Infectious Pulmonary Complications and Reinfection in Treated Cases of Pulmonary Tuberculosis: A Cohort Study from a Tertiary Care Centre in North India

Background: Post-tuberculosis lung disease (PTLD) is an emerging global health concern, yet comprehensive data on the spectrum of infectious complications in treated pulmonary tuberculosis (TB) patients from India remains limited, as most existing studies evaluate bacterial, fungal, or reinfection outcomes in isolation. This study aimed to determine the prevalence of bacterial pathogens, fungal pathogens, and TB reinfection from respiratory samples in treated cases of pulmonary TB, and to identify associated clinical and laboratory predictors. Methods: This cohort study enrolled 100 patients who had completed pulmonary TB treatment at least six months prior, attending Pt. B.D. Sharma PGIMS, Rohtak. Respiratory samples were subjected to Gram stain, bacterial culture, acid-fast bacilli (AFB) smear, cartridge-based nucleic acid amplification test (CBNAAT), potassium hydroxide (KOH) mount, and fungal culture. Demographic, clinical, and laboratory parameters were analyzed for associations with infectious outcomes. Results: Bacterial infection was the most prevalent complication (36%), with Klebsiella pneumoniae (10%) and Pseudomonas aeruginosa (8%) being the commonest isolates. TB reinfection was confirmed in 26%, of which 7% demonstrated rifampicin resistance. Fungal infection was identified in 11%, including Candida (6%) and Aspergillus species (5%). Fever (p<0.001), hemoptysis (p<0.001), and leukocytosis (p=0.026) were significant predictors of bacterial infection. Anaemia was significantly associated with TB reinfection (p=0.028). A significant inverse association was observed between bacterial infection and TB reinfection (p=0.021). Conclusion: Treated pulmonary TB patients harbour a substantial infectious burden. Comprehensive microbiological evaluation and structured post-TB follow-up programs are essential for early detection and management of these complications.