Nasal microbiota predictors for methicillin resistant Staphylococcus colonization in critically ill children.

Background: Surveillance cultures to identify patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) is recommended at pediatric intensive care unit (PICU) admission but doesn't capture other methicillin-resistant Staphylococcus and is resource intensive. We determined the prevalence and identified nasal microbiome predictors for methicillin-resistant Staphylococcus colonization at the time of PICU admission.

Methods: A prospective cohort study was performed in a 20-bed pediatric intensive care unit (PICU) between 2020-2021. Anterior nares nasal swabs processed for MRSA culture, nasal microbiome and mecA+ qPCR were obtained within first five days after PICU admission. Predictive values of methicillin-resistant Staphylococcus carriage on symptoms of infection and for nasal microbiome attributes were calculated.

Results: A total of 5 (8.0%) of 62 patients had a nares culture positive for MRSA and 22 (35.5%) of 63 patients had methicillin-resistant Staphylococcus (MRSA or methicillin-resistant coagulase-negative Staphylococci). In univariate analysis, carriage with MRSA or MRCoNS was associated with having a fever during PICU stay. Colonization with a distinct set of microbes (including Haemophilus, Streptococcus, Prevotella and Corynebacterium sp.) was predictive of having methicillin-resistant Staphylococcus colonization.

Conclusions: Carriage with methicillin-resistant Staphylococcus may lead to transmission in critically ill pediatric patients. Carriage of particular nasal microbes appears to facilitate colonization with methicillin-resistant Staphylococcus.