Porphyromonas gingivalis has been associated with severe forms of peri
odontitis. The question can be raised about the origin of this suspect
ed periodontal pathogen. The purpose of the present investigation was
to study the possibility of transmission of P. gingivalis between spou
ses. 18 patients were selected with severe periodontitis and colonized
with P. gingivalis. 10 of their spouses appeared to be colonized with
P. gingivalis too. 8 of the patients and their spouses were investiga
ted further clinically and microbiologically. Microbiological evaluati
on revealed mostly high %s of P. gingivalis in the pockets, not only o
f the patients (5-48% of the cultivable flora), but also in 7 of the 8
spouses (0.2-61%). Furthermore, this species was isolated often from
the saliva, the tongue, the buccal mucosa and the tonsillar area from
both patients and spouses. For typing purposes, bacterial DNA was isol
ated, treated with the restriction endonucleases Bam HI or Pst I, afte
r which the DNA fragments were separated by agarose gelelectrophoresis
. With one exception, each individual was colonized with only one clon
al type of P. gingivalis. The DNA patterns of all P. gingivalis isolat
es from unrelated individuals were found to be distinct. In contrast,
in 6 of the 8 couples, the DNA patterns of isolates from husband and w
ife were indistinguishable. From these data, it can be concluded that
it is most likely, that P. gingivalis can be transmitted between spous
es. It remains to be investigated whether transmission of P. gingivali
s is a risk factor for developing periodontal destruction.