Urinary tract infections (UTIs) are among the most prevalent infectious diseases globally, impacting 150 million people annually, resulting in significant morbidity and high medical expenses. While the symptoms of UTIs can differ based on the location of these infections, they adversely affect patients’ personal and social relationships, leading to diminished quality of life. In India, the prevalence of UTIs ranges from 21.8% to 31.3%.
Bacteria are the predominant causative agents responsible for UTIs, although more rarely, other microorganisms like fungi and certain viruses have also been identified. Uropathogenic E. coli (UPEC) is the most frequent cause of uncomplicated and complicated UTIs. Most UTIs are caused by Gram-negative and Gram-positive bacteria that reside in the colon, like E. coli, Enterococcus faecalis, Proteus mirabilis, and Klebsiella pneumoniae. Other pathogens, including Staphylococcus saprophyticus, Group B Streptococcus (GBS), and Pseudomonas aeruginosa, can also be responsible.
UTIs often begin when uropathogens from the gut colonize the urethra and later the bladder by specific adhesins. If the host’s inflammatory response does not clear all bacteria, they proliferate, producing toxins and enzymes that facilitate their survival. Further colonization of the kidneys can lead to bacteremia if the pathogen crosses the kidney epithelial barrier.