Infections in Newborns

Newborns are at a high risk of infection because their immune systems are not developed enough to fight bacteria, viruses, and other pathogens as effectively as an adult or older child could. Infections can be transmitted from mother to baby during pregnancy or the birthing process, or an infant may become infected shortly after birth. Often, newborn infections can be prevented through the use of prophylactic antibiotics, a scheduled C-section, or by ensuring that vaginal delivery is not prolonged (because this increases a time period in which infants are particularly vulnerable to certain infections that ascend through the uterus). Newborns that become infected often need to spend time in a neonatal intensive care unit (NICU). If infant infections are not recognized and treated in a timely fashion, they can lead to serious brain infections and injuries such as meningitis, encephalitis, hypoxic-ischemic encephalopathy (HIE), and cerebral palsy (CP), and in some cases can even be fatal.

Babies can become infected via either “vertical” or “horizontal” transmission. Vertical transmission typically refers to infections which occur when the baby is coming down the birth canal. An infection that is horizontally transmitted is acquired after the baby is born.

Neonatal infections can be caused by bacteria, viruses, or fungi. In some cases, different categories of infections can result in similar outcomes. For example, sepsis  – an infection of the bloodstream that can lead to brain damage and other permanent, negative outcomes  – can be caused by many different pathogens (1).

Newborns that are infected may show the following symptoms, among others (1, 2):

• Inactivity
• Apnea or other respiratory problems
• An unusually slow or fast heart rate
• Decreased or elevated body temperature
• Poor feedings (i.e. sucking problems)
• Irritability
• Odd skin color (e.g. jaundice or cyanosis)
• Low blood pressure
• Low blood sugar (hypoglycemia)
• Seizures
• Digestive problems (vomiting, diarrhea)
• Swollen stomach area
• Impaired consciousness
• Bulging fontanelle

Doctors will usually test fluid samples and run blood tests and cultures from the infant, and often the mother, to diagnose the infection. Treatment for most infections includes antibiotics or antiviral medications as well as supportive care (intravenous [IV] fluids, oxygen or a breathing machine, and other medicines).

There can be severe consequences if a newborn’s infection is not quickly diagnosed and properly treated. The infection can rapidly spread and become a much more serious, acute infection. Generalized infection or infection of the blood is called sepsis, an infection that settles around the brain is meningitis, infection of the brain is called encephalitis, and infection of the lungs is pneumonia.

This is a serious infection that involves the spread of germs throughout the blood and tissues. The most common microorganisms associated with sepsis are Group B Streptococcus (GBS) and Escheria coli (E. coli). Other types of bacteria that can cause sepsis include Listeria, Staphylococcus, and Enterococcus. Sepsis can also be caused by non-bacterial pathogens, such as Herpes simplex virus, Enterovirus, Parechovirus, and Candida (3). Tools for diagnosing neonatal sepsis include lumbar puncture (spinal tap), chest x-rays, and cultures of blood, urine, skin, and stool. Because sepsis is so dangerous, the threshold for treatment is fairly low — treatment must begin before a formal diagnosis is made if a baby is exhibiting signs of infection. Newborns who are particularly high risk (e.g. their mother has an infection) may be treated even without showing any signs of sepsis. Treatment usually involves broad spectrum antibiotics, although if the pathogen causing sepsis is not bacterial, then other medications will be necessary. The prognosis for properly-treated newborns is very good, with little to no residual physical or mental problems. However, if untreated or not effectively treated, there is a high chance of permanent disability or even death (1).

Meningitis is inflammation of the membranes around the brain and spinal cord. Neonatal meningitis is a very serious infection in newborns. Group B Streptococcus (GBS)  and Escheria coli (E. coli) are the most common causes of bacterial meningitis in newborns. Meningitis should be suspected in any neonate with clinical signs of sepsis, since the features (and causes) are very similar. Important indications of sepsis and meningitis include fever, hypothermia, irritability, and feeding problems.

Diagnosis of meningitis in newborns is done through a spinal tap. Depending on the cause, antibiotics or antiviral medications are given. Supportive care in the neonatal intensive care unit (NICU) is required. Meningitis is a very serious threat to newborn health, so if it is suspected, medical professionals will often begin treatment before a diagnosis is confirmed (4).

Encephalitis is an inflammation of the brain caused by a virus, most often herpes simplex virus (“genital herpes”). If a pregnant woman has the virus, she can pass it on to her baby through the infected birth canal (occasionally, a baby can be exposed earlier in pregnancy). A mother who experiences a first outbreak of the virus during the third trimester of pregnancy has a much higher chance of transmitting the virus to her baby than a woman with recurrent herpes. Fortunately, the mother’s medical team can usually prevent transmission of HSV from mother to baby. This includes screenings for maternal HSV and appropriate management of pregnancies involving HSV (which may include antiviral therapy and/or a C-section delivery) (5). Diagnosis of neonatal herpes encephalitis often involves taking cultures of blood, cerebrospinal fluid, and other bodily fluids, in addition to CT scans and MRIs (6, 7). Herpes encephalitis is extremely dangerous to a newborn, so doctors will begin medication (typically IV acyclovir) without waiting for confirmatory results (5). The prognosis for infants with encephalitis depends on the severity of the case, the strength of the newborn’s immune system, and the timing of the diagnosis and treatment. Some make a complete recovery, while others may develop permanent conditions such as cerebral palsy.  With early treatment, the prognosis is very good.

This bacterial lung infection can be caused by a wide variety of bacterial, viral, and fungal pathogens (8). Pneumonia can cause lung damage, respiratory problems, and can develop into sepsis (9). Diagnosis is based on clinical, radiographic, and microbiologic findings. Treatment includes initial broad-spectrum antibiotics, later changed to organism-specific drugs. Prognosis varies depending on the gestational age of the patient, infecting pathogen, underlying medical problems, and severity of the disease (8), but is usually good with timely treatment.