title: Coagulase-negative staphylococci causing blood stream infection at an Indian tertiary care hospital: Prevalence, antimicrobial resistance and molecular characterisation.
abstract: BACKGROUND
  Recent years have seen a rise of coagulase-negative staphylococci (CoNS) from common contaminants to agents of nosocomial blood stream infections (BSI's). Molecular typing and establishing a correlation with antibiotic resistance is essential particularly in countries like India where genotyping studies for drug-resistant CoNS are sparse.
  
  
  METHODS
  A prospective study was done over 18 months, wherein 42,693 blood samples were received, and 59 patients with BSI due to CoNS were evaluated. The isolates recovered were identified by a biochemical test panel and matrix-assisted laser desorption ionization - time of flight mass spectrometry followed by antimicrobial susceptibility testing by Kirby-Baur disc diffusion method and E-test strips. Staphylococcal chromosomal cassette mec (SCCmec) element was characterised by multiplex polymerase chain reaction for all methicillin-resistant (MR) isolates.
  
  
  RESULTS
  The majority of CoNS isolated were constituted by Staphylococcus haemolyticus (47.5%) followed by Staphylococcus epidermidis (33.9%), Staphylococcus hominis (11.86%), Staphylococcus cohnii (5.08%) and Staphylococcus warneri (1.69%). Among all isolates 57.6% were MR with statistically significant higher resistance versus methicillin sensitive-CoNS. This difference was significant for erythromycin (76% vs. 44%, P = 0.011), rifampicin (50% vs. 12%,P= 0.002) and amikacin (26.5% vs. 4%, P = 0.023), ciprofloxacin (64.7% vs. 20%, P = 0.001) and cotrimoxazole (55.9% vs. 20%, P = 0.006). SCCmec type I was predominant (61.8%, P = 0.028) and exhibited multidrug resistance (76.2%). Coexistence of SCCmec type I and III was seen in 8.82% MR isolates.
  
  
  CONCLUSIONS
  CoNS exhibit high antimicrobial resistance thereby limiting treatment options. The presence of new variants of SCCmec type in hospital-acquired CoNS may predict the antibiotic resistance pattern. This is the first evaluation of the molecular epidemiology of CoNS causing BSI from India and can serve as a guide in the formulation of hospital infection control and treatment guidelines.
authors.affiliation: Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: S
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Microbiology, All Institute of Medical Sciences, New Delhi, India.
authors.forename: B
authors.initials: B
authors.lastname: Dhawan
authors.affiliation: Department of Microbiology, All Institute of Medical Sciences, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Kapil
authors.affiliation: Department of Pediatrics, All Institute of Medical Sciences, New Delhi, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Kabra
authors.affiliation: Department of Neurosurgery, All Institute of Medical Sciences, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Suri
authors.affiliation: Department of Biostatistics, All Institute of Medical Sciences, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Sreenivas
authors.affiliation: Department of Microbiology, All Institute of Medical Sciences, New Delhi, India.
authors.forename: B K
authors.initials: BK
authors.lastname: Das
mesh_terms: D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology; D015373:Bacterial Typing Techniques; D003030:Coagulase / Q000032:analysis*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D015995:Prevalence; D011446:Prospective Studies; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D013212:Staphylococcus epidermidis; D041162:Staphylococcus haemolyticus; D041181:Staphylococcus hominis; D062606:Tertiary Care Centers
chemical_list: D003030:Coagulase