Bacterial urinary tract infections (UTIs) most commonly involve the bladder (cystitis) or kidneys (pyelonephritis). Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain, and flank pain. Systemic symptoms and even sepsis may occur with kidney infection. Diagnosis is based on analysis and culture of urine. Treatment is with antibiotics and removal of any urinary tract catheters and obstructions.
(See also Introduction to Urinary Tract Infections, Gram-Negative Bacilli, Prostatitis, and Urinary Tract Infection in Children.)
Urinary tract infections (UTIs) are more common among women than men. Approximately 40 to 50% of women have ≥ 1 UTI in their lifetime, compared to approximately 5 to 12% of men (1, 2).
The incidence of cystitis in men increases with age because of structural changes that impair normal voiding such as benign prostatic hyperplasia (2).
General references
1. Bavanandan S, Keita N. Urinary Tract Infection Prevention and Treatment. Semin Nephrol. 2023;43(5):151468. doi:10.1016/j.semnephrol.2023.151468
2. Schaeffer AJ, Nicolle LE. Urinary Tract Infections in Older Men. N Engl J Med. 2016;374(22):2192. doi:10.1056/NEJMc1603508
Pathophysiology of Bacterial UTIs
The urinary tract, from the kidneys to the urethral meatus, is normally sterile and resistant to bacterial colonization despite frequent contamination of the distal urethra with colonic bacteria. The major defense against UTI is complete emptying of the bladder during urination. Other mechanisms that maintain the tract’s sterility include urine acidity, the vesicoureteral valve, and various immunologic and mucosal barriers.
The majority of UTIs occur when bacteria ascend the urethra to the bladder and, in the case of pyelonephritis, ascend the ureter to the kidney (1). The remainder of UTIs are hematogenous. Systemic infection can result from UTI, particularly in older adults. UTIs are a common cause of health care-associated infections (2).
Risk factors
Because many risk factors for UTIs differ significantly between men and women, it is useful to distinguish sex-specific factors from those that are common to both. General risk factors for UTI include the following (3):
History of previous UTIs
Recent instrumentation or indwelling catheters
Structural abnormalities (eg, urethral strictures, bladder diverticula)
Renal stones
Neurologic conditions that interfere with normal voiding (eg, spinal cord injury)
Cognitive impairment, fecal incontinence, or urinary incontinence
Immunosuppression
Risk factors for UTI in women include the following (4):
Sexual intercourse
Diaphragm and spermicide use
Antibiotic use
New sex partner within the past year
History of UTIs in first-degree female relatives
First UTI at an early age
Vesicovaginal fistula
Risk factors for UTI in men include the following (3):
Benign prostatic hyperplasia with obstruction, common among men over age 50
Any other cause of obstruction of the urinary tract (eg, prostate cancer, urethral stricture)
Unprotected anal intercourse
Uncircumcised
Previous or recurrent prostatitis
The increased risk of UTI in women using antibiotics or spermicides probably occurs because of alterations in the vaginal microbiota that allow overgrowth of Escherichia coli (5). In older women, soiling of the perineum due to fecal incontinence increases risk.
Anatomic, structural, and functional abnormalities are risk factors for UTI. A common consequence of anatomic abnormality is vesicoureteral reflux (VUR), which is identified on imaging studies in 30 to 40% of children after UTI (6, 7). VUR is usually caused by a congenital defect that results in incompetence of the ureterovesical valve. VUR can also be acquired in patients with a flaccid bladder due to spinal cord injury or after urinary tract surgery. Other anatomic abnormalities predisposing to UTI include urethral valves (a congenital obstructive abnormality), delayed bladder neck maturation, bladder diverticulum, and urethral duplications (see Overview of Congenital Genitourinary Anomalies).
Structural and functional urinary tract abnormalities that predispose to UTI usually involve obstruction of urine flow and poor bladder emptying. Urine flow can be compromised by calculi and tumors. Bladder emptying can be impaired by neurogenic dysfunction, pregnancy, uterine prolapse, cystocele, and prostatic enlargement. UTI caused by congenital factors manifests most commonly during childhood. Most other risk factors are more common among older adults.
Other risk factors for UTI include instrumentation (eg, bladder catheterization, stent placement, cystoscopy) and recent surgery.
Pathophysiology references
1. Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ. Urinary tract infections: epidemiology, mechanisms of infection and treatment options. Nat Rev Microbiol. 2015;13(5):269-284. doi:10.1038/nrmicro3432
2. Magill SS, Edwards JR, Bamberg W, et al. Multistate point-prevalence survey of health care-associated infections. N Engl J Med. 2014;370(13):1198-1208. doi:10.1056/NEJMoa1306801
3. Hooton TM, Stamm WE. Diagnosis and treatment of uncomplicated urinary tract infection. Infect Dis Clin North Am. 1997;11(3):551-581. doi:10.1016/s0891-5520(05)70373-1
4. Hooton TM. Clinical practice. Uncomplicated urinary tract infection. N Engl J Med. 2012;366(11):1028-1037. doi:10.1056/NEJMcp1104429
5. Handley MA, Reingold AL, Shiboski S, Padian NS. Incidence of acute urinary tract infection in young women and use of male condoms with and without nonoxynol-9 spermicides. Epidemiology. 2002;13(4):431-436. doi:10.1097/00001648-200207000-00011
6. Carpenter MA, Hoberman A, Mattoo TK, et al. The RIVUR trial: profile and baseline clinical associations of children with vesicoureteral reflux. Pediatrics. 2013;132(1):e34-e45. doi:10.1542/peds.2012-2301
7. Tullus K, Shaikh N. Urinary tract infections in children. Lancet. 2020;395(10237):1659-1668. doi:10.1016/S0140-6736(20)30676-0
Etiology of Bacterial UTIs
Cystitis and pyelonephritis are caused by enteric, usually gram-negative aerobic bacteria (most often) and by gram-positive bacteria (less often).
