Antepartum Antibiotic Therapy under 34 Weeks of Gestation and Its Impact on Early-Onset Neonatal Infection and Maternal Vaginal Microbiota

Round 1

Reviewer 1 Report

the topic is extremely interesting and is conducted with scientific methodology and accuracy.

However, we think it is appropriate to include some clinical characteristics of newborns (e.g., whether they have central catheterization or mechanical ventilation) as risk factors for neonatal infections, as widely demonstrated in the literature. 

Also interesting is the non-significance found in relation to infections with low birth weight, in disagreement with most of the scientific literature on neonatal infections, so it would be interesting, in our opinion, to include a few lines on this finding in the discussion.

 For the reasons listed above, we recommend reading this article, "Predictive Analysis of Healthcare-Associated Blood Stream Infections in the Neonatal Intensive Care Unit Using Artificial Intelligence: A Single-Center Study," to discuss more broadly and critically your findings.

Author Response

Please see the attachment

Dear Dr

Your suggestions have been very helpful in improving the manuscript. We also thank you for your careful reading of our text.

All the comments we received on this study have been taken into account in improving the quality of the article, and we present our reply to your comments separately.

Comment 1. We think it is appropriate to include some clinical characteristics of newborns (e.g., whether they have central catheterization or mechanical ventilation) as risk factors for neonatal infections, as widely demonstrated in the literature. 

Thank you for your valuable comments. We compared the number of central catheterization and mechanical ventilation between infection group and non-infection group. As a result, there were no difference the number of them between two groups. We added these findings in Table 2.  

Comment 2. Also interesting is the non-significance found in relation to infections with low birth weight, in disagreement with most of the scientific literature on neonatal infections, so it would be interesting, in our opinion, to include a few lines on this finding in the discussion.

Thank you for your valuable suggestions. We added the following sentence in Discussion.

Birthweight was not independent predictive factor of EoNI in this study. This result was not consistent with that by Montella et al. We speculated this was due to be excluded FGR in our study. If fetal growth severely affected, infants could be born small for gestational age (SGA). It was reported that the infants born SGA showed lower blood neutrophil counts at birth and immune response. It is difficult to separate the effect of prematurity and SGA on life threatening infections in the neonates, because both overlapping and independent factors (e.g., maternal infection/inflammation, poor placental function, reduced blood supply/oxygenation, or genetic factors) may predispose to preterm delivery and growth restriction at birth. We thought it was required to simplify the study population to observe the effect of antibiotics on early onset infection. Thus, we excluded the patients with obstetrical complications in this study.

Comment 3. For the reasons listed above, we recommend reading this article, "Predictive Analysis of Healthcare-Associated Blood Stream Infections in the Neonatal Intensive Care Unit Using Artificial Intelligence: A Single-Center Study," to discuss more broadly and critically your findings.

Thank you for introducing the literature. We read with great interest the paper by Montella. They found the neonate affected by HABSI had a shorter gestational age and lower birthweight than non-HABSI neonates. However, the significant predictors of suffering from HABSI were only birthweight and central line catheterization days in the multivariate analysis. Their result was something different with our study. We speculated the reason of this difference as below; we excluded the neonates born small for gestational age (fetal growth restriction). Infants born SGA, whether preterm or not, show a higher postnatal mortality than infants of adequate birth weight. Infants born SGA also show lower blood neutrophil counts at birth and less responsive leucocytes to ex vivo infectious challenges (Watts et al. Semin Neonatal, 1999, 4: 41-54. Li, et al. Cell Mol Immunol, 2013, 10: 437-43.) Some observational studies indicate an association between SGA and increase mortality and sepsis in preterm infants (Tröger, et al. Pediatr Infect Dis J, 2014, 33: 238-43. Zeitlin et al. J Pediatr, 2010, 157: 733-9. Bernstein et al. Am J Obstet Gynecol, 2000, 182: 198-206). It may be difficult to separate the effect of prematurity and SGA on life threatening infections in the clinical field, because both overlapping and independent factors (e.g., maternal infection/inflammation, poor placental function, reduced blood supply/oxygenation, or genetic factors) may predispose to preterm delivery and growth restriction at birth. We thought it was required to simplify the study population to observe the effect of antibiotics on early onset infection. Thus, we excluded the patients with obstetrical complications including FGR, Hypertensive disorder of pregnancy in this study. Regarding central line catheterization, there was no difference in the number of central line catheterization between two groups in our study. This was not consistent with the result by Montella et al.. I guess their study included the infants with the late onset sepsis. On the other hand, we targeted only infants revealed septic sign within 72 hours. 

We referred to the report by Montella et al in this manuscript. 

Reviewer 2 Report

The manuscript presented for evaluation describes a study that is very interesting for the clinician. The topic discussed by the authors is in line with the global tendencies to verify the indications for the use of antibiotics. The aim is to limit their use. We all experience the effects of excessive use of antibiotics: microbiota disorders, selection of multiresistant bacterial strains and others.

The authors of the study showed that the use of prenatal antibiotics in women who gave birth before 34 weeks of gestation did not affect the incidence of congenital infection in their newborns, but caused adverse changes in the vaginal microbiota and the emergence of resistant bacterial strains.

