may be evident A bulging or tense fontanel may be found if meningitis is present Otitis media, abdominal rigidity, joint swelling, tenderness in one extremity, or chest findings such as rales indicate the infection has localized Soft tissue infections from MRSA are becoming a more common cause of sepsis Always examine the neonate for signs of omphalitis, an ascending infection originating in the umbilicus Finally, if the disease process has progressed, the infant may develop shock and hypotension The laboratory is often helpful in suggesting a diagnosis of sepsis; however, definitive cultures require time for processing Potential abnormal laboratory studies include a complete blood count (CBC) with a leukocytosis or leukopenia with left shift, a coagulation profile with evidence of DIC, and blood chemistries with hypoglycemia or metabolic acidosis Recent risk stratification criteria utilize elevated c-reactive protein (CRP) and procalcitonin (PCT) to identify infants at high risk for serious bacterial infection If localized infection is suspected, aspiration and Gram stain of urine, joint fluid, spinal fluid, or pus from the middle ear may reveal the offending organism, and a chest radiograph may show a lobar infiltrate if pneumonia is present Cerebrospinal fluid (CSF) cultures are diagnostic for meningitis, and polymerase chain reaction (PCR) tests for CSF are now readily available to screen for the most common viral and bacterial etiologies A promising new approach, in development, is the identification of differing host mRNA response patterns to specific pathogens, which can be determined more quickly than waiting for culture results Other Infectious Diseases Overwhelming viral infections may cause systemic inflammatory response syndrome (SIRS) and sepsis (see Chapter 10 Shock ) Approximately, 25% of infants younger than month with enteroviral infections develop sepsis, with high mortality Respiratory distress, hemorrhagic manifestations of the gastrointestinal tract and skin, seizures, icterus, splenomegaly, congestive heart failure, and abdominal distention often occur Viral isolates from stool and CSF or enterovirus PCR of the CSF may confirm the offending enterovirus Epidemics of respiratory syncytial virus (RSV) occur in the wintertime, leading to respiratory distress, cyanosis, or apnea Premature infants or those with previous respiratory or cardiac disorders are especially susceptible to apnea Knowledge of illness prevalence in the community and wheezing on chest examination may lead to the suspicion of RSV bronchiolitis Some infants develop wheezing later in the course, making the initial diagnosis in these patients difficult A rapid nasal wash test for RSV will be quickly diagnostic, and a more expensive respiratory viral panel will diagnose other viral pathogens