In patients with structurally normal genitourinary tracts, strains of E. coli with specific attachment factors for transitional epithelium of the bladder and ureters account for 80% of cases (1). The remaining gram-negative urinary pathogens are usually other enterobacteria, typically Klebsiella or Proteus mirabilis, and occasionally Pseudomonas aeruginosa. Among gram-positive bacteria, Staphylococcus saprophyticus is isolated in approximately 10 to 15% of bacterial UTIs. Less common gram-positive bacterial isolates are Enterococcus faecalis (group D streptococci) and Streptococcus agalactiae (group B streptococci), which may be contaminants, particularly if they were isolated from patients with uncomplicated cystitis.
In hospitalized patients, E. coli accounts for approximately 50% of cases (2). The gram-negative species Klebsiella, Proteus, Enterobacter, Pseudomonas, and Serratia account for approximately 40%, and the gram-positive bacterial cocci E. faecalis, S. saprophyticus, and Staphylococcus aureus account for the remainder.
Etiology references
1. Ronald A. The etiology of urinary tract infection: traditional and emerging pathogens. Dis Mon. 2003;49(2):71-82. doi:10.1067/mda.2003.8
2. Mathai D, Jones RN, Pfaller MA; SENTRY Participant Group North America. Epidemiology and frequency of resistance among pathogens causing urinary tract infections in 1,510 hospitalized patients: a report from the SENTRY Antimicrobial Surveillance Program (North America). Diagn Microbiol Infect Dis. 2001;40(3):129-136. doi:10.1016/s0732-8893(01)00254-1
Classification of Bacterial UTIs
UTIs are most commonly classified based on whether the infection is confined to the bladder or has extended beyond it (1).
Uncomplicated UTI refers to infection that is confined to the bladder in afebrile men or women. It is characterized by local bladder symptoms (eg, dysuria, urgency, frequency, suprapubic pain) without systemic symptoms or signs.
Complicated UTI refers to infection extending beyond the bladder and includes:
Febrile or bacteremic UTI
Acute cystitis
Cystitis is infection of the bladder.
Cystitis is common among women, in whom cases of uncomplicated cystitis are usually preceded by sexual intercourse.
In men, bacterial cystitis usually results from ascending infection from the urethra or prostate or is secondary to urethral instrumentation. The most common cause of recurrent cystitis in men is chronic bacterial prostatitis.
Acute pyelonephritis
Pyelonephritis is bacterial infection of the kidney parenchyma. In women, pyelonephritis is a common cause of community-acquired bacteremia. Pyelonephritis is uncommon in men with a normal urinary tract (2).
Pyelonephritis typically occurs because bacteria ascend through the urinary tract. Although obstruction (eg, strictures, calculi, tumors, neurogenic bladder, VUR) predisposes to pyelonephritis, most women with pyelonephritis have no demonstrable functional or anatomic defects. In men, pyelonephritis is always due to some functional or anatomic defect. Cystitis alone or anatomic defects may cause reflux. The risk of bacterial ascension is greatly enhanced when ureteral peristalsis is inhibited (eg, during pregnancy, by obstruction, by endotoxins of gram-negative bacteria). Pyelonephritis is common among young girls and pregnant patients after bladder catheterization.
Pyelonephritis not caused by bacterial ascension is caused by hematogenous spread, which is particularly characteristic of virulent organisms such as S. aureus, P. aeruginosa, Salmonella species, and Candida species.
The affected kidney is usually enlarged because of inflammatory polymorphonuclear neutrophils and edema. Infection is focal and patchy, beginning in the pelvis and medulla and extending into the cortex as an enlarging wedge. Cells mediating chronic inflammation appear within a few days, and medullary and subcortical abscesses may develop. Normal parenchymal tissue between foci of infection is common.
Papillary necrosis may occur in acute pyelonephritis associated with diabetes, obstruction, sickle cell disease, pyelonephritis in renal transplants, pyelonephritis due to candidiasis, or analgesic nephropathy.
Although acute pyelonephritis is frequently associated with renal scarring in children, similar scarring in adults is not detectable in the absence of reflux or obstruction.
Asymptomatic bacteriuria
Asymptomatic bacteriuria is absence of UTI symptoms or signs in a patient whose urine culture satisfies criteria for UTI. Pyuria may or may not be present. Because it is asymptomatic, such bacteriuria is found mainly when high-risk patients are screened or when urine culture is done for other reasons.
