ABSTRACT
The molecular-based magnet test for malaria is shown to be more sensitive than the thin blood film test. The globally used thin blood film test is less sensitive because it uses preparation steps that result in the reduction of the absolute number of diagnostically pertinent erythrocytes. Several reports of diagnostic error with the thin film test and the thick film test have appeared in the literature. In marked contrast to the commonly accepted tests, the magnet test concurrently partitions and concentrates the infected erythrocytes present in the initial sample. The magnetic test permits a brief and sensitive microscopic-based enumeration of the malaria-infected erythrocytes in the enriched sample. Diagnostically pertinent hemozoin is simply identified through two of its specific molecular properties: paramagnetism and birefringence. The former property mediates the capture and enrichment of malaria-infected erythrocytes within the magnetic flux and the latter property manifests the characteristic birefringence demonstrated by polarized light.
Subject(s)
Erythrocytes/parasitology , Magnetics , Malaria/diagnosis , Plasmodium falciparum/isolation & purification , Animals , Birefringence , Equipment Design , Equipment and Supplies , Feasibility Studies , Hemeproteins/chemistry , Humans , Malaria/blood , Malaria/parasitology , Microscopy, PolarizationABSTRACT
Several antibiotics that inhibit protein synthesis on 70S ribosomes, including the macrolide erythromycin, and the azalides azithromycin (ZITHROMAX) and CP-63,956, demonstrated antimalarial activity against two strains of Plasmodium berghei. In a four-day in vivo test, the azalides were 25-fold more potent than erythromycin against the chloroquine-sensitive P. berghei N strain, and displayed additive effects with chloroquine. This effect was not observed with the erythromycin-chloroquine combination. Against the chloroquine-resistant P. berghei MSU/RC strain, the azalides were 60-fold more potent than erythromycin. Additive effects were observed with azalide-chloroquine combinations against this strain, but these results were not significantly different from the erythromycin-chloroquine combination.
Subject(s)
Erythromycin/analogs & derivatives , Erythromycin/therapeutic use , Malaria/drug therapy , Plasmodium berghei/drug effects , Animals , Antiprotozoal Agents/pharmacology , Antiprotozoal Agents/therapeutic use , Azithromycin , Chloroquine/therapeutic use , Dose-Response Relationship, Drug , Drug Interactions , Drug Therapy, Combination , Erythromycin/pharmacology , Male , Mice , Specific Pathogen-Free OrganismsABSTRACT
Several antibiotics, including the macrolide erythromycin and the azalides azithromycin (CP-62,993) and CP-63,956, that inhibit protein synthesis on 70S ribosomes demonstrated antimalarial effects in vitro against two strains of Plasmodium falciparum, one sensitive to chloroquine and the other resistant. In 48-hr incubations, erythromycin was 10-fold less potent than the azalides against the chloroquine-resistant strain. Erythromycin and the azalides were essentially equipotent against the chloroquine-sensitive strain. An additive effect occurred with the azalides in combination with chloroquine against both strains, but this was not seen with erythromycin.