423. Staphylococcus aureus bacteremia without a localizing source at a children’s hospital
Session: Poster Abstract Session: Pediatric Infections
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Primary bacteremia without a localizing source is a well-documented entity with pathogens such as Streptococcus pneumoniae. Staphylococcus aureus bacteremia is associated with high morbidity and mortality in children, but most commonly is associated with a focal infection or a central venous line (CVL). We sought to examine the clinical and molecular epidemiology of primary S. aureus bloodstream infections without a focus or localizing source in pediatric patients

Methods: Patients with a positive blood culture for S. aureus infection were identified from a prospective surveillance study of S. aureus infections from 2001-2012.  Patients with a recognized source or focus of primary infection, a CVL in situ at the time of the infection or meeting modified Duke Criteria for definite/possible endocarditis were excluded. Isolates were characterized by pulsed field gel electrophoresis and antibiotic susceptibility data was compared.  Medical records for all patients were reviewed.

Results: Of the total 22,738 S. aureus infections catalogued during the study period, 42 cases of S. aureus bacteremia without a source were identified (0.2%). A positive blood culture was deemed as a contaminant in 6/42 cases by the physician of record. Methicillin-resistant S. aureus accounted for 13 (36.1%) cases; eight cases were a result of the USA300 pulsotype (21.6%).  The median age of patients was 1.7 years (range:  0.02-17.9 years); nine patients were neonates (25%). The majority of primary bacteremia cases were in patients with underlying comorbidities (31/36, 86.1%). The most frequent comorbidities included immunosuppression (14/36, 38.9%) and prematurity (3/36, 8.3%).  Death occurred in 3/36 cases (8.3%) all of which were a result of MRSA (3/3 in patients who died vs 10/33 in survivors, p=0.04).  Of those surviving, 11/33 (33.3%) required intensive care unit support.

Conclusion: S. aureus bloodstream infection rarely occurs in children without a focus or localizing source, but is most frequently seen in patients with serious comorbidities. These infections are associated with high morbidity and mortality particularly for MRSA.  Clinicians should be cognizant of this entity particularly when caring for immunocompromised children.

John Ligon, BS1, Jonathon Mcneil, MD2, Kristina G. Hulten, PhD3, Edward Mason Jr, PhD1 and Sheldon L. Kaplan, MD, FIDSA3, (1)Baylor College of Medicine, Houston, TX, (2)Department of Pediatrics, Baylor College of Medicine, Houston, TX, (3)Baylor College of Medicine and Texas Children's Hospital, Houston, TX


J. Ligon, None

J. Mcneil, Stiefel, Inc.: Grant Investigator, Research support

K. G. Hulten, None

E. Mason Jr, Stiefel, Inc.: , Research support

S. L. Kaplan, None

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