When the urinary tract becomes infected, urinary tract infections (UTIs) occur. The majority of UTIs are brought on by the intestinal bacteria E. coli.
Some people are more likely than others to develop a UTI. Due to shorter urethras and proximity to the rectum’s bacteria, UTIs are more common in females.
Additional factors that can raise the risk of UTIs:
A previous UTI
Sexual activity
Some forms of birth control
Variations in the bacteria that live inside the vagina (vaginal flora)
Pregnancy
Age (older adults and young children have a higher chance of getting UTIs)
Urinary tract blockage issues such as kidney stones or an enlarged prostate
Lack of proper hygiene — for example, in children who are potty training.
Compromised immune system
Using a catheter
It's not always the case that bacteria in the bladder indicate an infection. The bladder, like the intestines, contains healthy bacteria and other microbes that support its health and proper function.
Sources:
US Department of Health and Human Services, National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Bladder Infection in Adults (https://www.niddk.nih.gov/health-information/urologic-diseases/bladder-infection-uti-in-adults/definition-facts). Accessed 01/19/2023.
US Department of Health and Human Services, National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Bladder Infection in Adults (https://www.nichd.nih.gov/health/topics/urinary/conditioninfo/causes#f1). Accessed 01/19/2023.
Centers for Disease Control and Prevention. Antibiotic Use. (Urinary Tract Infection) (https://www.cdc.gov/antibiotic-use/uti.html). Accessed 01/19/2023
Mayo Clinic. Urinary Tract Infection. (https://www.mayoclinic.org/diseases-conditions/urinary-tract-infection/symptoms-causes/syc-20353447). Accessed 01/19/2023.