Oropharyngeal Microbiota Composition and Antibiotic Resistance Patterns in Patients with Chronic Obstructive Pulmonary Disease: A Single-Center Study

Abstract

Chronic obstructive pulmonary disease (COPD) is associated with dysbiosis of the respiratory microbiota, which may drive airway inflammation and antimicrobial resistance. Regional data from Central Asia remain scarce. Objective: To characterize the oropharyngeal microbiota composition and antibiotic resistance profiles in hospitalized COPD patients at a tertiary center in Uzbekistan. Methods: A cross-sectional descriptive study was conducted in 41 COPD patients (mean age 61.4 ± 12.0 years; range 36-86 years; 61.0% male) admitted to the Republican Specialized Scientific and Practical Medical Center of Therapy and Medical Rehabilitation, Tashkent, from January 2023 through March 2026. Oropharyngeal swabs were analyzed by standard culture and MALDI-TOF MS identification; antibiotic susceptibility was tested by disk diffusion according to EUCAST criteria. Antibiotics were selected to represent locally used empirical agents for respiratory infections and major antimicrobial classes relevant for Gram-positive and Gram-negative respiratory pathogens. Results: Pathogenic flora was detected in 35/41 patients (85.4%); 10 (24.4%) had polymicrobial infection (≥2 organisms). A total of 46 isolates were identified: Streptococcus mitis (n=22; 47.8%), Staphylococcus aureus (n=14; 30.4%), Streptococcus pneumoniae (n=3; 6.5%), Klebsiella pneumoniae (n=3; 6.5%), Gemella haemolysans (n=2; 4.3%), Candida albicans (n=1), and Pseudomonas aeruginosa (n=1). Streptococcus mitis showed 100% resistance to ceftazidime, gentamicin, amikacin, and ciprofloxacin, and 95% to co-trimoxazole, with retained susceptibility to chloramphenicol, vancomycin, and tetracyclines (100%, 100%, and 91%, respectively). Staphylococcus aureus demonstrated universal penicillin resistance and high macrolide resistance (71%), while remaining fully susceptible to vancomycin. Conclusions: Hospitalized COPD patients at this Uzbek tertiary center harbored a high burden of oropharyngeal pathogenic microbiota with clinically important multidrug resistance, particularly to aminoglycosides, fluoroquinolones, cephalosporins, and macrolides. Because this was a single-center descriptive study with a small and heterogeneous sample, the findings should be interpreted as local and hypothesis-generating. Microbiological surveillance and antibiotic stewardship are urgently needed.