The association between Actinomyces and the use of intrauterine devices (IUDs) is well known, judged by the number of publications on this topic. However, there is no direct evidence that colonization by Actinomyces is followed by invasive actinomycosis. The association between Actinomyces and IUDs is based on 2 types of observations: First, Actinomyces species can often be found in the cervical smears of generally asymptomatic women with IUDs.1,2 The occurrence of colonization increases exponentially with the time that the IUD is in situ, especially after 4 years.1,2 Second, according to some studies,2,3 invasive pelvic actinomycosis occurs almost exclusively in women with an IUD. Earlier Papanicolaou-stained cervical smears were not available or even mentioned in any of these studies. In theory, it is possible that colonization by Actinomyces is never followed by invasive infection, whereas invasive infection occurs from the outset in a susceptible subgroup of patients. However, the following observation refutes the latter hypothesis.
Arend SM, Oosterhof H, van Dissel JT. Actinomyces and the Intrauterine Device. Arch Intern Med. 1998;158(11):1270. doi: