Influence of environmental dust in transformation capacity of Streptococcus pneumoniae

Mechanistic Insights into the Impact of Air Pollution on Pneumococcal Pathogenesis and Transmission

Streptococcus pneumoniae (the pneumococcus) is the leading cause of pneumonia and bacterial meningitis. A number of recent studies indicate an association between the incidence of pneumococcal disease and exposure to air pollution. Although the epidemiological evidence is substantial, the underlying mechanisms by which the various components of air pollution (particulate matter and gases such as NO2 and SO2) can increase susceptibility to pneumococcal infection are less well understood. In this review, we summarize the various effects air pollution components have on pneumococcal pathogenesis and transmission; exposure to air pollution can enhance host susceptibility to pneumococcal colonization by impairing the mucociliary activity of the airway mucosa, reducing the function and production of key antimicrobial peptides, and upregulating an important pneumococcal adherence factor on respiratory epithelial cells. Air pollutant exposure can also impair the phagocytic killing ability of macrophages, permitting increased replication of S. pneumoniae. In addition, particulate matter has been shown to activate various extra- and intracellular receptors of airway epithelial cells, which may lead to increased proinflammatory cytokine production. This increases recruitment of innate immune cells, including macrophages and neutrophils. The inflammatory response that ensues may result in significant tissue damage, thereby increasing susceptibility to invasive disease, because it allows S. pneumoniae access to the underlying tissues and blood. This review provides an in-depth understanding of the interaction between air pollution and the pneumococcus, which has the potential to aid the development of novel treatments or alternative strategies to prevent disease, especially in areas with high concentrations of air pollution.

Microbiota and mobile genetic elements influence antibiotic resistance genes in dust from dense urban public places

Many contaminants were carried by dust, a common environment media that is easy to contact with human beings, and antibiotic resistance genes (ARGs) as an emergency pollutant also harbor in dust and pose serious threats to human health especially those carried by opportunistic pathogens because inactivation of antibiotics caused by ARGs may enhance pathogenicity. Considering there is a gap of investigation of dust ARGs, 16 S rRNA gene sequences and high-throughput quantitative PCR were employed to obtain information of microbial communities and accumulated ARGs in dust from different urban places, including the malls, hospitals, schools and parks, to investigate the distribution and influencing factors of ARGs and discover the potential hosts of ARGs in dust. Here, 9 types of ARGs such as sulfonamide, tetracycline, and beta-lactamase and 71 subtypes of ARGs like sul1, tetM-01, and drfA1 were detected in dust. ARGs had varying distribution in different public places and seasons in dust. The abundances of total ARGs, MLSB and tetracycline genes were higher in spring than summer. The diversity of ARGs was highest in malls, follow by hospitals, schools, and parks. Additionally, multi-drug resistance genes in dust were more abundant in hospitals than in schools and parks. The microbes were distinguished as the most important driving factors for ARGs in dust, followed by the mobile genetic elements (MGEs) and different places, while dust physicochemical parameters only exert a negligible impact. Notably, several opportunistic pathogens like the Streptococcus, Vibrio, and Pseudomonas were inferred as potential hosts of high-risk ARGs such as mecA, tetM-02, and tetO-01 in dust because of strongly positive co-occurrence. These results imply that dust is likely an important reservoir of ARGs. We should realize that ARGs may be harbored in some opportunistic pathogens occur in dust and endanger human health because of dust contacting to human easily.