The bacterial epidemiology of bacterascites and spontaneous bacterial peritonitis is evolving. Four hundred and eleven strains isolated from ascites in cirrhotic patients from 5 French hospitals were isolated in 2006 and 2007. Of these, 114 were definitely associated with spontaneous bacterial peritonitis. The proportion of Gram-positive and Gram-negative agents was quite similar, even after excluding coagulase-negative staphylococci, or when considering only definite spontaneous bacterial peritonitis or community-acquired strains. Staphylococci and Escherichia coli were the most frequent pathogens, but enterococci were also involved in nearly 15% of the cases. Among the E. coli, 28% were intermediate or resistant to amoxicillin+clavulanate, 5.3% expressed cephalosporinases or extended beta-lactamases and 17.3% were intermediate or resistant to fluoroquinolones. Resistance to methicillin was observed in 27% of Staphylococcus aureus. Cefotaxime and amoxicillin-clavulanate remained the most effective 'single' agents, however on less than 70% of isolates. Some combinations (such as cefotaxime+amoxicillin) extended coverage to a further 15% of strains. Since inadequate empiric antibiotic therapy is associated with increased mortality, these combinations may be of great interest as first-line treatment, even though they may also lead to the development of antimicrobial resistance. Repeated epidemiological surveys and new clinical trials are thus needed.