title: The Utility of Blood Culture Fluid for the Molecular Diagnosis of Leptospira: A Prospective Evaluation.
abstract: Leptospirosis is an important zoonosis worldwide, with infections occurring after exposure to contaminated water. Despite being a global problem, laboratory diagnosis remains difficult with culture results taking up to 3 months, serology being retrospective by nature, and polymerase chain reaction showing limited sensitivity. Leptospira have been shown to survive and multiply in blood culture media, and we hypothesized that extracting DNA from incubated blood culture fluid (BCF), followed by quantitative real-time polymerase chain reaction (qPCR) could improve the accuracy and speed of leptospira diagnosis. We assessed this retrospectively, using preincubated BCF of Leptospira spp. positive (N= 109) and negative (N= 63) febrile patients in Vientiane, Lao PDR. The final method showed promising sensitivities of 66% (95% confidence interval [CI]: 55-76) and 59% (95% CI: 49-68) compared with direct or direct and indirect testing combined, as the respective reference standards (specificities > 95%). Despite these promising diagnostic parameters, a subsequent prospective evaluation in a Lao hospital population (N= 352) showed that the sensitivity was very low (∼30%) compared with qPCR on venous blood samples. The disappointingly low sensitivity does suggest that venous blood samples are preferable for the clinical microbiology laboratory, although BCF might be an alternative if leptospirosis is only suspected postadmission after antibiotics have been used.
authors.forename: Sabine
authors.initials: S
authors.lastname: Dittrich
authors.forename: William E
authors.initials: WE
authors.lastname: Rudgard
authors.forename: Kate L
authors.initials: KL
authors.lastname: Woods
authors.forename: Joy
authors.initials: J
authors.lastname: Silisouk
authors.forename: Weerawat
authors.initials: W
authors.lastname: Phuklia
authors.forename: Viengmon
authors.initials: V
authors.lastname: Davong
authors.forename: Manivanh
authors.initials: M
authors.lastname: Vongsouvath
authors.forename: Koukeo
authors.initials: K
authors.lastname: Phommasone
authors.forename: Sayaphet
authors.initials: S
authors.lastname: Rattanavong
authors.forename: Michael
authors.initials: M
authors.lastname: Knappik
authors.forename: Scott B
authors.initials: SB
authors.lastname: Craig
authors.forename: Steven L
authors.initials: SL
authors.lastname: Weier
authors.forename: Suhella M
authors.initials: SM
authors.lastname: Tulsiani
authors.forename: David A B
authors.initials: DAB
authors.lastname: Dance
authors.forename: Paul N
authors.initials: PN
authors.lastname: Newton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003470:Culture Media; D005260:Female; D006801:Humans; D007223:Infant; D007812:Laos; D007919:Leptospira / Q000254:growth & development; D007922:Leptospirosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003470:Culture Media