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International Journal of Antimicrobial Agents 24S (2004) S44S48

Catheter-associated urinary tract infections:diagnosis and prophylaxis

Paul A. Tambyah

Division of Infectious Diseases, Department of Medicine, National University of Singapore, 5 Lower Kent Ridge Roa d, Singapore 119074, Singapore

Abstract

Catheter-associated urinary tract infections (CAUTI) are the commonest nosocomial infections worldwide. While they are often asymp-

tomatic and frequently cost less than nosocomial surgical site infections or nosocomial pneumonia, they are major reservoirs of antimicrobialresistant pathogens. Numerous strategies have been devised in an attempt to reduce the incidence of CAUTI but few have proven effective.

Novel technologies such as the potential use of antiseptic or antimicrobial coatings on catheters hold promise for possibly reducing these

infections in the fight against antimicrobial resistance.

2004 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Keywords: Catheter-associated urinary tract infection; Prevention; Urinary catheterization

1. Introduction

Catheter-associated urinary tract infection (CAUTI) is the

most common nosocomial infection in hospitals and nurs-ing homes world-wide with more than one million episodes

in the United States alone [1,2]. Although most CAUTIs

are asymptomatic[3],rarely extend hospitalization and add

only US$ 5001000 to the direct costs of acute care hos-

pitalization [4], asymptomatic infections often precipitate

unnecessary antimicrobial therapy. Although the costs of

catheter-associated urinary tract infections are not as high

as for example a deep surgical site infection or a nosoco-

mial pneumonia, CAUTIs are a cause for concern as they

are a major reservoir of resistant pathogens [5,6]. Numer-

ous studies have documented a high prevalence of resistant

pathogens in CAUTI and the association between nosoco-

mial CAUTI and surgical site infections has been made [7].

2. Diagnosis

In a study conducted almost 20 years ago, Stark and Maki

[8]showed that in the absence of antibiotics, even one mi-

Presented in part at the Surgical Infections: Prevention and Manage-

ment Conference held on 2930 May 2003 in Moscow, Russia. Tel.: +65-6779-5555; fax: +65-6779-4112.

E-mail address:[email protected] (P.A. Tambyah).

croorganism per ml would predictably multiply over time

to reach 105106 microorganisms per ml in the catheterized

urinary tract. They showed that 103 microorganisms per ml is

a sensitive cut-off for CAUTI. In non-catheterized patients,by convention, 105 organisms per ml of urine is used as a

criterion for diagnosis of UTI but for symptomatic women

with UTIs, a much lower colony count has been shown to

be valid[9].There is considerable variation in laboratories

and clinicians, in reporting and diagnosing CAUTI on the

basis of colony counts. However, the underlying principle

remains that the normally sterile urinary tract is vulnerable

to colonization and subsequent infection by microorganisms

once a catheter is in situ.

3. Pyuria

Pyuria is widely used as a criterion for diagnosing uri-

nary tract infections in non-catheterized patients. However,

in a large prospective study of more than 750 patients [10],

pyuria was found to be most useful in predicting CAUTI

in patients with UTI due to Gram-negative pathogens while

CAUTI caused by large numbers of yeasts and enterococci or

staphylococci were less significantly associated with pyuria.

This is thought to be due to less urinary tract inflammation

elicited by these organisms. Other studies have predomi-

nantly been conducted in long-term catheterized patients and

have shown variable results in terms of pyuria as a predictor

0924-8579/$ see front matter 2004 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

doi:10.1016/j.ijantimicag.2004.02.008


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P.A. Tambyah / International Journal of Antimicrobial Agents 24S (2004) S44S48 S45

for CAUTI[11,12].Pyuria alone cannot be used as the cri-

teria for obtaining a urine culture in a catheterized patient.

It has been argued that if a catheterized patient develops

signs of sepsis that cannot be linked to another source, such

as nosocomial pneumonia, surgical site infection, or vas-

cular catheter-related bloodstream infection, a urine culture

should be obtained even if the patient does not have demon-strable pyuria.

4. Symptoms

Symptoms are also not reliable for the diagnosis of

CAUTI. Although many guidelines [13,14] make the dis-

tinction between symptomatic CAUTI and asymptomatic

bacteriuria in the management of CAUTI, we were unable

to demonstrate a difference in presence of fever or symp-

toms related to the urinary tract in catheterized patients with

and without CAUTI, in a large prospective study [4]. The

catheter can itself be the source of symptoms as was notedin that study in which the proportion of catheterized patients

without CAUTI with symptoms was similar to those with

CAUTI. Part of the reason for the absence of symptoms of

urethral irritation such as dysuria or supra-pubic pain is that

the catheter itself prevents contact of inflammatory cells in

urine and large numbers of microorganisms with the urethral

mucosa. The presence of the urinary catheter in situ also

allows for decompression of the bladder, thus preventing

the development of symptoms related to bladder distension

or reflux. It is interesting to note that the majority of cases

of bloodstream infection [15] and even in one report [16]

mortality associated with CAUTI are in patients where thereis significant urinary obstruction. It has also been shown

that patients with long-term indwelling catheters rarely have

febrile episodes even though they have chronic significant

amounts of bacteria in their urine [17,18]. This changes

when obstruction or encrustation occurs as in that setting,

decompression of the infected bladder is compromised.

5. Pathogenesis

The entry of a urinary catheter bypasses the normal host

defences at the meatus and allows the entry of pathogens

into the bladder. The presence of a foreign body also al-

lows for the formation of a biofilm, which is a conduit for

pathogens to multiply and cause infection. It has been pos-

tulated that there are two main routes for CAUTI. Firstly,

the extraluminal route: this could be either early at the time

of catheter insertion due to inadequate antisepsis or con-

tamination, or late due to colonisation of the meatus and

the ascent of microorganisms from the perineum along the

surface of the catheter. Early studies by Garibaldi et al.

[19]have shown that meatal colonisation is associated with

CAUTI. Women are also much more likely to have CAUTI

due to their shorter urethras and thus the shorter distance

microbes have to travel from the perineum to the bladder.

The second pathway for microorganisms to enter the bladder

is the intraluminal route. This is from breaks in the closed

drainage system that occurs through irrigation of the blad-

der without proper asepsis. Alternatively, and perhaps more

commonly, the collection-bag urine becomes contaminated

through healthcare workers not washing hands when goingfrom bag to bag emptying urine or when changing bags. Ei-

ther way, contaminated urine can ascend from the bag into

the catheter when the bag is raised, often during transport of

the patient into and out of operating rooms or radiological

suites. This allows microorganisms to flow into the bladder.

They can also rise by capillary action even when the bag is

below the bed.

In a large prospective study of more than 1000 patients

with indwelling catheters performed to determine the route

of entry of microorganisms causing CAUTI, daily urine cul-

tures were done from the drainage bag and the catheter col-

lection port[20].The assumption was that if the organism

ascended into the bladder by the intraluminal route fromthe bag, it would appear first in a culture from the bag.

On the other hand, if the microorganism came along the

surface of the catheter from the perineum, it would be de-

tected in the catheter sample before it was detected in the

bag. Overall, two thirds of infections were caused by or-

ganisms ascending along the surface of the catheter. This

was more marked for staphylococci and enterococci as well

as yeasts which are common commensals of the perineum.

For Gram-negative organisms which are often water-borne

such as Pseudomonas, Enterobacter or Acinetobacter, the

intraluminal route from the collection-bag was more impor-

tant. These organisms can be carried on the hands of health-care workers and can be readily transmitted to urine bags.

Once they enter the bag, they multiply and can occasion-

ally cause UTIs by either capillary action or by inadvertent

transfer into the bladder during transport. Outbreaks of these

organisms in particular, Serratia, have been well reported

and associated with a variety of urinary collection devices

[21].

6. Risk factors

At least five prospective studies[2226]have conducted

multivariate analysis of the risk factors associated with

CAUTI with daily urine cultures to detect all CAUTIs in

large numbers of patients. These studies were found to have

remarkably similar results. The most important risk fac-

tors have been prolonged catheterization and being female.

Other risk factors identified have included catheterization

outside the sterile environment of the operating room, being

on a urology service which might simply mean having a

urinary tract abnormality, other infections, diabetes, malnu-

trition and renal failure. Interestingly, most of the infection

control interventions were found to have a minimal im-

pact on the incidence of CAUTI with one exceptionif


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S46 P.A. Tambyah/ International Journal of Antimicrobial Agents 24S (2004) S44S48

the drainage tube was allowed to be above the level of the

patient; that was a major risk factor for infection. Antibi-

otics were in general protective, but the infections (when

they occurred) tended to be caused by antibiotic-resistant

organisms.

7. Prevention

The best way of preventing a CAUTI is to remove the

catheter or to avoid its use. All studies have shown the du-

ration of catheterization as a significant risk factor for noso-

comial CAUTI[2225]. A recent study by Saint et al. [27]

showed that a number of physicians at various levels are

unaware that their patients are catheterized. Catheters have

been described as a one-point restraint for hospitalized

patients[28], and in a classic editorial nearly half a century

ago, Beeson made the case against the catheter [29]. One

problem is that there are few viable alternatives to a urinary

catheter for patients who are incontinent or have urinary ob-struction.

The use of diapers also has its own problems in terms of

skin damage and pressure sores. They are also very expen-

sive and demoralizing for the patient. Condom catheters have

been shown in at least one nursing home study to reduce the

risk of CAUTI but they are obviously limited to men without

obstruction[30].Although supra-pubic catheters are associ-

ated with a decreased rate of CAUTI [31], there are some

data suggesting that there are problems.

Many innovations have been tried to reduce CAUTI.

These have been targeted at both the extraluminal as well

as intraluminal routes of CAUTI. These have includedthe use of antiinfective lubricants at the time of insertion

[3234], sealed catheter-tube junctions to prevent breaks in

closed drainage [3537], antireflux valves or antiinfective

irrigation of the bladder or instillation of antiseptics in the

collection-bag[3840]. In well-designed randomized trials

over the last 20 or so years, all of these have failed to show

significant benefits. In the last few years, renewed interest

has arisen in the use of antiinfective catheter material. These

have been used successfully in central venous catheters and

have been studied for urinary catheters as well. The results

have been varied but promising. A novel silver hydrogel

catheter was recently found to be mainly beneficial for in-

fections arising by the extraluminal route along the catheter

surface[41].

8. Silver-coated catheters

Silver is a well-known antiseptic with a long history, as an

antiseptic rather than an antibiotic and the risk of generating

antibiotic resistance would be expected to be low. Argyrism

is a potential concern that has limited the use of silver on

the internal coating of catheters and possibly limited its ef-

ficacy. There are a number of studies that have evaluated

silver-coated catheters including silver oxide catheters and

silver alloy catheters. Silver oxide catheters were found to

have no benefit in prevention of CAUTI in two large studies

[42,43]while a meta-analysis of silver alloy coated catheters

suggests that they are beneficial[44].

9. Antibiotic coated catheters

Antibiotic coated catheters using a combination of

rifampicin and minocycline [45] have been used and

were found to be effective in preventing nosocomial in-

travenous catheter related infections as well [46]. The

rifampicin-minocycline catheter was most effective in

preventing CAUTI caused by Gram-positive rather than

Gram-negative bacteria thus limiting its practical efficacy.

The concern has been in the development of antibiotic re-

sistance. In many parts of the world, where Mycobacterium

tuberculosis is endemic, the widespread use of rifampicin

coated catheters would be a cause for concern, if this wasfound to be associated with increased rates of drug-resistant

tuberculosis.

10. Novel technologies

Other technologies that appear promising on the hori-

zon include the use of urethral stents [47]. Even further on

the horizon perhaps are technologies, which translate bench

research into cell-cell communications which would inhibit

the formation of the biofilm in the first place. Quorum sens-

ing is an area of intense research interest. A quorum sensinginhibitor has been shown in vivo to be effective in prevent-

ing the development of a biofilm by Staphylococcus epider-

midis[48]and this could possibly be translated into a novel

device for the prevention of CAUTI.

11. Conclusion

There are clearly many challenges that face researchers

and clinicians working in the field of CAUTI. Foremost

among these must be the prevention of these infections.

Effective interventions to prevent CAUTI will doubtless help

to reduce the reservoir of resistant pathogens in the intensive

care units, wards and long-term care facilities. This will be

a critical step in the battle against antibiotic resistance.

References

[1] Burke JP, Riley DK. Nosocomial urinary tract infection. In: Mayhall

CG, editor. Hospital Epidemiology and Infection Control. Baltimore,

MD: Williams and Wilkins; 1996. p. 13953.

[2] Kunin CM. Care of the urinary catheter. In: Urinary Tract Infections:

Detection, Prevention and Management. 5th ed. Baltimore, MD:

Williams & Wilkins; 1997. p. 22779.


4/5

P.A. Tambyah / International Journal of Antimicrobial Agents 24S (2004) S44S48 S47

[3] Tambyah PA, Maki DG. Catheter-associated urinary tract infection is

rarely symptomatic: a prospective study of 1497 catheterized patients.

Arch Intern Med 2000;160:67882.

[4] Tambyah PA, Knasinski V, Maki DG. The direct economic costs

of nosocomial catheter-associated urinary tract infection in the

era of managed care. Infect Control Hosp Epidemiol 2002;23:27

31.

