Sterile and microbial-associated intra-amniotic inflammation in preterm prelabor rupture of membranes

Figures & data

Table 1. Maternal characteristics and demographic data of the study population.

	Median (IQR) or % n
Maternal age (years)	27 (22–32)
Body mass index (kg/m^2)	25.1 (21–28)
Nulliparity	29 (17/59)
Tobacco use during pregnancy	34 (20/59)
Illicit drug use	27 (16/59)
Cervical dilatation at admission (cm)	1 (0–1.5)
GA at amniocentesis (weeks)	28 (25–31)
Route of delivery
Vaginal	56 (33)
Cesarean	44 (26)
Clinical signs of chorioamnionitis	7 (4/59)

IQR: interquartile range; AF: amniotic fluid; GA: gestational age; PCR: polymerase chain reaction; ESI-MS: electrospray ionization mass spectrometry.

Figure 1. Bacteria and viruses detected in amniotic fluid of patients with preterm PROM standard cultivation techniques versus PCR/ESI-MS. Amniotic fluid culture includes routine cultivation techniques for bacteria (aerobes, anaerobes and genital mycoplasmas). PCR/ESI-MS refers to broad range PCR and ESI-MS.

Table 2. Amniotic fluid IL-6 concentrations, white blood cell count, placenta pathology results, pregnancy outcome, microorganisms and microbial burden detected in the amniotic fluid of patients with PPROM using cultivation techniques versus PCR/ESI-MS.

Group	Amniotic Fluid Culture	PCR/ESI-MS		(GE/well)	AF IL-6 (ng/mL)	(Cell/mm^3) AF WBC	GA at delivery	Acute placental inflammation
Microbial-associated  intra-amniotic  inflammation  (n = 17)	Bacteroides ureolyticus	Sneathia species		554	5.4	10	29.7	Yes
	Negative	Sneathia species		311	284.9	660	27.6	Yes
	Negative	Sneathia species		156	24.6	58	22.6	Yes
	Ureaplasma spp.	Ureaplasma parvum		664	23.9	159	33.1	Yes
	Negative	Ureaplasma parvum	Streptococcus Mitis	651/194	144	210	23.6	No information
	Negative	Ureaplasma parvum		2470	74.1	28	23.1	Yes
	Ureaplasma spp.	Ureaplasma urealyticum		59	7.9	2	27.0	Yes
	Negative	Mycoplasma hominis	Human enterovirus	373/>1000	22.7	158	30.3	Yes
	Prevotella bivia	Prevotella bivia	Mycoplasma hominis	32/83	145.6	765	27.6	Yes
	Streptococcus pneumoniae	Streptococcus mitis	Streptococcus pneumoniae	217	120.4	723	22.9	Yes
	Candida albicans	Candida albicans		9	337.5	225	22.3	Yes
		Candida albicans	Gardnerella vaginalis	Candida albicans	52/62	18.5	43	25.1	Yes
Negative		Bacteroides fragilis		207	40.4	15	33.0	Yes
Negative		Rothia mucilaginosa		15	4.80	1	22.3	No information
Bacteroides Ureolyticus		Negative		N/A	326.2	19	20.1	Yes
Streptococcus spp.		Negative		N/A	157.5	760	24.3	Yes
Candida albicans		Negative		N/A	5.1	4	26.7	No
Microbial invasion  of the amniotic cavity  (No inflammation)  (n = 7)		Negative	Sneathia species	Mycoplasma hominis	38/29	0.1	10	28.4	No
	Negative	Sneathia species		12	0.9	68	32.1	Yes
	Negative	Sneathia species		87	0.1	70	30.6	Yes
	Lactobacillus	Ureaplasma urealyticum		12	2.2	0	31.6	No
	Ureaplasma spp.	Ureaplasma urealyticum		522	0.9	20	29.6	No
	Saccharomyces cerevisiae	Neisseria gonorrhoeae		5	0.2	0	34.1	No
	Haemophilus influenzae	Haemophilus influenzae		173	1.8	0	32.1	Yes

AF: amniotic fluid; GA: gestational age; PCR: polymerase chain reaction; ESI-MS: electrospray ionization mass spectrometry; GE: Genome copies per PCR well reaction; WBC: white blood cell count.

Figure 2. Prevalence of microbial – associated and sterile intra-amniotic inflammation in patients with preterm PROM according to the gestational age at diagnosis. The earlier the gestational age at which rupture of the membranes occurs, the higher the frequency of both microbial-associated and sterile intra-amniotic inflammation.

Figure 3. Amniotic fluid concentrations of interleukin 6 in patients with a positive AF culture or PCR/ESI-MS according to the gestational age at which the rupture of the membranes occurred. Patients who presented with preterm PROM <25 weeks of gestation with a positive AF culture or PCR/ESI-MS had a significantly higher AF IL-6 concentrations than those who presented with a positive AF culture or PCR/ESI-MS between 25 and <33 weeks of gestation.

Table 3. Inflammatory markers in amniotic fluid, pregnancy outcome and placental pathology results in patients with preterm PROM according to the results of amniotic fluid culture and PCR/ESI-MS.

	No inflammation/ infection (n = 18)	p* value	Sterile intra-amniotic inflammation (n = 17)	p† value	Microbial associated intra-amniotic inflammation (n = 17)	p‡ value
GA at amniocentesis	31.5 (29.4–32.8)	0.02	28.5 (25.1–31.7)	0.04	24.8 (22.4–27.9)	<0.001
GA at delivery	33.7 (32.5–34.1)	0.006	31.8 (28–33)	0.003	25.1 (22.7–28.6)	<0.001
AF white blood cell count (cells/mm^3)	1 (0–4)	<0.001	175 (21–395)	0.4	58 (12.5–442)	<0.001
AF glucose (mg/dL)	25 (13.5–31.7)	0.005	10 (10–16)	0.4	13 (10–22)	0.02
AF IL-6 (ng/mL)	0.7 (0.5–1.1)	<0.001	12 (4.7–137)	0.1	40.4 (13.2–151.5)	<0.001
Interval amniocentesis to delivery	12 (1–22)	0.6	9 (1–22)	0.06	3 (1–4)	0.02
Composite neonatal morbidity	43.8 (7/16)	0.2	64.7 (11/17)	0.2	82.4 (14/17)	0.02
Acute placental inflammation	37.5 (6/16)	0.5	50 (8/16)	0.01	93.3 (14/15)	0.001
Acute histologic chorioamnionitis	37.5 (6/16)	0.5	50 (8/16)	0.01	93.3 (14/15)	0.001
Funisitis	25 (4/16)	0.4	37.5 (6/16)	0.1	66.7 (10/15)	0.02

IQR: interquartile range; AF: amniotic fluid; GA: gestational age; PCR: polymerase chain reaction; ESI-MS: electrospray ionization mass spectrometry.

Data presented as median (interquartile) and percentage and (n); AF: amniotic fluid; IL: interleukin.

*Comparison between no inflammation and sterile intra-amniotic inflammation.

†Comparison between patients with sterile intra-amniotic inflammation and microbial-associated intra-amniotic inflammation.

‡Comparison between patients with no inflammation/infection and microbial-associated intra-amniotic inflammation.