Catheter-associated urinary tract infection in adults

INTRODUCTION — 

Urinary catheters are placed for several reasons, including diagnostic and therapeutic needs. The presence of a catheter increases the risk of bacteriuria, which can be clinically benign or progress to infection (ranging from mild to severe).

This topic focuses on the clinical features, diagnosis, management, and prevention of catheter-associated urinary tract infection (UTI), which refers to symptomatic infection of the urinary tract in a patient who has an indwelling urethral, suprapubic, or external urinary catheter or undergoes intermittent bladder catheterization. This includes patients with neurogenic bladder. Appropriate diagnosis, in particular, is essential in the catheterized population to avoid unnecessary antimicrobial therapy.

Bacteriuria in a catheterized individual in the absence of symptoms referable to a UTI is not considered catheter-associated UTI and is discussed in detail elsewhere. (See "Asymptomatic bacteriuria in adults".)

The indications for catheter placement, methods of catheterization, and management of bladder catheters are discussed separately. (See "Placement and management of urinary catheters in adults".)

Issues related to UTI in patients without catheters are also discussed in detail elsewhere:

●(See "Acute simple cystitis in female adults".)

●(See "Acute simple cystitis in male adults".)

●(See "Acute complicated urinary tract infection (including pyelonephritis) in adults".)

●(See "Approach to infection in the older adult", section on 'Urinary tract infection'.)

EPIDEMIOLOGY

Incidence — Bacteriuria in patients with indwelling bladder catheters occurs at a rate of approximately 3 to 10 percent per day of catheterization [1,2]. In patients with long-term catheterization, bacteriuria is near universal. Of those with bacteriuria, small prospective studies suggest that 8 to 18 percent develop symptoms of urinary tract infection (UTI) [3,4].

This translates into a substantial burden of catheter-associated UTIs in hospitalized patients. In the United States, based on surveillance data reported to the Centers for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN), the incidence of catheter-associated UTIs in 2012 was 1.4 to 1.7 per 1,000 catheter days in inpatient adult and pediatric medical/surgical floors [5].

It is important to note that criteria used to designate a catheter-associated UTI for surveillance purposes is distinct from the clinical diagnosis, and so such surveillance data may not accurately reflect the true clinical burden. In the United States, the NHSN defines catheter-associated UTI in a patient with fever, suprapubic tenderness, or costovertebral angle pain who has a urine culture with bacterial counts ≥10⁵ colony-forming units (cfu)/mL of no more than two organism species (fungal isolates or minor pathogens do not count) [6]. Patients who are no longer catheterized but had a urethral catheter within the past 48 hours are also considered to have catheter-associated UTI per surveillance definitions. The NHSN definition does not indicate that other causes of fever should be ruled out, so it may overestimate the rate of clinically relevant catheter-related bacteriuria [7]. In contrast, it only counts indwelling urethral (Foley) catheters, so would not include UTI associated with suprapubic, intermittent, or external catheterization. Furthermore, because the NHSN definition sometimes changes, it can be difficult to compare infection rates across time. As an example, one hospital-based study noted that the measured infection rate as determined retroactively by an updated definition fell by half compared with the rate reported using the old definition [8].

The clinical diagnosis of catheter-associated UTI is discussed elsewhere. (See 'Diagnostic evaluation' below.)

Risk factors

Catheter factors — The duration of catheterization is an important risk factor for catheter-associated UTI and is a major target of prevention efforts [9,10]. (See 'Prevention' below.)

Chronic (eg, >30 days) indwelling urethral (Foley) catheters and suprapubic catheters are both associated with near-constant presence of bacteriuria. Whether the risk of bladder colonization is lower with chronic suprapubic catheters versus transurethral catheters is unclear. In studies of nursing home residents, suprapubic catheters have been associated with lower rates of physician-diagnosed and treated catheter-associated UTIs compared with transurethral catheters, but potential confounding factors reduce confidence in the finding [11,12]. Comparative trials have mainly evaluated shorter-term use (eg, less than two weeks) in hospitalized or postoperative patients [13,14].

Intermittent catheter use is also associated with bacteriuria, although the prevalence is unclear. Intermittent catheterization is typically preferred over an indwelling catheter because of the fewer mechanical complications and less anatomic damage; however, patient dexterity and health care access are important considerations in the selection of catheterization strategy.