[5] Jarlier V, Fosse T, Philippon A. Antibiotic susceptibility in aerobic

gram-negative bacilli isolated in intensive care units in 39 French

teaching hospitals. Intens Care Med 1996;22:105765.

[6] Bjork DT, Pelletier LL, Tight RR. Urinary tract infections with

antibiotic resistant organisms in catheterized nursing home patients.

Infect Control 1984;5:1736.

[7] Krieger JN, Kaiser DL, Wenzel RP. Nosocomial urinary tract in-

fections cause wound infections postoperatively in surgical patients.

Surg Gynecol Obstet 1983;156:3138.

[8] Stark RP, Maki DG. Bacteriuria in the catheterized patient. What

quantitative level of bacteriuria is relevant? N Engl J Med

1984;311:5604.

[9] Stamm WE, Hooton TM. Management of urinary tract infections in

adults. N Engl J Med 1993;329:132834.

[10] Tambyah PA, Maki DG. The relationship between pyuria and in-

fection in patients with indwelling urinary catheters: a prospectivestudy of 761 patients. Arch Intern Med 2000;160:6737.

[11] Peterson JR, Roth EJ. Fever bacteriuria and pyuria in spinal cord

injured patients with indwelling urethral catheters. Arch Phys Med

Rehabil 1989;70:83941.

[12] Musher DM, Thorsteinsson SB, Airola VM. Quantitative urinalysis:

diagnosing urinary tract infection in men. JAMA 1976;236:2069

72.

[13] OGrady NP, Barie PS, Bartlett J, et al. Practice parameters for

evaluating new fever in critically ill adult patients. Crit Care Med

1998;26:392408.

[14] National Institute on Disability and Rehabilitation Research. The

prevention and management of urinary tract infections among peo-

ple with spinal cord injuries: National Institute on Disability and

Rehabilitation Research Consensus Statement. J Am Paraplegia Soc

1992;15:194204.[15] Bryan CS, Reynolds KL. Hospital acquired bacteremic urinary tract

infection: epidemiology and outcome. J Urol 1984;132:4948.

[16] Quintiliani R, Klimek J, Cunha BA, Maderazo EG. Bacteraemia

after manipulation of the urinary tract: the importance of preexisting

urinary tract disease and compromised host defences. Postgrad Med

J 1978;54:66871.

[17] Kunin CM, Chin QF, Chambers S. Morbidity and mortality associated

with indwelling urinary catheters in elderly patients in a nursing

home: confounding due to the presence of associated diseases. J Am

Geriatr Soc 1987;35:10016.

[18] Warren JW, Damron D, Tenney JH, Hoopes JM, Deforge B, Muncie

HL. A prospective microbiologic study of bacteriuria in patients with

chronic indwelling urinary catheters. J Infect Dis 1987;6:11518.

[19] Garibaldi RA, Burke JP, Britt MR, Miller MA, Smith CB. Metal

colonization and catheter-associated bacteriuria. N Engl J Med

1980;30:33168.

[20] Tambyah PA, Halvorson K, Maki DG. A prospective study of the

pathogenesis of catheter-associated urinary tract infection. Mayo Clin

Proc 1999;74:1316.

[21] Maki DG, Hennekens C, Bennet J. Prevention of catheter-associated

urinary tract infection. JAMA 1972;221:12701.

[22] Garibaldi RA, Burke JP, Dickman ML, Smith CB. Factors predis-

posing to bacteriuria during indwelling urethral catheterization. N

Engl J Med 1974;291:2159.

[23] Platt R, Polk BF, Murdock B, Rosner B. Risk factors for nosocomial

urinary tract infection. Am J Epidemiol 1986;124:97785.

[24] Shapiro M, Simchen E, Izraeli S, Sacks TO. A multivariate analysis

of risk factors for acquiring bacteriuria in patients with indwelling

urinary catheters for longer than 24 hours. Infect Control 1984;5:525

32.

[25] Johnson JR, Roberts PL, Olsen RJ, Moyer KA, Stamm WE. Pre-

vention of catheter-associated urinary tract infection with a silver

oxide-coated urinary catheter: clinical and microbiologic correlates.

J Infect Dis 1990;162:114550.

[26] Riley DK, Classen DC, Stevens LE, Burke JP. A large randomized

clinical trial of a silver impregnated urinary catheter: lack of ef-

ficacy and staphylococcal superinfection. Am J Med 1995;98:349

56.

