Immune response status and development of Streptococcus pneumoniae carriage as health risk factors for workers engaged in coke production and basic oxygen steelmaking

Occupational hazards affect immunological reactivity and increase the risk of infection with respiratory pathogens. The purpose of our work was to study the mechanisms and causes of developing carriage of streptococci possessing genetic determinants of resistance to antibiotics as health risk factors for workers engaged in coke production and basic oxygen steelmaking. We examined 136 workers of a ferrous metals industry and compared the prevalence of the carriage of Streptococcus pneumoniae, Streptococcus spp. and macrolide resistance genes (Mef, ErmB) in those engaged in coke production and basic oxygen steelmaking. We also collated the results of immunological examination of the carriers and non-carriers of S. pneumoniae. The control cohort was formed of engineering and technical personnel. We established that, compared with the controls, Streptococcus pneumoniae was a more frequent finding in the workers engaged in coke production and basic oxygen steelmaking (p ˂ 0.05). The cycle threshold value of Streptococcus spp. in them was also statistically higher. The Mef gene was more abundant in the steelmakers, including those carrying Streptococcus pneumoniae (p ˂ 0.05), and a change in immunological reactivity was detected in the cases carrying Streptococcus pneumoniae. In those engaged in basic oxygen steelmaking, significant changes were detected at the cellular level expressed by a reduced absolute number of mature T-lymphocytes (CD3+), T-helpers (CD4+), and T-suppressor/cytotoxic cells (CD8+) (p ≤ 0.05). At the humoral level, both the relative and absolute number of B-lymphocytes (CD19+) and the level of IgM were reduced, while that of IgG was, on the opposite, increased (p ≤ 0.05). In the coke plant workers carrying Streptococcus pneumoniae, the level of IgG was significantly higher than the control and reference values. We conclude that Streptococcus pneumoniae carriage in the steelmakers as a health risk factor was accompanied by a change in immunological reactivity and higher abundance of the Mef gene compared to the controls while in the coke production workers the related differences were detected only in the IgG level.