From: Maternal and early life exposures and their potential to influence development of the microbiome
Year | Endometrium or decidua | Placenta parenchyma | Chorion | Amnion | Amniotic fluid | Meconium or fetal intestine | Culture-independent detection | Culture-dependent detection a | Ref. | ||
---|---|---|---|---|---|---|---|---|---|---|---|
Method | Conclusion | Method | Conclusion | ||||||||
1958 | ✓ | n/a | n/a | Aerobic and anaerobic; Blood and Chocolate | 1/10 patients yielded positive endometrial culture, suggests endometrium is usually sterile | [251] | |||||
1962 | ✓ | n/a | n/a | Culture, unspecified | Occasional diphtheroid colonies in 2/44 abdominal punctures, suggests contamination not intrauterine infection | [252] | |||||
1966 | ✓ | n/a | n/a | Aerobic: serum broth, PPLO, cooked meat, thiol, blood. Anaerobic: chocolate, thioglycolate, Casman’s | Positive endometrial culture decreases with time following intrauterine device insertion | [253] | |||||
1967 | ✓ | n/a | n/a | Aerobic: blood, MacConkey. Anaerobic: blood, thioglycolate | Pathogens were cultured in 6% of endometrial samples, suggests uterine cavity is usually sterile | [271] | |||||
1969 | ✓ | n/a | n/a | Aerobic: blood, desoxycholate, chocolate. Anaerobic (with H2): blood H2 | 44/50 negative cultures, 2/50 grew Staphylococcus albus. 4/50 grew Mycoplasma hominis. Trauma of vaginal exams introduces microbiota to enter uterus | [254] | |||||
1970 | ✓ | Histology (Gram) | Unspecified | Aerobic and anaerobic culture in blood, MacConkey | 1/39 positive pre-labor amniotic fluid culture. 8/78 positive mid-labor amniotic fluid cultures | [255] | |||||
1971 | ✓ | Histology (Gram) | Unspecified | Aerobic and anaerobic culture | 11/140 positive mid-labor amniotic fluid cultures. No maternal or fetal morbidity supports that amniotic fluid has antibacterial activity | [256] | |||||
1976 | ✓ | n/a | n/a | Aerobic: TSA, blood. Anaerobic: PRAS chopped-meat glucose, blood | Postive amniotic culture in cases of obvious intraurterine infection. Amniotic fluid removed from the intact amniotic cavity appears to be sterile. | [257] | |||||
1984 | ✓ | ✓ | Histology (Gram) | 6/46 uncomplicated vaginal deliveries was positive for Gram-positive rods | Aerobic: blood, chocolate, MacConkey, thioglycolate. Anerobic: blood, KV | 1/46 uncomplicated vaginal deliveries was positive (Group B Strep) | [258] | ||||
1987 | ✓ | n/a | n/a | Aerobic: SP-4, 10-B, Thayer-Martin. Murine and primate tissue culture. Anaerobic: BHI | All cultures were negative for tested microbes suggesting the nonpregnant endometrium is sterile. | [259] | |||||
2015 | ✓ | PCR coupled with electrospray ionization mass spectrometry | Microbes were identified in 29/231 amniotic fluid samples without the presence of intra-amniotic inflammation | Aerobic and anaerobic culture | 5/231 positive amniotic fluid samples without intra-amniotic inflammation. 24/231 negative AF samples with intra-amniotic inflammation. | [260] | |||||
2016 | ✓ | ✓ | 16S rRNA sequencing of the V1-2 HVRs using Illumina MiSeq | Could not distinguish placental samples from contamination controls | n/a | n/a | [261] | ||||
2018 | ✓ | ✓ | 16S rRNA sequencing of the V1-2 HVRs using Illumina HiSeq | Could not detect placenta microbiome in preterm or term births. DNA detection limited to contamination with vaginal fluids or contaminants shared with negative controls | n/a | n/a | [262] | ||||
2018 | ✓ | 16S rRNA sequencing of the V5-7 HVRs using Illumina MiSeq | No evidence of reproducible preterm placental microbiome. Differences depend on placental delivery abdominally or vaginally (thus, delivery contamination) | n/a | n/a | [263] | |||||
