Sensibilidade ao antimonial pentavalente in vitro de amostras de Leishmania (Viannia) braziliensis isoladas antes e após o tratamento de pacientes
Pentavalent antimonials are the first drug of choice for leishmaniasis treatment
and in Brazil meglumine antimoniate (Gl
u
cantime

) is used. The variability of
the re
sponse to treatment may be conditioned to factors related to the host, the
parasites or even the therapeutic plan. In this study we assessed the
susceptibility to meglumine antimoniate of samples of
Leishmania (Viannia)
braziliensis
in
in vitro
tests. We
compared the DL
50
of both promastigote and
amastigote forms of samples isolated at diagnosis before treatment (sample
A
)
and samples isolated after the first cycle of treatment (sample
B
). Seven pairs
of samples (
A
and
B
) were selected, four isolated from
patients with treatment
failure and three from patients with reactivation. The promastigote forms were
exposed to meglumine antimoniate concentrations between 3,955 μg and 8,1
mg/mL and were assessed after 24 and 48 hours of exposition. The
amastigotes, in
murine macrophages, were exposed to concentrations of 20, 40
and 80 μg/mL of meglumine antimoniate, and the infection kinetics was
assessed at time intervals of 0, 24, 48 and 72 hours, through two parameters:
percentage of infected cells and average numbe
r of amastigotes per
macrophage. All
B
samples of promastigotes presented DL
50
values higher than
those obtained with
A
samples, except for one patient. In tests with
amastigotes, the
B
samples showed higher DL
50
values than sample
A
in 4
cases, with incr
eases ranging from 17 to 20%
in
3 patients and 100% increase
in one case. In other patients, DL
50
values of
A
and
B
were similar. One of the
seven patients studied abandoned treatment and six were clinically healed after
retreatment with Anphotericin B (4
cases) or meglumine antimoniate (2 cases).
It was not possible to correlate the results of this study with the clinics or
response to treatment.
It is possible that other patient related factors such as
immunological condition or response to infection may
influence the response to
antimonial treatment