CHARLESTON, S.C. — Asymptomatic trichomoniasis during pregnancy appears to elicit a maternal inflammatory response, and should not be ignored, Brenna L. Anderson, M.D., said during the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology.
In a nested case-control study of 199 serum samples from women enrolled in the Vaginal Infections and Prematurity Study between 23 and 26 weeks' gestation and followed until delivery, median concentrations of granulocyte-macrophage colony-stimulating factor (GM-CSF) were significantly higher in samples from women with asymptomatic trichomoniasis than in those without the infection, indicating a systemic inflammatory response.
Also, those with trichomoniasis were significantly more likely to have a GM-CSF concentration in the highest quartile.
The association between infection and GM-CSF concentrations persisted even after the investigators controlled for center, tobacco use, and bacterial vaginosis, said Dr. Anderson of the University of Pittsburgh.
She noted that both the case and control samples were matched for race and sexually transmitted disease coinfection.
The two groups did not differ in regard to maternal age, gestational age at delivery, and rate of chlamydia or gonorrhea, she reported.
The inflammatory response appears to be exacerbated by coinfection with other sexually transmitted infections. There was a significant test for trend in those coinfected with gonorrhea or chlamydia, compared with those infected with only trichomoniasis and those with no sexually transmitted infection, she said.
In addition to GM-CSF, Dr. Anderson compared concentrations of five other cytokines, interleukin-β (IL-β, IL-6, IL-8, macrophage inflammatory protein-1α, and regulated on activation, normal T-cell expressed and secreted, in the serum samples.
The concentrations of these cytokines were uniformly unchanged between the groups, Dr. Anderson said during the meeting.
The cytokines IL-2, IL-4, IL-10, interferon-γ, and IL-12p40 were not measured, because a pilot analysis of 40 serum samples showed they did not have reliably detectable concentrations.
The local host response to a number of sexually transmitted infections has been well studied, providing evidence of a local host inflammatory response to organisms including Trichomonas vaginalis, Neisseria gonorrhoeae, and Chlamydia trachomatis.
In addition, there is a long-established association between lower genital tract infection and preterm birth and premature rupture of membranes. Furthermore, inflammatory mediators of local host response have been found in cervicovaginal fluid.
But the current study is one of few that attempt to characterize systemic inflammatory response to such infections, Dr. Anderson said.
Although one large multicenter trial showed a link between preterm birth and treatment of trichomoniasis in pregnancy, the study had several limitations, and failed to explain the mechanism for preterm birth in treated patients. Therefore, the option of not treating patients with asymptomatic trichomoniasis remains unattractive due to medical and public health concerns, Dr. Anderson said.
“We believe that GM-CSF represents a biologically plausible link between a local infection and a systemic response,” Dr. Anderson said at the meeting, explaining that serum GM-CSF has been shown to be elevated in other systemic response syndromes, and has been shown to be an important mediator of local infection in animal models of trichomoniasis.
The cytokine may be an important growth factor in placental implantation, she added.
“We therefore conclude that trichomoniasis in pregnancy should not be regarded as a benign condition,” Dr. Anderson said.
Further study to “more fully characterize the inflammatory response” to trichomoniasis and other sexually transmitted infections in pregnancy will be planned, Dr. Anderson noted at the meeting.