Respiratory Bacterial Profiles and Antimicrobial Resistance Patterns in Hospitalized Patients with COPD and Pneumonia in Almaty, Kazakhstan

Background: Local antimicrobial resistance surveillance and stewardship require up-to-date information on bacterial isolates recovered from respiratory specimens and their antimicrobial susceptibility patterns. In Kazakhstan, contemporary microbiological surveillance remains limited, particularly for hospitalized patients with chronic obstructive pulmonary disease (COPD) and pneumonia. This study aimed to characterize the microbial profiles and antimicrobial susceptibility patterns in respiratory specimens from these patient groups in Almaty, Kazakhstan. Methods: This retrospective observational study included adult patients hospitalized at a tertiary referral center between January 2024 and December 2025. Respiratory specimens (sputum and bronchoalveolar lavage) underwent bacterial culture, species identification using MALDI-TOF MS, and antimicrobial susceptibility testing via EUCAST disk diffusion. Susceptibility was interpreted according to EUCAST categories (S, I, R). Group comparisons were performed using Pearson’s chi-square or Fisher’s exact test with Benjamini–Hochberg correction. Results: Among 713 patients (255 with COPD exacerbation and 458 with pneumonia), Streptococcus pyogenes was the most frequently isolated organism in both groups, followed by viridans group streptococci (VGS) and Streptococcus pneumoniae. Gram-negative isolates included most frequently Klebsiella pneumoniae, Klebsiella aerogenes, and Pseudomonas aeruginosa. After correction for multiple testing, bacterial distribution did not differ significantly between COPD and pneumonia. Streptococcal isolates demonstrated consistently high susceptibility to β-lactams, while susceptibility to macrolides, clindamycin, and doxycycline was lower. Gram-negative organisms demonstrated more variable resistance profiles. MDR phenotypes were observed among K. pneumoniae isolates in 3/18 (16.7%) COPD and 9/29 (31.0%) pneumonia cases, and among P. aeruginosa isolates in 2/9 (22.2%) COPD and 5/28 (17.9%) pneumonia cases, with no statistically significant between-group differences. Conclusions: No statistically significant differences in bacterial isolate distributions were detected between the COPD exacerbation and pneumonia groups after correction for multiple comparisons; however, equivalence between the groups cannot be inferred from these findings. High in vitro susceptibility to β-lactams among streptococcal isolates contrasted with heterogeneous antimicrobial resistance patterns and the presence of MDR/XDR phenotypes among Gram-negative isolates. These findings provide institution-specific microbiological data that may support antimicrobial stewardship and future surveillance efforts, while recognizing that bacterial isolation from respiratory specimens does not necessarily establish an etiological role in infection.