title: Inducible Clindamycin Resistance among Clinical Isolates of Staphylococcus aureus from Sub Himalayan Region of India.
abstract: BACKGROUND
  Clindamycin is an alternative antibiotic in the treatment of Staphylococcus aureus (S.aureus) infections, both in infections by methicillin susceptible and resistant (MSSA and MRSA) strains. The major problem of use of clindamycin for staphylococcal infections is the presence of inducible clindamycin resistance that can lead to treatment failure in such infections.
  
  
  OBJECTIVE
  To determine inducible and constitutive clindamycin resistance among clinical isolates of S. aureus in a tertiary care centre of sub Himalayan region of India.
  
  
  METHODS
  A total of 350 isolates of S. aureus from various clinical samples were subjected to routine antibiotic sensitivity testing by Kirby Bauer disc diffusion method. Methicillin resistance was detected by cefoxitin (30μg) disc. All isolates were subjected to inducible clindamycin resistance was by Clinical Laboratory Standards Institute (CLSI) recommended D test.
  
  
  RESULTS
  Among 350 S.aureus isolates, 82 (23.42%) were MRSA and 268 (76.57%) were MSSA. Erythromycin resistance was detected in 137 (39.14%) isolates. Erythromycin resistance in MRSA and MSSA was 71.6% and 29.36% respectively. Overall clindamycin resistance was seen in 108 (30.85%) isolates. Constitutive MSLB phenotype predominated (29.62% MRSA; 13.38% MSSA) followed by iMLSB (28.39% MRSA; 9.29% MSSA) and MS phenotypes (13.58% MRSA; 6.69%MSSA). Both inducible and constitutive clindamycin resistance was significantly higher (p=0.00001, 0.0008 respectively) in methicillin resistant strains than in methicillin susceptible strains.
  
  
  CONCLUSIONS
  The present study gives a magnitude of clindamycin resistance among clinical isolates of S. aureus from this region of the country. Our study recommends routine testing of inducible clindamycin resistance at individual settings to guide optimum therapy and to avoid treatment failure.
authors.affiliation: Assistant Professor, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Kiran K
authors.initials: KK
authors.lastname: Mokta
authors.affiliation: Associate Professor, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Santwana
authors.initials: S
authors.lastname: Verma
authors.affiliation: Senior Resident, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Divya
authors.initials: D
authors.lastname: Chauhan
authors.affiliation: Assistant Professor, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Sunite A
authors.initials: SA
authors.lastname: Ganju
authors.affiliation: Professor, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Digvijay
authors.initials: D
authors.lastname: Singh
authors.affiliation: Professor and Head, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Anil
authors.initials: A
authors.lastname: Kanga
authors.affiliation: Junior Resident, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Anita
authors.initials: A
authors.lastname: Kumari
authors.affiliation: Junior Resident, Department of Microbiology, Indira Gandhi Medical College , Shimla, India .
authors.forename: Vinod
authors.initials: V
authors.lastname: Mehta
keywords: Constitutive clindamycin resistance; D test; Inducible clindamycin resistance; Staphylococcus aureus