Inducible Clindamycin resistance among clinical isolates of Staphylococcus aureus from a tertiary care teaching hospital in Solapur, Maharashtra

Dr Anu Sharma; Dr Ravi Prakash Sharma; Dr Mayuri Bhise; Dr N.K. Shaikh

Volume : IX, Issue : VII, July - 2019

Inducible Clindamycin resistance among clinical isolates of Staphylococcus aureus from a tertiary care teaching hospital in Solapur, Maharashtra

Dr Anu Sharma, Dr Ravi Prakash Sharma, Dr Mayuri Bhise, Dr N. K. Shaikh

Abstract :

Background– Clindamycin is commonly used to treat skin and soft tissue infections caused by Staphylococcus aureus especially methicillin resistant S. aureus (MRSA) infections. The resistance to antimicrobial agents among Staphylococci is an increasing problem globally. Inducible clindamycin resistance detection is important as it guides physician for better patient outcome. The study has been undertaken with the aim to detect inducible clindamycin resistance both inducible as well as constitutive MLSB (Macrolide–Lincosamide–Streptogramin–B) phenotype among Staphylococcus aureus isolates. Material and method– A total of 269 non duplicate Staphylococcus aureus isolates from various clinical samples were obtained from patients attending OPD or admitted in the hospital (IPD). These isolates were included in the study. Identification of Staphylococcus aureus was based on culture characteristics and other standard biochemical tests. Antimicrobial susceptibility testing was done on Mueller Hinton agar by Kirby baeur disc diffusion method. MRSA were detected using disc of Cefoxitin 30 µg, zone of inhibition less than 22 mm in Staphylococcus isolates were considered as MRSA. Inducible clindamycin resistance was detected by D–zone test as per CLSI guidelines. Result–Among 269 Staphylococcus aureus isolates MRSA were 66 (24.53%) while MSSA were 203 (75.5%). Majority of MRSA (n=66) & MSSA (n=203) isolates were from patients admitted in the hospital (IPD) which were 61 (92.42%) and 155 (76.4%) respectively. Staphylococcus isolates were predominantly isolated from pus/wound swab 135 (50.2%) followed by blood 62 (23.04%), urine 58 (22%), tracheal aspirate 09 (3.34%) and pleural fluid 03 (1.11%). Among Staphylococcus aureus isolates MS phenotype accounted for 13.01% of isolates, iMLSB phenotype were 15% while cMLSB phenotype seen in 20.44% of the isolates. On comparison between MRSA and MSSA isolates cMLSB phenotype and iMLSB phenotype is common among MRSA. Among MRSA cMLSB seen in 39.4% isolates and iMLSB in 30.33% isolates respectively as compared to MSSA where cMLSB was seen in 16.74% isolates while iMLSB phenotype was seen in 10% of isolates. MS phenotype in MRSA was seen in 15.2% of isolates while in MSSA MS phenotype seen in 10% of isolates. Conclusion– Present study will help in assessment of the magnitude of clindamycin resistance among clinical isolates of S. aureus. Routine testing of such resistance will guide physicians for optimum therapy, to avoid treatment failure and better patient outcome.