Infectious Diseases Society of America Guidelinesfor the Diagnosis and Treatment of AsymptomaticBacteriuria in Adults
Lindsay E. Nicolle,1 Suzanne Bradley,2 Richard Colgan,3 James C. Rice,4 Anthony Schaeffer,5 and Thomas M. Hooton6
1University of Manitoba, Winnipeg, Canada; 2University of Michigan, Ann Arbor; 3University of Maryland, Baltimore; 4University of Texas,Galveston; 5Northwestern University, Chicago, Illinois; and 6University of Washington, Seattle
SUMMARY OF RECOMMENDATIONS
• Periodic screening for recurrent bacteriuria
The diagnosis of asymptomatic bacteriuria should
should be undertaken following therapy (A-III).
be based on results of culture of a urine specimen col-
• No recommendation can be made for or against
lected in a manner that minimizes contamination (A-II)
repeated screening of culture-negative women in
For asymptomatic women, bacteriuria is definedas 2 consecutive voided urine specimens with
Screening for and treatment of asymptomatic bac-
isolation of the same bacterial strain in quanti-
teriuria before transurethral resection of the prostate is
A single, clean-catch voided urine specimen with
An assessment for the presence of bacteriuriashould be obtained, so that results will be avail-
1 bacterial species isolated in a quantitative countу
able to direct antimicrobial therapy prior to the
105 cfu/mL identifies bacteriuria in men (B-
• Antimicrobial therapy should be initiated shortly
A single catheterized urine specimen with 1 bac-
terial species isolated in a quantitative countу
• Antimicrobial therapy should not be continued
102 cfu/mL identifies bacteriuria in women or
after the procedure, unless an indwelling catheter
Pyuria accompanying asymptomatic bacteriuria is
Screening for and treatment of asymptomatic bac-
not an indication for antimicrobial treatment (A-II).
teriuria is recommended before other urologic proce-
Pregnant women should be screened for bacte-
dures for which mucosal bleeding is anticipated (A-III).
riuria by urine culture at least once in early pregnancy,
Screening for or treatment of asymptomatic bac-
and they should be treated if the results are positive
teriuria is not recommended for the following persons.
• Premenopausal, nonpregnant women (A-I).
The duration of antimicrobial therapy should be
• Older persons living in the community (A-II).
Received 29 October 2004; accepted 2 November 2004; electronically published
• Elderly, institutionalized subjects (A-I).
• Persons with spinal cord injury (A-II).
These guidelines were developed and issued on behalf of the Infectious
Diseases Society of America and have been endorsed by the American Society
• Catheterized patients while the catheter remains
of Nephrology and the American Geriatric Society.
Correspondence: Dr. Lindsay E. Nicolle, University of Manitoba, Health Sciences
Centre, Rm. GG443, 820 Sherbrook St., Winnipeg, MB R3A 1R9, Canada
Antimicrobial treatment of asymptomatic wo-
men with catheter-acquired bacteriuria that persists
Clinical Infectious Diseases 2005; 40:643–54
48 h after indwelling catheter removal may be con-
ᮊ 2005 by the Infectious Diseases Society of America. All rights reserved. 1058-4838/2005/4005-0001$15.00
IDSA Guidelines for Asymptomatic Bacteriuria • CID 2005:40 (1 March) • 643
No recommendation can be made for screening for or
DEFINITIONS
treatment of asymptomatic bacteriuria in renal transplant or
“Asymptomatic bacteriuria,” or asymptomatic urinary infec-
other solid organ transplant recipients (C-III).