Screening patients for asymptomatic bacteriuria should generally be limited to the following patient groups (3, 4):
Pregnant patients at 12 to 16 weeks gestation or at the first prenatal visit, if later (because of the risk of symptomatic UTI, including pyelonephritis during pregnancy, and of adverse pregnancy outcomes, including low-birth-weight neonate and preterm delivery)
Sometimes patients who have had a kidney transplant within the previous 1 to 2 months
Before certain invasive genitourinary procedures that can cause mucosal bleeding (eg, transurethral resection of the prostate)
Certain patients (eg, postmenopausal women; patients with controlled diabetes; patients with ongoing use of urinary tract foreign objects such as stents, nephrostomy tubes, and indwelling catheters) often have persistent asymptomatic bacteriuria and sometimes pyuria. If they are asymptomatic, these patients should not be screened routinely because they are at low risk. In patients with indwelling catheters, treatment of asymptomatic bacteriuria often does not clear the bacteriuria and only leads to development of antibiotic-resistant organisms. Patients with a kidney transplant also do not routinely require screening for asymptomatic bacteriuria (5).
Acute urethral syndrome
Acute urethral syndrome, which occurs in women, is a syndrome involving dysuria, frequency, and pyuria (dysuria-pyuria syndrome) and resembles cystitis. However, in acute urethral syndrome (unlike in cystitis), routine urine cultures are negative or show colony counts that are lower than the traditional criteria for diagnosis of bacterial cystitis. Urethritis due to organisms such as C. trachomatis, M. genitalium, and Ureaplasma urealyticum, which are not detected on routine urine culture, is a possible cause of acute urethral syndrome.
Noninfectious causes have been proposed, but supporting evidence is not conclusive, and most noninfectious causes usually cause little or no pyuria. Possible noninfectious causes include anatomic abnormalities (eg, urethral stenosis), physiologic abnormalities (eg, pelvic floor muscle dysfunction), hormonal imbalances (eg, atrophic urethritis), localized trauma, gastrointestinal system symptoms, and inflammation.
Classification references
1. Trautner BW, Cortes-Penfield NW, Gupta K, et al. Complicated Urinary Tract Infections (cUTI): Clinical Guidelines for Treatment and Management. Infectious Diseases Society of America. Published July 17, 2025.
2. Johnson JR, Russo TA. Acute Pyelonephritis in Adults. N Engl J Med. 2018;378(1):48-59. doi:10.1056/nejmcp1702758
3. US Preventive Services Task Force, Owens DK, Davidson KW, et al. Screening for Asymptomatic Bacteriuria in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2019;322(12):1188-1194. doi:10.1001/jama.2019.13069
4. Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2019;68(10):e83-e110. doi:10.1093/cid/ciy1121
5. Goldman JD, Julian K. Urinary tract infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice. Clin Transplant. 2019;33(9):e13507. doi:10.1111/ctr.13507
Symptoms and Signs of Bacterial UTIs
When symptoms are present, they may not correlate with the location of the infection within the urinary tract because there is considerable overlap; however, some generalizations are useful.
Cystitis onset is usually sudden, typically with frequency, urgency, and burning or painful voiding of small volumes of urine. Nocturia, with suprapubic pain and often low back pain, is common. The urine is often turbid, and microscopic (or rarely gross) hematuria can occur. A low-grade fever may develop. Pneumaturia (passage of air in the urine) can occur when infection results from a vesicoenteric or vesicovaginal fistula or from emphysematous cystitis. In men, prostatitis should be suspected as the cause of cystitis if they also have pain or pressure in the perineum.
In acute pyelonephritis, symptoms may be the same as those of cystitis. One-third of patients have urinary frequency and dysuria. However, with pyelonephritis, symptoms typically include chills, fever, flank pain, colicky abdominal pain, nausea, and vomiting. If abdominal rigidity is absent or slight, a tender, enlarged kidney is sometimes palpable. Costovertebral angle percussion tenderness is generally present on the infected side. Symptoms of UTI in children often are nonspecific and less characteristic.
Older adults and patients with a neurogenic bladder or an indwelling catheter may sometimes present with sepsis and delirium but without symptoms referable to the urinary tract.
Diagnosis of Bacterial UTIs
Urinalysis
Sometimes urine culture
Diagnosis by culture is not always necessary. If done, diagnosis by culture requires demonstration of significant bacteriuria in properly collected urine.
Urine collection
To obtain a clean-catch, midstream specimen, the urethral opening is washed with a mild, nonfoaming disinfectant and air dried. Contact of the urinary stream with the mucosa should be minimized by spreading the labia in women and by pulling back the foreskin in uncircumcised men. The first 5 mL of urine is not captured; the next 5 to 10 mL is collected in a sterile container.
A specimen obtained by catheterization is preferable in older women (who typically have difficulty obtaining a clean-catch specimen) and in women with vaginal bleeding or discharge. Many clinicians also use catheterization to obtain a specimen if evaluation includes a pelvic examination. Diagnosis in patients with indwelling catheters is discussed elsewhere. (See also How To Do Urethral Catheterization in a Female and How To Do Urethral Catheterization in a Male.)