Similarly, external catheters are also associated with bacteriuria and UTI [15], although the relative risk compared with internal catheters is uncertain [16]. If collected appropriately from a freshly placed external catheter, microorganisms in the external catheter urine specimen probably reflect true bladder bacteriuria [17].

Errors in catheter care (eg, errors in sterile technique, not maintaining a closed drainage system) have also been associated with catheter-associated UTI [18].

Patient factors — Patient-specific risk factors for catheter-associated UTI include [19,20]:

●Female sex

●Older age

●Diabetes mellitus

PATHOGENESIS — 

Urinary tract infection (UTI) associated with catheterization may be extraluminal or intraluminal. Extraluminal infection occurs via entry of bacteria into the bladder along the biofilm that forms around the catheter in the urethra [21-24]. Intraluminal infection occurs due to urinary stasis because of drainage failure, or due to contamination of the urine collection bag with subsequent ascending infection.

MICROBIOLOGY

Spectrum of organisms — The causative pathogens in catheter-associated urinary tract infection (UTI) are similar to those that are associated with acute complicated UTI in general. Specifically, Escherichia coli and other Enterobacteriaceae are common, but Pseudomonas aeruginosa, enterococci, staphylococci, and Candida species are also significant causes. (See "Acute complicated urinary tract infection (including pyelonephritis) in adults", section on 'Microbiology'.)

As an example, of approximately 154,000 catheter-associated UTIs reported by acute care hospitals and long-term acute care facilities to the United States National Healthcare Safety Network (NHSN) between 2011 and 2014, the most common causative pathogens identified were [25]:

●E. coli – present in 24 percent of cases

●Candida spp (or yeast, not otherwise specified) – 24 percent

●Enterococcus spp – 14 percent

●P. aeruginosa – 10 percent

●Klebsiella spp – 10 percent

Ambulatory patients with indwelling catheters tend to acquire urinary bacteria similar to those found in hospitalized patients rather than the types usually seen in the outpatient setting. Prolonged catheterization can be associated with polymicrobial bacteriuria or changing urinary flora.

Some of the organisms associated with catheter-related UTI may lack virulence factors that allow typical uropathogens to adhere to uroepithelium but instead take advantage of easy access to the bladder via the catheter. A good example of such an organism is Candida spp, which rarely cause symptomatic UTI in the absence of an indwelling catheter. In contrast, candiduria is a common finding in patients with indwelling bladder catheters, particularly in those who are taking antimicrobials or have diabetes mellitus [26]. However, in most such patients, the candiduria merely represents colonization, there are no symptoms of UTI, and progression to candidemia is uncommon (1.3 percent in one series) [26]. This issue is discussed in detail separately. (See "Candida infections of the bladder and kidneys", section on 'Infection versus colonization'.)

Antimicrobial resistance — Antimicrobial resistance is highly prevalent in catheter-associated UTIs.

This is generally reflected in the high rate of resistance among organisms that cause UTI in hospitalized patients, many of whom are catheterized. In a review of almost 900,000 urinary Enterobacterales (gram-negative) isolates from urine cultures among hospitalized patients from 2011 to 2020 (catheter status unknown), E. coli accounted for 62 percent, Klebsiella pneumoniae 18 percent, and Proteus mirabilis 9 percent [27]. Among all the Enterobacterales, the rates of resistance to antibiotics often used for UTI was high:

●Beta-lactam resistance – 65 percent

●Fluoroquinolone resistance – 29 percent

●Nitrofurantoin resistance – 28 percent (notably, only 5 percent of E. coli were resistant; other species drove up the resistance rate)

●Trimethoprim-sulfamethoxazole – 26 percent

Extended-spectrum beta-lactamase (ESBL) production was noted in 12 percent.

CLINICAL FEATURES

Presenting features — Patients with catheter-associated UTIs often present with systemic symptoms, suggesting that either the organisms or the inflammation has spread beyond the bladder. Fever is the most common symptom [3,28,29]. Localizing symptoms may include flank or suprapubic discomfort and costovertebral angle tenderness. Patients may note catheter obstruction, which can increase the risk of UTI. However, these findings are highly nonspecific, and many catheterized patients without evidence of UTI or even bacteriuria may have similar symptoms. As an example, in an observational study that included 89 hospitalized patients who developed bacteriuria following placement of a urethral catheter, 18 percent had a temperature >38.5°C (101.3°F), 6 percent had dysuria, and 6 percent had urinary urgency [3]. These symptoms were present in the same proportion of 945 catheterized patients without bacteriuria.

