Ain R, Rao J, Peter A T, Vijaykumar B R, Sridhar H, Satish K S, Seshagiri P B
Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
Indian J Exp Biol. 1998 Sep;36(9):867-74.
During mammalian preimplantation development, a substantial numbers of embryos are believed to be lost for reasons that are unclear. Using female rats, we investigated whether the developmental status of embryos is influenced by bacterial infection and endotoxin in the reproductive tract. From the vagina of cycling rats (n = 11), 21 bacterial isolates were identified; they were Streptococcus faecalis (S. faecalis; 38%), Escherichia coli (E. coli; 19%), Acinetobactor calcoaceticus (A. calcoaceticus; 14%), and coagulase negative staphylococcus (14%), Micrococcus sp. (5%), Bacillus subtilis (B. subtilis; 5%) and Proteus vulgaris (P. vulgaris; 5%). From the vagina of day 4 pregnant rats (n = 12), 26 isolates were identified; they were S. faecalis (23%), A. calcoaceticus (23%), E. coli (15%), Micrococcus sp. (15%), B. subtilis (8%), P. vulgaris (4%), Staphylococcus aureus (4%), beta-hemolytic streptococcus (4%) and Pseudomonas aeruginosa (4%). Gram negative bacteria found in the vagina of cycling and day 4 pregnant rats were 38% and 46%, respectively. In both, bacterial load was 10(3)-10(5) colony forming units and there was no association with the abnormality of the recovered embryos. However, in two day 4 pregnant animals, pathogenic bacteria (Staphylococcus aureus and beta-hemolytic streptococcus) were isolated and embryos recovered from them were degenerated and deformed. The vagina of day 9 pregnant animals (n = 7) were, however, sterile. Consistently, in all animals, the upper reproductive tract (uterus and oviduct) was devoid of any bacteria and no anaerobic bacteria were isolated from any part of the tract. The levels of endotoxin in the vagina of cycling and day 4 pregnant rats were 1.35 +/- 0.1 and 1.17 +/- 0.1 endotoxin units (EU), respectively. It was undetectable in the oviduct and uterus of all animals (n = 5) except one which showed high levels of endotoxin in uterus (4.5 EU) and oviduct (2.2 EU) and the animal also produced degenerated and deformed embryos. These results indicate that common bacterial flora of vagina may not affect embryo development and the presence of pathogenic bacteria in the vagina and/or endotoxin in reproductive tract could be detrimental to viability of gametes and preimplantation embryos in rats.
在哺乳动物着床前发育过程中，大量胚胎据信因不明原因而丢失。我们以雌性大鼠为实验对象，研究了生殖道中的细菌感染和内毒素是否会影响胚胎的发育状态。从处于发情周期的大鼠（n = 11）阴道中，鉴定出21种细菌分离株；它们分别是粪肠球菌（粪肠球菌；38%）、大肠杆菌（大肠杆菌；19%）、醋酸钙不动杆菌（醋酸钙不动杆菌；14%）、凝固酶阴性葡萄球菌（14%）、微球菌属（5%）、枯草芽孢杆菌（枯草芽孢杆菌；5%）和普通变形杆菌（普通变形杆菌；5%）。从妊娠第4天的大鼠（n = 12）阴道中，鉴定出26种分离株；它们分别是粪肠球菌（23%）、醋酸钙不动杆菌（23%）、大肠杆菌（15%）、微球菌属（15%）、枯草芽孢杆菌（8%）、普通变形杆菌（4%）、金黄色葡萄球菌（4%）、β-溶血性链球菌（4%）和铜绿假单胞菌（4%）。在处于发情周期和妊娠第4天的大鼠阴道中发现的革兰氏阴性菌分别为38%和46%。在这两种情况下，细菌载量均为10³ - 10⁵ 菌落形成单位，且与回收胚胎的异常情况无关。然而，在两只妊娠第4天的动物中，分离出了病原菌（金黄色葡萄球菌和β-溶血性链球菌），从它们体内回收的胚胎出现了退化和变形。然而，妊娠第9天的动物（n = 7）阴道是无菌的。一直以来，在所有动物中，上生殖道（子宫和输卵管）均未检测到任何细菌，且在生殖道的任何部位均未分离出厌氧菌。处于发情周期和妊娠第4天的大鼠阴道中的内毒素水平分别为1.35 ± 0.1和1.17 ± 0.1内毒素单位（EU）。在所有动物（n = 5）的输卵管和子宫中均未检测到内毒素，但有一只动物子宫内（4.5 EU）和输卵管内（2.2 EU）内毒素水平较高，该动物产出的胚胎也出现了退化和变形。这些结果表明，阴道中的常见菌群可能不会影响胚胎发育，而阴道中病原菌的存在和/或生殖道中的内毒素可能对大鼠配子和着床前胚胎的活力有害。
