Detection of Tn554 carrying erm(A) gene in a clinical isolates of S. pyogenes

Abstract

Background:This study was conducted to investigate the genetic organization of erm(A)-carrying Tn554 in clinical isolates of Streptococcus pyogenes. Tn554 is a communicable sequence to multiple plasmid sites, it contains erm(A) gene and has the ability to bind the resistance of MLS and spectinomycin. Over the past two decades, erythromycin resistance rates have increased in S. pyogenes in many countries. To obtain information that may be useful in solving the spread of antimicrobial resistance, antibiotic-resistant genes can be identified as well as their association with mobile genetic elements. Material and Methods:A total of 22 isolates of S. pyogenes were obtained from 93 bacterial isolates. These isolates were examinedby detecting their antibiotic susceptibility against two different antibiotics groups (Macrolides and Tetracycline) thengenomic DNA was extracted from each isolate for detection Tn554 by using specific primers to amplify erm(A) gene carried by this transposable element. Results:Results showed that there is a high level of resistance to erythromycin, (90.9%), then to Minocycline (68.1%), Tetracycline (54.5%), Azithromycin and Clarithromycin (36.3%), Doxycycline (31.8%) and then to Oxytetracycline (27.2%). Resultsalso showed that 13 of S. pyogenes isolates were harboring Tn554 transposable element carrying erm(A) gene. On the other hand, results showed that there are another isolates resistant to erythromycin that may possess a chromosomal or plasmid copy of the erythromycin resistance gene, or maybe the resistance was caused by another structural erythromycin gene carried by other type of transposable elements rather than Tn554. Conclusion:Our findings suggest that the isolates of S. pyogenes are harboring chromosomal copy of Tn554 conferring erythromycin resistance. One possible explanation for the presence of genes at different isolates is due to erm gene, which was most likely located on Tn554.