Diagnostic Testing and Sepsis
The infant's birth weight, chronologic, and gestational age at the onset of sepsis also has an impact on the expected mortality rate.[2,3] Between 5% and 50% of infants with early-onset sepsis will succumb compared with a mortality rate of 10% to 20% with late-onset sepsis.[2,3,4,5,6] The rate of sepsis in term infants is 0.8 cases per 1,000 live births, and the mortality rate is 2.3%. Two or more maternal risk factors escalate the risk to 4% to 5%.
Low-birth-weight (LBW) infants are at the highest risk for both early- and late-onset neonatal sepsis.[4,5] This is caused, in part, by an immature, inexperienced immune system; a fragile cutaneous barrier; and a prolonged hospital stay with increased exposure to the neonatal intensive care unit (NICU) environment, including various invasive devices and procedures.[3,4,5,9,10] A large prospective National Institute of Child Health and Human Development (NICHD) Neonatal Research Network study of very low-birth-weight (VLBW) infants reported 19 cases of early-onset sepsis per 1,000 live births and 25 cases of late-onset sepsis per 1,000 live births in infants weighing between 401 and 1,500 g. Fifty percent of infants weighing between 405 and 750 g developed late-onset sepsis.
Infants who present with clinical signs of infection are evaluated with a variety of diagnostic tests, commonly referred to as a sepsis workup, and treatment with broad-spectrum antibiotics is initiated until a definitive diagnosis can be made.[3,11,12,13,14] Isolation of microorganism(s) from one or more blood cultures is the gold standard to establish a definitive diagnosis of neonatal sepsis.[12,13,15]
The sole use of blood cultures to diagnose neonatal infection has a number of limitations. It may take 24 to 72 hours to obtain culture results.[16,17] The sensitivity of blood cultures may be impaired by exposure to intrapartum antibiotics, which are administered to 15% to 40% of mothers in labor.[5,7,18] Intrapartum antibiotic exposure can result in a partially treated infant, delaying the onset of clinical signs and symptoms of infection and further complicating the expedient definitive diagnosis of early-onset sepsis in the infant. With the development of multiple drug-resistant bacteria and the cost of therapy with multiple antibiotics, the ability to diagnose or rule out sepsis is an essential tool to limit inappropriate antibiotic exposure.[13,19,20,21,22]
Over the last decade, a variety of laboratory tests have been developed to enhance the early and accurate identification and treatment of infants with suspected sepsis.[12,23,24,25,26,27] Common laboratory tests include the following:
White blood cell count (WBC) with differential
Calculation of the immature to total neutrophil (I:T) ratio and absolute neutrophil count (ANC)
Erythrocyte sedimentation rate
Although these tests are readily available and provide useful information, none of them has been found to be absolutely reliable in detecting all septic infants; therefore, they cannot be considered diagnostic.[3,12,13,25]
Adv Neonatal Care. 2003;3(1) © 2003 W.B. Saunders
Cite this: The Role of C-Reactive Protein in the Evaluation and Management of Infants With Suspected Sepsis - Medscape - Feb 01, 2003.