Clinical and molecular epidemiology of staphylococcus aureus catheter-related bacteremia in children

BACKGROUND: Staphylococcus aureus (SA) is an important cause of catheter-related bacteremia (CRB). The USA300 clone increasingly causes healthcare associated infections. We compared children with SA-CRB due to USA300 versus non-USA300 isolates and identified risk factors for complications. METHODS: Children at Texas Children's Hospital (TCH) with SA-CRB were identified from a prospective S. aureus surveillance study. S. aureus isolates were characterized by methicillin susceptibility and pulsed field gel electrophoresis. RESULTS: From August 2001 to October 2007, 112 children with a first episode of SA-CRB and corresponding isolates were identified. USA300 accounted for 21 isolates. Metastatic infection complicated 10.7% of cases and was associated with methicillin resistance. Other complications were recurrence (n = 16), death (n = 13), thrombosis (n = 9), and intravascular "cast" (n = 6). Four patients with non-USA300 SA-CRB had endocarditis. Prolonged bacteremia was more common in methicillin-resistant SA (12/29) than in methicillin-susceptible SA SA-CRB (14/83) (P = 0.007). Complications were more common in patients with bacteremia≥ 4 days (16/26 [61.5%]) versus patients with bacteremia <4 days (25/86 [29%]) (P = 0.003). The complication rate was lower in patients who had the catheter removed <4 days (22.5%) versus patients whose catheter was removed ≥ 4 days after infection or not removed (44.4%) (P = 0.02). Children with USA300 versus non-USA300 isolates did not differ with respect to frequency or type of complications. CONCLUSIONS: At Texas Children's Hospital, the USA300 clone caused 19% of initial SA-CRB episodes and was associated with methicillin resistance. Complications occurred in 36.6% of the patients and were associated with prolonged bacteremia and catheter removal 4 days after infection or failure to remove the catheter.