Antimicrobial Resistance of Streptococcus pneumonia in Russia: Profile and 25-Year Dynamics

Background . Streptococcus pneumoniae is a leading cause of community-acquired respiratory tract infections. Macrolideresistant S. pneumoniae was included in the 2024 WHO bacterial priority pathogens list. The change of susceptibility testing standards in 2010 made published estimates from different years incomparable; thereby, the long-term antimicrobial resistance (AMR) dynamics in Russia have not been described. Aim. Assessment of the profile and 25-year dynamics of AMR of S. pneumoniae in Russia. Methods . A retrospective analysis of 5,383 clinical isolates collected at the Institute of Antimicrobial Chemotherapy from 2000 to 2024 was conducted. MICs were determined via broth microdilution (ISO 207761); the number of isolates tested varied by agent from 471 to 5,049. All accumulated MIC values were interpreted using the uniform criteria (Russian «Determination of microorganism susceptibility to antimicrobial agents» guidelines, version 2026–01), making clinical categories comparable across periods. Results. No isolates resistant to linezolid or vancomycin were detected. Resistance rates were 0.4 % for moxifloxacin, 2.4 % for ceftriaxone, 6.1 % for amoxicillin, 18.8 % for co-trimoxazole, 19.3 % for azithromycin, and 29.4 % for tetracycline. Amoxicillin resistance rose from 0.3 % to 16.7 % (OR = 1.185/year; 95 % CI 1.159–1.212), macrolide resistance — from 5–6 % to 27–31 %, co-trimoxazole resistance — from 10.7 % to 28.1 %, whereas tetracycline resistance remained persistently high (31.7 % and 30.0 %). Multidrug resistance was found in 10.1 % of isolates (496/4919), with isolated β-lactam resistance in 0.1 %. Conclusion. Amoxicillin and ceftriaxone retain activity despite a sustained rise in resistance to aminopenicillins, macrolides, and co-trimoxazole. Estimates differ up to four-fold between the two breakpoint sets, making explicit reporting of the criteria applied mandatory.