Just sat on a cold park bench, didn't change out of a wet swimming costume immediately, didn't drink enough, or had a particularly romantic weekend - for many women, just one of these activities is enough to be confronted with a constant urge to urinate, a burning sensation when urinating, pain in the abdomen and perhaps even a fever a short time later.

There it is again, cystitis. But what is actually behind this clinical picture, which - depending on the source - occurs in 60 to 80 percent of all women at least once in their lives, and in around half of them repeatedly?

Cystitis is - as the name suggests - an inflammation of the bladder. The inflammation is triggered by unwanted bacteria finding their way into the bladder and attaching themselves to the bladder wall.

But how do intestinal bacteria get into the vagina in the first place? The reason is of a "logistical" nature: in women, the exits of the bowel and bladder are very close together - so it doesn't take much for a bacterium to be able to cross this short distance. This usually happens due to poor intimate hygiene or frequent sexual intercourse - the latter also coined the term honeymoon cystitis.

From there, the bacterium only has to make its way through the urethra to reach the bladder. And this is also the second reason why men hardly ever have to deal with bladder infections, while for many women they are a sad everyday occurrence: The urethra measures 20 cm on average in men - in women it is just 4 cm.

Bladder infections are usually treated with antibiotics. Although they combat the infection and its annoying side effects relatively quickly, a course of antibiotics also has its pitfalls. In addition to the well-known side effects such as rashes and gastrointestinal problems, women in particular often also have to deal with vaginal fungi afterwards - they virtually swap one infection for another.

What's more, the next bladder infection often comes soon afterwards and with it the need for further antibiotic therapy, including its accompanying symptoms.

At this point at the latest, it becomes clear that a new approach is urgently needed. Fortunately, this already seems to have been found! We are talking about the vaginal microbiome.

The vaginal microbiome - also known as intimate flora - refers to the community of all microorganisms that colonise the vaginal mucosa: a diverse community of bacteria, fungi and other microbes that exist in a delicate balance.

The exact composition of the vaginal microbiome varies from woman to woman, but in general lactic acid-producing bacteria dominate. Each individual bacterial strain in this community has clearly defined tasks. It is therefore not only important that the microbiome is as diverse as possible, but above all that very specific bacterial strains are present in large numbers.

Overall, it is helpful if the microbiome contains as many "good" bacteria as possible - also because this means that there is simply no space for "bad" bacteria to colonise and multiply.

• Lactobacillus gasseri: As the name suggests, lactic acid bacteria produce lactic acid. This in turn creates an acidic environment that combats potentially pathogenic, i.e. harmful, germs - such as the aforementioned E. coli. Bacteria of the gasseri family are particularly effective.
• Lactobacillus crispatus: Bacteria of the crispatus family produce particularly high levels of hydrogen peroxide (H₂O₂), which also has an antimicrobial effect and thus prevents the growth of harmful germs.
• Lactobacillus delbrueckii: Studies have shown that bacteria from this family have great potential to protect against fungal infections.
• Lactobacillus plantarum: Here too, studies show that bacteria from the plantarum family have an effect on fungal infections.

This is where a crucial negative side effect of antibiotics comes into play. This is because they do not differentiate between "good" and "bad" bacteria. However, if certain bacterial strains are suppressed disproportionately by the therapy, for example, other strains can become prevalent.

Often the overall colonisation is simply inhibited, which means that there are too few bacteria overall to carry out the tasks at hand - fighting germs. As a result, the door is opened to a new infection - a vicious circle. For this reason, many affected women turn to so-called probiotics.

Probiotics are preparations that contain specific bacteria that colonise a microbiome and thus bring it back into balance. It should then be able to fully fulfil its tasks again - in the case of the vaginal microbiome, the defence against potentially harmful germs. Annoying infections could thus become a thing of the past.

But can this really work? And, if so, which preparation is best suited for this? Before we go into these questions in more detail, we would like to take a closer look at some common myths surrounding intimate health, the microbiome and probiotics.

Those affected by recurrent cystitis in particular report that the unpleasant burning sensation disappears after the first infections and that their cystitis is later mainly characterised by abdominal pain.

However, similar to a classic cold, it does favour an illness as it can impair the immune system. This in turn makes it easier for bacteria to settle and multiply. With regard to cystitis, it is also assumed that cold reduces blood circulation in the pelvic area, which in turn reduces the body's defences.

Several studies show that when certain lactobacilli are taken orally over a certain period of time, these same lactobacilli are found in greater quantities in the vaginal microbiome. A trial with Lactobacillus plantarum in women with a fungal infection even showed an improvement in symptoms in addition to the higher colonisation with this strain.

We explain below why all these points are decisive for the quality of a product. One thing is certain in any case: microculture preparations are clearly the kind of products that should not be bought on the spur of the moment, but only after thorough research if you don't want to be disappointed.