Neonatal infections: what they are and how to react


Newborn babies can get infections easily because their defenses against infections are not well developed.

The more premature a baby is, the more likely she is to get an infection.

Many newborns are tested and treated for infection, because:

  • Infections are a common problem for newborns.
  • Newborns can get sick very fast.
  • Babies respond very quickly to antibiotics. They do very well if they start getting antibiotics when an infection has just begun.


Most newborn infections are caused by bacteria.

Bacteria normally live in the birth canal, and the baby is exposed to them during birth.

The baby may swallow or breathe in the fluid in the birth canal and then the bacteria may get into the baby’s lungs and bloodstream.

A baby may be sick at the time of birth or get sick during the first week after birth.

You may not notice the first symptoms, but as the bacteria multiply the baby can get quite sick very fast.

If an infection is found and treated early, the baby will do very well.

If the baby is not treated until later, the baby may get very sick and need intensive care to recover.

Sometimes newborns catch a viral infection.

Viruses cause colds, flu, and some diseases such as herpes and chickenpox.

A virus may travel from the placenta into a baby’s bloodstream before birth.

Or the baby may be exposed to a virus in the birth canal during delivery.

Sometimes a newborn catches a virus after birth by being exposed to someone with a viral infection.

Neonatal infection can be acquired :

  • In utero transplacentally or through ruptured membranes
  • In the birth canal during delivery (intrapartum)
  • From external sources after birth (postpartum)

Common viral agents include herpes simplex viruses, HIV, CMV, and hepatitis B.

Intrapartum infection with HIV or hepatitis B occurs from passage through an infected birth canal or by ascending infection if delivery is delayed after rupture of membranes; these viruses can less commonly be transmitted transplacentally. CMV is commonly transmitted transplacentally.

Bacterial agents include group B streptococci, enteric gram-negative organisms (primarily Escherichia coli), Listeria monocytogenes, gonococci, and chlamydiae.

In utero infection

In utero infection, which can occur any time before birth, results from overt or subclinical maternal infection. Consequences depend on the agent and timing of infection in gestation and include spontaneous abortion, intrauterine growth restriction, premature birth, stillbirth, congenital malformation (eg, rubella), and symptomatic (eg, cytomegalovirus [CMV], toxoplasmosissyphilis) or asymptomatic (eg, CMV) neonatal infection.

Common infectious agents transmitted transplacentally include rubella, toxoplasma, CMV, and syphilis. HIV and hepatitis B are less commonly transmitted transplacentally.

Intrapartum infection

Neonatal infections with herpes simplex viruses, HIV, hepatitis B, group B streptococci, enteric gram-negative organisms (primarily Escherichia coli), Listeria monocytogenes, gonococci, and chlamydiae usually occur from passage through an infected birth canal. Sometimes ascending infection can occur if delivery is delayed after rupture of membranes.

Postpartum infection

Postpartum infections are acquired from contact with an infected mother directly (eg, TB, which also is sometimes transmitted in utero) or through breastfeeding (eg, HIV, CMV) or from contact with family or visitors, health care practitioners, or the hospital environment.

Risk factors for neonatal infection

Risk of contracting intrapartum and postpartum infection is inversely proportional to gestational age. Neonates are immunologically immature, with decreased polymorphonuclear leukocyte, monocyte, and cell-mediated immune function; premature infants are particularly so .

Maternal IgG antibodies are actively transported across the placenta, but effective levels for all organisms are not achieved until near term.

IgM antibodies do not cross the placenta.

Premature infants have decreased intrinsic antibody production and reduced complement activity.

Premature infants are also more likely to require invasive procedures (eg, endotracheal intubation, prolonged IV access) that predispose to infection.


When a baby first develops an infection, the baby might:

  • Not feed well
  • Be very sleepy, not wake up for feedings
  • Be irritable, not settle down after feedings
  • Breathe fast (over 60 breaths a minute)
  • Have trouble keeping a normal temperature (a normal rectal temperature is 99.8°F, or 37.5°C)
  • Not act right, have a change in behavior

Many healthy newborns have these symptoms at times. However, if a baby keeps having these symptoms, she needs to be checked.