tion, is isolation of a specified quantitative count of bacteria
in an appropriately collected urine specimen obtained from aperson without symptoms or signs referable to urinary infection
The purpose of this guideline is to provide recommendations
[3]. “Acute uncomplicated urinary tract infection” is a symp-
for diagnosis and treatment of asymptomatic bacteriuria in
tomatic bladder infection characterized by frequency, urgency,
adult populations 118 years of age. The recommendations were
dysuria, or suprapubic pain in a woman with a normal geni-
developed on the basis of a review of published evidence, with
tourinary tract, and it is associated with both genetic and be-
the strength of the recommendation and quality of the evidence
havioral determinants [4]. “Acute nonobstructive pyelone-
graded using previously described Infectious Diseases Society
phritis” is a renal infection characterized by costovertebral angle
of America (IDSA) criteria (table 1) [1]. Recommendations are
pain and tenderness, often with fever; it occurs in the same
relevant only for the treatment of asymptomatic bacteriuria and
population that experiences acute uncomplicated urinary in-
do not address prophylaxis for prevention of symptomatic or
fection. “Complicated urinary tract infection,” which may in-
asymptomatic urinary infection. This guideline is not meant
volve either the bladder or kidneys, is a symptomatic urinary
infection in individuals with functional or structural abnor-
Screening of asymptomatic subjects for bacteriuria is appro-
malities of the genitourinary tract [5]. Uncomplicated urinary
priate if bacteriuria has adverse outcomes that can be prevented
infection occurs rarely in men, and urinary infection in men
by antimicrobial therapy [2]. Outcomes of interest are short
is usually considered complicated. A “relapse” is a recurrent
term, such as symptomatic urinary infection (including bac-
urinary tract infection after therapy resulting from persistence
teremia with sepsis or worsening functional status), and longer
of the pretherapy isolate in the urinary tract. “Reinfection” is
term, such as progression to chronic kidney disease or hyper-
recurrent urinary tract infection with an organism originating
tension, development of urinary tract cancer, or decreased du-
from outside of the urinary tract, either a new bacterial strain
ration of survival. Treatment of asymptomatic bacteriuria may
or a strain previously isolated that has persisted in the colo-
itself be associated with undesirable outcomes, including sub-
nizing flora of the gut or vagina [4]. “Pyuria” is the presence
sequent antimicrobial resistance, adverse drug effects, and cost.
of increased numbers of polymorphonuclear leukocytes in the
If treatment of bacteriuria is not beneficial, screening of asymp-
urine and is evidence of an inflammatory response in the uri-
tomatic populations to identify bacteriuria is not indicated,
unless performed in a research study to further explore thebiology or clinical significance of bacteriuria. Thus, there are
LITERATURE REVIEW
2 topics of interest: whether asymptomatic bacteriuria is as-sociated with adverse outcomes, and whether the interventions
The recommendations in this guideline were developed after a
of screening and antimicrobial treatment improve these
review of studies published in English. These were identified
through a search of the PubMed database supplemented by
Infectious Diseases Society of America–US Public Health Service Grading System for ranking recommendations in clinical guidelines.
Good evidence to support a recommendation for use; should always be offered
Moderate evidence to support a recommendation for use; should generally be offered
Poor evidence to support a recommendation; optional
Moderate evidence to support a recommendation against use; should generally not be offered
Good evidence to support a recommendation against use; should never be offered
Evidence from у1 properly randomized, controlled trial
Evidence from у1 well-designed clinical trial, without randomization; from cohort or case-
controlled analytic studies (preferably from 11 center); from multiple time-series; or fromdramatic results from uncontrolled experiments
Evidence from opinions of respected authorities, based on clinical experience, descriptive
644 • CID 2005:40 (1 March) • Nicolle et al.
review of references of relevant papers to identify additional
were symptomatic [18]. If urine specimens are collected using
reports, particularly early studies not accessed through the
a freshly applied condom catheter and leg bag, however, у105
PubMed search. In addition, experts in urinary infection were
cfu/mL is the appropriate quantitative criterion, with 90% va-
asked to identify any additional trials not accessed through
lidity for identifying asymptomatic bacteriuria in the voided
review. Clinical studies include prospective, randomized clinical
specimen, compared with a paired catheterized specimen [19,
trials; prospective cohort studies; case-control studies; and
20]. With single urine specimens obtained by urethral cathe-
other descriptive studies. When appropriate, the methodolog-
terization, lower quantitative counts of у102 cfu/mL are con-
ical rigor of studies was evaluated using accepted criteria (e.g.,
sistent with bacteriuria for both men and women [21, 22].
the CONSORT statement [7]). Studies were excluded if the
Patients who have chronic kidney disease, who are experiencing
study population was not adequately characterized to assess
diuresis, or who are infected with selected fastidious organisms
generalizability, if procedures for patient follow-up or exclu-
may have bacteriuria with lower quantitative counts in voided
sions may have introduced sufficient bias to limit the credibility
specimens, but the criteria for bacteriuria in such patients are
of observations, or if there were insufficient numbers of patients
enrolled to support valid statistical analysis.
