Detection of Inducible Clindamycin Resistance in Clinical Isolates of Staphylococcus aureus

Deepali S. Kamble, Swati S. Nale, Dnyaneshwari P. Ghadage, Vrishali A. Muley and Arvind V. Bhore

Microbiology and Smt.Kashibai Navale Medical College and General Hospital. Pune - 411 041 (India).

ABSTRACT: Clindamycin is commonly used in the treatment of Staphylococcus aureus. In vitro routine tests for clindamycin susceptibility may fail to detect inducible clindamycin resistance due to erm genes resulting in treatment failure, thus necessitating the need to detect such resistance by a simple D test on routine basis. 140 Staphylococcus aureus isolates were subjected to routine antibiotic susceptibility testing including oxacillin (1µg) by Kirby Bauer disc diffusion method. Inducible clindamycin resistance was detected by D test, as per CLSI guidelines on Staphylococcus aureus isolates. 76 (54.28%) were Staphylococcus aureus and 64 (45.71%) were Methicillin resistant Staphylococcus aureus. In MRSA 07 (10.93%) isolates showed inducible clindamycin resistance, 08 (12.5%) showed constitutive resistance, 02 (3.1%)showed MS phenotype while in MSSA 02 (2.63%) isolates showed only inducible clindamycin resistance and not the constitutive resistance , 55 (72.36%) showed MS phenotype. Inducible resistance and Constitutive resistance were found to be higher in MRSA as compared to MSSA. The present study showed that, to avoid the therapeutic failure D test must be performed by all laboratories routinely.

KEYWORDS: Clindamycin resistance; Constitutive MLSB phenotype; Inducible MLSB phenotype; MRSA; MS phenotype

[ HTML Full Text]