The ACEP does not specifically endorse a management strategy for febrile infants in the 29- to 90-day age group, but instead acknowledges that no age cut-off within this group can be considered absolute when determining management strategy, and suggests that children up to 60 days old should be managed in a manner similar to neonates.2 The published guidelines do not include consideration of specific history exposure in the management recommendations.
Typhoidal Serotypes
Salmonella can be divided into typhoidal (including S typhi and S paratyphi) and nontyphoidal serotypes (NTS), with the two groups manifesting as very different diseases.7 Typhoidal serotypes lead to the disease process known as typhoid, which typically presents with fever, chills, abdominal pain, nonbloody diarrhea or constipation, nausea, anorexia, headache, hepatosplenomegaly, and rose spots.8 These symptoms typically present after a 14-day incubation period and persist for 21 days.9 Humans are the only known infected source of these species, which are spread via the fecal-oral route.10
In contrast, disease from NTS manifests within 12 hours of exposure with watery diarrhea, nausea, vomiting, and fever, with symptoms lasting up to 10 days.11 Both groups cause disease by invading the intestinal epithelium12; however, typhoidal species induce less intestinal inflammation, facilitating bacterial invasion and making systemic disease more likely.13
Transmission
Many animals are known to carry NTS, including reptiles, where Salmonella occurs naturally in their gastrointestinal tract.14 Twenty-five percent of Salmonella infections in children younger than age 5 years have been attributed to contact with a pet,15 with small turtles (shell diameter <4 inches) accounting for 42% of all pet-related Salmonella infections.
Though gastroenteritis is the most common clinical manifestation of infection with NTS, approximately 5% of patients will develop invasive disease, including bacteremia, meningitis, septic arthritis, or osteomyelitis.16 Children with invasive disease are more likely to have been exposed to an iguana, snake, or bearded dragon than to a turtle. If the pet is kept indoors, the risk of invasive disease is more likely. The average age of patients with invasive disease is 62 days, versus 2 years for noninvasive disease.17
Diagnosis
Growth of Salmonella on cultures of stool, blood, urine, or CSF dishes is the mainstay of diagnosis of typhoid and nontyphoidal disease, but bacterial concentrations are higher in bone marrow aspirate, making it superior to blood cultures.18 Biopsy of the rose spots of typhoid may also provide the diagnosis.
Management
Since Salmonella gastroenteritis is usually a self-limited disease, current recommendations reserve treatment with antibiotics for patients with severe disease or who are immunocompromised. When necessary, treatment consists of 7 to 10 days of a fluoroquinolone or third-generation cephalosporin, which is the same regimen suggested for typhoid. Treatment of central nervous system (CNS) salmonellosis consists of at least 3 weeks of a third-generation cephalosporin; the AAP recommends at least 4 weeks of treatment.19
Case Conclusion
Prior to the patient’s transfer to our facility, she was treated empirically with ceftriaxone without prior CSF analysis—an approach that does not follow any current guidelines for the treatment of a febrile infant. Though an LP was not performed until approximately 24 hours after the initial antibiotic was given, the patient demonstrated CSF pleocytosis with no organisms on gram stain and no growth on culture. Given this pleocytosis and Salmonella bacteremia in the context of prior antibiotic treatment, and MRI consistent with CNS involvement, the patient was treated for 21 days for presumed Salmonella meningitis. A CSF analysis performed on her initial visit could have more accurately directed the type and duration of treatment if the findings on subsequent imaging studies and CSF analysis were ambiguous.
Summary
Emergency physicians may underestimate the likelihood of SBI in otherwise well-appearing febrile infants. While certain aspects of the history and physical examination in a febrile, well-appearing infant have been shown to correlate with an increased risk of SBI, no single finding can definitively rule in or rule out the disease.20 Opinions differ as to optimal management strategies for febrile, well-appearing infants outside the neonatal period. However, an appropriate level of clinical suspicion, within the context of a thorough investigation into the infant’s health history and social situation, can aid the clinician and guide treatment and disposition.