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The following is a summary of “ICESp1109, a novel hybrid Integrative Conjugative Element of macrolide-resistant Streptococcus pyogenes serotype M77 collected between 2003 and 2017 in Poland,” published in the October 2024 issue of Infectious Disease by Gawor et al.
Researchers conducted a retrospective study to characterize the genetic determinants of antibiotic resistance and the linked mobile genetic elements (MGEs) among Streptococcus pyogenes (Group A streptococci or GAS) clinical isolates of an M77 serotype collected in Poland between 2003 and 2017.
They sequenced the genomes of 136 M77 GAS isolates using Illumina sequencing, selected some long-read sequencing isolates using Oxford Nanopore, and analyzed the whole genome sequences to identify macrolide resistance determinants with genetic context.
The results showed that all strains carried the tet(O) gene (100%, N=136) and, were classified as a single sequence type ST63 for erythromycin resistance; the erm (TR) determinant was detected in 76.5% (N=104) isolates. A single appearance of tet(M) and erm(B) on Tn3872 was observed. The mefA, mefE, and msr(D) genes were undetected while, the correlation with the detected strain phenotypes – 11 exhibited cMLSB, 93 – iMLSB, and no M phenotype. The erm (TR) gene was predominantly (N=74) found within a hybrid Integrative Conjugative Element composed of the ICESp1108-like sequence and ICESp2906 variant, which was named ICESp1109. In strains isolated before 2008, erm (TR) was located within ICESp2905 (N=27) and was detected within stand-alone ICESp1108-like sequences in 3 strains.
Investigators concluded that the clonal spread of the macrolide-resistant Streptococcus pyogenes M77/ST63 strain, carrying the novel hybrid ICESp1109, occurred between 2008 and 2017 in Gram-positive bacteria.
Source: academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiae473/7818965
