Medical Author: John Mersch, MD, FAAP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
Neonatal sepsis is any infection involving an infant during the first 28 days of life. Neonatal sepsis is also known as "sepsis neonatorum." The infection may involve the infant globally or may be limited to just one organ (such as the lungs with pneumonia). It may be acquired prior to birth (intrauterine sepsis) or after birth (extrauterine sepsis). Viral (such as herpes, rubella [German measles]), bacterial (such as group B strep) and more rarely fungal (such as Candida) causes may be implicated.
During her pregnancy, a woman's obstetrician is constantly monitoring the health of both of the pregnant woman and her fetus for any signs or symptoms that might indicate sepsis. Prior to birth, many indicators can signal that a potential infection is developing. Women are screened for infectious diseases at their first OB office visit. Some of these include HIV, gonorrhea, syphilis, herpes, Chlamydia, and hepatitis B, as well as immunity to rubella and chickenpox. Between the 35th and 37th week of pregnancy, screening for group B strep is commonly performed. Some symptoms and signs, such as slower than anticipated fetal growth, may be subtle indications of threatened fetal well-being. Measurement of uterine size via the traditional tape measure or ultrasound examination of the uterus, placenta, and fetus will both provide critical information. Throughout the pregnancy, office visits provide the opportunity to monitor fetal heart rate. The obstetrician commonly evaluates both the actual heart rate at rest as well as the infant's cardiac response to a mild stress (for example, uterine contraction). If concerns develop, specialized evaluations can be performed ("stress testing") during which fetal heart rate, fetal movement and fetal tone are monitored and an objective risk assessment may be made. Maternal fever during her pregnancy warrants a timely and thorough evaluation. Equally significant would be the onset of premature labor or premature rupture of the amniotic sac (termed "premature rupture of membranes").
During labor, several indicators may raise concern regarding the possibility of neonatal sepsis. Abnormalities of fetal heart rate, maternal fever, premature separation of the placenta from the uterine wall, or foul smelling/cloudy amniotic fluid all indicate a high-risk labor and delivery. These situations will commonly prompt consultation with the pediatrician or neonatologist regarding the potential for delivery and/or postpartum complications.
Any infant who fails to make a smooth transition from intrauterine to extrauterine life should be considered at high risk for sepsis. Close monitoring of vital signs (heart rate, respiratory rate and effort, skin color, temperature, and "vigor") is a crucial part of the evaluation of the newborn. Infants may manifest neonatal sepsis by subtle signs such as poor feeding, jaundice, unusual rashes, or more obvious indicators such as seizures, projectile vomiting, or abdominal distention. The importance of the clinical observations of the postpartum nurse cannot be understated.
By definition, any infant less than 28 days of age with a rectal temperature greater than 100.4 degrees F must receive a thorough and complete evaluation for neonatal sepsis. In addition to a complete history (including pregnancy, labor, and delivery) and physical examination, various laboratory tests are done. Blood tests include (but are not limited to) CBC (complete blood count), CRP (nonspecific marker for inflammation), and blood chemistries (blood sugar, kidney- and liver-function tests). Positive cultures of body fluids (blood, urine, CSF [spinal fluid]) will help identify the cause of sepsis in the neonate as well as guide antibiotic therapy. Radiological studies (for example, chest and abdominal X-rays, ultrasound studies) are also often necessary.
Therapy of the septic infant involves correcting any abnormal vital signs as well as directed antibiotic therapy. A septic infant will commonly need IV fluids and may require medications to support blood pressure and heart function. Since many of these infants are too sick to feed, nutritional support will commonly involve administration of either breast milk/formula via a tube passed through the nose directly into the stomach ("nasogastric tube") or rely solely on IV mixtures of proteins, carbohydrates, and fats. For some critically ill neonates, assisted ventilation (via a tube passed into the larynx) may be necessary.
The old adage "an ounce of prevention is worth a pound of cure" certainly applies to the deterrence of neonatal sepsis. Timely and focused prenatal care, close observation during labor and delivery, and detailed monitoring of the newborn will provide the best guarantee for an uneventful and successful outcome.