Pyuria is evidence of inflammation in the genitourinary tract
and is common in subjects with asymptomatic bacteriuria [13,
DIAGNOSIS
24–27]. Pyuria is present with asymptomatic bacteriuria in∼32% of young women [13], 30%–70% of pregnant women
Asymptomatic bacteriuria is a microbiologic diagnosis deter-
[25, 26], 70% of diabetic women [24], 90% of elderly insti-
mined with a urine specimen that has been collected in a man-
tutionalized patients [27], 90% of hemodialysis patients [28],
ner to minimize contamination and transported to the labo-
30%–75% of bacteriuric patients with short-term catheters in
ratory in a timely fashion to limit bacterial growth. The usual
place [29], and 50%–100% of individuals with long-term in-
quantitative definition is у105 cfu/mL in 2 consecutive urine
dwelling catheters in place [30]. Pyuria also accompanies other
specimens [3], initially proposed after studies performed in the
inflammatory conditions of the genitourinary tract in patients
1940s and 1950s [8, 9]. In these studies, a bacterial count of
with negative urine culture results. These may be either infec-
у105 cfu/mL in a clean, voided specimen was confirmed by a
tious, such as renal tuberculosis and sexually transmitted dis-
concomitant count in a catheterized specimen in 195% of sub-
eases, or noninfectious, such as interstitial nephritis. Thus, by
jects in several asymptomatic clinical groups, whereas lower
itself, the presence of pyuria is not sufficient to diagnose bac-
quantitative counts in the voided specimen were not usually
teriuria, and the presence or absence of pyuria does not dif-
confirmed by the catheterized specimen [8]. When the screen-
ferentiate symptomatic from asymptomatic urinary infection.
ing of asymptomatic women using multiple voided specimens
Recommendation.
was evaluated, bacteriuria documented in an initial voided
riuria should be based on culture of a urine specimen collected
urine specimen was confirmed in a second voided specimen,
in a manner that minimizes contamination (A-II).
usually obtained several days later, only 80% of the time. If 2successive bacteriuric voided specimens had similar positive
• For asymptomatic women, bacteriuria is defined as 2 con-
culture results, a third consecutive specimen also yielded con-
secutive voided urine specimens with isolation of the same
sistent results in 95% of cases [9, 10]. Some studies involving
bacterial strain in quantitative counts of у105 cfu/mL (B-II).
women have used a more restrictive criterion of 3 consecutive
• A single, clean-catch, voided urine specimen with 1 bacterial
voided urine specimens collected over 3 weeks with consistent
species isolated in a quantitative count of у105 cfu/mL iden-
bacteriologic results [11, 12], whereas other studies have used
tifies bacteriuria in asymptomatic men (B-III).
a more permissive criterion of a single positive urine specimen
• A single catheterized urine specimen with 1 bacterial species
yielding у105 cfu/mL [13, 14]. Because transient bacteriuria is
isolated in a quantitative count of у102 cfu/mL identifies
common in healthy young women [13, 15, 16], the prevalence
will be lower if 11 specimen is required for identification ofbacteriuria [13].
Pyuria accompanying asymptomatic bacteriuria is not an in-
Microbiologic criteria for diagnosis of asymptomatic bac-
dication for antimicrobial treatment (A-II).
teriuria in men are not as well validated. The finding of a single
PREVALENCE OF ASYMPTOMATIC
voided urine specimen with у105 cfu/mL of an Enterobacter-
BACTERIURIA
iaceae was reproducible in 98% of asymptomatic ambulatorymen when the culture was repeated within 1 week [17]. A
Asymptomatic bacteriuria is common, but the prevalence in
voided specimen with the lower quantitative count of у103
populations varies widely with age, sex, and the presence of
cfu/mL was 97% sensitive and 97% specific for identification
genitourinary abnormalities (table 2). For healthy women, the
of bacteriuria in ambulatory men, but most of these patients
prevalence of bacteriuria increases with advancing age, from
IDSA Guidelines for Asymptomatic Bacteriuria • CID 2005:40 (1 March) • 645 Prevalence of asymptomatic bacteriuria in selected populations.