Patients with spinal cord injury may have especially atypical and nonspecific symptoms, including increased spasticity, malaise/lethargy, and autonomic dysreflexia.

Individuals who develop UTI soon after removal of a catheter may be more likely to have the typical urinary symptoms of dysuria, frequency, and urgency.

Rarely, purple discoloration of the urine, collection bag, and tubing (purple urine bag syndrome [PUBS]) can occur due to metabolic byproducts of certain bacteria (eg, Providencia spp, Klebsiella, and Proteus) that may be present in the system [30-32]. Risk factors include bacteriuria, constipation, and female sex. PUBS is benign and does not necessarily indicate the presence of a UTI. Other changes in the quality of the urine are not specific for bacteriuria or UTI. (See 'Establishing symptoms/signs of UTI' below.)

Complications — Important complications of catheter-associated UTI include sepsis, bacteremia, and involvement of the upper urinary tract.

Contemporary rates of bacteremia associated with indwelling urinary catheters are not well established. Older estimates suggested that approximately 20 percent of health care-associated bacteremias arose from the urinary tract [33]. Obstruction or dislodgement of the urinary catheter increases the risk of sepsis or bacteremia.

Complicated upper UTI is another important consequence of catheter-associated UTI. In an autopsy series of 75 nursing home patients, the incidence of renal parenchymal inflammation was higher in those with a catheter in place at the time of death than in those who were not catheterized (38 versus 5 percent) [34].

The indwelling catheter itself can cause anatomic damage and limit mobility [35]. (See "Complications of urinary bladder catheters and preventive strategies", section on 'Complications specific to type of catheter'.)

DIAGNOSTIC EVALUATION — 

The diagnosis of a catheter-associated urinary tract infection (UTI) is made by identifying bacteriuria (or candiduria) plus pyuria in a catheterized patient (including urethral, suprapubic, or external catheterization and intermittent catheterization) who has signs and symptoms that are consistent with UTI or systemic infection that are otherwise unexplained. Since the diagnosis depends on the presence of symptoms related to bacteria in the urinary tract, symptom assessment should precede urinary testing.

Establishing symptoms/signs of UTI — The diagnosis of catheter-associated UTI is contingent on the presence of symptoms or signs that are consistent with a UTI (see 'Presenting features' above). The diagnosis should not be made in the absence of such features.

Attributing symptoms or signs to a potential UTI is relatively straightforward when they are specific to the urinary tract (eg, flank pain, suprapubic discomfort, costovertebral angle tenderness). However, since the presenting features in catheterized patients are most often nonspecific (eg, fever, leukocytosis, sepsis), a fair amount of clinical judgment and individualization is required to make the diagnosis. In particular, the assessment should reasonably rule out the possibility of other causes (eg, other infections such as respiratory tract or skin and soft tissue infections) prior to attributing nonspecific findings to a catheter-associated UTI. This judicious approach is important for all patients to reduce the risk of overdiagnosis and overtreatment of UTI, but is especially relevant for two populations:

●Older or debilitated patients – Such patients often present to medical care with nonspecific signs or symptoms, such as falls, change in functional status, and change in mental status. These findings are often attributed to UTI because bacteriuria is common in this population, especially in the setting of catheterization. However, growing evidence indicates that these features are not reliable predictors of bacteriuria or UTI, and treatment for presumptive UTI does not improve these symptoms [36-38]. Thus, we do not routinely test urine in such patients in the absence of focal urinary tract symptoms or systemic signs of infection (eg, fever), and instead hydrate, correct metabolic abnormalities, and assess other potential contributing factors. (See "Approach to infection in the older adult", section on 'Urinary tract infection'.)

●Patients with spinal cord injury – UTI symptoms in such patients may manifest as increased spasticity, autonomic dysreflexia, and other nonspecific findings. However, other stimuli can also precipitate these symptoms, including poor sleep, increased bladder distention (without infection), fecal impaction, and other medical issues. Before attributing such features to UTI, we ensure that other potential stimuli have been addressed or reasonably excluded. In some cases (ie, patients with relatively mild symptoms, stable vital signs, and no history of sepsis related to UTI), it is reasonable to monitor symptoms for a few days and only attribute them to UTI and manage accordingly if they do not resolve.

