Lactitol and neomycin: monotherapy or combined therapy in the prevention and treatment of hepatic encephalopathy?

The beneficial effect of disaccharides, lactulose and lactitol, in prevention adn treatment of hepatic encephalopathy is well established but their use in combination with neomycin is still controversial. We studied in vitro the fecal bacterial growth, acid and gas formation in presence of lactitol (beta-galactoside-sorbitol) and neomycin alone or in combination. The results indicate that neomycin only inhibits the growth of susceptible bacteria (E. coli, Staph. aureus) which, conversely, are poor lactitol fermenters. The resistant organisms (Lactobacillus acidophilus, Clostridium perfringens) that are efficient disacchride fermenters continue to metabolize lactitol still when antibiotic is added. Addition of lactitol 10% increaded the inhbitory effect of neomycin on bacterial growth by 25-50% within 60-70 min. These preliminary data suggest that lactitol and neomycin may have additional or symergistic effects in vivo when used together in presence of favourable intestinal microbial environment.