Clindamycin Resistance in PVL Positive Isolates of Staphylococcus aureus, Belgaum, North Karnataka (India)

The widespread use of Macrolide Lincosamide Streptogramin B (MLSB) antibiotics has led to an increase in the resistant strains. Although Clindamycin is effective against MRSA but its use in the presence of Erythromycin can lead to induction of cross-resistance among members of the MLSB group which could limit the effectiveness of this drug. Furthermore, at times, some strains are also harbored with PVL genes which are encoded by two contiguous and co-transcribed genes viz., lukF-PV and lukS-PV. The results of a study conducted to find the prevalence of inducible Clindamycin resistance in PVL positive isolates of Staphylococcus aureus from Belgaum, Karnataka, India. Method: More than 120 isolates of S.aureus were collected from hospital in Belgaum during the period 2010-2012, out of which, 72 isolates confirming S.aureus status were kept for further study at RMRC (ICMR), Belgaum. They were characterized as resistant/sensitive using various conventional, molecular and automated techniques. PVL genes LukS and LukF in these strains were detected by PCR. Phenotypic inducible resistance to clindamycin was detected by Double Disk Diffusion test. Result: Out of 72 isolates, 46 were MRSA and 26 were MSSA. In all, 50 isolates (69.44%) showed the presence of PVL genes. Out of these, 14 PVL positive S. aureus isolates (26.38%) showed iMLSB phenotype which included 13 MRSA and 1 MSSA. ConclusionThe cause of concern is the 13 isolates which are MRSA, PVL positive and show inducible clindamycin resistance. Such a combination can be a treatment challenge to the clinicians who are left with very few options.