title: Evaluation of HiaureusTMCoagulase Confirmation Kit in Identification ofStaphylococcus aureus.
abstract: BACKGROUND
  Staphylococcus aureusis a facultative anaerobic Gram positive coccal bacterium whose incidence ranges to different infections. It is a cause of various uncomplicated skin infections, abscesses, septicaemia/bacteraemia, gastroenteritis, endocarditis, toxic shock syndrome and food intoxications. Various methods with varied time, sensitivities, specificities and costs are available, but may not be used as a reliable test for the identification and differentiation ofS. aureus. Therefore, there is a need to evaluate newer tests.
  
  
  OBJECTIVE
  To compare the conventional tests with a commercial available kit for reliable, cost effective identification and confirmation ofS. aureus.
  
  
  METHODS
  The current prospective study was conducted in the Department of Clinical Pathology, Haffkine Institute for a period of six months. A total of 341 clinical isolates of staphylococci isolated from pus, urine, blood culture and sterile body fluids were subjected to conventional tests like Tube Coagulase Test (TCT) using Rabbit Plasma (RP) and Human Plasma (HP), culture media such as Mannitol Salt Agar (MSA) and Deoxyribonuclease (DNase) media in parallel to HiaureusTMCoagulase Confirmation Kit (HACCK), a commercially available kit for identification ofS. aureus. Amplification of thefemA gene was used as a comparative reference point test to calculate the sensitivity, specificity and concordance values of the conventional tests.
  
  
  RESULTS
  Amongst the coagulase based tests, HACCK was 100% sensitive and specific. The TCT using RP was 98.58% sensitive while TCT using HP was less sensitive (95.37%). A total of 100% specificity was observed for TCT using RP while TCT using HP was 96.68% specific. The MSA and DNase media were 97.86% vs 96.44% and 96.67% vs 91.67% sensitive and specific respectively. The combination tests had varying sensitivity and specificity ranges. The HACCK demonstrated 100% concordance withfemA amplification and was labelled as an ideal perfect test (κ=1) with MSA as an alternative test forS. aureusidentification.
  
  
  CONCLUSIONS
  The HACCK can be used as an exclusive, reliable and cost effective test for identification ofS. aureus. Alternatively, in view of the cost factor MSA either as a single test or in combination with TCT using HP could be used as screening tests and confirm discordant results with HACCK.
authors.affiliation: Ph.D. Scholar, Department of Clinical Pathology, Haffkine Institute , Mumbai, Maharashtra, India .
authors.forename: Arunagiri
authors.initials: A
authors.lastname: Subramanian
authors.affiliation: Research Fellow, Department of Clinical Pathology, Haffkine Institute , Mumbai, Maharashtra, India .
authors.forename: Vidushi K
authors.initials: VK
authors.lastname: Chitalia
authors.affiliation: Senior Molecular Biology Executive, Department of Molecular Biology, HiMedia Laboratories , Mumbai, Maharashtra, India .
authors.forename: Kushminda
authors.initials: K
authors.lastname: Bangera
authors.affiliation: Assistant Director and Head, Department of Clinical Pathology, Haffkine Institute , Mumbai, Maharashtra, India .
authors.forename: Shashikant P
authors.initials: SP
authors.lastname: Vaidya
authors.affiliation: Director, Department of Molecular Biology, HiMedia Laboratories , Mumbai, Maharashtra, India .
authors.forename: Rajas
authors.initials: R
authors.lastname: Warke
authors.affiliation: Professor and Head, Department of Microbiology, Grant Medical College and Sir J.J. Group of Hospitals , Byculla, Mumbai, Maharashtra, India .
authors.forename: Abhay
authors.initials: A
authors.lastname: Chowdhary
authors.affiliation: Former Director and Visiting Scientist, Department of Virology and Immunology, Haffkine Institute , Mumbai, Maharashtra, India .
authors.forename: Ranjana A
authors.initials: RA
authors.lastname: Deshmukh
keywords: Deoxyribonuclease; Mannitol; Plasma; Polymerase Chain Reaction; Rabbit