Probiotic bacteria improve diarrhea in infants

Each year more than half a million infants worldwide, primarily in developing countries, die from diarrhoea caused by rotavirus.

Even in industrialised countries management of the infection costs economies about $1 billion a year. Now a study in the online open access journal, BMC Microbiology demonstrates that with the addition of probiotic bacteria, preventative measures can potentially be made far cheaper but just as effective.

In a collaborative study by researchers investigating rotaviral diarrhoea, 'good bacteria' (probiotics) were combined with antibodies known to cure rotaviral-caused diarrhoea, resulting in a reduced incidence of gastro-intestinal infection in animal model. The researchers found that the Lactobacillus rhamnosus GG probiotic strain, in combination with a lower dose than usual of antibodies, provides protection against infection that is almost as effective as a higher dose of the antibodies alone, thus making a saving of up to 90% on antibodies to treat diarrhoea.

The antibody chosen, hyperimmune bovine colostrums (HBC), is known to be effective in clinical settings as a cure of rotaviral diarrhoea, but is an expensive treatment.

The research team led by Neha Pant at the Karolinska Institute and the University of Linkoping in Sweden and from the Nestle Research Center in Switzerland, compared the efficacy of six probiotic bacteria in combating diarrhoea in animal models. Research showed that 59 percent of animal subjects did not develop rotaviral diarrhoea when L. rhamnosus GG was given before infection with rotavirus. In comparison, only 7 percent of mice escaped rotavirus infection without prophylactic intervention. The other five probiotic bacteria strains tested were either less efficacious preventives or were not at all effective.

Armed with these results the team next tested the same six probiotics strains as a prophylactic in combination with the antibody, HBC. Crucially for the potential of prophylactic combination therapy, intestinal measurements of viral loads confirmed that HBC in combination with L. rhamnosus GG provided almost total protection at the low dose of 10 µg. If administered alone a higher dose of 100 µg of the antibody (HBC) is needed to be effective.

A dose of 100 µg is the most promising approach to prophylaxis against rotaviral diarrhoea, but a combination therapy of a low, 10 µg dose of HBC and L. rhamnosus GG is nearly as effective. "The implications of this study are very positive for low-income countries" says Neha Pant "Antibodies and probiotics could be used to complement the standard oral rehydration therapy for fluid loss during diarrhea, and may help to relieve the immense disease burden posed by rotavirus in the developing world.