Molecular epidemiology of invasive neonatal Streptococcus agalactiae isolates in Germany.

Background: Streptococcus agalactiae [group B streptococcus (GBS)] is a well-known cause of invasive infections leading to sepsis and meningitis in neonates. A comprehensive nationwide active surveillance study over 2 years was performed in Germany to describe the molecular epidemiology among 296 invasive neonatal GBS isolates.

Methods: Isolates were typed by pulsed-field gel electrophoresis (PFGE). Typing results were compared with serotypes as well as to clinical data on disease onset, meningitic involvement, and outcome.

Results: A remarkable clustering was found with about 60% of all typeable invasive isolates being annotated to one of 7 major PFGE groups, and clusters being nationally widely spread over the whole time period. Despite heterogenic elements, certain PFGE groups were closely related to singular serotypes, especially serotypes V (82%), Ia (84%), and Ib (77%). PFGE groups and serotypes were also partly related to clinical presentation as either early onset disease or late onset disease, and either meningitis or nonmeningitic GBS disease, but not to outcome.

Conclusions: There is a remarkable clonality among invasive GBS isolates that are widely spread geographically and in time; however, no specific clonal lines could be correlated to disease severity and outcome.