The PAV trial: Does lactobacillus prevent post-antibiotic vulvovaginal candidiasis? Protocol of a randomised controlled trial [ISRCTN24141277]

A randomised placebo-controlled blinded 2 × 2 factorial design is being used. General practitioners or pharmacists approach non-pregnant women, aged 18–50 years, who present with a non-genital infection requiring a short course of oral antibiotics, to participate in the study. Participants are randomised in a four group factorial design either to oral lactobacillus powder or placebo and either vaginal lactobacillus pessaries or placebo. These interventions are taken while on antibiotics and for four days afterwards or until symptoms of vaginitis develop. Women self collect a vaginal swab for culture of Candida species and complete a survey at baseline and again four days after completing their study medications. The sample size (a total of 496 – 124 in each factorial group) is calculated to identify a reduction of half in post-antibiotic vulvovaginitis from 23%, while allowing for a 25% drop-out. An independent Data Monitoring Committee is supervising the trial. Analysis will be intention-to-treat, with two pre-specified main comparisons: (i) oral lactobacillus versus placebo and (ii) vaginal lactobacillus versus placebo.Use of complementary and alternative medicines (CAM) by the lay public and doctors remains a topic of controversy. In Australia and the United States, the estimated annual expenditure associated with CAM usage is $AUD2.3 billion and $US27.1 billion respectively, which is more than that spent on prescription medicines [1,2]. There is a relative lack of an evidence-base for CAM [3,4], which was emphasised by recent calls from a Health Minister for an investigation into whether health insurance funds should reimburse for use of unproven CAM therapies [5]. However, scant resources are available for CAM research [6,7] and the accepted method of assessing medical therapies, randomised controlled trials, can be challenging to apply to CAM [7,8].A common condition of concern to women, the largest consumers of CAM [1,9], is post-antibiotic vulvovaginitis (PA