on 25-Sep-2023 (Mon)

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Pyuria is evidence of inflammation in the genitourinary tract and is present in almost all persons with symptomatic UTIs. It is also common in persons with ASB,4 including 30% to 75% of bacteriuric patients with short-term indwelling urethral catheters and 50% to 100% of individuals with long-term indwelling catheters.

In a longitudinal study of patients with long-term urinary catheters, bacteriuria and pyuria were common, even during asymptomatic periods, and did not change during symp- tomatic UTI episodes.79

Of note, interventions that reduce the risk of catheter-associated ASB are likely to also reduce the risk of CAUTI

It should be noted that our ability to prevent catheter-associated ASB or CAUTI in patients who have appropriate indications for catheterization is quite limited, especially in those patients requiring long-term bladder drainage.92

Reducing unnecessary catheterization is the most effective way to prevent catheter-associated ASB and CAUTI. Other reasons to reduce urinary catheterization are that catheters cause discomfort, restrict mobility, and delay hospital discharges.99

In studies of hospitalized patients with urinary catheters, the initial indication for catheter use was judged inappropriate in up to 50% of cases, and continued catheterization was judged inappropriate for almost half of catheter-days.27,101–103

In the medical ICU, many unjustified catheter-days are due to monitoring of urine output when it is no longer indicated, and on medical wards, urinary incontinence is a major reason for unjustified initial and continued urinary catheterization.

In one study, providers were unaware of patient catheterization for 28% of the 319 provider-patient observations—21% for students, 22% for interns, 27% for residents, and 38% for attending physicians.105

Use of portable bladder ultrasound devices to reduce unnecessary catheterization warrants further study in the care of oliguric patients.110,111

Strategies shown to reduce inappropriate insertion of catheters include education and use of a catheter indication sheet in the emergency department,106 use of a multifaceted intervention restricting urinary catheterization in the operating room and postanesthesia care unit and expedited catheter removal on the postoperative surgical ward,107 use of an ultrasound bladder scanner to assess bladder volumes following surgery,108 and use of in-and-out catheterization rather than short-term indwelling catheterization in postoperative patients with urinary reten- tion.109

Indications for Use of Indwelling Urinary Catheters Perioperative use for selected surgical procedures Use during prolonged surgical procedures with general or spinal anesthesia Urine output monitoring in critically ill patients Management of urinary retention and urinary obstruction Assistance in pressure ulcer healing for incontinent patients Prolonged immobilization Improve comfort for end-of-life care or patient preference

Although comparative studies are sparse, the consensus is that indwell- ing urethral catheterization places the patient at the greatest risk for catheter-associated bacteriuria and traumatic complications, and that alternative bladder drainage modalities should be used when appropri- ate.86,87

In nonrandomized studies, use of condom catheters has been shown to result in a lower incidence of catheter-associated bacteriuria compared with indwelling urethral catheters.20

Thus in men with low postvoid residual volume who are not cognitively impaired, condom catheters are preferable to indwelling urethral catheters for short-term catheterization and probably for long-term catheterization.

Intermittent catheterization is a technique in which the bladder is drained of urine by catheterization usually every 4 to 6 hours, so the amount of urine obtained with each collection is generally no more than 500 mL.129 The schedule of intermittent catheterization is tailored for each individual to minimize the number of catheterizations while not allowing the bladder to become overdistended.

Guttman and Frankel130 in 1966 described intermittent catheterization using sterile technique, and Lapides and colleagues131 later demonstrated that the clean (non- sterile) technique was safe and associated with a low incidence of complications in patients with neurogenic bladders.

Intermittent catheterization is widely viewed to be associated with fewer complications than indwelling catheterization, including catheter-associated bacteriuria, hydronephrosis, bladder and renal calculi, bladder cancer, and autonomic dysreflexia,132,133 and it has become the standard of care for appropriate women and men with spinal cord injury (SCI)

On the other hand, a meta-analysis of trials comparing catheterization methods in patients (mostly postsurgical) undergoing short-term catheterization found no difference in ASB between indwelling and intermittent catheterization (20% vs. 22%; risk ratio [RR], 1.04; 95% confidence interval [CI], 0.85–1.28), although urinary retention was lower in patients with indwelling compared with intermittent catheterization (RR, 0.45; 95% CI, 0.22–0.91).125

Nevertheless, intermittent catheterization is not commonly used for short-term catheterization because of the educational, motivational, and staff-time requirements necessary for its implementation.

