Fiona M. Lewis There has been increasing interest in the normal human microbiological environment over recent years. Previous studies have been based around culture of the organisms which showed micrococci, haemolytic streptococci, diphtheroids, lactobacilli, Staphylococcus aureus, and coagulase negative staphylococci on the vulva. With advances in molecular techniques, the ability to demonstrate many new and different species has shown distinct microbiomes that vary with site. The microbiological environment is a balance between resident and transient organisms. Resident organisms are ones that live at a site and multiply there, whereas transient ones come from another source but do not stay. The vaginal microbiota has been studied intensively, but far less is known about the normal microbiology of the vulva. However, the vaginal microbiome is important in the management of vulval disease as the vulva can be affected by changes in the vaginal environment. The vulva is a unique site as it is a junction between keratinised skin and non‐keratinised mucosa. It is also close to areas that have their own distinct microbiome such as the urethra, anus, and inguinal fold. Contamination with transient organisms from these sites can therefore complicate the assessment of what is normal for the vulval micro‐environment. The normal microbiome is important as disruption will lead to an increase in organisms that may cause bacterial vaginosis, candidiasis, and urinary tract infections. The vulval microbiome is complex and diverse. In a series of four women studied with targeted 16S rRNA gene studies, the microbiota was different in each case, and no single organism was common to all individuals [1]. In a previous study of 39 healthy women, microbial counts were significantly higher on the vulva than on the forearm, with a greater incidence of S. aureus (67% versus 11%) [2]. The microbiome is unique to the individual but can be influenced by the local environment and host factors such as menstruation, pregnancy, and menopause. Hygiene practices, the oral contraceptive, and spermicides will all have an effect. The vulval micro‐environment can be influenced by the use of sanitary products, but vapour‐permeable panty liners did not seem to have a significant effect as opposed to those that are non‐permeable [3]. The human skin microbiome has distinct patterns at different sites [4]. The inguinal fold is an occluded site with increased temperature and humidity. The commonest organisms at these sites are Corynebacterium species and S. aureus as they thrive in the moist conditions found here. Moving to the inner vulva, differences between the labia majora and labia minora have been demonstrated [1]. The microbiological environment on the labia majora was similar to that of the skin, with S. epidermis and Corynebacterium species predominating, but Enterococcus faecalis was also present.
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Normal Microbiology of the Vulva
The vulval microbiome
Variations in site
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