Testing, particularly culturing, should be done within 2 hours of specimen collection; if not, the sample should be refrigerated.
If an STI is suspected, a urethral swab for STI testing is obtained prior to voiding. Urine culture is then obtained by clean-catch or catheterization.
Urine testing
Microscopic examination of urine is useful but not definitive. Pyuria is defined as ≥ 8 white blood cells (WBCs)/mcL of uncentrifuged urine, which corresponds to 2 to 5 WBCs/high-power field in spun sediment. Most truly infected patients have > 10 WBCs/mcL, but the optimal threshold is unclear (1). The presence of bacteria in the absence of pyuria, especially when several strains are found, is usually due to contamination during sampling. Microscopic hematuria occurs in up to 50% of patients, but gross hematuria is uncommon. WBC casts, which may require special stains to differentiate from renal tubular casts, indicate only an inflammatory reaction; they can be present in patients with pyelonephritis, glomerulonephritis, or noninfective tubulointerstitial nephritis.
Pyuria in the absence of bacteriuria and of UTI is possible, for example, if patients have nephrolithiasis, a uroepithelial tumor, appendicitis, or inflammatory bowel disease or if the sample is contaminated by vaginal WBCs. Women who have dysuria and pyuria without significant bacteriuria may have interstitial cystitis.
Dipstick tests also are commonly used. A positive nitrite test on a freshly voided specimen (bacterial replication in the container renders results unreliable if the specimen is not tested rapidly) is highly specific for UTI, but the test is not very sensitive. The leukocyte esterase test is very specific for the presence of > 10 WBCs/mcL and is fairly sensitive. In adult women with uncomplicated UTI with typical symptoms, most clinicians consider positive microscopic and dipstick tests sufficient; in these cases, given the likely pathogens, cultures are unlikely to change treatment but add significant expense.
Urine cultures are recommended in patients whose characteristics and symptoms suggest complicated UTI or an indication for treatment of bacteriuria. Common examples include the following:
Pregnant patients
Postmenopausal women
Men
Prepubertal children
Patients with urinary tract abnormalities or recent instrumentation
Patients with immunosuppression or significant comorbidities
Patients whose symptoms suggest pyelonephritis or sepsis
Patients with recurrent UTIs (≥ 3/year)
Samples containing large numbers of epithelial cells are contaminated and are unlikely to be helpful. An uncontaminated specimen must be obtained for culture. Culture of a morning specimen is most likely to reveal UTI. Samples left at room temperature for > 2 hours can give falsely high colony counts due to continuing bacterial proliferation. Criteria for culture positivity include isolation of a single bacterial species from a midstream, clean-catch, or catheterized urine specimen.
For asymptomatic patients, criteria for culture positivity are the following (2):
For women, 2 consecutive clean-catch, voided specimens (for men, 1 specimen) from which the same bacterial strain is isolated in colony counts of > 105 colony-forming units (CFU)/mL
For women or men, in a catheter-obtained specimen, a single bacterial species is isolated with > 102 CFU/mL
Although most laboratory thresholds consider > 105 CFU/mL the standard for a UTI, the threshold may be adjusted based on the method of collection and/or specific patient populations (3).
For example in symptomatic patients, culture criteria are the following (3):
In general, > 104 CFU/mL should be considered clinically significant in symptomatic patients (103 CFU/mL increases the sensitivity).
If urine is collected by cystoscope or suprapubic aspiration, the threshold is lower: > 103 CFU/mL.
Any positive culture result, regardless of colony count, in a sample obtained via suprapubic bladder puncture should be considered a true positive.
In midstream urine, E. coli in mixed flora may be a true pathogen (4).
Occasionally, UTI is present despite lower colony counts, possibly because of prior antibiotic therapy, very dilute urine (specific gravity < 1.003), or obstruction to the flow of grossly infected urine. Repeating the culture improves the diagnostic accuracy of a positive result, ie, may differentiate between a contaminant and a true positive result. Molecular (eg, PCR) urine testing may sometimes reveal unusual pathogens in patients with refractory or recurrent UTI.
Infection localization
Differentiating upper from lower UTI relies mainly on whether systemic and upper tract symptoms are present; advanced imaging is usually unnecessary. When the patient has high fever, costovertebral angle tenderness, and gross pyuria with casts, pyelonephritis is highly likely.
Symptoms similar to those of cystitis and urethritis can occur in patients with vaginitis, which may cause dysuria due to the passage of urine across inflamed labia. Vaginitis can often be distinguished by the presence of vaginal discharge, vaginal odor, and dyspareunia.
Men with symptoms of cystitis who do not respond to usual antimicrobial therapy may have prostatitis. A digital rectal examination may illicit pain or tenderness in the prostate.
