Effect of polymyxin B on gram-negative bacterial infection during pregnancy.

OBJECTIVE Polymyxin B (PB) is a naturally occurring cationic cyclic decapeptide which is highly bactericidal to Gram-negative bacteria. The objective of this study was to investigate the effect of PB on the viability of developing embryos during pregnancy and to validate its protective effect on the embryotoxic effect of Gram-negative bacterial lipopolysaccharide (LPS). MATERIAL AND METHODS Animals were injected intraperitoneally (i.p.) with PB (5-100 μg/animal), (Minimum effective dose) MD of LPS and MD of LPS+PB (5-100 μg/animal) on day 0.5 of pregnancy. The percentage of normal gestational sacs and histopathologic analysis were assessed. RESULTS PB treatment of pregnant females disturbs the pregnancy in a dose dependent manner and increases the substantial risk of congenital abnormalities in the growing fetuses of the mother. However, PB does not show any adverse effect on implantation of embryos. The embryotoxic effect of LPS can be prevented completely by 25 μg PB/animal; however other lower and higher doses of PB were not able to protect against the effect of LPS on pregnancy. CONCLUSIONS Our results demonstrate that PB has the ability to protect the LPS-induced pregnancy loss but may not be recommended as a safe drug for the treatment of a mother suffering from Gram-negative bacterial infection during pregnancy.