Intrapartum antibiotics and early onset neonatal sepsis caused by group B Streptococcus and by other organisms in Australia

Objective. Early onset group B streptococcal (EOGBS) infection, the major n eonatal infection in industrialized countries, can be prevented by intrapar tum antibiotics, but population studies are lacking. This study aimed to de termine the incidence of early onset infections caused by group B Streptoco ccus (GBS) and other organisms in Australia and to assess intrapartum antib iotic use. Design. Longitudinal, prospective surveillance of neonatal infections in Au stralian neonatal units from 1991 to 1997. Early onset infection defined as clinical sepsis in first 48 h after birth, with positive cultures of blood or cerebrospinal fluid or positive urine GBS antigen detection. Results. The incidence of EOGBS sepsis fell from 2.0 per 1000 live births ( 95% confidence interval, 1.4, 2.5) in 1991 to 1993, to 1.3 (1.2, 1.4) in 19 93 to 1995, to 0.5 (0.4, 0.7) in 1995 to 1997 (P < 0.0001), The incidence i n Aboriginal babies was 5.2 (1.8, 8.6) in 1991 to 1993, 5.1 (3.0, 7.2) in 1 993 to 1995 and 1.8 (1.1, 2.5) in 1995 to 1997 (P < 0.05). The incidence of early onset infections caused by organisms other than GBS also fell, from 1.2 per 1000 lire births (0.8, 1.7) in 1991 to 1993, to 0.8 (0.7, 0.9) in 1 993 to 1995 and 0.5 (0.3, 0.7) in 1995 to 1997 (P < 0.0001). In 1991, 3 of 9 study hospitals had a formal policy on intrapartum antibiotic use, wherea s in 1997 all 11 hospitals had a formal policy (P = 0.002). Conclusions. A steady fall in EOGBS infections in Australia from 1991 to 19 97 has been associated with increasing use of intrapartum antibiotics. Incr eased antibiotic use is probably causal in the fall in GBS, because the inc idence of early onset Infections caused by other organisms has also fallen.