IMMUNO-MICROBIOLOGICAL CHARACTERISATION OF THE SPECIES COMPOSITION OF THE BACTERIAL MICROFLORA OF THE RESPIRATORY TRACT IN COVID-19 PATIENTS WITH COMORBIDITIES

A significant proportion of COVID-19 cases are linked to recurrent respiratory infections, such as chronic and acute bronchitis, pneumonia, and various upper and lower respiratory tract diseases. This highlights the need to investigate the mechanisms contributing to airway dysfunction and immune suppression, especially regarding the long-term effects of SARS-CoV-2 infection. The development of these complications likely depends on factors like immune dysregulation, microbiome imbalance, and viral damage to airway epithelial cells. Understanding how these factors influence prolonged symptoms and recovery challenges is crucial.                          The role of the microbiome in the pathogenesis of respiratory infections has gained increasing attention. Disruption of the normal microbiota can lead to immune hyperreactivity and promote infections. In COVID-19, it is believed that SARS-CoV-2 infection may alter the microbiome, leading to secondary bacterial infections, such as pneumonia, and exacerbating chronic respiratory conditions.                      This study aimed to explore the microbiome of the upper and lower respiratory tracts and its association with clinical outcomes in patients with SARS-CoV-2 infection. It included 159 patients from Shymkent, Kazakhstan, confirmed positive for SARS-CoV-2 by PCR. Specific IgG antibodies were measured to assess immune responses to coinfections. Among patients with comorbidities, the most common antibodies were to Mycoplasma pneumoniae (41.41%), Staphylococcus aureus (35.35%), and Klebsiella pneumoniae (23%). In contrast, antibodies to Streptococcus pyogenes (23%) were more common in patients without comorbidities. Statistically significant differences in antibody avidity were observed for Klebsiella pneumoniae (p = 0.036) and Mycoplasma pneumoniae (p = 0.028), suggesting a role for these pathogens in post-COVID complications.                         These results support the hypothesis that coinfections play a significant role in post-COVID respiratory diseases. The higher frequency of bacterial antibodies in patients with comorbidities indicates that chronic infections or microbiome imbalances may contribute to more severe COVID-19 outcomes and increase the risk of long-term symptoms, underscoring the need for further microbiological research and rehabilitation strategies.