Many clinicians and patients believe that a cloudy appearance, foul smell, or other changes in the quality of their urine is suggestive of the presence of a UTI. However, none of these findings has been demonstrated to be clearly associated with either bacteriuria or a UTI [28,29]. Purple discoloration of urine in the catheter collection bag has been associated with bacteriuria, but it does not necessarily indicate UTI. In isolation, these findings should not be attributed to UTI or prompt testing of urine to evaluate for bacteriuria.

Urine testing

Indications — We submit urine for urinalysis and culture only when patients have symptoms or signs that are potentially attributable to a catheter-associated UTI, as outlined above (see 'Establishing symptoms/signs of UTI' above). The objective is to confirm pyuria and bacteriuria, which are expected in patients with UTI, and to identify a pathogen to tailor antimicrobial therapy. (See 'Antimicrobial therapy' below.)

In the absence of symptoms, we refrain from submitting urine for urinalysis or culture to evaluate for UTI. Bacteriuria is very common among catheterized patients, even if they have no symptoms of UTI [3]. Thus, obtaining urine studies in such patients can lead to inappropriate diagnoses of UTI and overtreatment in patients who simply have asymptomatic bacteriuria. Treatment of asymptomatic bacteriuria does not affect patient outcomes, including the risk of complications and or the subsequent development of UTI symptoms, and increases the likelihood of emergence of resistant bacteria [28,39,40]. The pitfalls of screening and testing for asymptomatic bacteriuria, and the rare reasons to screen, are discussed in detail elsewhere. (See "Asymptomatic bacteriuria in adults", section on 'Rationale for not screening/treating'.)

In attempts to limit overuse of urine culture and overdiagnosis of UTI, some laboratories only test urine for culture as a reflex if a urinalysis on the specimen documents pyuria, since UTI is unlikely in the absence of pyuria.

Specimen collection — Suspicion for catheter-associated UTI is a good reminder to assess whether there is an ongoing medical indication for catheterization and to remove the catheter if not. In such cases, a midstream urine should be collected for evaluation following catheter removal. (See "Sampling and evaluation of voided urine in the diagnosis of urinary tract infection in adults".)

For patients who need ongoing catheterization (see "Placement and management of urinary catheters in adults", section on 'Indications for urinary catheters'), urine should be collected in a way that maximizes the likelihood of collecting urine from the bladder rather than from the catheter collection system:

●For patients with a chronic indwelling catheter (urethral or suprapubic catheter in place for >2 weeks), we generally suggest that they change the catheter and collect the first void when the new catheter is placed [28]. Such patients may have polymicrobial bacteriuria on culture, which can conceal the true pathogen in a patient with catheter-associated UTI. Changing the catheter before collecting the specimen may reduce the number and counts of organisms recovered. For those with a catheter-associated UTI, changing the catheter may also be associated with a lower likelihood of relapse after antimicrobial therapy (see 'Catheter management' below). However, evidence supporting this practice is limited and many institutions have different time limits on when to change a catheter prior to collecting a culture.

Many systems have a "needleless" site that can be cleansed prior to specimen collection. If a sample is being collected without catheter removal, urine should be obtained from the port in the drainage system (figure 1) [41]. Culture results from urine collected from the drainage bag cannot be used to guide treatment.

●For those using a condom catheter, the condom should be removed and a urine obtained either through a midstream specimen or from a freshly applied condom catheter after cleaning the glans [42,43]. Otherwise, it can be difficult to distinguish true infection from skin and mucosal contamination [22,42].

Test interpretation — Bacteriuria plus pyuria in a catheterized patient with symptoms that are consistent and concerning for UTI and have no other clear cause are sufficient to make the diagnosis of catheter-associated UTI. Absence of either of these makes catheter-associated UTI unlikely.

●Bacteriuria threshold – The threshold that the Infectious Diseases Society of America (IDSA) guidelines use to define catheter-associated UTI in a symptomatic patient is culture growth of ≥10³ colony-forming units (cfu)/mL of uropathogenic bacteria [28].

The main reason to set thresholds for diagnosis is to identify a level of bacterial growth that is more likely to reflect true bladder bacteriuria than specimen contamination. Because periurethral contamination is less likely in catheterized specimens, a relatively low level of bacterial growth in a symptomatic patient is likely to represent true bladder bacteriuria. Although the IDSA guidelines acknowledge that growth as low as 10² cfu/mL has been associated with bladder bacteriuria in the setting of symptoms, the threshold of 10³ cfu/mL was chosen since many labs do not quantify growth below that threshold. The vast majority of patients with UTI have bacterial culture growth ≥10⁵ cfu/mL in urine; the frequency of low count bacteriuria in the setting of catheter-associated UTI is not clearly defined but expected to be very low [28,29].

