The Validity of Positive Coagulase-Negative Staphylococcus Cultures for the Diagnosis of Sepsis in the Neonatal Unit

Am J Perinatol. 2022 May 31. doi: 10.1055/a-1817-5698. Online ahead of print.

Abstract

Objective: Coagulase-negative Staphylococcus (CoNS) is the most frequent pathogen causing late-onset sepsis (LOS) in neonatal intensive care units (NICUs). Technical difficulties hinder blood culture (BC) collection and obtaining only one culture before initiating antibiotic therapy is a common practice. We sought to assess specific clinical information and CoNS cultures for the diagnosis of true bacteremia in the NICU.

Study design: This historical cohort study was conducted in NICUs at the Hadassah-Hebrew University Medical Center of Jerusalem in Israel. Clinical and laboratory data in every CoNS bacteremia were collected and compared between bacteremia groups as follows: true positive, two positive BCs; contaminant, one positive BC out of two; undefined, one BC obtained and found positive.

Results: For 3.5 years, CoNS was isolated in 139 episodes. True positive was identified in 44 of 139 (31.7%), contaminant in 42 of 139 (30.2%), and the event was undefined in 53 of 139 (38.1%). Vancomycin treatment was more frequent in the true positive and undefined groups than the contaminant group (100, 90.6, and 73.8% respectively, p = 0.001); treatment was also prolonged in these two groups (p < 0.001). No clinical variables were associated with true bacteremia on multivariable analysis.

Conclusion: Diagnosis should definitely be based on at least two positive BCs, despite objective difficulties in obtaining BCs in neonates.

Key points: · CoNS is a frequent pathogen causing LOS in neonates.. · Due to technical difficulties, often only one culture is collected prior to antibiotic therapy.. · No clinical/laboratory variables were associated with the diagnosis of true CoNS bacteremia.. · Diagnosis should definitely be based on at least two positive BCs..