granulocyte colony–stimulating factor but are not commonly used clinically CBC, CRP, and other nonspecific markers are useful indicators of disease None of these tests alone or in combination are sensitive enough to be used solely to exclude the diagnosis of bacterial infection Definitive diagnosis is isolation of a specific pathogen from a normally sterile site, such as blood, urine, or CSF culture Blood samples for culture should be at least mL to allow for identification of low levels of bacteremia A catheterized urine specimen or suprapubic aspiration for urinalysis and urine culture is recommended for all infants since ascending infection can lead to bacteremia CSF will show elevation in WBC count (20 to 30 cells/μL definitive), high protein, and/or low glucose in bacterial infections HSV encephalitis may demonstrate elevated CSF protein only CSF Gram stain may show presence of bacteria Lumbar puncture prior to antibiotic administration is recommended for all neonates due to high incidence of meningitis (23%) in cases of bacteremia and up to 30% of neonates may have a negative blood culture even in the presence of bacterial meningitis Lumbar puncture can be deferred if the infant has hemodynamic instability but should be performed as soon as the infant is stable Infants should be placed on cardiorespiratory monitors during the lumbar puncture procedure Traumatic results should be interpreted with care Correction of CSF WBC count according to the RBC count in traumatic taps does not improve the ability to diagnose meningitis Clinicians should avoid this correction and presume meningitis until the CSF culture results are available Other specific testing can be done (e.g., HSV CSF PCR, liver function tests, and CSF enteroviral PCR) if specific pathogens are suspected CXR can be helpful if the neonate has respiratory or cardiac symptoms but is not routine Management Any neonate with concern for bacterial or serious viral infection should be admitted to the hospital Initial management should include placing the infant on cardiorespiratory monitoring, with vital sign monitoring and clinical reassessments Normal saline boluses may be given in cases of hypoperfusion and shock Blood pressure stabilization with pressors may be needed In some cases hydrocortisone may be required Hypothermia should be corrected by gradual warming of the baby Hypoglycemia and electrolyte abnormalities should also be corrected Oxygen, humidified nasal cannula, or other respiratory support may be needed for neonates with apnea or respiratory distress Antibiotics should be given as soon as possible Whenever feasible, cultures should be obtained before starting antibiotics Obtaining cultures and starting antibiotics are a priority Lumbar puncture may be delayed if the baby is unstable