OROPHARYNGEAL MICROBIOTA DYSBIOSIS AND ANTIBIOTIC RESISTANCE PATTERNS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE: A CROSS-SECTIONAL STUDY FROM UZBEKISTAN

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Oropharyngeal microbiota dysbiosis has been implicated in COPD pathogenesis and disease progression, yet data from Central Asian populations remain scarce. Objective: To characterize oropharyngeal microbial composition and antibiotic resistance profiles in COPD patients in Tashkent, Uzbekistan, and to assess the association between microbiota dysbiosis and COPD severity (GOLD staging). Methods: A cross-sectional study enrolled 60 COPD patients at the Republican Specialized Scientific-Practical Medical Center for Therapy and Medical Rehabilitation. Oropharyngeal swabs were processed by MALDI-TOF mass spectrometry (Bruker Biotyper). Antibiotic susceptibility was tested for 26 agents across six drug classes using disk diffusion (EUCAST 2024). A composite antibiotic resistance index (ARI) was calculated per isolate. Seventy-five microbiological culture records were obtained in total. Results: Pathogenic or conditionally pathogenic flora was detected in 52 of 60 patients (86.7%). Streptococcus mitis was the dominant pathogen (50.0%), followed by Staphylococcus aureus (28.3%), Candida albicans (6.7%), Streptococcus pneumoniae (6.7%), and Gemella haemolysans (5.0%). CFU counts ranged from 10² to 10⁷. Resistance to ceftazidime and cefoperazone-sulbactam exceeded 90% among S. mitis isolates (92%). Penicillin resistance was identified in 57% of S. mitis and 46% of S. aureus isolates. Amoxicillin-clavulanate retained activity against both pathogens (≤8%). Vancomycin remained fully active against all gram- positive isolates. The mean ARI was 10.6 ± 6.4 (range 0–21). Patients with severe-to-very severe COPD (GOLD III–IV) demonstrated a significantly higher mean ARI (13.8 ± 6.2) compared to mild-to-moderate disease (GOLD I–II: 7.2 ± 5.1). Conclusions: COPD patients in Uzbekistan exhibit a high prevalence of oropharyngeal dysbiosis with extensive antibiotic resistance, particularly to beta-lactams and fluoroquinolones. Dysbiosis severity correlates positively with COPD severity. Routine microbiological surveillance and susceptibility-guided therapy are warranted in this population