JAC Advance Access published online on June 12, 2003
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkg294
© 2003 by The British Society for Antimicrobial Chemotherapy
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Original article
1 Centre International de
Recherches Médicales de Franceville, Unité de
Parasitologie Médicale,
BP 769 Franceville, Gabon
* Corresponding author. E-mail: Philippe.Deloron{at}ird.fr.
Received 25 September 2002
; revised 17 March 2003
; accepted 22 April 2003
Objectives: To assess the relationship
between the presence of DHFR and DHPS mutations
in Plasmodium falciparum, parasite in
vitro resistance, and in vivo efficacy of
sulfadoxine-pyrimethamine (SP) treatment. Patients and methods: Measurement of SP treatment
efficacy in malaria-infected children in Gabon was combined with in vitro tests of susceptibility to pyrimethamine
and cycloguanil, and molecular genotyping at several DHFR and DHPS loci of parasites isolated before treatment. DHFR was studied at codons 108, 51, and 59, whereas DHPS gene was typed at positions 436, 437, 540
and 581. Results: SP treatment was effective in 86% of
children by day 28. Seventy-five percent of isolates were in vitro resistant
to pyrimethamine and 65.5% to cycloguanil. No mutation
was detected at codons 540 and 581 of the DHPS gene.
Most isolates (71.8%) presented with the triple mutant DHFR genotype, whereas 64.3% combined
at least three DHFR and one DHPS mutations.
The increase in the number of DHFR mutations was associated
with an increase in in vitro resistance to pyrimethamine
and cycloguanil; three DHFR mutations conferred
pyrimethamine and to a lesser extent cycloguanil resistance. Treatment
failures only occurred with isolates presenting at least two DHFR mutations
(S108N and C59R) and one DHPS mutation (S436A or A437G),
but SP treatment of infections with such parasites gave treatment
success in 82.0% of children. Conclusions: DHFR mutations
that lead to high-level in vitro resistance to
pyrimethamine plus 1-2 DHPS mutations
are not sufficient to induce in vivo failure of
SP treatment in young children from Gabon.
Keywords: malaria, drug resistance, antifolates, molecular
markers
DHFR and DHPS genotypes
of Plasmodium falciparum isolates from Gabon correlate
with in vitro activity of pyrimethamine and cycloguanil,
but not with sulfadoxine-pyrimethamine treatment efficacy
2 Hôpital
Bichat-Claude Bernard,
Laboratoire de Parasitologie, 46 rue Henri Huchard, 75877 Paris, France
3 Centre International de
Recherches Médicales de Franceville, Unité de
Parasitologie Médicale,
BP 769 Franceville, Gabon; Institut de Recherche pour le
Développement (IRD), UR010, Mother and Child Health in
the Tropics,
BP1386, Dakar, Senegal
4 Bakoumba
Hospital, BP52, Bakoumba, Gabon
5 Centre International de
Recherches Médicales de Franceville, Unité de
Parasitologie Médicale,
BP 769 Franceville, Gabon; IRD UR010, Faculté de
Pharmacie, Laboratoire de Parasitologie, 4 Avenue de l'Observatoire,
75006 Paris, France
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