Saving Infants From Killer Bacteria: NE
BACKGROUND: Approximately 1 in 2,000 to 4,000 babies are born affected by necrotizing enterocolitis (NEC). A disease that mostly affects premature infants, NEC causes inflammation and infection, which can lead to the destruction of the bowels. It is the most common and serious gastrointestinal disorder that premature infants experience. This disorder usually occurs within the first two weeks of life after milk feeding has begun.
CAUSES AND SYMPTOMS: Although the specific causes of NEC are unknown, the theory is that because infants' intestinal tissue is underdeveloped, the tissue is weakened by too little oxygen or blood flow, so when feeding is started, the added stress allows bacteria in the intestines to invade and damage the intestinal tissue wall. The damage may be extensive or only affect a small portion of the intestines. After the bacteria begin to spread, the infant is unable to eat as the bacteria causes them to get sick. If the bacteria are able to invade the bloodstream, the infant can experience imbalances of minerals in the blood. In severe cases, a hole may develop in the intestines, which will allow bacteria to leak into the abdomen and cause life-threatening infections that can have serious complications.
NEW NEC RESEARCH: NEC is a serious disease with a death rate of about 25 percent. Currently, researchers are investigating the ontogeny of salivary epidermal growth factor (sEGF) in premature infants to determine the correlation to the development of NEC. Investigators found that there is a positive relation between the two, and patterns of sEGF levels over the first two weeks of life were related to the development of NEC in infants with very low birth weight.
Jacqueline Saito, MD, Assistant Professor, Division of Pediatric Surgery at Washington University School of Medicine in St. Louis, talks about a condition that affects babies.
What is necrotizing enterocolitis?
Dr. Saito: Necrotizing enterocolitis is a condition that can affect the intestine of a baby and it most often occurs in babies who are born prematurely but it can occur in babies who are born at full term at all. And its a real tricky disease because it can occur n a mild form where babies may will just get slightly ill, they may have bloody stools, may have vomiting or get a little bit of a bloated abdomen but actually recover with not feeding them and treating them with antibiotics. And in the worst case all the intestine can be affected and actually go on to die. Theres an in between form where maybe just a portion of the intestine gets sick and forms a hole. But its really a quite variable disease. Unfortunately we dont fully understand what causes it which is obviously a source of great frustration.
Whats going on inside the intestine when this happens?
Dr. Saito: Well there is definitely inflammation that occurs there can be bacterial invasion of the intestine itself. But again its not really well understood what the process is triggered by. There are several theories about what causes it theres the thought that maybe the intestine is immature in its defense because when you think about it our intestine has a pretty hefty job. It has to absorb the nutrients from what we eat yet defend itself against the bacteria that live inside the intestine and so it has to be a defense as well. And so I think that it makes sense that there might be something wrong with the defense aspect in a baby who is born prematurely or even in the young term baby.
Does it come on all of a sudden and without warning?
Dr. Saito: Sure it can occur very suddenly and within hours the intestine can be profoundly affected, in other children its a little bit more of a gradual onset. And so sometimes we can see some early signs, sometimes babies will have breath holding spells, sometimes they will have a low heart rate or their temperature wont be stable. And then some of the other signs that I mentioned that they may start having vomiting or bloody stools, get a larger abdomen. And so one of the things that we can do to try to sort out whats going on is just get a plain abdominal x-ray and so there will be certain signs of necrotizing enterocolitis on those films.
What do you see on those x-rays?
Dr. Saito: So the earliest sign can be something called pneumatosis intestinalis and what happens there is gas from the bacteria in the intestine can actually get in to the wall of the intestine and that has a very distinct pattern that you can see on x-ray. The next more worrisome signs that you can see are actually signs of actual hole in the intestine. And that can be seen where if you put the baby on their side that air will float up and become very obvious. Another worrisome sign can be actually gas within the liver itself and the thought is there is that the gas that is in the intestine wall gets in to the blood draining from the intestine and then goes on in to the liver and thats called portavenal gas.
In a worst-case scenario what happens to these babies?
Dr. Saito: The worst-case scenario is that babies can die from this and thats one thing that makes if really tough for anyone who takes care of these babies is that we realize that it can be a fatal disease. The other problem is that in the youngest premature babies theyre in a delicate balance and so any stress on their body has downstream affect. So if you get bad infection do to necrotizing enterocolitis that can strain their very delicate lungs make it hard for them to breathe well. If theyre not breathing well and getting good oxygen to their bloodstream that strains the heart and so its those cascade of events. The other thing thats becoming more apparent is that theres some concern that babies who have necrotizing enterocolitis and develop the most severe forms where they actually form a hole in the intestine or part of the intestine dies that, that can impact their development later on in life and we dont really understand why that is.
Whats the role that microbes play in all this and are there lots of microbes in our body?
Dr. Saito: There are a lot of microbes in our bodies but obviously we dont start with that. So when a baby is first born the intestine is sterile because the baby has been inside mom in a sterile environment. And thats actually one of the focuses of interest is how do we acquire the bacteria within our intestine, what determines what bacteria end up there. And some of the things that have been linked to that are even the type of formula or whether baby takes breast milk. So the diet that a baby has, what they eat can affect the bacteria within the intestine, whether theyve been exposed to antibiotics, whether theyve been sick with other infections. In babies even where they are hospitalized can have an impact on that so the environment.
In your current study where youre looking the babies gut what are you doing and what are you trying to find out?
Dr. Saito: Well what were trying to find out is in babies who develop necrotizing enterocolitis whether theres an alteration of the bacteria within their intestine. Because the thought is that there may be certain types of bacteria that this may interact with the intestine itself and make some babies more predisposed to necrotizing enterocolitis.
Are there particular microbes that can kill us? Are there some that show up that shouldnt and thats it?
Dr. Saito: I think thats a hard question to answer because we know that there are a lot of bacteria that just reside in our bodies and dont do a whole lot. You know we hear about infections that can be very severe. Certainly if your defenses are down if youre sick with other illnesses or in the case of babies if you are born very prematurely where your defenses may be down a little bit for that, a bacteria that doesnt bother you or me may be fatal. So a little bit depends on the person or the baby as well. I think that it also depends where is the bacteria? So bacteria in the bloodstream is very different than bacteria in the intestine and so once a bacteria can gain entry in to the intestine yes, it can be fatal. We do have powerful antibiotics but then again bacteria are smart because every time we seem to come up with sophisticated antibiotics they figure out a way to evade it. So I think thats one of the things thats a concern about in the medical community is making sure that we are judicious about our antibiotic usage in order to hopefully not promote the development of these really tough bacteria that are hard to treat.
And Isaac is a success story maybe of early intervention or was he just one of the lucky ones.
Dr. Saito: You know I like to think that early prompt intervention helped him but hes probably a tough little guy too and I think that probably helped him get through this. And I think like I said its that delicate balance that I think for him he was able to withstand the stress of necrotizing enterocolitis, his lungs could take it his heart could take it and he was able to kind of just truck on through and recover.
FOR MORE INFORMATION, PLEASE CONTACT:
Associate Director Media Relations
Washington University School of Medicine in St. Louis
Copyright 2011 by Ivanhoe Broadcast News and KSAT.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.