title: Prevalence and molecular characterization of methicillin resistance among Coagulase-negative Staphylococci at a tertiary care center.
abstract: BACKGROUND
  Methicillin-resistant Coagulase-negative Staphylococci (MR-CoNS) have emerged as an important cause of nosocomial infections especially in patients with prosthetic devices and implants. This study was conducted with an aim to determine the prevalence of methicillin resistance among CoNS isolates at a tertiary care center by both phenotypic and genotypic methods.
  
  
  METHODS
  This cross sectional study was carried out from September 2011 to February 2014 in which 150 non-repetitive clinical isolates of CoNS were identified at the species level by conventional phenotypic methods. Cefoxitin disk (30 μg) diffusion testing was used to determine methicillin resistance and confirmed by detection ofmecA gene by polymerase chain reaction (PCR).
  
  
  RESULTS
  Out of 150 CoNS isolates, 51 were methicillin resistant by cefoxitin disk diffusion method. Out of these 51 isolates,mecA gene was detected only in 45 isolates. Moreover,mecA gene was also detected in 4 isolates, which were cefoxitin sensitive. Thus, the prevalence of methicillin resistance among CoNS was found to be 32.7% by PCR.
  
  
  CONCLUSIONS
  The prevalence of methicillin resistance among Coagulase-negative Staphylococci (CoNS) was 32.7% by PCR detection ofmecA gene. The sensitivity and specificity of cefoxitin disk diffusion method againstmecA gene detection by PCR were found to be more than 90%. It can be concluded from this study that cefoxitin disk diffusion test can be used as a useful screening method to detect methicillin resistance among CoNS isolates. However, detection ofmecA gene by PCR remains a more accurate method of detecting methicillin resistance among CoNS.
authors.affiliation: Graded Specialist (Microbiology), Command Hospital (Southern Command), Pune 411040, India.
authors.forename: Puneet
authors.initials: P
authors.lastname: Bhatt
authors.affiliation: Graded Specialist (Microbiology), Defence Research & Development Establishment, Gwalior, India.
authors.forename: Kundan
authors.initials: K
authors.lastname: Tandel
authors.affiliation: Assistant Professor, Nepalese Army Institute of Health Sciences, Nepal.
authors.forename: Alina
authors.initials: A
authors.lastname: Singh
authors.affiliation: Professor, Dept of Microbiology, Armed Forces Medical College, Pune 411040, India.
authors.forename: M
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Professor & Head, Dept of Microbiology, Armed Forces Medical College, Pune 411040, India.
authors.forename: Naveen
authors.initials: N
authors.lastname: Grover
authors.affiliation: Commandant, 174 Military Hospital, C/o 56 APO, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Sahni
keywords: Cefoxitin disk; Methicillin-resistant Coagulase-negative Staphylococci (MR-CoNS); Polymerase chain reaction (PCR); mecA gene