Scientist - News - 17-07-2009:

Lactobacillus and vaginal infection
Beintema, Nienke

Two recent studies presented positive results on the use of Lactobacillus against bacterial vaginosis. One concluded that the probiotic supports the effect of certain antibiotics, and the other investigated the mechanisms behind its antibacterial action.

Bacterial vaginosis (BV) is a very common cause of vaginal infection. Although symptoms are not always present, the condition may cause rash, itchiness or even pain. It has also been associated with an increased risk of gynaecologic complications and transmission of HIV.
BV is usually treated with one or more antibiotics. These, however, may result in side effects such as diarrhoea and nausea, and also in bacterial resistance. Scientists are therefore searching for alternative ways to combat the bacterial infection.

Review
The Cochrane Collaboration, an independent international organisation dedicated to studying and disseminating healthcare information, conducted a systematic review into the effectiveness and side effects of a number of treatments against BV. The review, which was published mid-July, analysed 24 trials involving 4422 women. The conclusion was that Lactobacillus combined with the antibiotic metronidazole was more effective than metronidazole alone. This was the case both for oral administration of Lactobacillus, and for administration in the form of an intravaginal gelatin tablet. The researchers concluded that the probiotic is an effective help in the treatment of BV, but that more research is needed into possible side effects.
"Treating BV could help reduce susceptibility of women to HIV," said lead researcher Oyinlola Oduyebo, of the University of Lagos in Nigeria, in the Cochrane press release. "Therefore it is important, particularly in the developing world, to establish the most effective and appropriate forms of treatment."

Bactericidal peptins
The second study, performed by the Lactobacillus Reference Centre in Tucumán, Argentina, was published online in the journal Research in Microbiology on 8 July. It looked into two bactericidal peptins produced by Lactobacillus salivarius, a probiotic naturally present in the human vagina. It concluded that the two peptins, salivaricin α and β, are most effective when present in equal proportions. The researchers studied the effect of these two peptins on cells of the bacterium Enterococcus faecalis, a common cause of BV. They noted that the peptins alter the membrane potential of the bacterial cell, and effectuates changes in the bacterial cell wall. Both these effects were shown to impair the functioning of the bacterial cell.
The Argentineans suggest that Lactobacillus could prevent bacterial overgrowth by other bacteria, and could offer a potential alternative for replacement of antibiotics in the prophylaxis of urogenital tract infections.

More information:
Cochrane review
Cochrane press release
Article in the journal Research in Microbiology