The transmission of Pneumocystis carinii from person to person was studied
by detecting P. carinii-specific DNA in prospectively obtained noninvasive
deep-nasal-swab samples from a child with a documented P. carinii pneumonia
(PCP), his mother, two contact health care workers, and 30 hospital staff
members who did not enter the patient's room (controls). Nested-DNA amplifi
cation was done by using oligonucleotide primers designed for the gene enco
ding the mitochondrial Large subunit rRNA of rat P, carinii (P. carinii f.
sp, carinii) that amplifies all forms of P. carinii and internal primers sp
ecific for human P. carinii (f. sp, hominis). P. carinii f, sp, hominis DNA
was detected in samples from the patient and all of his contacts versus no
ne of the 30 hospital staff members, The results, as previously shown in mu
rine models of P, carinii pneumonia, document that person-to-person transmi
ssion of P. carinii is possible. This observation suggests that immunocompr
omised patients not on PCP prophylaxis should not enter the room of a patie
nt with PCP, and it also raises the question as to whether healthy contacts
can transmit the disease to immunocompromised patients at risk.