Amniotic fluid – the fluid present in the surroundings of the unborn baby – may contain a number of micro-organisms including bacteria. In 1995, researchers found Fusobacterium nucleatum, Bacteroides ureolyticus and Gardnerella vaginalis in the amniotic fluid. The amniotic fluid has more chances of bacteria in women with bacterial vagibnosis as compared to women without bacterial vaginosis. (Sharon L. Hillier et al.; 1995)
Using polymerase chain reaction (PCR) analysis technique, researchers found a number of bacteria in the PCR-positive specimens of amniotic fluids. Among those bacteria were B streptococci, Enterococcus species, E. coli, Klebsiella pneumoniae, Mycoplasma hominis, Gardnerella vaginalis, Fusobacterium nucleatum, Bacteroides ureolyticus, Prevotella oulora, Clostridium species, and Peptostreptococcus asaccharolyticus. (Jane Hitti et al.; 1997)
Researchers found that the amniotic fluid may not be sterile in the midtrimester of pregnancy. They found bacterial RNA in 18% of 78 amniotic fluid samples. Researchers did not find mycoplasma – a group of bacteria with no cell wall – in the samples. (Markenson GR et al.; 2003) However, genital mycoplasma was found in another study. (Sharon L. Hillier et al.; 1995)
In 2009, scientists found a number of bacterial species in the amniotic fluid of women, who experience preterm births. They attributed this finding to the cause of inflammations in the inner womb of some of the pregnant women without any signs of infection and who give spontaneous births to preterm babies at less than 32 weeks of pregnancy. (Scientists published their finding in the Journal of Clinical Microbiology) However, researchers are also of the opinion that the presence of bacteria is not necessarily the cause of inflammatory responses around the time of birth. (Markenson GR et al.; 2003)
Recently researchers have found that Staphylococcus lugdunensis, a virulent coagulase-negative staphylococcus (bacteria), in the amniotic fluid at Cesarean section. They proposed to work on this bacterium as it may be the cause of infection in both the mother and the new born baby after birth. This bacterium has been found to be involved in a number of infections including cardiovascular infections, urinary tract infection and bone and joint infection. (Zbigniew Marchocki et al.; 2013).
This article does not contain the complete list of bacteria found in the amniotic fluid but it can give you some of the information.
Jane Hitti, Donald E. Riley, Marijane A. Krohn, Sharon L. Hillier, Kathy J. Agnew, John N. Krieger, David A. Eschenbach, (1997). Broad-Spectrum Bacterial rDNA Polymerase Chain Reaction Assay for Detecting Amniotic Fluid Infection Among Women in Premature Labor. Clinical Infectious diseases.
Marchocki, Z., Collins, K., Lehane, E., Reilly, P., & O’Donoghue, K. (2013). Staphylococcus lugdunensis Cultured from the Amniotic Fluid at Caesarean Section PLoS ONE, 8 (2) DOI: 10.1371/journal.pone.0056373
Markenson GR, Adams LA, Hoffman DE, Reece MT, (2003). Prevalence of Mycoplasma bacteria in amniotic fluid at the time of genetic amniocentesis using the polymerase chain reaction. J Reprod Med., 48(10):775-9.
Sharon L. Hillier, Marijane A. Krohn, Ellen Cassen, Thomas R. Easterling, Lorna K. Rabe and David A. Eschenbach, (1995). The Role of Bacterial Vaginosis and Vaginal Bacteria in Amniotic Fluid Infection in Women in Preterm Labor with Intact Fetal Membranes. Clinical Infectious Diseases, S276-S278