Relationship between mutations in dihydropteroate synthase of Pneumocystiscarinii f. sp hominis isolates in Japan and resistance to sulfonamide therapy
T. Takahashi et al., Relationship between mutations in dihydropteroate synthase of Pneumocystiscarinii f. sp hominis isolates in Japan and resistance to sulfonamide therapy, J CLIN MICR, 38(9), 2000, pp. 3161-3164
We examined mutations in the dihydropteroate synthase (DHPS) genes of Pneum
ocystis carinii f. sp. hominis (P. carinii) strains isolated from 24 patien
ts with P. carinii pneumonia (PCP) in Japan. DHPS mutations were identified
at amino acid positions 55 and/or 57 in isolates from 6 (25.0%) of 24 pati
ents. The underlying diseases for these six patients were human immunodefic
iency virus type 1 infection (n = 4) or malignant lymphoma (n = 2), This fr
equency was almost the same as those reported in Denmark and the United Sta
tes. None of the six patients whose isolates had DHPS mutations were recent
ly exposed to sulfa drugs before they developed the current episode of PCP,
suggesting that DHPS mutations not only are selected by the pressure of su
lfa agents but may be incidentally acquired. Co-trimoxazole treatment faile
d more frequently in patients whose isolates had DHPS mutations than in tho
se whose isolates had wild-type DHPS (n = 4 [100%] versus n = 2 [11.1%]; P
= 0.002). Our results thus suggest that DHPS mutations may contribute to fa
ilures of co-trimoxazole treatment for PCP.