Elderly persons in a long-term care facility
Sphincterotomy and condom catheter in place
∼1% among schoolgirls to 120% among healthy women у80
five percent to 50% of elderly women and 15%–40% of elderly
years of age living in the community [31]. The prevalence of
men in long-term care facilities are bacteriuric [27]. The ma-
bacteriuria among young women is strongly associated with
jority of these elderly persons have chronic neurologic illnesses,
sexual activity. It was 4.6% among premenopausal married
with the highest prevalence of bacteriuria observed in the most
women but only 0.7% among nuns of similar age [12]. Pregnant
highly functionally impaired residents. The clinical assessment
and nonpregnant women have a similar prevalence of bacte-
of elderly bacteriuric residents to ascertain the presence or ab-
riuria (2%–7%) [31]. Bacteriuria is more common in diabetic
sence of symptoms may be problematic, and observations of
women, with a prevalence of 8%–14%, and is usually correlated
cloudy or smelly urine by themselves should not be interpreted
with duration of diabetes and presence of long-term compli-
as indications of symptomatic infection [39]. Use of a long-
cations of diabetes, rather than with metabolic parameters of
term indwelling catheter [22] or permanent ureteric stent [40]
diabetic control [36]. Asymptomatic bacteriuria is rare in
is associated with bacteriuria virtually 100% of the time.
healthy young men [37]. The prevalence in men increases sub-stantially after the age of 60 years, presumably because of ob-
MICROBIOLOGY OF ASYMPTOMATIC
structive uropathy and voiding dysfunction associated with pro-
BACTERIURIA
static hypertrophy [27, 37]. From 6% to 15% of men 175 yearsof age who reside in the community are bacteriuric [31]. Di-
Escherichia coli remains the single most common organism iso-
abetic men do not appear to have an increased prevalence of
lated from bacteriuric women [11, 12, 41], although this hap-
bacteriuria, compared with nondiabetic men [32].
pens proportionally less frequently than for women with acute
Many patient groups with chronic disabilities or comorbid-
uncomplicated urinary tract infection. E. coli strains isolated
ities characterized by impaired urinary voiding or with in-
from women with asymptomatic bacteriuria are characterized
dwelling urinary devices have a very high prevalence of asymp-
by fewer virulence characteristics than are those isolated from
tomatic bacteriuria, irrespective of sex. Patients with short-term
women with symptomatic infection [42]. Other Enterobacter-
indwelling urethral catheters acquire bacteriuria at the rate of
iaceae (such as Klebsiella pneumoniae) and other organisms
2%–7% per day (table 2) [35, 38]. Patients with spinal cord
(including coagulase-negative staphylococci, Enterococcus spe-
injury have a prevalence of 150%, whether voiding is managed
cies, group B streptococci, and Gardnerella vaginalis) are com-
by intermittent catheterization or by sphincterotomy and con-
mon as well. For men, coagulase-negative staphylococci are also
dom drainage [33, 34]. Patients undergoing hemodialysis have
common, in addition to gram-negative bacilli and Enterococcus
a prevalence of asymptomatic bacteriuria of 28% [28]. Twenty-
species [43, 44]. Subjects with abnormalities of the genitouri-
646 • CID 2005:40 (1 March) • Nicolle et al.
nary tract, including elderly institutionalized subjects, have a
antoin or placebo [50]. The antibiotic group had a signifi-
wide variety of organisms isolated. E. coli remains the single
cantly lower prevalence of bacteriuria at 6 months but not at
most common organism isolated from women, but other or-
1 year. Episodes of symptomatic infection 1 year after therapy
ganisms, such as Proteus mirabilis, are more common in men
occurred with a similar frequency in the treatment and pla-
[27]. Men and women with a long-term urologic device in
place usually have polymicrobial bacteriuria, which often in-
These studies support the conclusions that healthy, bacter-
cludes Pseudomonas aeruginosa and urease-producing organ-
iuric, premenopausal women are at an increased risk for symp-
isms, such as P. mirabilis, Providencia stuartii, and Morganella
tomatic urinary infection and are more likely to have bacteriuria
at follow-up. However, asymptomatic bacteriuria is not asso-ciated with long-term adverse outcomes, such as hypertension,
THE MANAGEMENT OF ASYMPTOMATIC
chronic kidney disease, genitourinary cancer, or decreased du-
BACTERIURIA
ration of survival. The association of asymptomatic bacteriuriawith symptomatic urinary infection is likely attributable to host
Premenopausal, Nonpregnant Women
factors that promote both symptomatic and asymptomatic uri-
The natural history of asymptomatic bacteriuria in premeno-
nary infection, rather than symptomatic infection being attrib-
pausal nonpregnant women has been described in short-term
utable to asymptomatic bacteriuria. Finally, treatment of
[13] and long-term [41, 45–48] prospective cohort studies. In
asymptomatic bacteriuria neither decreases the frequency of
young women, symptomatic urinary infection occurred sig-
symptomatic infection nor prevents further episodes of asymp-
nificantly more frequently in bacteriuric women than in non-
bacteriuric women within 1 week after a urine culture (8% of
Recommendation.
