[T lymphocyte immunophenotype as a diagnostic marker of late-onset neonatal sepsis]

Abstract

Background: Given the high risks associated with neonatal sepsis, there is a need for a diagnostic marker that would predict the disease before the results of blood or cerebrospinal fluid cultures are available. We evaluated changes in the CD4+ T lymphocyte immunophenotype in neonates with late-onset sepsis to try to improve the test combinations currently used (C reactive protein, immature:total neutrophil ratio, leukocytosis).

Patients and methods: We performed a prospective cohort study in 24 neonates with late-onset sepsis and 48 non-infected controls with a gestational age of 37 weeks or less. CD4+ T lymphocyte subpopulations in peripheral blood samples were identified by labeling with monoclonal antibodies and quantified by flow cytometry. Diagnostic performance curves were constructed by logistic regression.

Results: As a marker of late-onset neonatal sepsis, a percentage of CD4+/CD45RO+/CD45RA- T lymphocytes of >3.5% showed a sensitivity of 94.1%, specificity of 69.2%, positive predictive value of 80.0%, negative predictive value of 90.0%, and odds ratio of 36.0 (p<0.001). When we combined this marker with a C-reactive protein level of >10.0 mg/L, the specificity of this combination of tests increased to 94.7% and the positive predictive value to 85.7%.

Conclusions: A percentage of CD4+/CD45RO+/CD45RA- T lymphocytes of >3.5% is an effective indicator of late-onset neonatal sepsis in preterm infants. If this marker is combined with a C-reactive protein level of >10.0 mg/l, its diagnostic performance is improved.