Other testing
Seriously ill patients require evaluation for sepsis, typically with complete blood count, electrolytes, lactate, blood urea nitrogen, creatinine, and blood cultures. Patients with abdominal pain or tenderness should be evaluated for other causes of an , typically with complete blood count, electrolytes, lactate, blood urea nitrogen, creatinine, and blood cultures. Patients with abdominal pain or tenderness should be evaluated for other causes of anacute abdomen.
Patients who have dysuria/pyuria but no bacteriuria should have testing for an STI, typically using nucleic acid-based testing of swabs from the urethra and cervix (see Diagnosis of Urogenital Chlamydial Infections).
Most adults do not require assessment for structural abnormalities unless any of the following apply (5, 6):
Recurrent UTIs
Complicated (eg, diabetes, immunocompromise)
History of renal stones
Prior renal surgery
Not responding to therapy
Urinary tract imaging modalities include ultrasonography, CT, and IV urography (IVU). Occasionally, voiding cystourethrography, retrograde urethrography, or cystoscopy is warranted. Urologic investigation is not routinely needed in women with symptomatic cystitis or asymptomatic recurrent cystitis because findings do not influence therapy. Children with UTI often require imaging.
Diagnosis references
1. Bilsen MP, Conroy SP, Schneeberger C, et al. A reference standard for urinary tract infection research: a multidisciplinary Delphi consensus study. Lancet Infect Dis. 2024;24(8):e513-e521. doi:10.1016/S1473-3099(23)00778-8
2. Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2019;68(10):e83-e110. doi:10.1093/cid/ciy1121
3. Miller JM, Binnicker MJ, Campbell S, et al. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). Clin Infect Dis. Published online March 5, 2024. doi:10.1093/cid/ciae104
4. Hooton TM, Roberts PL, Cox ME, et al. Voided midstream urine culture and acute cystitis in premenopausal women. N Engl J Med. 2013;369(20):1883-1891. doi:10.1056/NEJMoa1302186
5. Expert Panel on Urological Imaging, Venkatesan AM, Oto A, et al. ACR Appropriateness Criteria® Recurrent Lower Urinary Tract Infections in Females. J Am Coll Radiol. 2020;17(11S):S487-S496. doi:10.1016/j.jacr.2020.09.003
6. Expert Panel on Urologic Imaging, Nikolaidis P, Dogra VS, et al. ACR Appropriateness Criteria® Acute Pyelonephritis. J Am Coll Radiol. 2018;15(11S):S232-S239. doi:10.1016/j.jacr.2018.09.011
Treatment of Bacterial UTIs
Antibiotics
Occasionally surgery (eg, to drain abscesses, correct underlying structural abnormalities, or relieve obstruction)
All forms of symptomatic bacterial UTI require antibiotics. For patients with severe dysuria, phenazopyridine may be used as an adjunct to reduce symptoms while the antibiotics treat the underlying infection (, phenazopyridine may be used as an adjunct to reduce symptoms while the antibiotics treat the underlying infection (1, 2). Phenazopyridine should be used for no more than 2 days because data are lacking as to whether there is added benefit with longer use. It is contraindicated in patients with renal insufficiency and causes a reddish-orange discoloration of urine.
Choice of antibiotic should be based on the patient’s allergy history, local resistance patterns (if known), antibiotic availability and cost, and patient and provider tolerance for risk of treatment failure. Propensity for inducing antibiotic resistance should also be considered. When urine culture is completed and sensitivity results are available, choice of antibiotic should be modified to the most narrow-spectrum antibiotic effective against the identified pathogen.
Surgical correction is usually required for obstructive uropathy, anatomic abnormalities, and neuropathic urinary tract lesions such as compression of the spinal cord. Catheter drainage of an obstructed urinary tract aids in prompt control of UTI. Occasionally, a renal cortical abscess or perinephric abscess requires surgical drainage. Instrumentation of the lower urinary tract in the presence of infected urine should be deferred if possible. Sterilization of the urine before instrumentation and antibiotic therapy for 3 to 7 days after instrumentation can prevent life-threatening urosepsis.
Cystitis
First-line treatment of uncomplicated cystitis in women who do not have risk factors for a multidrug-resistant gram-negative organism is nitrofurantoin 100 mg orally twice a day for 5 days (it is contraindicated if creatinine clearance is who do not have risk factors for a multidrug-resistant gram-negative organism is nitrofurantoin 100 mg orally twice a day for 5 days (it is contraindicated if creatinine clearance is< 60 mL/min), trimethoprim/sulfamethoxazole (TMP/SMX) 160/800 mg orally twice a day for 3 days, or fosfomycin 3 g orally once (60 mL/min), trimethoprim/sulfamethoxazole (TMP/SMX) 160/800 mg orally twice a day for 3 days, or fosfomycin 3 g orally once (2). Less desirable choices include a fluoroquinolone or a beta-lactam antibiotic. If cystitis recurs within a week or two, a broader spectrum antibiotic (eg, a fluoroquinolone) can be used and the urine should be cultured. For patients with allergies or resistance to first-line antibiotics, alternative oral agents include gepotidacin and sulopenem etzadroxil/probenecid (). Less desirable choices include a fluoroquinolone or a beta-lactam antibiotic. If cystitis recurs within a week or two, a broader spectrum antibiotic (eg, a fluoroquinolone) can be used and the urine should be cultured. For patients with allergies or resistance to first-line antibiotics, alternative oral agents include gepotidacin and sulopenem etzadroxil/probenecid (3, 4).
