Detection of Tn1545 conferring erythromycin resistance in clinical isolates of Streptococcus pneumonoiae

Abstract

This study was conducted to investigate the genetic organization of erm-carrying Tn1545 in clinical isolates of Streptococcus pneumonia. A total of fifteen isolates of S. pneumoniae isolates were examined and was found to contain Tn1545 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 and trimethoprim (87%), clindamycin (73%), kanamycin (67%), erythromycin,  tetracycline and azithromycin (60%), ciprofaxin and levofloxacin (53%).

  Genomic DNA was extracted from S. pneumoniae isolates for detection Tn1545 by using specific primers to amplify erm gene carried by this transposable element. Results showed that seven of S. pneumoniae isolates were found to contain Tn1545 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..