As the infection gets worse, a baby might:

  • Have pale or greyish skin
  • Work hard to breathe
  • Have a bluish color around the lips and mouth
  • Have a low body temperature even when wrapped in clothes or blankets (a rectal temperature under 98°F, or under 36°C)
  • Have a high body temperature (a rectal temperature over 100°F, or over 38°C)

Some newborns may have an infection in only one part of their body. In these cases you might see:

  • Redness or swelling of skin, often around the umbilical cord or circumcision
  • Redness, swelling, or yellowish discharge from the eyes
  • Blisters on the skin.


If your baby has 1 or 2 signs of infection, he is often tested for infection and antibiotics are given even before the results of the tests come back. The results are usually back in 48 to 72 hours.

Certain lab tests will show if a baby has an infection and where it is located:

Blood test: 

A sample of the baby’s blood is taken for a blood count (CBC) and blood culture.

The CBC counts the different types of cells in the blood.

The blood culture is a test to see if bacteria can be grown from the blood.

If a baby does have an infection, bacteria usually grow in a culture within 2 to 3 days.

If the test is negative (no bacteria grew) and the baby’s symptoms go away quickly, or if some other cause is found for the symptoms, the baby probably does not have an infection and the antibiotics will probably be stopped.

Urine Test: 

A sample of the baby’s urine is tested for signs of infection.

Secretion Test: 

If there is an obvious site of infection, a sample of secretions (for example, pus from around the umbilical cord or eye) may be cultured.

Chest X-ray: 

If a baby is having trouble breathing, a chest X-ray may be taken to look for signs of pneumonia.

Spinal Tap: 

Meningitis is a serious infection of the fluid surrounding the brain.

Any baby who is very sick from infection or has bacteria in her blood could get meningitis.

Meningitis is diagnosed by doing a test called a spinal tap (or lumbar puncture, LP) to get a sample of spinal fluid.Spinal taps are safe for babies.

The baby is curled on her side for the test.

To make sure that she is breathing OK during the test, the baby is attached to a monitor.

A nurse watches the baby during the spinal tap.

A hollow needle is put into the space in the baby’s back below the spinal cord and a small amount of spinal fluid is taken. The fluid is then tested for infection.

Most babies do not like to be held in this position and will cry during the test, but a spinal tap is no more painful than drawing blood.

It takes 5 to 10 minutes to do a spinal tap.

If a baby is having problems, the doctor may start antibiotics and wait to do the spinal tap until the baby is better able to handle the test.

Parents are asked for their written or verbal consent before the spinal tap is done.

Some parents worry that putting a needle so close to the spinal cord will cause the baby to be paralyzed. However, there is almost no risk of paralysis because the needle is put into the space below the end of the spinal cord.


The Special Care Nursery (SCN)

If a baby has signs of infection, she is taken to the special care nursery (SCN) for evaluation and treatment.

The baby is placed on a warming bed. She is attached to a monitor that continuously measures heart rate and breathing.

If the baby has trouble breathing, she may also be attached to a pulse oximeter that records the amount of oxygen in her skin.


Suspected bacterial infections are treated with antibiotics.

An IV is put into one of the baby’s veins.

The IV delivers the right amount of antibiotic to the baby’s bloodstream.

Antibiotics are not well absorbed from a baby’s stomach.

If the lab tests are positive for a bacterial infection or the baby’s symptoms strongly suggest infection, the baby will get IV antibiotics for 7 to 14 days.

Antibiotics do not treat a viral infection.

Most babies will be able to fight the infection without medicine.

There are some antiviral medicines that can be used for specific viral infections, such as herpes and chickenpox.

Supportive care

If the baby is breathing too fast to eat, he is given fluids through the IV so he won’t get dehydrated.

If he is too sleepy to eat, he may be given IV fluids or he may be fed by dripping milk through a tube that passes through his mouth and into the stomach.

If the baby needs extra oxygen, he is given extra oxygen.Some babies are not very sick and the only treatment they need is antibiotics. These babies are able to breast-feed or bottle-feed.


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