Men with uncomplicated cystitis should always receive antibiotics; urine culture and susceptibility results guide the antibiotic choice (5–7). Clinicians should also consider the possibility of urethritis and prostatitis in men with UTI symptoms. First-line antibiotics for men with uncomplicated UTI include trimethoprim and trimethoprim/sulfamethoxazole for 7 days. However, ). Clinicians should also consider the possibility of urethritis and prostatitis in men with UTI symptoms. First-line antibiotics for men with uncomplicated UTI include trimethoprim and trimethoprim/sulfamethoxazole for 7 days. However,nitrofurantoin is not recommended for men because of poor tissue penetration and lack of efficacy in case there is potential prostatic involvement.
Complicated cystitis should be treated with empiric broad-spectrum antibiotics chosen based on local pathogens and resistance patterns and adjusted based on culture results. Urinary tract abnormalities must also be managed.
Acute pyelonephritis
Antibiotics are required. Outpatient treatment with oral antibiotics is possible if all of the following criteria are satisfied (1):
Patients must be able to take oral antibiotics and are expected to be adherent.
Patients are immunocompetent.
Patients do not have nausea or vomiting or evidence of volume depletion or sepsis.
Patients do not have urinary tract obstruction or anatomic defects and do not have renal calculi.
Patients should have adequate analgesia with oral pain medications.
Ciprofloxacin 500 mg orally twice a day for 7 days or levofloxacin 750 mg orally once a day for 5 to 7 days is a first-line antibiotic if Ciprofloxacin 500 mg orally twice a day for 7 days or levofloxacin 750 mg orally once a day for 5 to 7 days is a first-line antibiotic if< 10% of the uropathogens in the community are resistant. An alternative option for patients at risk of adverse effects with fluoroquinolones (eg, tendinitis and tendon rupture) is usually TMP/SMX 160/800 mg orally twice a day for 14 days (2). However, local sensitivity patterns should be considered because in some parts of the United States > 20% of E. coli are resistant to sulfa.
Patients who are not eligible for outpatient treatment should be hospitalized and given parenteral therapy selected on the basis of local sensitivity patterns. First-line antibiotics for patients without risk factors for infection with a multidrug-resistant organism are usually renally excreted fluoroquinolones, such as ciprofloxacin and levofloxacin. Other choices, such as ampicillin plus gentamicin, the aminoglycoside plazomicin (Patients who are not eligible for outpatient treatment should be hospitalized and given parenteral therapy selected on the basis of local sensitivity patterns. First-line antibiotics for patients without risk factors for infection with a multidrug-resistant organism are usually renally excreted fluoroquinolones, such as ciprofloxacin and levofloxacin. Other choices, such as ampicillin plus gentamicin, the aminoglycoside plazomicin (8), broad-spectrum cephalosporins (eg, ceftriaxone, cefotaxime, cefepime), aztreonam, beta-lactam/beta-lactam inhibitor combinations (ampicillin/sulbactam, ticarcillin/clavulanate, piperacillin/tazobactam), and imipenem/cilastatin, are usually reserved for patients with critical illness and/or urinary tract obstruction (eg, with calculi, resistant bacteria, or a health care-associated infection).), broad-spectrum cephalosporins (eg, ceftriaxone, cefotaxime, cefepime), aztreonam, beta-lactam/beta-lactam inhibitor combinations (ampicillin/sulbactam, ticarcillin/clavulanate, piperacillin/tazobactam), and imipenem/cilastatin, are usually reserved for patients with critical illness and/or urinary tract obstruction (eg, with calculi, resistant bacteria, or a health care-associated infection).
Parenteral therapy is continued until defervescence and other signs of clinical improvement occur, which frequently occurs within 72 hours. Oral therapy can then begin, and the patient can be discharged for the remainder of a 7- to 14-day treatment course. Longer courses of IV antibiotics (eg, total duration of 2 to 3 weeks) may be appropriate for patients who require urologic correction of anatomic defects.
Pregnant patients with pyelonephritis should initially be treated as inpatients (9). First-line IV antibiotics include cephalosporins, aztreonam, or ampicillin plus gentamicin. If pyelonephritis is severe, possibilities include piperacillin/tazobactam or meropenem. Fluoroquinolones and TMP/SMX should be avoided because of potential adverse fetal effects (). First-line IV antibiotics include cephalosporins, aztreonam, or ampicillin plus gentamicin. If pyelonephritis is severe, possibilities include piperacillin/tazobactam or meropenem. Fluoroquinolones and TMP/SMX should be avoided because of potential adverse fetal effects (10). Recurrence is common, and although there is limited evidence, some clinicians consider recommending prophylaxis after the acute infection resolves with nitrofurantoin 100 mg orally or cephalexin 250 mg orally every night during the remainder of the pregnancy and for 4 to 6 weeks after pregnancy (). Recurrence is common, and although there is limited evidence, some clinicians consider recommending prophylaxis after the acute infection resolves with nitrofurantoin 100 mg orally or cephalexin 250 mg orally every night during the remainder of the pregnancy and for 4 to 6 weeks after pregnancy (9).
