Leptospires in the blood can be detected on the first few days after
onset by dark-field microscopy, but the results need to be supported by other laboratory methods irrespective of positive results.
On the second week, leptospires are cleared from the bloodstream
as antibodies are produced and higher numbers of leptospires are
excreted in the urine. During this stage, the sensitivity of antibody
detection increases, whereas the sensitivity of DNA detection in the
blood decreases and that in urine may increase.
2 Culture
Leptospires can be isolated from clinical materials such as blood,
cerebrospinal fluid (CSF), urine, and postmortem samples of various tissues. Cultures are incubated at 28–30
C and checked regularly by dark-field microscopy. On primary isolation, the growth of
leptospires is slow, their generation times can be up to 20 h, and the
cultures are recommended to be maintained for up to 13 weeks
[9]. Therefore, culture is not useful for early diagnosis, although it
constitutes the definitive diagnosis of leptospirosis. The isolation of
leptospires requires specialized culture media such as EllinghausenMcCullough-Johnson-Harris (EMJH) and Korthof’s media [10],
and its sensitivity is as low as less than 10% in NAAT-positive
patients [11], which hamper the routine application of culture in
many clinical settings.
Blood culture should be performed as soon as possible after the
onset of the disease during the leptospiremia phase and before the
administration of antibiotics. For the blood culture, a few drops of
blood are inoculated into 5–10 ml liquid or semi-solid culture
media and, if possible, separated into multiple tubes. In addition
to whole blood, a culture using deposits from centrifuged plasma
Table 1
WHO case definitions of leptospirosis [8]
Confirmed cases: Clinical signs and symptoms consistent with leptospirosis and any one of the following:
Fourfold increase in microscopic agglutination test (MAT) titer in acute and convalescent serum
samples
MAT titer 1:400 in single or paired serum samples
Isolation of pathogenic species from normally sterile site
Detection of pathogenic species in clinical samples by histological, histochemical, or immunostaining
technique
Detection of pathogenic species DNA by PCR
Probable cases: Clinical signs and symptoms consistent with leptospirosis and one of the following:
Presence of IgM or a fourfold increase of antibody titer in immunofluorescence assay in acute and
convalescent serum samples
Presence of IgM antibodies by ELISA or dipstick
MAT titer 1:100 in single acute-phase serum sample in non-endemic regions
278
Nobuo Koizumi
onset by dark-field microscopy, but the results need to be supported by other laboratory methods irrespective of positive results.
On the second week, leptospires are cleared from the bloodstream
as antibodies are produced and higher numbers of leptospires are
excreted in the urine. During this stage, the sensitivity of antibody
detection increases, whereas the sensitivity of DNA detection in the
blood decreases and that in urine may increase.
2 Culture
Leptospires can be isolated from clinical materials such as blood,
cerebrospinal fluid (CSF), urine, and postmortem samples of various tissues. Cultures are incubated at 28–30
C and checked regularly by dark-field microscopy. On primary isolation, the growth of
leptospires is slow, their generation times can be up to 20 h, and the
cultures are recommended to be maintained for up to 13 weeks
[9]. Therefore, culture is not useful for early diagnosis, although it
constitutes the definitive diagnosis of leptospirosis. The isolation of
leptospires requires specialized culture media such as EllinghausenMcCullough-Johnson-Harris (EMJH) and Korthof’s media [10],
and its sensitivity is as low as less than 10% in NAAT-positive
patients [11], which hamper the routine application of culture in
many clinical settings.
Blood culture should be performed as soon as possible after the
onset of the disease during the leptospiremia phase and before the
administration of antibiotics. For the blood culture, a few drops of
blood are inoculated into 5–10 ml liquid or semi-solid culture
media and, if possible, separated into multiple tubes. In addition
to whole blood, a culture using deposits from centrifuged plasma
Table 1
WHO case definitions of leptospirosis [8]
Confirmed cases: Clinical signs and symptoms consistent with leptospirosis and any one of the following:
Fourfold increase in microscopic agglutination test (MAT) titer in acute and convalescent serum
samples
MAT titer 1:400 in single or paired serum samples
Isolation of pathogenic species from normally sterile site
Detection of pathogenic species in clinical samples by histological, histochemical, or immunostaining
technique
Detection of pathogenic species DNA by PCR
Probable cases: Clinical signs and symptoms consistent with leptospirosis and one of the following:
Presence of IgM or a fourfold increase of antibody titer in immunofluorescence assay in acute and
convalescent serum samples
Presence of IgM antibodies by ELISA or dipstick
MAT titer 1:100 in single acute-phase serum sample in non-endemic regions
278
Nobuo Koizumi