Impact of Environmental Toxicity on Systemic Inflammation and the Progression of Bacterial and Fungal Infections in a Rat Model

Abstract

Background and Aims: The intensification of human activities in recent years has led to persistent environmental pollution, marked by the accumulation of heavy metals and pesticides due to their widespread and excessive use, raising serious health concerns. At the same time, the resurgence of infectious diseases and the emergence of resistant strains are complicating therapeutic management. This study aims to examine the correlations between exposure to pollutants, inflammatory response, and worsening of microbial infections Study Design: Experimental study. Place and Duration of Study: Laboratory of Biotechnology and Valorization of Bioactive Natural Substances Laboratory of the National Center for Floristics (CNF) (Abidjan, Côte d’Ivoire), between July 2023-december 2023. Methodology: To examine the correlations between exposure to pollutants, inflammatory response, and the worsening of microbial infections. Thus, Wistar rats were exposed to three common environmental pollutants, lead (15 µg. L-1) or glyphosate (0.5 mg/kg/day) orally or mercury (0.3 µg/m3) by inhalation over a 28-days period, and then infected with Escherichia coli (1 mL) or Candida albicans (0.1 mL) orally. Results: The results obtained show that co-exposure to pollutants and infectious agents significantly worsened the physiological condition of the rats, inducing leukocyte disarray, persistent systemic inflammation, as well as variable immunosuppression responsible for increased susceptibility to infections. This impairment exhibited increasing severity depending on the toxin dose (mercury, lead, glyphosate). In contrast, in the absence of toxins, infections remained generally reversible, the maintenance of stable immune parameters. Furthermore, Escherichia coli isolates from rats exposed to lead or mercury showed resistance to fluoroquinolones and reduced sensitivity to beta-lactams and aminoglycosides, while glyphosate did not alter this profile. In addition, Candida albicans isolates remained sensitive to antifungals. Conclusion: The study showed that exposure to lead and mercury caused severe immunosuppression persistent inflammation and promoted antibiotic resistance, while glyphosate activated persistent chronic systemic inflammation without altering microbial sensitivity.