Abstract: The frequency of critical
PI resistance substitutions (amino acid changes
D30N,
V82A/F/T,
I84V,
N88D, and
L90M) among Brazilian isolates is very low (mean, 2.5%), and the associated secondary substitutions (amino acid positions 10L, 20K, 36M, 46M, 48G, 54I, 63P, 71A, and 77A) are infrequent.