This clinical threshold for bacteriuria is distinct from that used by the United States Centers for Disease Control and Prevention (CDC) National Health Safety Network (NHSN), which was created for surveillance purposes, not specifically for clinical care [6].

Assessment of candiduria is discussed in detail elsewhere. (See "Candida infections of the bladder and kidneys", section on 'Diagnosis'.)

●Pyuria is necessary but not sufficient for diagnosis – Pyuria is frequently found in catheterized patients with or without bacteriuria and whether they have symptoms or not, and so in isolation cannot establish the diagnosis of a catheter-associated UTI. The degree of pyuria does not have predictive value for bacteriuria, candiduria, or urinary symptoms in catheterized patients [3,44]. In contrast, the absence of pyuria in a symptomatic catheterized patient suggests a diagnosis other than UTI. (See 'Clinical features' above.)

In a series of 761 catheterized patients, quantitative urine white blood cell count (WBC) >10 cells/microL had low sensitivity for predicting growth of >10⁵ cfu/mL (47 percent) [44]. Specificity, on the other hand, was 90 percent (ie, bacteriuria was unlikely present if pyuria was not). The majority of these patients had no symptoms attributable to UTI.

As discussed elsewhere, bacteriuria or pyuria in an individual without symptoms is not indicative of a catheter-associated UTI; patients without symptoms should generally not undergo urinary testing. (See 'Indications' above.)

Assess for complications — Obstruction of the urinary catheter or anywhere along the urinary drainage system puts the patient at high risk for bacteremia. The possibility of both obstruction and bacteremia should be considered and assessed in patients presenting with catheter-associated UTI and systemic symptoms.

DIFFERENTIAL DIAGNOSIS — 

The differential diagnosis of catheter-associated urinary tract infection (UTI) is generally the same as for UTI in patients without a catheter and depends on the presenting symptoms (table 1).

In particular, since catheter-associated UTI most commonly presents with fever, other causes of fever, mostly other acute infections, including acute bacterial prostatitis, are the primary differential diagnoses. The alternative possibilities of pneumonia or other respiratory infections, skin and soft-tissue infections, intraabdominal infections, and intravascular catheter-associated bloodstream infections should be considered. (See 'Establishing symptoms/signs of UTI' above.)

TREATMENT — 

The approach to treatment of catheter-associated urinary tract infection (UTI) includes antimicrobial therapy and catheter management.

Antimicrobial therapy — Antimicrobial therapy of catheter-associated UTI is often initiated empirically, while awaiting susceptibility testing on urinary isolates. The approach to empiric antimicrobial regimen selection depends in part on the presentation and whether there are features that suggest an infection that has extended beyond the bladder (which we use to distinguish acute complicated UTI from acute simple cystitis):

●Patients with symptoms of acute complicated UTI – Most patients with catheter-associated UTI come to clinical attention because of fever, flank pain, costovertebral angle tenderness, or systemic signs or symptoms of infection in the setting of pyuria and bacteriuria; such cases are consistent with acute complicated UTI and we treat them as such. Contemporary trials evaluating antibiotic regimens for acute complicated UTI include catheterized patients [45-47]. Empiric antibiotic selection takes into account severity of illness (septic versus not septic), risk factors for resistant infection (informed by past urine cultures, use of antimicrobial therapy, health care exposures, community prevalence of antimicrobial resistance) and antibiotic allergies (table 2). This is discussed in detail elsewhere. (See "Acute complicated urinary tract infection (including pyelonephritis) in adults", section on 'Management'.)

Once culture and susceptibility results are available, the antimicrobial regimen should be tailored to the specific organism isolated. If the patient was initially started on a parenteral regimen, an oral agent can be used for some or all of the treatment course if the organism is susceptible and the patient is well enough to take oral medication with adequate absorption. Directed therapy and duration are also discussed in detail elsewhere. (See "Acute complicated urinary tract infection (including pyelonephritis) in adults", section on 'Directed antimicrobial therapy'.)

