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

الملخص EN

Multiple resistance of Streptococcus pneumoniae is 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 Tn916 family transposons, carrying tet(M) and int/xisTn916, was observed in all of the tested strains.

Tn916 was detected in 16 strains resistant only to tetracycline.

Tn6002 and Tn3872-related element were found among 99 erm(B)-carrying strains (83.8% and 3.0%, resp.).

Eight strains harbouring mef(E) and erm(B) genes were detected, suggesting the presence of Tn2010 and Tn2017 transposons.

Among 101 chloramphenicol-resistant strains, two variants of Tn5252-related transposon were distinguished depending on the presence of int/xis5252 genes specific for cat gene-containing Tn5252 (75.2% of strains) or intSp23FST81 gene, specific for cat-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.