[Biological indicators of bacterial infection in newborn infants]

Biological markers of neonatal bacterial infection are useful if they bring early indications and if they are sensitive and specific. There are two kinds of tests: hematological signs and acute phase proteins. The most specific hematological signs are, in chronological order: leuconeutropenia--myelemia--neutrophilic polynucleosis. Gestational and post-natal ages have to be taken in consideration for correct interpretation of white cell count and differential. Several acute phase proteins increase in infected newborns: fibrinogen, C reactive protein, orosomucoïd. If determined quantitatively, C reactive protein is a sensitive, specific and early marker allowing, in addition, to follow the reaction to treatment: the return to normal range of CRP and later of orosomucoïd attest for recovery. These biological tests have to be sequentially determined during the first days in order to obtain a maximal information.