[27] Saint S, Wiese J, Amory JK. Are physicians aware of which of their

patients have indwelling urinary catheters? Am J Med 2000;109:476

80.

[28] Saint S, Lipsky BA, Goold SD, et al. Indwelling urinary catheters:

a one-point restraint? Ann Intern Med 2002;137:1257.

[29] Beeson PB. The case against the catheter. Am J Med 1958;24:13.

[30] Warren JW. Uretheral catheters. Infect Control Hosp Epidemiol

1996;17:2124.

[31] Shapiro J, Hoffmann J, Jersky J. A comparison of suprapubic and

transurethral drainage for postoperative urinary retention in general

surgical patients. Acta Chirurgica Scandinavia 1982;148:3237.

[32] Butler HK, Kunin CM. Evaluation of polymyxin catheter lubricant

and impregnated catheters. J Urol 1968;100:5606.[33] Kunin CM, Finkelberg Z. Evaluation of an intraurethral lubricating

catheter in prevention of catheter-induced urinary tract infections. J

Urol 1971;106:92830.

[34] Schiotz HA. Antiseptic catheter gel and urinary tract infection after

short-term postoperative catheterization in women. Arch Gynecol

Obstet 1996;258:97100.

[35] Huth TS, Burke JP, Larsen RA. Clinical trial of junction seals for

the prevention of urinary catheter-associated bacteriuria. Arch Intern

Med 1992;152:80712.

[36] Platt R, Polk BF, Murdock B, Rosner B. Reduction of mortality asso-

ciated with nosocomial urinary tract infection. Lancet 1983;i:8937.

[37] Classen DC, Larsen RA, Burke JP. Stevens LE. Prevention of

catheter-associated bacteriuria: clinical trial of methods to block three

known pathways of infection. Am J Infect Control 1991;19:136

42.

[38] Warren JW, Platt R, Thomas RJ, Rosner B, Kass EH. Antibiotic

irrigation and catheter associated urinary tract infections. N Engl J

Med 1978;299:5703.

[39] Gillespie WA, Simpson RA, Jones JE, Nashef L, Teasdale C, Speller

DCE. Does the addition of disinfectant to urine drainage bags prevent

infection in catheterized patients. Lancet 1983;i:10379.

[40] Thomson RL, Haley CE, Searcy MA, et al. Catheter-associated

bacteriuria: failure to reduce attack rates using periodic instillations

of a disinfectant into urinary drainage systems. JAMA 1984;251:747

51.

[41] Maki DG, Tambyah PA. Engineering out the risk of infection with

urinary catheters. Emerg Infect Dis 2001;7:3427.

[42] Johnson JR, Roberts PL, Olsen RJ, Moyer KA, Stamm WE. Pre-

vention of catheter-associated urinary tract infection with a silveroxide-coated urinary catheter: clinical and microbiologic correlates.

J Infect Dis 1990;162:114550.

[43] Riley DK, Classen DC, Stevens LE, Burke JP. A large randomized

clinical trial of a silver-impregnated urinary catheter: lack of effi-

cacy and staphylococcal superinfection. Am J Med 1995;98:349

56.

[44] Saint S, Elmore JG, Sullivan SD, Emerson SS, Koepsell TD. The

efficacy of silver alloy-coated urinary catheters in preventing uri-

nary tract infection: a meta-analysis. Am J Med 1998;105:234

6.

[45] Darouiche RO, Smith A, Hanna H, Dhabuwala CB, Steiner MS,

Babian RJ, et al. Efficacy of antimicrobial-impregnated bladder

catheters in reducing catheter-associated bacteriuria: a prospective

randomized multi-center trial. Urology 1999;4:97681.


5/5

S48 P.A. Tambyah/ International Journal of Antimicrobial Agents 24S (2004) S44S48

[46] Raad I, Darouiche RO, Dupuis J, et al. Central venous

catheters coated with minocycline and rifampin for the pre-

vention of catheter-related colonization and bloodstream infec-

tions. A randomized double-blind trial. The Texas Medical

Center Catheter Study Group. Ann Intern Med 1997;127:267

74.

[47] Nissenkorn I. The intraurethral catheter-three years of experience.

Eur Urol 1993;24:2730.

[48] Balaban N, Giacometti A, Cirioni O, et al. Use of the quorum-sensing

inhibitor RNA. IIIinhibiting peptide to prevent biofilm formation

in vivo by drug-resistant Staphylococcus epidermidis. J Infect Dis

2003;187:62530.

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