Group B streptococcus colonization of Greek pregnant women and neonates: prevalence, risk factors and serotypes

Objective To evaluate the prevalence and risk factors of group B streptococcus (GBS) colonization among pregnant women and their neonates in Greece, and to examine the serotype distribution of the GBS strains isolated and their susceptibility to antibiotics. Methods A vaginal and a rectal swab were obtained from 1014 pregnant or parturient women followed at public and private hospitals in Athens and in a city of northern Greece. Cultures were also taken 24 h after birth from 428 neonates born to these women. Results The overall maternal and neonatal colonization rates were 6.6% and 2.4%, respectively. The vertical transmission rate was 22.5%. By logistic regression analysis, multiparity (greater than or equal toIII) was associated with a lower colonization rate (odds ratio 4.4, 95% confidence interval 1.08-18.63). In contrast with other studies, middle-class women followed privately were more frequently colonized (10%) than those followed at the public hospital (3.9%) (odds ratio 3.1, 95% confidence interval 1.83-5.42). A higher number of prenatal visits was also associated with a higher colonization rate (change in true odds ratio when visits increased by one, 1.3; 95% confidence interval 1.14-1.60). No association was found between colonization and maternal age, previous obstetric history, marital status, nationality, prematurity, Caesarean section, or infant birth weight. The most common serotypes were II (26.9%), III (22.4%), Ia (19%), Ib (12%), and V (9%). A considerable proportion of the isolated strains was resistant to erythromycin (4.5%), clindamycin (6%), or both (6%). Conclusion The rate and risk factors of maternal and neonatal GBS colonization may vary in different communities. These rates, as well as the incidence of neonatal disease, need to be thoroughly evaluated in each country to allow the most appropriate preventive strategy to be selected.