title: An evaluation of dark field microscopy, culture and commercial serological kits in the diagnosis of leptospirosis.
abstract: BACKGROUND
  This study was conducted to analyze the clinical utility of various leptospira diagnostic modalities.
  
  
  OBJECTIVE
  To evaluate the role of dark field microscopy (DFM), culture, immunochromatography (IgM Leptocheck), IgM enzyme-linked immunosorbent assay (IgM ELISA), macroscopic slide agglutination test (MSAT) and microscopic agglutination test (MAT) in diagnosing leptospirosis in febrile patients.
  
  
  METHODS
  Descriptive study conducted in a tertiary care hospital from January 2011 to April 2012.
  
  
  METHODS
  Blood, urine and paired sera from 100 patients with clinical suspicion of leptospirosis (study group) were collected and subjected to DFM, culture, IgM Leptocheck, IgM ELISA and MSAT. Fifty randomly selected sera from febrile patients tested positive for infections other than leptospirosis (control sera) were also subjected to the aforementioned serological assays. All the leptospira seropositive samples were subjected to MAT.
  
  
  METHODS
  Positive predictive values (PPV) and coefficient of agreement (kappa).
  
  
  RESULTS
  None of the clinical samples showed positivity by DFM. Leptospira inadai was isolated from a urine sample. The seropositivity of IgM Leptocheck, IgM ELISA and MSAT was 16%, 46% and 47%, respectively. The PPV of these assays was 14.3%, 8.7% and 6.5%, respectively. Poor agreement was obtained among these assays. Only four study group leptospira seropositive samples were confirmed by MAT with Australis being the predominant serovar. None of the leptospira-positive control sera were confirmed by MAT.
  
  
  CONCLUSIONS
  DFM and culture have limited utility in diagnosing leptospirosis with serology being the mainstay. The present study shows discordant results with the commercially available serological kits. Further studies should be done to evaluate the various diagnostic modalities.
authors.affiliation: Department of Microbiology, Govind Ballabh Pant Institute of Post Graduate Medical Education and Research, Jawahar Lal Nehru Marg, New Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Bhatia
authors.forename: B L
authors.initials: BL
authors.lastname: Umapathy
authors.forename: B V
authors.initials: BV
authors.lastname: Navaneeth
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007919:Leptospira / Q000302:isolation & purification*; D007922:Leptospirosis / Q000175:diagnosis*; D008297:Male; D008853:Microscopy / Q000379:methods*; D008875:Middle Aged; D012698:Serologic Tests / Q000379:methods*; D062606:Tertiary Care Centers; D014556:Urine / Q000737:chemistry / Q000382:microbiology; D055815:Young Adult