No significant increase in chromosome aberrations and sister chromatid exchanges in cultured human lymphocytes treated with spiramycin

Evaluation of Possible Genotoxic Activity of Dirithromycin in Cultured Human Lymphocytes

Dirithromycin antibiotic is a 14-membered lactone ring macrolide and is widely used in medicine to treat many different types of bacterial infections. In the present study, the possible genotoxicity of dirithromycin was evaluated in cultured human lymphocytes by using sister chromatid exchanges (SCEs), chromosome aberration (CA), and micronucleus (MN) tests and also cell proliferation kinetics such as mitotic index (MI), replication index (RI), and nuclear division index (NDI) were analyzed for cytotoxicity. Cell cultures were treated with four different concentrations of dirithromycin (37.75, 67.50, 125, and 250 µg/mL) for 24 and 48 h periods. Dirithromycin significantly induced SCE and MN frequency at all concentrations in both 24 and 48 h treated cells. In addition, CA level has been markedly increased in the cells treated with almost all concentrations of dirithromycin for 24 (except 37.75 µg/mL) and 48 h treatment periods as compared to control. However, MI, RI, and NDI values were not affected by the dirithromycin treatment (p > 0.05). The results of this study indicated that dirithromycin treatment caused genetic damage by increasing the level of cytogenetic endpoints, suggesting its genotoxic and mutagenic action on human lymphocytes in vitro.

Impact of spiramycin treatment and gestational age on maturation of Toxoplasma gondii immunoglobulin G avidity in pregnant women

The objective of the present study was to investigate the maturation of immunoglobulin G (IgG) avidity after Toxoplasma gondii seroconversion during pregnancy and the factors that affect IgG avidity over time. The study used 309 serum samples from 117 women and a multiple linear mixed regression analysis to show the patterns of variation of IgG avidity throughout gestation. The IgG avidity ratios and the patterns of their evolution with time were quite diverse among the women and were statistically heterogeneous (P = 0.011); however, the trend was toward a statistically significant increase (P < 0.0001). On average, a 1.0167-fold increase was observed for each additional gestational week after the putative date of infection. At 12 weeks after putative infection (the expected IgG avidity maturation time), the mean avidity ratio was 16.6% (95% confidence interval, 15.4 to 17.9%). At all times, the avidity ratio remained significantly heterogeneous among the women (P < 0.05); for 95% of them, that ratio ranged from 7.8 to 35.3% at 12 weeks after putative infection. Maternal age at the putative time of infection did not influence the maturation of IgG avidity. However, on average, a 1.009-fold decrease (P = 0.03) in that avidity was observed for each additional week of gestational age before infection and a 1.03-fold increase (P = 0.0003) was observed for each additional week of delay to the onset of spiramycin treatment. The rate of increase in the avidity ratio was lower if infection occurred late in pregnancy and higher if the delay to treatment was long. This information cannot allow accurate determination of the delay since the time of infection. The present results provide support for interpretation of the assay and caution against overinterpretation.