Asymptomatic bacteriuria
Asymptomatic bacteriuria should not be treated in most patients, including those with diabetes or with chronic indwelling bladder catheters, or in older adults (11, 12). However, pregnant patients or patients undergoing certain invasive genitourinary procedures that can cause mucosal bleeding should be treated with antibiotics as for cystitis (see Urinary Tract Infections (UTI): Screening).
In pregnant patients, only a few antibiotics can be safely used. Oral beta-lactams, sulfonamides, and nitrofurantoin are considered safe in early pregnancy, but trimethoprim should be avoided during the first trimester, and sulfamethoxazole should be avoided during the third trimester, particularly near parturition. In pregnant patients, only a few antibiotics can be safely used. Oral beta-lactams, sulfonamides, and nitrofurantoin are considered safe in early pregnancy, but trimethoprim should be avoided during the first trimester, and sulfamethoxazole should be avoided during the third trimester, particularly near parturition.
Patients with untreatable obstructive problems (eg, calculi, reflux) may require long-term suppressive therapy.
Acute urethral syndrome
Treatment depends on clinical findings and urine culture results:
Women with dysuria, pyuria, and colony growth of > 102/mL of a single bacterial species on urine culture can be treated as for uncomplicated cystitis.
Women who have dysuria and pyuria with no bacteriuria should be evaluated for an STI (including for N. gonorrhoeae and C. trachomatis).
Women who have dysuria but neither pyuria nor bacteriuria do not have the true acute urethral syndrome. They should be evaluated for noninfectious causes of dysuria. Evaluation may include therapeutic trials, for example, of behavioral treatments (eg, biofeedback and pelvic musculature relaxation), surgery (for urethral stenosis), and medications (eg, hormone replacement for suspected atrophic urethritis; anesthetics; antispasmodics).
Treatment references
1. Trautner BW, Cortes-Penfield NW, Gupta K, et al. Complicated Urinary Tract Infections (cUTI): Clinical Guidelines for Treatment and Management. Infectious Diseases Society of America. Published July 17, 2025.
2. Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011;52(5):e103-e120. doi:10.1093/cid/ciq257
3. Wagenlehner F, Perry CR, Hooton TM, et al. Oral gepotidacin versus nitrofurantoin in patients with uncomplicated urinary tract infection (EAGLE-2 and EAGLE-3): two randomised, controlled, double-blind, double-dummy, phase 3, non-inferiority trials. Lancet. 2024;403(10428):741-755. doi:10.1016/S0140-6736(23)02196-7
4. Dunne MW, Aronin SI, Das AF, et al. Sulopenem or Ciprofloxacin for the Treatment of Uncomplicated Urinary Tract Infections in Women: A Phase 3, Randomized Trial [published correction appears in Clin Infect Dis. 2023 Sep 18;77(6):937. doi: 10.1093/cid/ciad216.]. Clin Infect Dis. 2023;76(1):66-77. doi:10.1093/cid/ciac738
5. Kurotschka PK, Gágyor I, Ebell MH. Acute Uncomplicated UTIs in Adults: Rapid Evidence Review. Am Fam Physician. 2024;109(2):167-174.
6. Schaeffer AJ, Nicolle LE. Urinary Tract Infections in Older Men. N Engl J Med. 2016;374(22):2192. doi:10.1056/NEJMc1603508
7. Drekonja DM, Rector TS, Cutting A, Johnson JR. Urinary tract infection in male veterans: treatment patterns and outcomes. JAMA Intern Med. 2013;173(1):62-68. doi:10.1001/2013.jamainternmed.829
8. Wagenlehner FME, Cloutier DJ, Komirenko AS, et al. Once-daily plazomicin for complicated urinary tract infections. N Engl J Med. 2019;380(8):729-740. doi:10.1056/NEJMoa1801467
9. Urinary Tract Infections in Pregnant Individuals. Obstet Gynecol. 2023;142(2):435-445. doi:10.1097/AOG.0000000000005269
10. Bookstaver PB, Bland CM, Griffin B, Stover KR, Eiland LS, McLaughlin M. A Review of Antibiotic Use in Pregnancy. Pharmacotherapy. 2015;35(11):1052-1062. doi:10.1002/phar.1649
11. Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2019;68(10):e83-e110. doi:10.1093/cid/ciy1121
12. US Preventive Services Task Force, Owens DK, Davidson KW, et al. Screening for Asymptomatic Bacteriuria in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2019;322(12):1188-1194. doi:10.1001/jama.2019.13069
Prevention of Bacterial UTIs
In women with recurrent UTI, physical examination should include pelvic examination to detect manageable conditions, such as vulvovaginal atrophy, urethral diverticulum, fecal incontinence, and vaginal prolapse. Men with recurrent UTI should be evaluated for prostatitis, urethritis, and incomplete bladder emptying.
