“Introduction” Despite high rates (>70%) of oropharyngeal carriage of Kingella kingae in children attending daycare, Kingella kingae endocarditis remains rare with 43 reported cases.1 Neurologic complications were present in 32.5% of cases and there is 16% overall mortality.2,3 As Kingella kingae is the most commonly isolated bacteria in pediatric osteoarticular infections, early detection is vital.4 “Case Report” A previously healthy 18-month-old male presented with congestion, fever, and refusal to ambulate. He was seen at other healthcare facilities twice in the preceding 48 hours and discharged with diagnosis of viral illness. Physical exam revealed tachycardia and new heart murmur. In the emergency department, the patient developed evidence of cardiogenic shock with hypotension and hypoxia. Echocardiogram on admission showed severe aortic insufficiency, paravalvular aortic abscess, and left ventricular systolic ejection fraction of 25-30%. During intubation the patient became increasingly bradycardic and hypotensive resulting in a brief code event. He underwent emergent aortic root debridement and valve replacement subsequently requiring three days of veno-arterial extracorporeal membrane oxygenation (ECMO). Blood and surgical cultures grew Kingella kingae and MRI showed left tibial osteomyelitis. He completed 4 weeks of ceftriaxone. The patient improved clinically and echocardiogram at discharge showed normal systolic function. “Discussion” Kingella kingae endocarditis typically occurs in older children and 33% have known congenital heart disease. Although our patient was only 18 months at diagnosis, he was noted to have a bicommissural aortic valve on initial echocardiogram.2 While mitral valve involvement is most common, aortic abscess was identified in this case, requiring valve replacement.2 Repairing the native valve is the standard of care for valvar abscesses, but when irreparable damage is present, valve replacements have been shown to provide ten-year freedom from endocarditis-related death and re-intervention of 94.2% and 91.6% respectively.5 “Conclusion” This case highlights the importance of a high index of suspicion for endocarditis in previously healthy young children, and the use of aortic valve replacement and ECMO as life-saving interventions for aortic insufficiency secondary to endocarditis. References Yagupsky, Pablo, Eric Porsch, Joseph W. St Geme III. “Kingella kingae: An Emerging Pathogen in Young Children.” Pediatrics. 127.3 (2011): 557-65. PubMed Medline. Foster, Monique A, Tony Walls. “High Rate of Complications Following Kingelle kingae Infective Endocarditis in Children: A Case Series and Review of the Literature.” The Pediatric Infectious Disease Journal. 33 (2014): 785-786. PubMed Medline. Chometon, Sylvia, et al. “Specific real-time polymerase chain reaction places Kingella kingae as the most common cause of osteoarticular infections in young children.” The Pediatric Infectious Disease Journal. 26.5 (2007): 377-381. PubMed Medline. Xiao, Jian, et al. "A 20-year study on treating childhood infective endocarditis with valve replacement in a single cardiac center in China." Journal of Thoracic Disease. 8.7 (2016): 1618-624 . PubMed Medline.

Figure 1: Average hemolysis of USA100 isolates

Hemolysis as percentage of colony size for USA100 wild type and agr mutants. Wild type demonstrated more hemolysis as compared to their agr mutant pairs. However, there are two agr mutants that did have a small amount of hemolysis. This suggests that virulence factor expression is controlled by the agr system.

Figure 1: Average hemolysis of USA100 isolates

Hemolysis as percentage of colony size for USA100 wild type and agr mutants. Wild type demonstrated more hemolysis as compared to their agr mutant pairs. However, there are two agr mutants that did have a small amount of hemolysis. This suggests that virulence factor expression is controlled by the agr system.

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