Prenatal antibiotic therapy turned out to be the factor most strongly associated with early-onset infection in neonates. However, it would be difficult to assume a cause-and-effect relationship in this case.

Antibiotics were used in pregnant women at risk of preterm labor due to urinary tract infection and prolonged leakage of amniotic fluid, or both. In 2 cases, due to unknown GBS status. According to recommendations.

It is noted that more than half of the newborns (55%) born to mothers who underwent amniocentesis on admission (n = 39) developed EoNI. You may possibly wonder if this invasive procedure was necessary.

1. It would be interesting for a neonatologist to learn about the results of microbiological tests obtained from newborns. To what extent did they overlap with the mother's flora? Antibiotic given at antenatal time reduces the chance of obtaining an additional blood culture from the newborn. How was this study group? Has it been confirmed?

2. I propose to improve the introduction, which in its present form largely resembles the discussion. I believe that it can be shortened and only present the current state of knowledge about the study.

The imperfection of this study is the small size of the sample, which does not allow us to draw more general conclusions. The difficulty in selecting homogeneous, comparable groups of patients is a weakness in all research in the field of neonatology.

The article is suitable for publication after minor additions.

Author Response

Please se the attachment.

Dear Dr

 Your suggestions have been very helpful in improving the manuscript. We also thank you for your careful reading of our text. As you pointed out, we wanted to discuss about the global tendencies to verify the indications for the use of antibiotics, especially in obstetrical field.

All the comments we received on this study have been taken into account in improving the quality of the article, and we present our reply to your numbering comments separately.

It is noted that more than half of the newborns (55%) born to mothers who underwent amniocentesis on admission (n = 39) developed EoNI. You may possibly wonder if this invasive procedure was necessary.

Amniocentesis is the only method used to identify intra-amniotic inflammation in clinical practice. However, as it is an invasive procedure, many women and physicians are hesitant about amniocentesis on this indication. Our colleague reported the usefulness of amniocentesis for threatened preterm labor with intact membranes during 22 to 28 weeks of gestation (Maki et al. Early Human Development, 2015, 91: 333-337). Thus, we believe that amniocentesis should be performed when indicated. 

1. It would be interesting for a neonatologist to learn about the results of microbiological tests obtained from newborns.

1-1. To what extent did they overlap with the mother's flora?

Reply: We added the following sentence in Result.

In EoNI group, 25 neonates had positive culture results from several sites, i.e. blood cultures (n=12; 9 exposed and 3 not exposed to antepartum antibiotics), oral cavities or skin surfaces only (n=10; 7 exposed and 3 not exposed to antepartum antibiotics), amniotic fluids (n=3; 2 exposed and 1 not exposed to antepartum antibiotics). Among them, microorganisms of 12 neonates isolated from 7 blood culture (5 exposed and 2 not exposed to antepartum antibiotics) and 5 oral cavities or skin surfaces only (3 exposed and 2 not exposed to antepartum antibiotics) were consisted with them in maternal vaginal specimens on admission.

1-2. Antibiotic given at antenatal time reduces the chance of obtaining an additional blood culture from the newborn. How was this study group? Has it been confirmed?

Reply

Among 29 neonates developed EoNI, 21 their mothers received antepartum antibiotics. Among them, 9 neonates (43%) showed the positive blood culture. On the other hand, among the remaining 8 neonates, whose mothers did not receive antepartum antibiotics, 3 neonates (38%) showed the positive blood culture. There was no statistical difference in the frequency of positive blood culture between use of antepartum antibiotics and not use of antepartum antibiotics group (p=0.66). The positive rates of blood culture in both group were not so high. This may be due to the low sensitivity of this method for diagnosis of sepsis. In addition, we think that the blood culture for low birth weight infants has the limitation. Ideally, a minimum of 0.5-1 mL of blood should be obtained, preferably from two different venipunctures from two separate sites. This procedure is not easy in low birth weight infant. Thus, we did not conclude if use of antepartum antibiotics effect on the neonatal blood culture. However, we should describe the result of blood culture according to use of antepartum antibiotics or not. Accordingly, we added the following sentence in Result.

Among the infants of the 40 women exposed to antepartum antibiotics, 21 developed EoNI. Twelve neonates in EoNI group showed positive blood culture on admission. Among them, 9 mothers received antepartum antibiotics. The proportion of neontates with positive blood culture in mother used and mother not used antepartum antibiotics were 43% (9/21) and 38% (3/8), respectively. No statistical difference observed in the frequency of positive blood culture between two groups (p=0.66).

2. I propose to improve the introduction, which in its present form largely resembles the discussion. I believe that it can be shortened and only present the current state of knowledge about the study.

Reply: We have been shortened the introduction according to your suggestion.

The imperfection of this study is the small size of the sample, which does not allow us to draw more general conclusions. The difficulty in selecting homogeneous, comparable groups of patients is a weakness in all research in the field of neonatology.

Thank you for your valuable comments. We agree with you. Accordingly, we described it in Discussion of original version.