Although there are no data that reuse of catheters increases infection risk, catheter reuse is inconvenient for many patients who find it difficult to clean their catheters away from home, and others find it nonaesthetic

Complications associated with long-term intermittent catheterization, although apparently less common than with indwelling urethral catheterization, include catheter-associated bacteriuria, prostatitis, epididymitis, urethritis, urethral trauma with bleeding, urethral strictures, and false passages.129,133

Limitations to intermittent catheterization include limited availability of staff to perform the procedure or educate patients, inability or unwillingness of patients to perform frequent catheterizations, or abnormal urethral anatomy such as stricture, false passages, or bladder neck obstruction. UTIs and urethral trauma are the main complications.137

Potential advantages of suprapubic catheters in patients who need bladder drainage, compared with indwelling urethral catheters, include lower risk of catheter-associated bacteriuria because abdominal skin is less likely to be colonized with uropathogens compared with the urethra, reduced risk of urethral trauma and stricture, less interference with sexual activity, and, in those undergoing short-term catheterization, ability to more easily assess the appropriate time for catheter removal

Suprapubic catheters appear to be commonly used in gynecologic surgery in some centers, but their use is limited, presumably because their insertion is an invasive procedure, and they are harder to change when necessary. Potential complications include visceral injury (rare) and less serious complications, such as leakage, catheter blockage, and hematuria.139

A meta-analysis of randomized trials in primarily surgical patients undergoing short-term catheterization found insufficient evidence to determine whether indwelling urethral catheterization, compared with suprapubic catheterization, was associated with higher risk of UTI.125

Although use of aseptic technique for inserting indwelling urethral catheters is widely recommended,140 few data exist to support such a recommendation.

However, no significant difference in risk of catheter- associated bacteriuria was found in a study of 156 patients undergoing preoperative urethral catheterization who were randomized to sterile versus clean technique for catheter insertion.141

Moreover, in patients managed with intermittent catheterization who are catheterized multiple times daily, there appears to be no difference in infection risk with nonsterile compared with sterile technique.

Nevertheless, given the ubiquity of multidrug-resistant pathogens in the health care environment, it seems prudent to use aseptic technique for inserting indwelling urethral catheters in patients in the hospital or LTCF.140

Introduction of the closed catheter drainage system, in which the collecting bag is attached to the distal end of the collecting tube, was perhaps the most important advance in prevention of catheter-associated bacteriuria.14,17,20

In patients managed with catheter drainage into open containers, 95% of patients develop catheter-associated bacteriuria by 96 hours.142 By comparison, about 50% of patients managed with closed drainage systems develop catheter-associated bacteriuria by 14 days of continuous catheterization.17

Discon- nections at the catheter–collecting tube junctions have been shown to increase the risk of catheter-associated bacteriuria,4,16,143 so many hospitals use preconnected urinary drainage systems in which the catheter, tubing, and drainage bag are supplied as a single connected unit.

Diagnostic urine samples should be aspirated using aseptic technique through ports in the distal catheter, and larger volumes of urine for special analyses (not microbiologic studies) should be collected aseptically from the drainage bag with care not to contaminate the end of the drainage tube from potentially contaminated measuring containers.64

The catheter should be properly anchored to minimize movement because movement of urethral catheters may cause urethral trauma and may facilitate the ascension of organisms up the urethra-catheter interface.

Importantly, the drainage tube should not be allowed to move above the level of the bladder or below the level of the collection bag.21

In vitro studies have shown antiadherence or antimicrobial activity associated with silver-, minocycline- and rifampin-, and nitrofurazone- coated catheters,145–147 although nitrofurazone appears to be the most inhibitory.148,149

There are no data to show that antimicrobial-coated catheters are beneficial in patients managed with long-term catheterization (>30 days).153

