Dysbiosis of the urinary microbiome - a potential cause for cystitis in women

Background: Urinary tract infection (UTI) is a common bacterial infection that is usually diagnosed by symptoms such as dysuria and frequency, and the golden standard is to take a urine culture to identify bacteria that may cause UTI. This method was founded with the idea that normal urine is sterile, but this is now being questioned because of growing evidence of a urinary microbiota thus giving a new approach to methods for UTI diagnosis. Aim: To identify and re-evaluate findings of bacteria from urine cultures in the ongoing paradigm shift of a potential urinary microbiome, and dysbiosis as a cause for UTI. Materials and Methods: This study used MALDI-TOF MS to identify approximately 250 bacteria isolates that had been cultured by Expanded Quantitative Urine Culture (EQUC) from 162 women with symptoms of cystitis. EQUC had allowed the bacteria to grow in both CO2 and anaerobic conditions, which differs from standard techniques. Results and Conclusion: Escherichia coli and Enterococcus faecalis dominated the results of most frequently identified bacteria. However, other bacteria were commonly present within the same culture which is traditionally considered as contamination but may now indicate a urinary flora. Anaerobic bacteria – such as Porphyromonas sp. – were also identified, but their connection to UTI is unclear. Lactobacillus sp. – which are associated with a healthy flora in women – were found in urine cultures and often in smaller quantities which could suggest dysbiosis. More research on Lactobacillus sp. and their correlation with UTI is suggested for a more accurate indication of urinary dysbiosis in women.