Background
The GNRCS has monitored invasive infections associated with Streptococcus agalactiae (Group-B streptococcus, GBS) in Germany since 1990. Here, we report on the progression of invasive group-B streptococcal disease (IBD) between 2010 and 2021 with special attention to serotype distribution and antimicrobial resistance.
Methods
Species identification was based on haemolysis-assessment, Lancefield-typing, catalase-, pyrrolidonyl-arylamidase- and leucine-aminopeptidase-test. Serotype assignment was performed using multiplex-PCR techniques and serum-agglutination. Determination of minimum inhibitory concentration for eleven antibiotics was executed following CLSI guidelines.
Results
In the study period, 1238 cases of IBD were reported. More than 90% of the isolates were cultivated from blood with serotypes III (34%), Ia (21%) and V (17%) dominating. In the age group 51-90 years, the serotype distribution was considerably diverse, whereas in newborns a domination of serotype III was observed, mainly in late onset disease (LOD). In early onset disease (EOD) the serotype distribution was more various, comparable to GBS isolates from asymptomatic anal-vaginal-swabs. IBD isolates were mostly susceptible to penicillins, cefotaxime, vancomycin and chloramphenicol, but non-susceptibility to tetracycline remained stable at ≈80%. Erythromycin non-susceptibility increased from ≈1% in 2010 to ≈33% in 2021 and levofloxacin-resistance increased from ≈1% to ≈7%. First penicillin/amoxicillin resistant isolates were observed for serotypes Ia (2 in 2018) and Ib (1 in 2019), which are increasing, especially in EOD and the elderly.
Conclusions
IBD in Germany mainly affects older people and newborns, with serotype III dominating LOD. The observed gain in antimicrobial resistance, especially the appearance of penicillin/amoxicillin non-susceptible isolates in the expansionary serotypes Ia and Ib is alarming.