In women who experience ≥ 3 UTIs/year, behavioral measures are recommended, including increasing fluid intake, avoiding spermicides and diaphragm use, not delaying urination, wiping front to back after defecation, avoiding douching, and urinating immediately after sexual intercourse. If these techniques are unsuccessful, antibiotic prophylaxis should be considered. Common options are continuous and postcoital prophylaxis.
The use of cranberry products, in addition to other behavioral measures, may be considered another strategy to prevent recurrent cystitis. This approach is based on evidence suggesting that cranberry products may decrease the risk of simple cystitis in women with recurrent UTIs, children, and people susceptible to UTIs after intervention involving the bladder (1). However, there is insufficient evidence to support its use in older adults, pregnant patients, patients with bladder emptying disorders, and patients with impaired bladder emptying (2).
Continuous prophylaxis regimens typically range from 6 months to 2 years (3). Choice of antibiotic depends on susceptibility patterns of prior infections. Common options are trimethoprim/sulfamethoxazole 40/200 mg orally once a day or 3 times a week, nitrofurantoin 50 or 100 mg orally once a day, cephalexin 125 to 250 mg orally once a day, and fosfomycin 3 g orally every 10 days. Fluoroquinolones are effective but are not usually recommended because resistance is increasing. Also, fluoroquinolones are contraindicated in pregnant patients and in children. ). Choice of antibiotic depends on susceptibility patterns of prior infections. Common options are trimethoprim/sulfamethoxazole 40/200 mg orally once a day or 3 times a week, nitrofurantoin 50 or 100 mg orally once a day, cephalexin 125 to 250 mg orally once a day, and fosfomycin 3 g orally every 10 days. Fluoroquinolones are effective but are not usually recommended because resistance is increasing. Also, fluoroquinolones are contraindicated in pregnant patients and in children.Nitrofurantoin is contraindicated if creatinine clearance is < 60 mL/min. Long-term use can rarely cause damage to the lungs, liver, and nervous system. Methenamine has been shown to be efficacious in the prevention of UTI in older adults with creatinine clearance 60 mL/min. Long-term use can rarely cause damage to the lungs, liver, and nervous system. Methenamine has been shown to be efficacious in the prevention of UTI in older adults with creatinine clearance> 30 mL/min (4).
Postcoital prophylaxis in women may be more effective if UTIs are temporally related to sexual intercourse. Usually, a single dose of one of the antibiotics used for continuous prophylaxis (other than fosfomycin) is effective (in women may be more effective if UTIs are temporally related to sexual intercourse. Usually, a single dose of one of the antibiotics used for continuous prophylaxis (other than fosfomycin) is effective (3).
Contraception is recommended for women using a fluoroquinolone because these medications can potentially injure a fetus. Although concern exists that antibiotics may decrease the effectiveness of oral contraceptives, pharmacokinetic studies have not shown a significant or consistent effect. Nonetheless, some experts still recommend that women who use oral contraceptives use barrier contraceptives while they are taking antibiotics.
In pregnant patients, effective prophylaxis of UTI is similar to that in nonpregnant patients, including use of postcoital prophylaxis. Appropriate patients include those with acute pyelonephritis during a pregnancy, patients with > 1 episode (despite treatment) of UTI or bacteriuria during pregnancy, and patients who required prophylaxis for recurrent UTI before pregnancy.
In postmenopausal patients, antibiotic prophylaxis is similar to that described previously. Additionally, topical estrogen therapy markedly reduces the incidence of recurrent UTI in patients with atrophic vaginitis or atrophic urethritis (3).
Prevention references
1. Jepson RG, Williams G, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2012;10(10);CD001321. Published 2012 Oct 17. doi:10.1002/14651858.CD001321.pub5
2. Williams G, Hahn D, Stephens JH, Craig JC, Hodson EM. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2023;4(4):CD001321. Published 2023 Apr 17. doi:10.1002/14651858.CD001321.pub6
3. Anger JT, Bixler BR, Holmes RS, Lee UJ, Santiago-Lastra Y, Selph SS. Updates to Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline. J Urol. 2022;208(3):536-541. doi:10.1097/JU.0000000000002860
4. Chwa A, Kavanagh K, Linnebur ASA, et al. Evaluation of methenamine for urinary tract infection prevention in older adults: A review of the evidence. Ther Adv Drug Saf. 2019;10:2042098619876749. Published 2019 Sep 23. doi:10.1177/2042098619876749
Key Points
The most common causes of bacterial UTI and UTI overall are E. coli and other gram-negative enteric bacteria.
Do not test for or treat asymptomatic bacteriuria except in pregnant patients or before an invasive urologic procedure.
In general, culture urine in patients with suspected complicated UTI but not in patients with uncomplicated cystitis.
Test patients for structural abnormalities if infections recur or are complicated, nephrolithiasis is suspected, there is painless hematuria or new renal insufficiency, or fever persists for ≥ 72 hours.
If available, consider local resistance patterns when choosing antibiotic therapy for UTI.
For women with ≥ 3 UTIs/year despite behavioral prophylactic measures, consider continuous or postcoital antibiotic prophylaxis.