bacteriuric women became symptomatic, compared with 1%
tomatic bacteriuria in premenopausal, nonpregnant women is
of women without bacteriuria) [13]. The increased risk of
symptomatic infection remained at 1 month after new-onsetbacteriuria [13]. Long-term cohort studies also report an in-
Pregnant Women
creased frequency of symptomatic urinary infection in womenidentified with asymptomatic bacteriuria at initial screening
Women identified with asymptomatic bacteriuria in early preg-
[46, 47]. In a Swedish study, after 15 years of follow-up, symp-
nancy have a 20–30-fold increased risk of developing pyelo-
tomatic urinary infection and pyelonephritis occurred at least
nephritis during pregnancy, compared with women without
once in 55% and 7.5% of women with bacteriuria at enrollment,
bacteriuria [26, 51–59]. These women also are more likely to
respectively, and in 10% and 0% of those without bacteriuria,
experience premature delivery and to have infants of low birth
respectively [47]. Women with bacteriuria at enrollment were
weight. Prospective, comparative clinical trials have consistently
also more likely to be bacteriuric at follow-up, regardless of
reported that antimicrobial treatment of asymptomatic bacte-
whether antimicrobial therapy was given [41, 47, 49].
riuria during pregnancy decreases the risk of subsequent py-
In 3 prospective studies from Wales and Jamaica that enrolled
elonephritis from 20%–35% to 1%–4% (table 3) [60]. Meta-
women aged 15–84 years, increased mortality was observed
analyses of cohort studies and randomized clinical trials also
among bacteriuric women [49]. The association of bacteriuria
support the conclusion that antimicrobial treatment of asymp-
and mortality was not as strong when the bacteriuric and non-
tomatic bacteriuria decreases the frequency of low–birth weight
bacteriuric groups were age- and weight-matched, and no strat-
infants and preterm delivery [61, 62]. Most of these studies
ification for other potential confounders was performed. In a
were performed early in the antimicrobial era, with nitrofur-
Swedish study that enrolled women with a median age of 58
antoin and sulfonamides being the most common antimicro-
years (range, 35–72 years), there were no differences in the
bials. The consistency and robustness of observations from
rates of hypertension or chronic kidney disease between bac-
multiple studies resulted in screening for and treatment of
teriuric and nonbacteriuric women after 15 years of follow-up
asymptomatic bacteriuria during pregnancy becoming a stan-
[47]. In another Swedish study of women initially enrolled at
dard of care in developed countries. More-recent reports of
38–60 years of age, the rates of progression to chronic kidney
implementation of screening and treatment programs for
disease and mortality were similar for bacteriuric and nonbac-
asymptomatic bacteriuria in pregnant women report a decrease
teriuric subjects after 24 years [41]. Bacteriuric women and
in rates of pyelonephritis for all pregnant women, from 1.8%
nonbacteriuric control subjects did not differ with regard to
to 0.6% in a Spanish health care center [63], and 2.1% to 0.5%
serum creatinine levels and intravenous pyelogram findings af-
in a Turkish health care center [64]. These are consistent with
ter 3–5 years of follow-up in an English study [48].
the early reports of benefits with screening for and treatment
A prospective, controlled trial randomized bacteriuric
of asymptomatic bacteriuria during pregnancy.
women to receive a 1-week course of therapy with nitrofur-
In the therapeutic studies that established the benefit of treat-
IDSA Guidelines for Asymptomatic Bacteriuria • CID 2005:40 (1 March) • 647 Findings of comparative clinical trials of antimicrobial therapy for the treatment of asymptomatic bacteriuria in pregnancy.
furantoin, or mandelamine alone;mandelamine to term
a Microbiologic results from initial screening urine culture in pregnancy.
ment of asymptomatic bacteriuria during pregnancy, admin-
and they should be treated if the results are positive (A-I).
istration of antimicrobial therapy usually continued for the
• The duration of antimicrobial therapy should be 3–7 days
duration of the pregnancy (table 3). A prospective, randomized
study of continuous antimicrobial therapy to the end of preg-
• Periodic screening for recurrent bacteriuria should be un-
nancy compared with 14 days of nitrofurantoin or sulfameth-
izole, followed by weekly urine culture screening and re-treat-
• No recommendation can be made for or against routine
ment if bacteriuria recurred, reported similar outcomes for the
repeated screening of culture-negative women in the later
2 treatment groups [65]. A recent Cochrane systematic review
concluded that there was insufficient evidence to recommend
a duration of antimicrobial therapy for pregnant women among
Diabetic Women
single-dose, 3-day, 4-day, and 7-day treatment regimens [66].
