Bacterial infections are common in patients suffering viral hepatitis and critical for prognosis. However, any correlation between HBV and concomitant bacterial infections is not well characterized. A retrospective study was conducted from Jan 2012 to Jan 2014 on 1333 hospitalized patients infected with bacteria. Among them, 491 HBV-infected patients were co-infected with E. coli (268), S. aureus (61), P. aeruginosa (64) or K. pneumoniae (98). A group of 300 complication-free chronically HBV-infected patients were controls. We found that HBV DNA levels were elevated in patients with each of the bacterial infections (all P < 0.05). ALT and HBeAg were strong determinants of high HBV DNA concentration. Patterns of determinants varied in infections by Gram-positive and Gram-negative bacteria. Patients with HBV DNA ≥ 2000 IU/mL had higher rates of all four concomitant bacterial infections (all P < 0.001). All types of strains isolated from HBV-positive patients showed less resistance to tested antimicrobials. The HBV DNA serum concentrations were inversely correlated to the number of ineffective antimicrobials in E. coli, P. aeruginosa and K. pneumoniae infections (P = 0.022, 0.017 and 0.016, respectively), but not S. aureus (P = 0.194). In conclusion, bacterial infections are associated with a high level of HBV replication, which, in turn, has a significant positive impact on bacterial resistance to antimicrobials. These correlations vary between Gram-negative and Gram-positive bacteria.