Resistance Determinants and Their Association with Different Transposons in the Antibiotic-ResistantStreptococcus pneumoniae

Abstract

Multiple resistance ofStreptococcus pneumoniaeis generally associated with their unique recombination-mediated genetic plasticity and possessing the mobile genetic elements. The aim of our study was to detect antibiotic resistance determinants and conjugative transposons in 138 antibiotic-resistant pneumococcal strains isolated from nasopharynx of healthy young children from Lublin, Poland. These strains resistant to tetracycline and/or to chloramphenicol/erythromycin/clindamycin were tested by PCR using the specific genes as markers. The presence of Tn916family transposons, carryingtet(M) andint/xisTn916, was observed in all of the tested strains. Tn916was detected in 16 strains resistant only to tetracycline. Tn6002and Tn3872-related element were found among 99erm(B)-carrying strains (83.8% and 3.0%, resp.). Eight strains harbouringmef(E) anderm(B) genes were detected, suggesting the presence of Tn2010and Tn2017transposons. Among 101 chloramphenicol-resistant strains, two variants of Tn5252-related transposon were distinguished depending on the presence ofint/xis5252genes specific forcatgene-containing Tn5252(75.2% of strains) orintSp23FST81gene, specific forcat-containing ICESp23FST81 element (24.8% of strains). In 6 strains Tn916-like and Tn5252-like elements formed a Tn5253-like structure. Besides clonal dissemination of resistant strains of pneumococci in the population, horizontal transfer of conjugative transposons is an important factor of the high prevalence of antibiotic resistance.