TY - JOUR

T1 - The Utility of Blood Culture Fluid for the Molecular Diagnosis of Leptospira

T2 - A Prospective Evaluation

AU - Dittrich, Sabine

AU - Rudgard, William E.

AU - Woods, Kate L.

AU - Silisouk, Joy

AU - Phuklia, Weerawat

AU - Davong, Viengmon

AU - Vongsouvath, Manivanh

AU - Phommasone, Koukeo

AU - Rattanavong, Sayaphet

AU - Knappik, Michael

AU - Craig, Scott B.

AU - Weier, Steven L.

AU - Tulsiani, Suhella M.

AU - Dance, David A. B.

AU - Newton, Paul N.

PY - 2016/4

Y1 - 2016/4

N2 - 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.

AB - 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.

U2 - 10.4269/ajtmh.15-0674

DO - 10.4269/ajtmh.15-0674

M3 - Journal article

C2 - 26880775

VL - 94

SP - 736

EP - 740

JO - Journal. National Malaria Society

JF - Journal. National Malaria Society

SN - 0002-9637

IS - 4

ER -