2018 | ✓ | 16S rRNA sequencing of the V3-4 HVRs was quantified using digital droplet PCR then sequenced using Illumina MiSeq | No differences seen between membrane-intact and negative control amniotic fluids. Ruptured membranes was associated with higher bacterial DNA levels | Anaerobic and aerobic: BHI | No bacteria detected from membrane-intact or negative control amniotic fluids. Bacteria were detected in ruptured membrane samples | [264] | |||||
2018 | ✓ | 16S rRNA sequencing of the V4 HVR using Illumina MiSeq | Bacterial microbiota of amniotic fluid was indistinguishable from buffer extraction negative controls | n/a | n/a | [265] | |||||
2018 | ✓ | 18S rRNA sequencing of the V9 HVR using Illumina MiSeq | Unable to detect eukaryotic pathogens in placental biopsies from adverse pregnancy outcomes or healthy controls | n/a | n/a | [266] | |||||
2019 | ✓ | 16S rRNA sequencing of the V1-2 HVRs using Illumina HiSeq | Major source of bacterial DNA was contamination from lab reagents and equipment. Placental tissue samples become contaminated during labor and delivery. Only bacteria found before labor was S. agalactiae | n/a | n/a | [273] | |||||
2019 | ✓ | ✓ | ✓ | ✓ | 16S rRNA sequencing of the V4 HVR using nested PCR followed by Illumina MiSeq with comparative qPCR. WGS metagenomic sequencing using Illumina HiSeq | Could not detect microbes in Cesarean-delivered term placenta | Anaerobic and aerobic: TSA, chocolate, MacConkey | 28/29 placental cultures were negative. 1/29 cultures yielded aerobic Bacillus circulans, Bacillus pumilus, and Brevibacterium casei | [267] | ||
2020 | ✓ | PCR coupled with electrospray ionization mass spectrometry. Cell-free DNA sequencing by Illumina NextSeq 500 or HiSeq. Low-biomass background correction. Histology (Gram) | Reports reduced false-positive rate, suggesting the amniotic fluid is sterile in normal pregnancy | Traditional clinical culture including genital mycoplasma | 10/40 cultures were positive, all with clinical chorioamnionitis | [14] | |||||
2020 | ✓ | ✓ | ✓ | ✓ | 16S rRNA gene PCR amplification and visualization of the V2 and V4 HVRs. TaqMan qPCR of the 16S rRNA V3-5 HVRs and Erythromycin resistance methylase B gene. Histology (Gram, anti-lipoteichoic acid, anti-lipopolysaccharide). Scanning electron microscopy | No bacterial amplicons were identified (human and mouse) | TSA, chocolate, MacConkey, SDC, thioglycolate | None of the placental or environmental controls were positive for bacterial growth | [13] | ||
2020 | ✓ | ✓ | 16S rRNA sequencing of the V4 HVR by Illumina MiSeq with quantification by 16S rRNA amplification of the V1-2 HVRs by qPCR | Bacterial loads from murine placenta and fetal tissues did not exceed those of background technical controls. Samples from maternal sites did exceed controls | TSA, chocolate, MacConkey, SP4 with urea and arginine (for Mycoplasma and Ureaplasma) | 9/165 placental cultures were positive (5/9 from single mouse). 1/165 fetal intestine cultures grew Staphylococcus hominis | [12] | ||||
2021 | ✓ | ✓ | 16S rRNA sequencing of the V6-8 HVRs by Illumina MiSeq with comparative qPCR | Amniotic fluid and placenta have indistinguishable bacterial DNA from negative controls. No differences between elective Cesarean delivery and vaginal birth. Placenta has anti-microbial activity | Aerobic: LB. Anaerobic: Neisseria gonorrhoeae targeted culture | Cesarean delivery: 87/152 negative placental cultures, freq. human skin-associated genera. Vaginal delivery: 21/78 negative placental cultures, freq. human vaginal-associated genera | [15] | ||||
2021 | ✓ | 16S rRNA sequencing of the V3-4 HVRs by Illumina MiSeq | Neonatal rectal swabs could not be distinguished from negative controls | Anaerobic and Aerobic: Columbia, Chocolate, Schaedler, MacConkey, Sabouraud | 3/20 meconium samples were positive for anaerobic and aerobic culture. 5/20 samples were positive for only one condition | [272] |