Detection of Inducible Clindamycin Resistance in Methicillin-Resistant Staphylococcus aureus Isolates from National Orthopaedic Hospital, Dala, Kano.

Abstract

The effectiveness of the antibiotic (clindamycin) usually used in the treatment of skin, soft-tissue, bone and joints infections particularly those caused by Staphylococcal species is now put to test by the emergence of several methicillin-resistant Staphylococcus aureus (MRSA)strains carrying inducible erm gene.
This study intend to detect inducible-clindamycin resistance (iMLSB) and MRSA among Staphylococcus aureus (S. aureus) isolates from orthopaedic patients.
Staphylococcus aureus strains were isolated from the nasal, wound, and urine specimen of the patients using standard microbiological techniques. Antibiotic susceptibility was carried out using the disc diffusion method for erythromycin, clindamycin and cefoxitin. Strains that are resistant to erythromycin and susceptible to clindamycin were selected to determine iMLSB. The iMLSB was determined using the D-test phenotype by placing erythromycin and clindamycin 12-20 mm apart in order to induce in-vivo clindamycin resistance while MRSA was determined by the strains resistance to cefoxitin. The isolation rate of S. aureus from the samples (n=134) was 26.8%. A total of 29 (80.5%) expressed constitutive resistance to erythromycin, and 31 (86.1%) expressed constitutive resistance to clindamycin. Five (5) erythromycin-resistant isolates were simultaneously sensitive to clindamycin. Inducible-clindamycin resistance was detected in 2 (5.5%) of the isolates. Cefoxitin resistance (MRSA) was detected in 34 (94.4%) of the isolates, all the erythromycin-resistant S. aureus and inducible-clindamycin resistant isolates were MRSA. The resistance pattern observed and erm gene harboured by the isolates is a major challenge to the effectiveness of MLSB group of antimicrobial agents. Therefore, resistance should be prevented in order to preserve clindamycin as an optional treatment for skin and soft tissue infections.