We live in a world at the moment where the public has become increasingly aware of the dangers of antibiotic overuse.  Parents are more than ever requesting no erythromycin for the eyes after birth, and even on occasion questioning the need for antibiotics after delivery for the infant with risk factors for sepsis.  The media has latched on to the debate as well by publishing the sensational articles about superbugs and medicine running out of the last lines of defence such as this article from the CBC.

As teams caring for newborns both preterm and term we are also increasingly aware of the dangers of altering the microbiome of these vulnerable infants with antibiotic overuse. Some babies robbed of the vaginal microbiome when delivery occurs by C-section, have their parents swabbing their newborn with vaginal secretions to populate their child with the “good bacteria” that come through a “natural” delivery although recent commentary questions the safety of such practice.

Infants born through meconium stained amniotic fluid can certainly become sick after delivery.  Inhalation of meconium in the sickest infants often occurs during gasping episodes in utero after hypoxic stress causes evacuation of the rectal contents.  The fetuses who inhale this material may go on to develop, inflammatory changes, areas of atelectasis and hyperinflation and pulmonary hypertension; the so called meconium aspiration syndrome.  These infants of course may be extremely sick and need high frequency ventilation to manage their CO2 retention and in some cases may go on to ECMO although with inhaled nitric oxide this has become less common.  As another consideration, could infection such as chorioamnionitis be the inciting event to cause passage of meconium in utero?

The health care team though for as long as I have been in practice would add to the treatment plan a course of antibiotics.  In fact I would guess that many Neonatologists the world over have uttered the phrase “They are REALLY sick, please start antibiotics”.  The real question though is whether the baby is in fact infected.  Meconium is certainly a good growth medium for bacteria but with the short time from passage to delivery in most cases I doubt there is much time for significant growth.  Moreover, I have found myself saying many times that such infants have a chemical pneumonitis and have often questioned whether antibiotics are really needed.  Nonetheless it would take nerves of steel in some cases to not use antibiotics in these patients.

Then along came this study

Role of prophylactic antibiotics in neonates born through meconium-stained amniotic fluid (MSAF)a randomized controlled trial by Goel A et al.  This study was done prospectively by randomizing newborns born through meconium stained amniotic fluid to either antibiotics (N=121) for three days or no antibiotics (N=129) after diagnosis.  In each case blood and CRP were drawn and if the infant was symptomatic (presence of respiratory distress, lethargy, abdominal distension, temperature or hemodynamic instability, hypoglycemia, apnea, or any other systemic abnormalities) a lumbar puncture and chest x-ray were added.  The primary outcome variable was defined as ” the incidence of early (within first 72 h of birth) or late onset (after 72 h of birth) suspect sepsis (clinical symptoms or positive sepsis screen defined as 2 positive parameters) and confirmed sepsis (positive blood culture).”


outcomes MAS

Clinicians in the study were allowed to continue antibiotics past the 72 hours or start antibiotics in the no antibiotic group if they considered an infant to have suspected sepsis or in fact were found to be proven.  The outcomes for those possibilities are shown below.

why abx

Taking it all together whether you started antibiotics or not the primary outcomes were no different.  Furthermore there is no apparent harm based on outcomes that matter including the most important; death (3 in each group) that it does give one reason to pause when considering whether to treat prophylactically with antibiotics for babies born through meconium stained fluid.

What About The Sickest of The Sick

When attempting to answer this question the authors noted the following.

“On doing a subgroup analysis on incidence of sepsis in symptomatic babies (presenting with respiratory distress), both groups were found to have comparable incidence of suspect sepsis (p=0.084). The incidence of confirmed sepsis was more in symptomatic babies, although the total numbers was very few (p=0.01)”

Herein lies the challenge in declaring once and for all that we don’t need antibiotics at all in MAS.  While the study was powered to adequately answer the primary outcome, the subgroups are so small that declaring with any confidence that one can stand by and watch infants with severe MAS without starting antibiotics is a tough conclusion to come to.  The child though who is born through MSAF and has mild tachypnea as the only symptom I suspect is another story.  I might even argue that the baby who is in need of CPAP could be watched and if they deteriorate have antibiotics started.  As much as I would love to say none of these babies need antibiotics I would have to admit that I would cave once the baby was ventilated.  It is better to provide a couple of days of antibiotics while awaiting blood cultures than to have a patient with sepsis left untreated or at least that is my opinion.

The question is what would you do?