Historical risk factors for neonatally acquired bacterial infection in infants less than 3 months of age include premature delivery, ruptured amniotic membranes for more than 24 h prior to delivery, and maternal amnionitis prior to or following delivery. Specific symptoms suggestive of a focus of infection in this age group are rare. High fever is uncommon in this age group, and serious illness may be present in the setting of low-grade fever or normal temperature. 2 Infant temperatures should be obtained via the rectal route in the ED, as the axillary and auditory canal routes are less reliable in the identification of fever. 15 A history of fever measured by the parent via the rectal route carries the same significance as fever detected in the ED, although the perception of tactile fever at home in the setting of a normal temperature in the ED does not.16 Of greatest utility to emergency physicians, the symptoms and signs suggestive of bacteremia and SBI most frequently produce an overall ill appearance. Parents may note poor feeding, decreased responsiveness, or irritability in response to attempts to console. Physical examination findings suggestive of an ill appearance include poor eye contact and muscle tone, including weak suck, poor head control, and indifferent response to stimuli. Signs of respiratory distress and poor perfusion parameters are suggestive of septicemia and should be specifically sought. Although uncommon, findings suggestive of a specific focus of infection, such as otitis media, skin, soft tissue, bone, or joint inflammation, place young infants in a higher-risk group for SBI. However, due to the nonspecific nature of the signs and symptoms of illness at this age, the history and physical examination alone are unreliable screening tools for bacteremia and SBI in neonates, with marginally improved predictive value in infants 30 to 90 days old.17
Children 3 months of age and older found to have bacteremia and SBI most often are noted to have fever with rectal temperatures of 39.0°C or higher, 18 although serious infection can uncommonly occur without the finding of fever.19 As for younger infants, the most important historical and physical findings are related to overall appearance. Parental report of persistent lethargy or irritability with associated fever raises significant concern for SBI with associated bacteremia. Symptoms of respiratory, gastrointestinal, soft tissue, bone, or joint inflammation should be elicited. The reader is referred to subsequent chapters for a complete description of the symptoms suggestive of focal SBI in children. Historical risk factors of importance include immunization status, prior infections, and underlying conditions that impair immune response, such as sickle cell anemia and HIV. The physical examination is performed in two phases. The first is a global assessment of the child's appearance performed in order to categorize the child as "ill" versus "well," optimally after antipyretic therapy has been administered. This assessment should specifically include mental status, evaluated by observing response to parental physical and social stimulation, and perfusion and hydration parameters. A well appearance is evidenced by an awake, responsive infant or child with good eye contact, developmentally appropriate social interaction with family members, normal muscle tone, and vigorous cry. An ill appearance is evidenced by lethargy or irritability, failure to respond to or be consoled by family members, weak cry, poor muscle tone, or abnormal peripheral perfusion parameters. If the examination findings are equivocal, the child should be reassessed in a short period of time and, if unchanged, considered "ill-appearing." The performance of an overall assessment of appearance has been shown to improve the sensitivity of the history and physical examination in detecting SBI.20 The second phase of physical examination is devoted to eliciting signs of specific SBI as well as minor focal infection. Signs of meningitis are reviewed later in this chapter. The finding of a minor focus of infection, such as upper respiratory infection, otitis media, pharyngitis, or gastroenteritis, does not exclude the possibility of bacteremia or SBI.
The clinical presentation of the patient at risk for OB includes age 3 to 36 months, rectal temperature of 39°C or higher, a well appearance, and either no other signs of infection or signs of minor focal infection only. However, only 3 percent of patients with these findings will have a positive blood culture. A well-appearing child with a rectal temperature less than 39°C is extremely unlikely to be bacteremic. By definition, it is impossible to distinguish children with OB from those without bacteremia by clinical features alone.21
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