Abstract: Objectives　To explore the clinical characteristics and inflammatory indexes of early-onset and late-onset group B Streptococcus (GBS) sepsis in infants. Methods　The clinical data of infants diagnosed with GBS sepsis admitted from January 2011 to December 2019 were analyzed retrospectively. According to the onset age they were divided into earlyonset group (within 7 days) and late-onset group (rang 7 to 89 days). The perinatal factors, clinical characteristics and related inflammatory indexes between the two groups were compared. Results　There were 71 infants with GBS sepsis, including 43 in the early-onset group and 28 in the late-onset group. The median age at onset was 5 hours in the early-onset group and 17 days in the late-onset group. The incidence of primiparity, preterm delivery, premature rupture of membranes (PROM), PROM≥18h, tachypnea/grunting, pneumonia and thrombocytopenia in the early-onset group were higher than those in the late-onset group. The incidence of fever, the time to reach the lowest number of leukocytes and the lowest value of platelets were lower than those in the late-onset group, and the difference were statistically significant (P<0.05). Four children died, all of whom were in early onset group and 3 of whom were very low birth weight infants. The sensitivity of the two groups of infants to penicillin, ceftriaxone, vancomycin was 100%. Conclusions　Early-onset GBS sepsis often has respiratory symptoms as the primary manifestation, is prone to thrombocytopenia, and has a high mortality in very low birth weight infants. Fever is the primary symptom of late-onset GBS sepsis. The sensitivity of blood and cerebrospinal fluid culture strains to penicillin, ceftriaxone, and vancomycin was 100%.

Key words: 　group B streptococcus;　sepsis;　early-onset;　late-onset;　clinical characteristics