The largest and most clinically relevant trial of these coated catheters was a multicenter trial by Pickard and colleagues, in which 7102 patients undergoing short-term (1–14 days) catheterization were randomized to indwelling urethral catheterization with a silver alloy–coated catheter, a nitrofurazone-impregnated catheter, or a standard latex catheter.154,155 In this trial 95% of the patients were catheterized for perioperative monitoring. The primary outcome was symptomatic UTI, defined as UTI symptoms and signs plus prescription of an antimicrobial for UTI, and the time frame for CAUTI was up to 6 weeks after catheter removal (unusually long for catheter trials). Compared to standard catheters, silver alloy–coated catheters showed no reduction in CAUTI, while nitrofurazone-coated catheters showed a minimal reduction in CAUTI (−2.1%; 95% CI, −4.2 to −0.1%). This reduction was less than the 3.3% reduction established a priori to be of clinical significance.154

In summary, nitrofurazone-coated urinary catheters appear to have some benefit in the prevention of catheter-associated ASB in some trials of short-term catheterized patients, while silver alloy catheters have minimal effect. Whether the reduction in bacteriuria translates into reduction of secondary bloodstream infection or other health care– associated infections is unclear. Thus available data do not support routine use of antiseptic or antimicrobial urinary catheters to prevent CAUTI.

Meta-analysis of antimicrobial prophylaxis with long-term urinary catheter use only found one randomized, controlled trial in patients with indwelling catheters, and in this study, only 23 patients completed the 6-month study of norfloxacin suppression versus placebo.132,158 Although this study demonstrated a significant decrease in symptomatic CAUTI, 25% of strains in placebo patients versus 90% of strains in norfloxacin patients were resistant to norfloxacin at the end of the prophylaxis period.158

Clinical trials in adults with neurogenic bladders secondary to SCI, using either indwelling159 or intermittent catheterization,160 and those in older adults with indwelling catheters,161 have found that recurrent bacteriuria, after a course of targeted antimicrobials intended to sterilize the urine, is the rule rather than the exception.

Unfortunately, up to 60% to 80% of hospitalized, catheterized patients receive antimicrobial therapy for a variety of reasons,17,162 and not controlling for this important variable in the analyses of many intervention trials may explain why some interventions have not been shown to be effective in preventing catheter-associated bacteriuria

Methenamine salts (methenamine mandelate and methenamine hip- purate) are hydrolyzed to ammonia and formaldehyde, which is responsible for the antibacterial activity of methenamine. Antimicrobial activity in urine is correlated with urinary concentrations of formal- dehyde, and the urinary concentration of formaldehyde is dependent on the concentration of methenamine in the urine and the urine pH.163

In addition, the optimal method to acidify the urine in a patient on methenamine is not known. Ascorbic acid is often used to acidify the urine, but up to 4 g/day have shown no significant effect on mean urinary pH, and doses as high as 12 g/day may be required to adequately acidify the urine.163

Overall, the data are unconvincing that methenamine is effective in reducing the risk of catheter-associated bacteriuria or CAUTI in patients managed with long-term indwelling catheterization—patients most in need of an effective agent that does not select for antimicrobial resistance

A meta-analysis of 13 random- ized or quasi-randomized controlled studies of methenamine hippurate for the prevention of UTIs suggested that methenamine hippurate may have some benefit in patients without renal tract abnormalities (symp- tomatic UTI: RR, 0.24; 95% CI, 0.07–0.89; bacteriuria: RR, 0.56; 95% CI, 0.37–0.83), but not in patients with known renal tract abnormalities (symptomatic UTI: RR, 1.54; 95% CI, 0.38–6.20; bacteriuria: RR, 1.29; 95% CI, 0.54–3.07).166

However, periurethral cleansing with chlorhexidine solution versus water before insertion of an indwelling urinary catheter did not reduce the rate of catheter-associated bacteriuria in two different trials.170,171

Possible reasons why enhanced meatal care has not been effective in reducing catheter-associated bacteriuria include the negative effect of increased catheter manipulation associated with the interventions, inadequate residual antiseptic activity of the topical agent, and lack of effect on the intraluminal route of infection.

Randomized, placebo-controlled studies of cranberry in doses up to 2 g daily to prevent catheter-associated bacteriuria or CAUTI in patients with neurogenic bladders are mostly negative.168,172

The routine use of cranberry products for prevention of health care– associated UTI should be discouraged due to lack of clearly demonstrated efficacy in preventing catheter-associated ASB or CAUTI, problems of tolerance with long-term use, and cost.

