In this study, we demonstrated that, compared to patients who took only placebo following antibiotic therapy, participants who took the probiotic containing
Lactobacillus casei DG
® achieved milder symptoms and a faster recovery from prostatitis relapses. Prostatitis is an inflammation of the prostate gland quite common. As described in a systematic review, on a population exceeding 10.000 patients, prevalence can be estimated of 8.2%, with 35-50% of men that reported to have experienced a symptomatic prostatitis event in their lifetime [
15]. Chronic prostatitis, which we have examined, can present with very debilitating symptoms as urogenital pain, lower urinary tract symptoms (nocturia, dysuria, hematuria, stranguries), haemospermia, fever and/or sexual dysfunction [
16,
17]. The symptoms usually continue for at least 3 months and that present as relapses typical of the chronic condition after variably prolonged periods of remission [
18]. As numerous studies demonstrate, Bacterial infection is considered a causal factor that triggers the prostatic inflammatory response [
19,
20,
21]. Hence, the use of antibiotics as a treatment for chronic prostatitis, especially fluoroquinolones which have the best pharmacological properties for treating bacterial prostatitis. Antibiotics with good penetration into the prostate tissue also include trimethoprim-sulfamethoxazole, clindamycin, doxycycline, and azithromycin [
22]. Antibiotic therapy for chronic bacterial prostatitis is effective. However, it requires the use of a long-lasting treatments (fluoroquinolones up to 6 months, depending on the severity of the pathological form) and which therefore increases the risk of developing antibiotic resistance and triggering interactions especially in poly-treated patients [
22]. Probiotics are active microorganisms belonging to strains already present in the human intestine and which, once they reach the enteric tract, multiply and rebalance the intestinal microflora. Therefore, probiotics must resist the digestive action of gastric juice, bile salts and digestive enzymes and, once it reaches the intestine, it must be able to adhere to intestinal cells, multiply and colonize them. Therefore, it must give a beneficial effect by antagonizing pathogenic microorganisms without, however, triggering immune reactions. Probiotics are commonly used to strengthen intestinal immunity and counteract enteritis and diarrhea that is infectious, drug-related or food intolerance. Currently, however, many studies are underway to find new possible therapeutic uses given the varied influence that the microbiota regulation exerts on many systems. The gut microbiota, in fact, is considered almost as a "forgotten organ" capable of establishing multidirectional communications with other organs [
5]. Many studies reveal that probiotics promote the development of the postnatal immune system inhibiting the activated CD4+ T cells [
23].
Moreover, lactobacilli promote the activation of dendritic cells, which are essential for activating the immune response [
24]. In our study, we evaluated the effects of a formulation containing 24 billion live cells of
Lactobacillus casei DG
® in managing chronic prostatitis.
Lactobacillus casei DG
® is a Gram-positive bacterium normally present in our gut flora and commonly used to modulate the structure and functionality of the gut microbiota [
25,
26,
27]. All enrolled patients completed the study and showed a normalization in the composition of gut and seminal microorganisms at the end of the treatment. However, patients enrolled in
Lactobacillus casei DG
® group presented a faster recovery from prostatitis and milder symptoms than patients who took placebo alone. It is probably the reason for a faster clinical recovery demonstrated also by other authors [
22,
28]. Psychosocial and psychiatric disorders, as anxiety and depression, are usually also associated with chronic diseases and negatively affect the quality of life [
29,
30]. In agreement with this study, we reported that patients with chronic prostatitis show anxiety and depression with a decrease in the quality of life. These symptoms improved at the end of the study with a time-dependent pattern, particularly in patients enrolled in the probiotic group. Finally, in enrolled patients, we did not record the development of adverse drug reactions or drug interactions, revealing the probiotics are safe in all people. The low number of enrolled patients and the absence of a specific evaluation of inflammatory or immune biomarkers represent a limitation of the present study.