Prevalence and Virulence Gene Analysis of <i>Mycoplasma pneumoniae</i> Co-infection in Hospitalized COVID-19 Patients: A Case-Control Study in Iran

Background: The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has highlighted the need to investigate bacterial co-infections in patients with respiratory illnesses. Mycoplasma pneumoniae has been identified as a significant pathogen in COVID-19 patients. Understanding its prevalence and molecular characteristics is crucial for improving clinical management. Objectives: To molecularly identify virulence genes of M. pneumoniae as a secondary infection in COVID-19 patients hospitalized in Kerman, Iran. Methods: A descriptive analysis was performed on 200 COVID-19 patients and 200 non-COVID-19 individuals. Respiratory samples from both acute and chronic lung and pharyngeal infections were collected. DNA extraction and PCR were used to detect Mycoplasma and the virulence genes p1, p40, and p90 of M. pneumoniae. Statistical analysis assessed the infection frequency and factors affecting bacterial co-infections. Results: Eleven percent of the samples were positive for Mycoplasma, with a slightly higher prevalence in COVID-19 patients. Among individuals with chronic lung damage, M. pneumoniae infection was more frequent compared to those with acute lung damage. No significant difference was observed in the virulence genes between COVID-19 patients and controls. The highest frequency (23.8%) was associated with the p1 gene, while p90 was not detected in either group. Conclusions: The study suggests that M. pneumoniae is a common co-infecting pathogen in COVID-19 patients, particularly in those with chronic respiratory conditions. Targeted monitoring and treatment of bacterial co-infections could improve patient outcomes in COVID-19. Further research is needed to explore the molecular mechanisms of M. pneumoniae virulence and its interaction with SARS-CoV-2.