Background B2M has been used as a test in the diagnosis of central nervous system (CNS) infections. Its concentration in biological fluids is increased in the setting of immune activation and high cellular turnover. PHH is a frequent condition in preterm babies. Sometimes, OR is necessary and repeated punctures are required, increasing the risk of infection. The main objective of our study is to describe the evolution of B2M in CSF in neonates with PHH and OR.

Methods All the patients with PHH admitted in our unit between 2012 and 2014 were included. CSF was analysed including levels of B2M.

Results 13 patients were included (10 preterm). Mean patient age at PHH diagnosis was 9,3 days. First value of B2M before OR insertion was 5,86 mg/L (± 2,11 mg/L). In that moment, B2M and total protein concentration had a correlation (rs=0,5). No correlation with red cells, glucose and leucocytes was detected. After OR collocation, there was a rise of B2M in 71,4% of the patients. The maximum increase of B2M levels is detected immediately after surgery (median increase of 2,01 mg/L). B2M levels decreased the following days. 2 patients with OR duplicated B2M levels after nosocomial sepsis.

Conclusions Neonates with PHH exhibit higher levels of B2M in CSF compared with the literature. An isolated value of B2M could not be used as an infectious marker in patients with PHH. However, a sudden rises in patients with OR could be a good infectious predictor. Inflammatory response after surgery could increase B2M levels.