Objectives:

It has been shown that mecillinam affects the normal oropharyngeal, intestinal and skin microflora to a minor extent. The effect on the vaginal microflora is not known. The objective of this project was to study the ecological impact of pivmecillinam on the normal vaginal microflora.

Methods:

Eighteen healthy women, 24–40 years old, with one sexual partner and not being infected with sexually transmitted pathogens were included in the study. The day of ovulation was determined during three subsequent menstrual cycles. Microbiological and clinical examinations were performed on the day of ovulation and on day 3 in all cycles and also on day 7 in cycles 1 and 2. The clinical examinations included observation of vaginal and cervical epithelium, photographing of cervix, pH- measurements and inspection of any discharge. Vaginal specimens were collected with sterile swabs at each visit. The specimens were diluted in pre-reduced medium, diluted 10-fold and inoculated on selective and non-selective agar plates. All different colony types were counted and identified to genus level. Pivmecillinam was administered 200 mg t.i.d. for 7 days starting on the day of ovulation in cycle 2.

Results:

Anaerobic and facultative Gram-positive rods, mainly species of lactobacilli and actinomyces, dominated the vaginal microflora. Lactobacilli were only isolated sporadically in five of the women, all of whom were also colonised with Gardnerella vaginalis. G. vaginalis was further isolated from seven subjects. The aerobic microflora was dominated by species of corynebacteria. Seven women were colonised with Escherichia coli in low numbers in one to three samples. Four women were colonised in cycle one only, one in cycle one and on day 1 in cycle 2, and two women were colonised on day 3 and on day 7 in cycle 2, respectively. Candida albicans was isolated from four women and C. dublinensis from two. Five of these women had a microflora with a high percentage peroxidase-producing lactobacilli (>80%) while one subject had no H₂O₂-producing strains. Four of the women were colonised in all or in seven of eight samples, one was colonised on days 3 and 7 in cycle 2 and one women in cycle 3 only. There were variations in numbers of microorganisms between the menstrual cycles but not related to the administration of pivmecillinam.

Conclusion:

Administration of pivmecillinam did not have any major ecological impact on the normal vaginal microflora.