The Role of Surveillance Inspections in Reducing False-Positives of SARS-CoV-2 Omicron Variants during the COVID-19 Epidemic.

Objective: This study aims to assess the effectiveness of surveillance inspections conducted by the provincial health committee in Quanzhou city during a COVID-19 outbreak in reducing false-positive results in SARS-CoV-2 RT-PCR assays. Method: The team conducted on-site inspections of laboratories that participated in mass screening, recording any violations of rules. Results: The positive cases in five rounds of mass screening were 23, 173, and 4 in Licheng District, Fengze District, and Luojang District, respectively. The false-positive rates in the five rounds of mass screening were 0.0099%, 0.0063%, 0.0018%, 0.0006%, and 0%, respectively. The study also recorded that the number of violations in the seven selected laboratories was 36, 68, 69, 42, 60, 54 and 47. The corresponding false-positive rates were 0.0012%, 0.0060%, 0.0082%, 0.0032%, 0.0060%, 0.0027%, and 0.0021%, respectively. The study found a positive correlation between false-positive rates and the number of violations (r = 0.905, P=0.005), and an inverse correlation between false-positive rates and the frequency of surveillance inspections (r = -0.950, P < 0.001). Conclusion: Daily surveillance inspection in laboratories can remind laboratories to strictly comply with standard procedures, focus on laboratory quality control, and reduce the occurrence of false-positive cases in SARS-CoV-2 nucleic acid tests to some extent. This study recommends that government decision-making departments establish policies and arrange experts to conduct daily surveillance inspections to improve laboratory quality control.

Bacterial immune interaction in experimental colitis.

OBJECTIVES: This study aimed to analyze the effects of 5-aminosalicylic acid (5-ASA) on intestinal microbiota and immune regulation in inflammatory bowel disease (IBD) and to investigate the correlation between intestinal microbiota and immune factors. METHODS: Colitis in mice was induced by oxazolone. The community composition of luminal and mucosal microbiota was analyzed by a terminal restriction fragment length polymorphism. The expression of occludin, toll-like receptor (TLR)-2, TLR-4 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 proteins were measured by immunohistochemistry and Western blot. Linear correlation between intestinal microbial community and the severity of the colitis or intestinal microbial community and expressions of immune factors were determined. RESULTS: Protective bacteria decreased while aggressive bacteria increased in the colitis group. The richness and diversity of both luminal and mucosal microbiota decreased in the colitis group the decrease was enhanced in the 5-ASA-treated group. The diversity of mucosal microbiota significantly correlated with the extent of the colitis. Expressions of occludin, TLR-2, TLR-4, tumor necrosis factor-α and NF-κB p65 were significantly correlated with the diversity of mucosal microbiota. CONCLUSIONS: Mucosal microbiota are important in the pathogenesis of IBD. 5-ASA increases protective bacteria but decreases aggressive bacteria, thus inducing the new intestinal microbial homeostasis.