Stenotrophomonas maltophilia Associated Factors and Outcomes in a Neonatal Intensive Care Unit: A Retrospective Matched Case-control Study

Background: Stenotrophomonas maltophilia is a multi-drug-resistant, hospital-acquired Gram-negative bacillus associated with significant morbidity and mortality. The objective of this study is to identify risk factors and outcomes associated with S. maltophilia isolation in a high-risk neonatal population. Methods: This was a retrospective matched case-control study. Cases were matched 1:2 for years of neonatal intensive care unit admission, completed weeks’ gestational age and birth weight in 250-gram incremental categories. Results: A total of 15 cases and 35 controls were included in the analyses. Risk factors for S. maltophilia isolation included days of antibiotics (24 vs. 18, P = 0.036), days of broad-spectrum antibiotics (19 vs. 12 days, P = 0.027), days of meropenem (9 vs. 6 days, P = 0.018) and any meropenem exposure (100% vs. 22%, P = 0.005). Other risk factors were any corticosteroid exposure (66.7% vs. 20%, P = 0.001), days of total parenteral nutrition (55 vs. 31 days, P = 0.017) and days of invasive mechanical ventilation (28 vs. 7, P = 0.015). S. maltophilia isolation was associated with increased length of neonatal intensive care unit stay (134 vs. 69 days, P < 0.001) and mortality (33.3% vs. 0%, P = 0.001). Conclusions: Antibiotic stewardship efforts should be made to decrease the risk of S. maltophilia isolation and associated mortality. Carbapenem over-use should be specifically addressed with institutional policies and unit-based guidelines. Additional neonatal studies are needed to confirm these findings and explore other possible risk factors.