Lactulose is effective

EDITOR—D'Souza et al evaluated potential agents for the prevention of antibiotic associated diarrhoea, whose full spectrum of activity is immense both in the community and in hospital.1 In particular, the antitherapeutic default selection of Clostridium difficilewith resultant colitis is associated with a considerable morbidity and mortality.

Alteration of the faecal flora is attractive as a low risk means of preventing or, possibly, treating C difficileand associated infections.2 Induced disequilibrium of the colonic flora can be achieved either through supplemental probiotic loading or by therapeutic manipulation. Faecal flora can be manipulated through the use of lactulose, a synthetic disaccharide that is predominantly used as an osmotic laxative. It is neither absorbed nor metabolised in the upper gastrointestinal tract but is degraded by the bacterial flora of the proximal colon to organic acids. These acidify the proximal colon and result in a dose dependent catharsis.

Lactulose has several additional properties, including an antiendotoxin effect and alteration of faecal floral patterns.3 This quantitative alteration in faecal floral patterns, with an increase in faecal Lactobacillus acidophilus and a reduction in both coliforms and bacteroides, has been confirmed in our own unpublished work. A qualitative alteration in bacterial pathogenicity may result with lactulose as an alternative substrate.

Additional historical evidence shows effective treatment of shigellosis and salmonellosis with lactulose.45 Several …