The persistence of microbial infections is a significant issue in healthcare and needs to be addressed urgently. While many studies have investigated the role of adhesins and surface-exposed proteins in host interactions, the role of metabolic processes that provide the energy for pathogen survival in the host is generally less well understood. Here we have investigated how access to growth substrates and metabolic end-product production contribute to H. influenzae virulence. Phenotypic, metabolic and virulence properties of strains carrying mutations in ribose utilization genes rbsB, rbsK, rpiA and genes encoding succinate-producing enzymes, frdA and sucC, of H. influenzae (Hi) 2019 were investigated. For in vitro growth, ribose mutants showed defects growing with ribose as expected, and interestingly, both mutant types also showed reduced growth with nucleosides. End-product analysis by 1H-NMR metabolomics revealed Hi2019 to utilize ribose moiety from uridine and inosine, and left uracil and hypoxanthine, respectively in the medium. frdA mutant strain showed a strong phenotype with 3% of wildtype succinate production during anaerobic growth on glucose, while sucC mutant strain showed 17% reduced production of succinate. Ribose mutant strains showed wildtype metabolic end-product formation. All strains produced about 10-15% less ATP during the growth on glucose and uridine, indicating a less optimal use of the metabolic network. The rbsB and rpiA mutant strains exhibited increased biofilm formation, while the other mutations had no effect. Even though they showed less evidence of metabolic network issues, mutants in ribose metabolism showed reduced fitness during intracellular survival in infection assays using 16HBE14 bronchial epithelial tissue cells and mouse macrophages. In contrast, frdA and sucC mutant strains had no phenotype in tissue cell infections. Despite showing a less pronounced phenotype in vitro, the inability to access ribose as a growth substrate appeared to have a greater impact on Hi virulence and particularly affected intracellular survival. In contrast, the loss of succinate seemed to have little relevance for persistence.