Objective Mortality in very low birth weight infants following microbiology confirmed primary bloodstream infections varies with the type of causative pathogen. Given evidence from other studies that infections with gram negative bacteria and fungi cause a higher case fatality risk. We tried to confirm this in a nation-wide multi-center trial. Methods A cohort of 55,465 very low birth weight infants from 242 neonatal departments participating in the German national neonatal infection surveillance system NEO-KISS was used to investigate differences in the case fatality risk of microbiology confirmed primary bloodstream infections according to individual pathogens. Cox proportional hazard regression analyses were performed with the outcomes death and time from microbiology confirmed primary bloodstream infections. The results were adjusted to the recorded risk factors and hospital and department characteristics. Results A total of 4 094 very low birth weight infants with microbiology confirmed primary bloodstream infections were included in the analysis. The crude case fatality risk was 5.7%. The Cox proportional hazard regression analysis with adjustment for available risk factors revealed that microbiology confirmed primary bloodstream infections caused by Klebsiella spp. (HR 3.17 CI95 1.69–5.95), Enterobacter spp. (HR 3.42 CI95 1.86–6.27), Escherichia coli (HR 3.32 CI95 1.84–6.00) and Serratia spp. (HR 3.30 CI95 1.44–7.57) were associated with significantly higher case fatality risk compared to Staphylococcus aureus. After adjusting, case fatality risk of Candida albicans causing microbiology confirmed primary bloodstream infections was not higher than that of S. aureus. Conclusion In very low birth weight infants, bloodstream infections caused by gram negative pathogens have an increased case fatality risk compared to bloodstream infections caused by gram positive pathogens. This should be considered for prevention and therapy. Further research should address the specific risk factors for case fatality of C. albicans bloodstream infections.
