553 - Is Oxacillin Enough? - Challenging Current Trends of Antibiotic Use in Late Onset Neonatal Sepsis

Poster Number: 553
Publication Number: 553.428

Tiffany A. Robles, Dell Children's Medical Center of Central Texas, Austin, TX, United States; Jose A. Gonzales, Dell Children's Medical Center of Central Texas, Austin, TX, United States; Marisol Fernandez, Dell Children's Medical Center of Central Texas, Austin, TX, United States; Genene Wilson, Dell Children's Medical Center of Central Texas, Austin, TX, United States; Julia Sapozhnikov, Loyola University Chicago Stritch School of Medicine, Chicago, IL, United States

Background: Late onset neonatal sepsis (LONS) is a major cause of morbidity and mortality in neonates and is often managed with a variety of empiric regimens. There is insufficient evidence to favor any one antimicrobial regimen. Excessively broad antibiotic courses are associated with adverse events such as necrotizing enterocolitis and the development of antimicrobial resistance. Thus, judicious use of antibiotic regimens in these infants are crucial.

Objective: This study aims to evaluate composite clinical outcomes–such as pressor use, respiratory support and all cause mortality– in infants empirically treated with oxacillin-containing antibiotic regimens to those treated with vancomycin-containing regimens for LONS. Microbiological cultures were individually assessed to determine if the regimens were equivalent with regards to pathogen sensitivity and resistance.

Design/Methods: This was a single-center, retrospective quality improvement study of infants admitted to a level IV NICU in Central Texas from 06/01/2018-06/01/2021. Patients were included if they had onset of symptoms between 72 hours and 90 days of life and received either oxacillin or vancomycin-containing regimens for suspected sepsis as determined by the neonatal provider. Additionally, we used Chi-square analysis to evaluate differences between aforementioned regimens and composite outcomes, including pressor use, increased respiratory support and all-cause mortality.

Results: The study screened 202 patients and included 82 patients. 38 patients received an oxacillin-containing regimen, and 44 received a vancomycin-containing regimen. Oxacillin-containing regimens had in-vitro activity against fewer microorganisms than vancomycin in blood (57% vs 100%), urine (61% vs 100%) and cerebrospinal (0% vs 100%) cultures. Both regimens had in-vitro activity against isolated respiratory pathogens. Rates of increased respiratory support were similar in both regimens, whereas rates of pressor requirement and mortality were greater in infants on vancomycin-containing regimens. We found no significant association between empiric antibiotic regimens and composite outcomes (p = 0.125).Conclusion(s): Although vancomycin-containing regimens had activity against more organisms than oxacillin-containing regimens, there was no difference identified in composite outcomes. Due to a low number of clinically poor outcomes, we could not assume superiority of either regimen. Similar clinical outcomes may indicate that either treatment regimen is appropriate, but due to our small sample size,  these findings should be confirmed with randomized, multi-institutional studies.
Incidence of Clinical Events and Corresponding RegimensRates of increased respiratory support were similar in both regimens, whereas rates of pressor requirement and mortality were greater in infants on a vancomycin-containing regimen.
Comparison of coverage of positive cultures between two empiric antibiotic regimensOxacillin-containing regimens had in-vitro activity against fewer microorganisms than vancomycin in blood, urine, and cerebrospinal cultures.