Accociation between molecular mechanisms of antimicrobial resistance, pnenotypes and serotypes in Streptococcus pneumoniae

Abstract

Studies on pneumococcal resistome and molecular antimicrobial resistance mechanisms are relevant and may be used in large-scale epidemiological researches and surveillance of antimicrobial resistance.A study of antimicrobial molecular resistance in the pneumococcal strains, that were isolated from the patients having the different forms of the pneumococcal infection or carriage, and association of it with phenotypes, clinical and epidemiological features of the strains (serotype, form of the infection).We studied 546 pneumococcal strains and 5 specimens, that were isolated/obtained from the patients of various age (5 days – 81 years) having the different forms of the pneumococcal infection (meningitis and other invasive forms – 28, pneumonia – 27, acute rhinosinusitis – 18, acute otitis media – 118, conjunctivitis – 26) or carriage (331).We used multiplex PCR to detect the following molecular pneumococcal antimicrobial resistance determinants – genes mefA, ermB and mutations in the penicillin-binding proteins: pbp1a (574T→N, 575S→T, 576Q→G and 577F→Y); pbp2b (431T→K, 432Q→L) and pbp2x (338T→A).Among studied strains 60 % of 551 possess at least one resistance mechanism to macrolides/lincosamides, while 22 % were heteroresistant (mefA + ermB). About 65 % of the strains carry at least one pbp modification, 26 % – two modifications and 24 % – three pbp modifications. 23S RNA methylase (ermB gene) were discovered as a dominating mechanism and was detected in 43 % of genetically resistant strains. Pbp 1a + 2x + 2b and pbp 1a + 2x were more frequent modifications among penicillin genetically resistant pneumococci, while pbp2b genotype was not detected.