GROUP-B STREPTOCOCCUS IMPAIRS ERYTHROCYTE DEFORMABILITY IN NEONATES MORE THAN IN ADULTS

Group B beta-haemolytic Streptococcus (GBS) may cause severe septic sh ock and death in neonates, whereas this is rarely the case in adults. As impaired red blood cell (RBC) deformability might disturb microcirc ulation in septic shock, the in vitro effects of GBS (1.7 x 10(8) cfu/ ml) on RBC deformation (rheoscope) and haemolysis were studied in bloo d from preterm infants, term neonates, and adults. Furthermore, RBC de formation was studied in term neonates with GBS sepsis. RBC deformatio n at a shear stress of 4 Pa decreased significantly within 5 minutes o f GBS incubation in preterm infants (-13%) and term neonates (-9%). In adults RBC deformation did not change during the first 15 minutes, bu t decreased significantly after 30 (-10%) and 60 minutes (-13%). In th e term infants there was little further decrease in RBC deformation be tween 5 and 60 minutes of GBS incubation; RBC deformation in preterm i nfants decreased by 19% after 60 minutes compared with the preincubati on values. RBC deformation in septic neonates was significantly decrea sed at shear stresses of 1, 2, and 3 Pa (-19%, -18%, and -9%). Sixty m inutes of incubation of RBC from adults and neonates with GBS and with out GBS resulted in haemolysis below 4%. It is concluded that neither neonatal nor adult RBC are haemolysed by GBS. In vitro, neonatal RBC d eformability is more impaired than that in adults. This may contribute to the high risk of neonates for compromised microcirculation and cir culatory shock as a result of GBS sepsis.