●Patients with only cystitis symptoms – Some patients, in particular those who have recently had a urethral catheter removed, present with isolated symptoms of cystitis (eg, dysuria, urinary frequency or urgency) in the absence of fever or features that suggest ascending infection or prostatitis. Such patients can be managed as having acute simple cystitis, which is discussed in detail elsewhere. (See "Acute simple cystitis in female adults" and "Acute simple cystitis in male adults".)

For patients who have growth of Candida on urine cultures, the approach to management is discussed elsewhere. (See "Candida infections of the bladder and kidneys", section on 'Treatment'.)

Catheter management — Clinicians should minimize the use of indwelling catheters whenever possible.

Patients who no longer require catheterization should have the catheter removed [48,49]. Patients who require extended catheterization should be managed with intermittent catheterization, if possible. Intermittent catheterization is associated with a lower rate of bacteriuria and UTI than long-term indwelling catheterization [50]. (See "Placement and management of urinary catheters in adults", section on 'Indwelling catheter exchange or removal' and "Placement and management of urinary catheters in adults", section on 'Clean intermittent catheterization'.)

If long-term catheterization is needed and intermittent catheterization is not feasible, we suggest removing and replacing the catheter with a new one at the initiation of antimicrobial therapy, if not already performed when submitting urine specimens for testing. Biofilm penetration of most antimicrobials is poor [51]. Limited evidence suggests that catheter replacement improves clinical outcomes compared with retaining the original catheter [52]. In a randomized open-label trial of 54 patients treated for a catheter-associated UTI, catheter replacement prior to antibiotic therapy resulted in a higher rate of durable clinical cure at 28 days (89 versus 54 percent) and a lower rate of recurrence (3 versus 7 episodes) compared with retaining the catheter [53]. Another trial did not demonstrate a lower rate of recurrence with catheter replacement, but participants who retained the catheter also received a longer duration of antibiotic therapy [54].

PREVENTION

●General preventive strategies – In general, the most important aspects of prevention of catheter-associated urinary tract infections (UTIs) are avoidance of unnecessary catheterization, use of sterile technique when placing the catheter, and removal of the catheter as soon as possible. In prospective studies in the United States and Canada, implementing initiatives to reinforce these concepts was associated with a decline in the baseline rate of catheter-associated UTIs in non-intensive care units, long-term care units, and postoperative settings [55-57].

Guidelines from various expert groups also endorse these general strategies to reduce the overall burden of catheter-associated UTI [10,28,33,58]. Specifically, recommendations from a collaborative panel sponsored by the Society for Healthcare Epidemiology of America (SHEA) highlighted the importance of judiciously limiting urethral catheters to appropriate indications, adequate expertise and sterile technique for insertion, continued assessment of the necessity of catheterization, automated reminders to remove unnecessary catheters, and maintenance of a sterile, continuously closed drainage system that allows unobstructed urine flow [10]. They also endorsed urine culture stewardship as a strategy to prevent inappropriate diagnosis of catheter-associated UTI. (See 'Urine testing' above.)

●Strategies for chronically catheterized individuals – For individuals who require indwelling or chronic external catheters, given the frequency of bacteriuria, ensuring unobstructed urinary drainage and avoiding backflow of urine are thought to be essential to preventing UTI. This includes keeping the collection system open (not capped for prolonged periods), clear of kinks, and below the level of the bladder. For patients who have copious urinary debris in the catheter collection system, larger bore catheters may be helpful to ensure unimpeded flow.

Some preventive strategies that are effective for patients who are not catheterized but have recurrent cystitis may be potentially useful for catheterized individuals, although data informing their use are limited. In a trial of patients who were catheterized following pelvic surgery, adding methenamine to cranberry reduced rates of UTI over six weeks compared with cranberry alone, but these patients did not have long-term indwelling catheters [59]. In contrast, in a meta-analysis of three trials, there was no clear benefit of cranberry products for UTI prevention among adults with neurogenic bladders, including those with indwelling catheters and intermittent catheterization [60]. (See "Recurrent simple cystitis in women", section on 'Additional interventions for frequent recurrence'.)