Prospective, cohort studies of diabetic women report no dif-
Thus, the optimal duration of antimicrobial therapy for treat-
ferences in rates of symptomatic urinary infection, mortality,
ment of bacteriuria in pregnant women has not been
or progression to diabetic complications between initially bac-
teriuric and nonbacteriuric women at 18 months [70] or 14
The appropriate screening test is a urine culture [67]. Screen-
years [71] of follow-up. A randomized, controlled trial of an-
ing for pyuria has a low sensitivity—only ∼50% for identifi-
tibiotic therapy or no therapy for diabetic women with asymp-
cation of bacteriuria in pregnant women [25]. The optimal
tomatic bacteriuria and continued screening for bacteriuria
frequency of screening is not well defined. Women with a neg-
every 3 months reported, after a maximum of 3 years of follow-
ative urine culture result for a single screening specimen at 12–
up, that antimicrobial therapy did not delay or decrease the
16 weeks have a 1%–2% risk of developing pyelonephritis later
frequency of symptomatic urinary infection, nor did it decrease
in pregnancy (table 3). What proportion of this may be pre-
the number of hospitalizations for urinary infection or other
vented with repeated routine screening is not known. A single
causes [72]. There was no acceleration of progression of diabetic
urine sample obtained for culture at week 16 of gestation was
complications, such as nephropathy, in bacteriuric subjects who
concluded to be optimal in a Swedish study [68]. An American
did not receive antimicrobial therapy. Diabetic women who
cost evaluation from the viewpoint of the outcome of pyelo-
received antimicrobial therapy, however, had 5 times as many
nephritis concluded that a single screening culture in the first
days of antimicrobial use and significantly more adverse an-
trimester was cost-effective if the prevalence of bacteriuria was
timicrobial effects. Thus, there were no benefits for continued
12% and the risk of pyelonephritis in bacteriuric women was
screening and treatment of asymptomatic bacteriuria in diabetic
women, and there was evidence of some harm. Recommendation. Recommendation.
bacteriuria by urine culture at least once in early pregnancy,
tomatic bacteriuria in diabetic women is not indicated (A-I).
648 • CID 2005:40 (1 March) • Nicolle et al. Older Persons Residing in the Community
asymptomatic bacteriuria in older persons resident in the com-
Large, long-term, cohort studies of asymptomatic bacteriuria
have enrolled both pre- and postmenopausal women [41, 46,47, 49]. These studies uniformly report no excess adverse out-
Elderly Institutionalized Subjects
comes in women with asymptomatic bacteriuria. A prospective,
Prospective, randomized clinical trials of antimicrobial ther-
randomized study of nitrofurantoin or placebo also enrolled
apy or no therapy for elderly residents of long-term care
women aged 20–65 years, with a median age between 40–49
facilities have reported no benefits of screening for or treat-
years [50]. Thus, these studies report that outcomes of bac-
ment of asymptomatic bacteriuria (table 4) [76–79]. There
teriuria and treatment of bacteriuria in healthy postmenopausal
was no decrease in the rate of symptomatic infection or im-
women are similar to those observed in premenopausal, non-
provement in survival [76–78], and there were no changes in
chronic genitourinary symptoms [79] associated with anti-
A prospective, randomized clinical trial of antimicrobial
microbial therapy. Treatment of asymptomatic bacteriuria was
treatment versus placebo for bacteriuria enrolled ambulatory
associated with significantly increased adverse antimicrobial
women who resided in a geriatric apartment facility and re-
effects [76] and reinfection with organisms of increasing re-
ported a decrease in the prevalence of asymptomatic bacteriuria
sistance [76]. Prospective cohort studies report similar sur-
at 6 months, but there was no significant difference in the
vival data for long-term care facility residents with and those
number of symptomatic episodes [73]. A prospective cohort
without bacteriuria among women in the United States [78],
study of 134 ambulatory male veterans 165 years of age ob-
men in Canada [80], and women or men in Greece [81].
served for 1–4.5 years, including 29 subjects with bacteriuria,
Recommendation.
reported no adverse outcomes attributable to untreated bac-
tomatic bacteriuria in elderly institutionalized residents of long-
teriuria [44]. Population-based cohort studies report no as-
term care facilities is not recommended (A-I).
sociation between bacteriuria and survival for Swedish menand women at 5 years of follow-up [74] or Finnish men and
Subjects with Spinal Cord Injuries
women aged 185 years during 5 years of follow-up [75].
