Typing of Pneumocystis carinii f. sp. hominis by PCR-SSCP to indicate a high frequency of co-infections.
Broncho-alveolar lavage specimens from patients with Pneumocystis carinii pneumonia were investigated by PCR-single strand conformation polymorphism (SSCP) analysis of four genomic regions for P. carinii f. sp. hominis. In all, 32% of specimens produced two bands (one allele) for each of the four genomic regions, suggesting an infection with a single P.c. hominis type. The other specimens displayed more than two bands for at least one of the four genomic regions, suggesting several theoretical possibilities: co-infections, heterozygosity of diploid or polyploid organisms, or multicopy genes. Quantification of the different alleles and analysis of mixtures of specimens showed that different alleles of a genomic region were most often present in different proportions in a given specimen. In contrast, experiments with plasmid insertion of two alleles resulted in the detection of identical proportions of the two alleles. This suggests that neither heterozygosity of diploid organisms nor multicopy genes are responsible for the presence of two alleles. Unequal proportions are most likely explained by the occurrence of co-infections. The putative co-infecting types could be identified in the majority of specimens.
Nahimana
Aimable
A
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Blanc
Dominique S
DS
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Francioli
Patrick
P
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Bille
Jacques
J
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Hauser
Philippe M
PM
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
D000483:Alleles; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D004271:DNA, Fungal / Q000032:analysis; D006801:Humans; D011010:Pneumocystis / Q000145:classification* / Q000235:genetics; D011020:Pneumonia, Pneumocystis / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational
D004271:DNA, Fungal