Inducible Clindamycin Resistance in Staphylococcus aureus Isolated from Palms of Poultry Workers in Jos, Plateau State, Nigeria

Background: Clindamycin is used for the treatment of infections attributed to macrolide (erythromycin) resistant Staphylococcus aureus; particularly infections of skin and soft tissues. Therapy for staphylococcal infections may be complicated by the possibility of inducible macrolide-lincosamide-streptogramin B resistance (iMLS B ). Objective: This study was carried out to assess the prevalence of phenotypic expression of inducible clindamycin resistance of Staphylococcus aureus isolated from palms of poultry workers in Jos, Plateau State, Nigeria. Methods: A total of 186 Staphylococcus aureus were isolated and identified by conventional methods and subjected to antibiotic susceptibility testing by Kirby-Bauer disk diffusion method. Double disc approximation test (D-test) was used to investigate inducible and constitutive MLS B resistant phenotype. Results: From 186 S. aureus isolates, 113 (60.8%) were erythromycin resistant and 20 (10.8%) were clindamycin resistant. Most of the isolates 155 (83.3%) were methicillin-sensitive S. aureus (MSSA) while 31 (16.7%) were resistant to methicillin (MRSA). Out of the 186 isolates, 33 (17.7%) were iMLS B phenotype (D-test positive), 20 (10.8%) were constitutively resistant (cMLS B phenotype) and 60 (32.3%) were methicillin-sensitive (MS) phenotype (D-test negative). The incidence of constitutive and inducible clindamycin resistant phenotypes were higher in MRSA than MSSA. On the other hand, the incidence of MS phenotype was higher in MSSA than in MRSA. Conclusion: The study revealed that 17.7% of S. aureus were inducible clindamycin resistant which could have been misidentified as clindamycin susceptible by Kirby-Bauer disk diffusion method. The study also showed the importance of D-test in detecting inducible clindamycin resistance in S. aureus.