title: Utility and limitations of direct multi-locus sequence typing on qPCR-positive blood to determine infecting Leptospira strain.
abstract: Culture-independent molecular characterization of infecting Leptospira human blood specimens from a 2008 outbreak of human leptospirosis in central Sri Lanka was carried out. Of 58 quantitative real-time polymerase chain reaction-positive samples analyzed for seven multi-locus sequence typing (MLST) housekeeping genes (mreA, pfkB, pntA, sucA, tpiA, fadD, and glmU), interpretable data was obtained from 12 samples. Mean bacterial load was 2.2 × 10(5) among specimens with complete MLST profiles compared with 1.3 × 10(4) among specimens without complete MLST profiles; all specimens with complete profiles had at least 4.9 × 10(4) Leptospira/mL (t = 5, P < 0.001). Most (11/12) identified sequence types were ST1 (L. interrogans serovar Lai) and ST44 (L. interrogans serovar Geyaweera). MLST can be used to directly identify infecting Leptospira strains in blood samples obtained during acute illness without the need for culture isolation, but it shows important limitations related to bacterial load.
authors.affiliation: Department of Community Medicine, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura, Sri Lanka. sunethagampodi@yahoo.com
authors.forename: Suneth B
authors.initials: SB
authors.lastname: Agampodi
authors.forename: Angelo C
authors.initials: AC
authors.lastname: Moreno
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Vinetz
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthias
mesh_terms: D006801:Humans; D007919:Leptospira / Q000235:genetics / Q000302:isolation & purification*; D007922:Leptospirosis / Q000175:diagnosis / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D013045:Species Specificity