Increased prevalence of the pfdhfr/phdhps quintuple mutant and rapid emergence of pfdhps resistance mutations at codons 581 and 613 in Kisumu, Kenya

Table 1 In vitro geometric mean IC₅₀ data for antifolates in the follow-up study

Drug	N	Mean IC₅₀ (ng/ml)	Range (ng/ml)	Percent resistant
pyrimethamine	43	171	21-2028	16.3 (53.5)^a
chlorcycloguanil	41	2	0.5-11
proguanil	41	929	129-3376
sulphadoxine	41	9310	890-48,153	51.2
dapsone	27	648	16-129	14.8

^a percent resistant using the intermediate level of susceptibility of 500 nM (124.5 ng/ml) as the cutoff

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