Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections in Acutely Ill Children: A Retrospective Case-Control Study

Objectives: To test if admission clinical and laboratory variables could reliably discriminate community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections from methicillin-sensitive Staphylococcus aureus (MSSA) infections in acutely ill children, and to describe the epidemiology, clinical features and outcomes among children with Staphylococcal infections admitted to the hospital.

Methods: The authors conducted this retrospective case-control study comparing children with CA-MRSA and MSSA infections admitted to hospital between June 2014 and June 2017. They describe the evolving epidemiology and attempt to identify clinical and laboratory variables that can differentiate MRSA cases from MSSA controls. They used multivariate logistic regression to identify independent predictors of MRSA infection and Cox-proportional hazard analysis to compare survival times.

Results: Seventy-three children were enrolled, of which 35 had CA-MRSA and 38 had MSSA infections. Children in MRSA group were younger [median (IQR) age in months: 36 (12, 62) vs. 56 (37, 96); p = 0.032]. MRSA and MSSA groups had similar rate of skin and soft tissue involvement (SSTI) [62.9% vs. 54.1%; p = 0.449]. Median duration of illness was lower in MRSA, 6 vs. 8.5 d (p = 0.001). TLC of 8100 or less was 82% sensitive and 94% specific for MRSA sepsis at admission [AUROC = 0.64 (0.51-0.77), p = 0.04]. Mortality (8.6% vs. 10.5% p = 1.0) and length of ICU stay (7.2 vs. 9.3 d, p = 0.24) were similar in both. None of the admission variables were predictive of MRSA culture-positivity on regression analysis.

Conclusions: The hospital-based incidence of CA-MRSA infections among children appears to be increasing. None of the admission clinical or laboratory variables could reliably identify CA-MRSA infections. As there seems to be no reliable way to differentiate children with MSSA and MRSA infections, physicians may consider empiric initiation of broad-spectrum antibiotics at admission to cover both MSSA and MRSA, especially in critically ill children with suspected Staphylococcal infections.