Background: Bacteraemia with Streptococcus dysgalactiae has substantial mortality and morbidity. Time to positivity (TTP) from blood cultures has been proposed to be a possible predictor of mortality and of intravascular focus of infection in bloodstreams infections. This study aimed to determine possible correlations between TTP and outcome in invasive S. dysgalactiae infections.
Methods: This is a retrospective observational cohort study comprising all episodes of bacteraemia with Streptococcus dysgalactiae between the years of 2015-2018, in the Region of Skåne, Sweden. Clinical and microbiological data were collected from medical records. Primary outcome was set to 30-day mortality and secondary outcome was development of sepsis within 48 hours from obtained blood cultures.
Results: A total of 334 episodes of S. dysgalactiae bacteraemia were included in the study. The median TTP was 9.1 hours (interquartile range (IQR) 7.3-10.2). Thirty-one patients (9%) died within 30 days of infection. Median TTP was 7.5 hours (IQR 6.7-9.9) in patients who died within 30 days of admission, compared to 9.1 hours (IQR 7.5-10.2) surviving patients. This difference was statistically significantly shorter (p < 0.05 using Mann-Whitney U test). The majority of patient fulfilled criteria for sepsis (n = 191, 57%) within 48 hours from blood culturing. Median TTP was not statistically different in patients developing sepsis (9.0 hours (IQR 7-10.2)) compared to non-septic patients (9.1 hours (IQR 7.7-10.2)), p = 0.3.
Conclusions: TTP may be a beneficial tool in clinical practice, possibly providing prognostic information in bloodstreams infections with S. dysgalactiae.