Inducible Clindamycin resistance of Staphylococcus aureus isolates among burn patients in Motahari hospital, Tehran, Iran

Background and Aim : Background and aim: Inducible resistance to Clindamycin, an effective antibiotic against Staphylococcus aureus (S. aureus) in infections of skin and soft tissue, can lead to in vivo therapeutic failure. The aim of this study was to investigate the outbreak of inducible resistance to Clindamycin in S. aureus isolates.Methods : Material and Methods: A total number of ۲۱ S. aureus isolates from burn wound swabs which were confirmed by standard bacteriologic tests were subjected to antimicrobial susceptibility test (AST) and inducible Clindamycin resistance using D-test in accordance with Clinical and Laboratory Standards Institute ۲۰۱۹ (CLSI).In D test, a ۵ μg erythromycin (E) disk and a ۲ μg clindamycin (C) disk placed ۱۵ to ۲۰ mm apart on an agar plate that has been inoculated with the clinical isolate. Then the plate incubated at ۳۷°C for ۲۴h. Then the figuration of a D shape around clindamycin of inhibition were evaluated. A standard S. aureus ATCC ۲۵۹۲۳ were evaluated simultaneously.Results : Results: The majority of isolates (۸۰.۹۵%) were constitutively resistant to common antibiotics. Based on AST, ۹۷.۹% of isolates were resistant to: ۸۴.۴% to erythromycin, ۸۰% to cefoxitin, ۷۵% to gentamicin and ۶۶% to Clindamycin . Only ۴.۷۶% of the isolate was D-test positive (inducible resistance to Clindamycin) in this study.Conclusion : Conclusion: The increasing prevalence of resistance to different therapeutic options including Clindamycin in the treatment of S. aureus infections, could cause treatment failure. Therefore D-test, which is an easy and inexpensive text, is needed for clinicians to choose an appropriate treatment.

Keywords:

Staphylococcus aureus , Inducible Resistance , D-test , Clindamycin , Erythromycin