed to the human stomach model with a gastric acidity of pH 2.0. Compared to 0 % and 3.25 % milk, L. monocytogenes survived the best in 2 % chocolate milk, which appears to be due to the presence of milk fat (2 %) and the additional nutrients that are present in chocolate milk. A predictive mathematical model was developed that captured the population of the strains of L. monocytogenes under the in vitro conditions. This study advances our understanding of the behaviour of L. monocytogenes under various human gastric conditions and provides key parameters that can affect the survival of L. monocytogenes in the stomachs of adults. The mathematical models developed in this study can be used as a supplementary tool to help predict the survival of L. monocytogenes under similar scenarios and for relevant risk-assessment studies.

Clinical effect of minimally invasive technique of internal fixation device removal in patients with healed long tubular bone fractures.

Objective: To investigate the clinical effect of minimally invasive technique applied to internal fixation removal in patients with healed long tubular bone fractures. Methods: The records of patients with internal fixation of long tubular bone fracture who underwent the removal of the internal fixation device after fracture healing in The Second Affiliated Hospital of Hainan Medical College from May 2020 to December 2021 were reviewed. According to the different operation methods of taking out the internal fixation device, patients were divided into minimally invasive group (n=40) and traditional group (n=45). The perioperative indexes, levels of inflammatory factors tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), Karnofsky Performance Score (KPS), visual analog scale (VAS) pain score and complications were compared between the two groups. Results: The drainage volume, bleeding volume, incision length and hospital stay in the minimally invasive group were significantly lower than those in the traditional group (P<0.05). The KPS score of minimally invasive group was significantly higher than that of traditional group at one week and one month after the operation, and the VAS score of minimally invasive group was significantly lower than that of traditional group at one day and one week after the operation (P<0.05). The levels of TNF-α and CRP in the observation group were significantly lower than those in the control group(P<0.05). There was one case of infection in the minimally invasive group, one case of secondary fracture and two cases of infection in the traditional group(P>0.05). Conclusions: Minimally invasive surgery for the removal of the internal fixation device in patients with healed long tubular bone fractures with internal fixation is associated with significantly improved clinical effect, relieved symptoms, reduced inflammatory response, and improved functional recovery of patients.

Metagenomics of Wastewater Influent from Wastewater Treatment Facilities across Ontario in the Era of Emerging SARS-CoV-2 Variants of Concern.

We report metagenomic sequencing analyses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in composite wastewater influent from 10 regions in Ontario, Canada, during the transition between Delta and Omicron variants of concern. The Delta and Omicron BA.1/BA.1.1 and BA.2-defining mutations occurring in various frequencies were reported in the consensus and subconsensus sequences of the composite samples.