Volume 11, Number 2—February 2005
Dispatch
Malaria Epidemic and Drug Resistance, Djibouti
Table 3
In vitro drug sensitivity of 27 Plasmodium falciparum isolates collected in Djibouti, 1999
Drugs | Isolates studied (n) | Mean IC50* | 95% confidence interval | Cut-off value | % resistant isolates |
---|---|---|---|---|---|
Chloroquine | 27 | 326 nmol/L | 224–474 nmol/L | >100 nmol/L | 93 |
Amodiaquine | 27 | 10.0 nmol/L | 8.0–12.6 nmol/L | >80 nmol/L | 0 |
Cycloguanil | 24 | 13 nmol/L | 8–21 nmol/L | >500 nmol/L | 4 |
Pyrimethamine | 25 | 69 nmol/L | 41–117 nmol/L | >2,000 nmol/L | 4 |
*The 50% inhibitory concentration (IC50) of chloroquine diphosphate, amodiaquine, pyrimethamine dihydrochloride, and cycloguanil, i.e., the drug concentration corresponding to 50% of the uptake of 3H-hypoxanthine by the parasites in drug-free control wells, was determined by nonlinear regression analysis of log-dose/response curves. Mean IC50 and proportion of resistant isolates according to cut-off values are indicated. Data were expressed as the geometric mean IC50 and 95% confidence intervals were calculated.