There is no clear benefit to using either antimicrobial-coated urinary catheters or prophylactic antibiotics at the time of placement to reduce the risk of catheter-associated UTI. These and other issues related to catheter care for prevention of UTI are discussed in detail separately. (See "Placement and management of urinary catheters in adults", section on 'Indwelling catheter care' and "Placement and management of urinary catheters in adults", section on 'Indwelling catheter exchange or removal' and "Placement and management of urinary catheters in adults", section on 'No routine antibiotics' and "Placement and management of urinary catheters in adults", section on 'Specialized catheters'.)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Urinary tract infections in adults" and "Society guideline links: Asymptomatic bacteriuria in adults".)

SUMMARY AND RECOMMENDATIONS

●Incidence and risk factors – Catheter-associated urinary tract infections (UTIs) are a common health care-associated infection and include infections associated with indwelling urethral, suprapubic, or external catheterization as well as intermittent catheterization. Bacteriuria in patients with indwelling bladder catheters occurs at a rate of approximately 3 to 10 percent per day of catheterization. The most important risk factor for bacteriuria is the duration of catheterization. (See 'Epidemiology' above.)

●Microbiology – As with acute complicated UTI in general, the causative pathogens are most commonly Escherichia coli and other Enterobacteriaceae. Pseudomonas aeruginosa, enterococci, staphylococci, and Candida species are also significant causes. (See 'Microbiology' above.)

●Clinical features – Fever is the most common symptom. Localizing symptoms may include flank or suprapubic discomfort and costovertebral angle tenderness. However, these symptoms are not specific to UTI and may be seen in catheterized patients without bacteriuria. Catheter obstruction or dislodgement increases the risk for sepsis or bacteremia. (See 'Clinical features' above.)

●Diagnosis – The diagnosis can be made by identifying bacteriuria (or candiduria) plus pyuria in a catheterized patient who either has signs and symptoms that are specific to the urinary tract (as above) or has features of systemic infection that are otherwise unexplained. Since patients with chronic catheterization always have bacteriuria, establishing the presence of consistent symptoms is essential. If the diagnosis is based on nonspecific symptoms, the evaluation should rule out the possibility of other systemic infections (eg, bacteremia, pneumonia, skin or soft tissue infection) prior to attributing them to a catheter-associated UTI. (See 'Establishing symptoms/signs of UTI' above.)

In symptomatic patients, the absence of bacteriuria or pyuria makes the diagnosis of catheter-associated UTI unlikely. (See 'Test interpretation' above.)

●Selective indications for urine testing – We submit urine for urinalysis and culture only when patients have symptoms or signs that are potentially attributable to a catheter-associated UTI. Urine should not be routinely tested for bacteriuria in catheterized individuals who are asymptomatic or have very nonspecific features (eg, change in functional or mental status in older adults). (See 'Indications' above.)

●Optimal specimen collection – Ideally, urine samples for culture should be obtained by removing the indwelling catheter and obtaining a midstream specimen or, if ongoing catheterization is warranted, a specimen through a new catheter. When this is not possible, the culture should be obtained through the catheter port, not the drainage bag. (See 'Specimen collection' above.)

●Antimicrobial therapy – Empiric antimicrobial management of catheter-associated UTI depends on the extent of illness; those who have fever, flank pain, costovertebral angle tenderness, or features of systemic infection are treated as for acute complicated UTI. Regimen selection depends on severity of infection and risk factors for resistance and is discussed in detail elsewhere (table 2 and algorithm 1 and algorithm 2). (See "Acute complicated urinary tract infection (including pyelonephritis) in adults", section on 'Empiric antimicrobial therapy'.)

Once culture and susceptibility results are available, the antimicrobial regimen should be tailored to the specific organism isolated. Directed antimicrobial therapy and duration are also discussed elsewhere. (See "Acute complicated urinary tract infection (including pyelonephritis) in adults", section on 'Directed antimicrobial therapy'.)

●Catheter management – Patients who no longer require catheterization should have the catheter removed. If long-term catheterization is needed and intermittent catheterization is not feasible, we suggest removing and replacing the catheter when antimicrobial therapy is initiated, if not already done when urine was collected for testing (Grade 2C). (See 'Catheter management' above.)

●Prevention – Avoidance of unnecessary catheterization, use of sterile technique for insertion, and removal as soon as possible are essential to the prevention of catheter-associated UTI. Antimicrobial agents have no role in prevention of infection for the majority of patients with urinary catheters. (See 'Prevention' above and "Placement and management of urinary catheters in adults".)

ACKNOWLEDGMENT — 

The UpToDate editorial staff acknowledges Thomas Fekete, MD, who contributed to earlier versions of this topic review.