Detection of Tn917 Conferring Erythromycin Resistance in Clinical Isolates of Streptococcus pneumonoiae

Abstract

This study was conducted to investigate the genetic organization of erm-gene carrying Tn917 in clinical isolates of Streptococcus pneumonia. Swab samples were collected from pharyngitis, tonsillitis, sputum and cerebrospinal fluid samples were collected from patients suffering from respiratory tract infections who attended Al-Yarmouk Teaching Hospital, Central Child Teaching Hospital and The Baghdad Teaching Hospital in Baghdad during the period from November/2017 to April/2018. A total of 15 isolates of S. pneumoniae isolates were examined and was found to contain Tn917 element. Susceptibility of these isolates to different antibiotics was also examined, results showed that these isolates are resistant to penicillin in percentage of 93%, then to streptomycin (87%), clindamycin (73%), kanamycin (50%), erythromycin and azithromycin (40%), tetracycline and trimethoprim (80%), ciproflaxin and levofloxacin (20%). Genomic DNA was extracted from S. pneumoniae isolates for detection Tn917 by using specific primers to amplify erm gene carried by this transposable element. Results showed that five of S. pneumoniae isolates were found to contain Tn917 element giving them erythromycin resistance. erm gene encodes this antibiotic but does not mediate resistance to other antimicrobial agents. On the other hand, nucleotide sequence for erm gene was determined, and compared by alignment with the erm gene sequence located on the same transposable elements in standard strains of S. pneumoniae recorded in NCBI data base. Results of alignment showed 100% identity between these sequences.