More recently a double- blind, randomized, placebo-controlled trial of cranberry capsules in 185 noncatheterized women in nursing homes did not find any difference in the primary outcome of bacteriuria plus pyuria in the two arms of the study.173

In summary, bladder irrigation does not appear to be effective in preventing or eradicating catheter-associated bacteriuria in the majority of patients with short-term or long-term indwelling catheterization, is time consuming, may damage the bladder mucosa, and may select for antimicrobial-resistant organisms.

Urinary catheters readily develop biofilms on their inner and outer surfaces once they are inserted, and these biofilms protect uropathogens from antimicrobials and the host immune response.56

A meta-analysis found only one randomized, controlled trial of this practice; 17 men in a nursing home were randomized to catheter change only when obstructed/infected versus monthly scheduled changes as well as when necessary for obstruction/infection.176 The trial was too small to provide reliable evidence about CAUTI or blockage.

The practice of routine catheter change with the purpose of preventing infection or blockage, or both, is unlikely to change in the absence of data to address this issue

Fever and bacteremia can occur at the time of removal or replacement of a urethral catheter, and prophylactic antimicrobials are sometimes used to prevent such events.

Among catheterized and bacteriuric women in LTCFs, transient fever is twice as common within 24 hours of catheter replacement, compared with other days.29

Studies in chronically catheter- ized and bacteriuric men and women have shown that bacteremia occurs in 4% to 10% of patients after urethral catheter removal or replacement, but episodes are transient and asymptomatic.178–180

Overall, a benefit was seen with prophylactic antimicrobials, with a 5.8% absolute reduction in symptomatic UTI and a risk ratio of 0.45 (95% CI, 0.28–0.72). Nevertheless, prophylactic antimicrobial agents are not routinely recommended for catheter removal or replacement because it is unclear whether these findings apply to the more general medical inpatient population, and widespread implementation of prophylactic antimicrobials at the time of catheter removal has potential to cause harm in terms of cost, side effects, and resistance.

In a study in mice, mannosides provided significant protection against uropathogenic E. coli catheter-associated bacteriuria by preventing bacterial invasion and shifting the E. coli niche primarily to the extracel- lular milieu.184

For example, in 35 patients undergo- ing long-term catheterization, a prospective randomized trial of cepha- lexin or no antibiotic therapy for episodes of catheter-associated ASB caused by susceptible organisms reported no differences between the two groups in incidence and prevalence of catheter-associated bacteriuria, CAUTI, or catheter obstruction in patients followed up to 44 weeks.187

Even if treatment of catheter-associated ASB was found to be useful, one study in which daily catheter urine cultures were obtained found that 60% of 25 episodes of CAUTI occurred on the same day that catheter-associated bacteriuria was first detected,26 complicating attempts at preemptive therapy.

Prevention of inappropriate treatment of ASB is probably the second most beneficial strategy for patients related to health care–associated UTI, secondary only to avoidance of unnecessary urinary catheterization.

Estimates vary a bit by site of care delivery, but studies in acute-care hospitals, LTCFs, SCI clinics, and emergency departments have docu- mented that 20% to 83% of episodes of detected ASB are treated with antimicrobials.189–191

Unnecessary urine cultures in patients with ASB can lead to false elevation of the reported CAUTI rates, because a positive urine culture in a febrile patient must be reported to the NSHN as a CAUTI, regardless of whether the fever can be attributed to another cause.198

Removing unnecessary urinary catheters through CAUTI prevention efforts may have the side benefit of also reducing testing and treatment for ASB, because cloudy urine or visible sediment in the urine is a stimulus for urine cultures among nursing personnel.194,200

The issues relevant to clinical management of health care–associated UTI, particularly CAUTI, include whether the catheter should be changed prior to urine collection for culture, whether the catheter should be changed during the course of treatment, choice of drugs, duration of therapy, and when to consider complicating factors that may impair response to antimicrobials

Antimicrobials alone may not be successful, if underlying anatomic, functional, or metabolic defects are not corrected.

The culture should be obtained from a freshly placed catheter if the catheter has been in place for a few days because the catheter biofilm may result in spurious culture results.53,54

Moreover, clinical outcomes are improved if the catheter is replaced, as shown in a prospective, randomized, controlled trial in elderly nursing home residents with long-term indwelling catheters and CAUTI. This study demonstrated that patients whose catheters had been in place for longer than 2 weeks and who underwent catheter replacement before antimicrobial treatment had significantly shorter time to improved clinical status and significantly lower rates of polymicrobial catheter-associated bacteriuria and CAUTI after therapy, compared with those who did not undergo catheter replacement.203

Microbiologic data from urine cultures within the prior 2 years can be used to guide empirical antibiotic choice and improve the likelihood of choosing an antimicrobial agent effective against the current urinary pathogen.207

Health care exposure (such as hospitalization or stay in an LTCF) and receipt of antibiotics within the prior 6 months are also risk factors for colonization with resistant organisms.208

In nursing home residents, indwelling devices such as urinary catheters or feeding tubes are risk factors for colonization with, and thus infection by, multidrug-resistant organisms.209

Consideration should be given to providing an initial dose(s) of a broader-spectrum parenteral agent, such as ceftriaxone, a carbapenem, or an aminoglycoside, if there is concern about antimicrobial resistance, while waiting for urine culture results.

Patients who are critically ill should be empirically treated with an antipseudomonal carbapenem (meropenem, imipenem, or doripenem) and vancomycin or daptomycin.

Patients with prior carbapenem-resistant Enterobacte- riaceae cultures who are critically ill or unable to take an oral agent, may warrant, in consultation with an infectious diseases expert, empirical use of some of the newer, expensive, and very broad-spectrum agents such as ceftolozane-tazobactam, ceftazidime-avibactam, meropenem- vaborbactam, or plazomicin.

Reviews of complicated UTI have recommended treatment durations from 7 to 10 days,14 7 to 14 days,40 and 7 to 21 days,202 depending on the severity of the infection.

Most recently, clinical and microbiologic success rates following treatment were almost identical in a noninferiority study of 619 patients with acute pyelonephritis or complicated UTI treated with a 5-day course of levofloxacin or a 10-day course of ciprofloxacin.213

These data suggest that a 7-day regimen is reasonable for most patients with CAUTI, depending on their clinical response, and that shorter regimens, such as a 5-day regimen of a urinary fluoroquinolone, are likely to be sufficient in those patients who are less severely ill, are infected with uropathogens susceptible to the antimicrobial used, and have a rapid response to treatment

Nephrolithiasis at the at the time of tube placement can trigger either systemic inflammatory response syndrome or sepsis; the risk of both is low but higher in patients who have a preexisting UTI or infected stone.214

Intraoperative cultures of urine from the renal pelvis and stone material can be useful to guide postprocedure antibiotics.215

Once a percutaneous nephrostomy tube is in place, colonization of the tube and urine with bacteria and/or Candida occurs commonly, often with more than one organism. Usually this colonization is asymptomatic, but it can lead to fever, pyelonephritis, renal abscess, or bacteremia if drainage from the renal pelvis becomes obstructed or, less often, if instrumentation of an infected urinary tract introduces organisms into the blood stream.216

A clinical definition of nephrostomy-associated pyelonephritis, to help distinguish an actual infection from the more common asymptomatic colonization, is the presence of fever, costover- tebral angle tenderness, or flank pain associated with a positive urine culture, or a combination of these.217

Infected urine in the pelvis can track along the nephrostomy tube into the perinephric space and even extend down the iliacus muscle

Consideration should be given to exchange of the nephrostomy tube during treatment,218 analogous to the recommendation to change an indwelling urethral catheter during treatment of a CAUTI.

Penetration of the drug into the urine is not imperative in treating pyonephrosis or perinephric abscess but is relevant to treating bacteriuria or candiduria prior to a planned urologic procedure.219

Fluconazole and flucytosine obtain high urine concentrations, while intravenous conventional amphotericin B achieves low concentrations. Other antifungals, such as the echinocandins, may have insufficient urine concentrations to affect candiduria but are active within the renal parenchyma.

When used as prophylaxis, an antifungal or antibacterial should be begun prior to the procedure and discontinued shortly after an uncomplicated procedure (duration of 24 hours or less).222

Yeasts, mostly Candida species, are commonly isolated from the urine of catheterized patients.223 NHSN data from 2011 to 2014 reported that C. albicans was the second most common organism identified in CAUTI, second only to E. coli; other Candida species (including all except C. albicans) ranked 10th, and Candida glabrata alone ranked 14th.19