Subjects with spinal cord injuries have a high prevalence of
Recommendation.
bacteriuria, and they also experience a high incidence of symp-
Randomized clinical trials of treatment of asymptomatic bacteriuria in elderly populations.
given for symptomatic UTI, 16.4%vs. 7.9% (P p
patient-year for the therapy group(P p
Ϫ0.05 to +0.47); therapy recipi-ents had significantly more ad-verse drug-related events and rein-fections with resistant organisms
cin administered every 14 days;cultures were performed every6 months
RR, relative risk; TMP, trimethoprim; UTI, urinary tract infection.
a Data are mean age, unless otherwise indicated. b Median age.
IDSA Guidelines for Asymptomatic Bacteriuria • CID 2005:40 (1 March) • 649
tomatic urinary infection [34, 82]. When asymptomatic bac-
guria 2 weeks after therapy for catheterized subjects and no
teriuria was uniformly treated in a cohort of catheter-free, pri-
clinical benefits of treatment [94].
marily male, spinal cord–injured subjects, early recurrence of
A prospective, randomized, placebo-controlled trial of an-
bacteriuria after therapy was the usual outcome. After 7–14
timicrobial treatment of asymptomatic bacteriuria persisting 48
days of antibiotic therapy, 93% of subjects were again bacter-
h after removal of short-term catheters in women with catheter-
iuric by 30 days after completion of therapy, and after a 28-
acquired bacteriuria reported significantly improved microbi-
day course of antibiotic therapy, 85% were bacteriuric by 30
ologic and clinical outcomes at 14 days in treated women [95].
days [83]. Reinfecting strains showed increased antimicrobial
Although 15 (36%) of 42 women randomized to receive no
resistance. When 52 patients with a relatively recent onset of
therapy had spontaneous microbiologic resolution by 14 days,
spinal cord injury were observed prospectively for 4–26 weeks,
7 (17%) developed symptoms. No women in the treatment
the results of 78% of weekly urine cultures were positive, but
group became symptomatic. This study enrolled a selected
only 6 symptomatic episodes occurred, all of which responded
group of hospitalized women characterized by being relativelyyoung (median age, 50 years) and experiencing a short period
promptly to antimicrobial treatment [84]. In a small, random-
of catheterization (median duration, 3 days).
ized, placebo-controlled trial, rates of symptomatic urinary in-
Long-term catheters.
fection and recurrence of bacteriuria were similar among re-
cephalexin therapy versus no antibiotic therapy for bacteriuric
cipients of either antimicrobial or placebo for patients with
patients with long-term indwelling urethral catheters in place
bladder emptying managed by intermittent catheterization [85].
and drug-susceptible organisms isolated reported a similar in-
A prospective, randomized trial of antimicrobial treatment or
cidence of fever among both treated and untreated patients
no treatment of asymptomatic bacteriuria enrolled 50 patients
observed for 12–44 weeks [96]. Rates of reinfection were also
who were treated with intermittent catheterization and reported
similar, but 75% of reinfecting organisms in the control group
a similar frequency of symptomatic urinary infection during
remained susceptible to cephalexin, compared with only 36%
an average of 50 days of follow-up, irrespective of whether
in the cephalexin treatment group. A prospective, noncom-
prophylactic antimicrobials were given [86]. Although there
parative study of consecutive courses of antimicrobial treatment
have been a limited number of clinical trials, and although
to eradicate bacteriuria in elderly patients with long-term cath-
interpretation of results is compromised by relatively short du-
eters reported no decrease in the number of episodes of fever
rations of follow-up and small study numbers, review articles
with treatment, compared with the pretreatment period, and
[87, 88] and consensus guidelines [89] uniformly recommend
there was immediate recurrence of bacteriuria after therapy,
treatment only of symptomatic urinary tract infection in pa-
often with organisms of increasing resistance [97]. Recommendation. Recommendation.
should not screened for or treated in patients with an indwelling
screened for or treated in spinal cord–injured patients (A-II). Patients with Indwelling Urethral Catheters
• Antimicrobial treatment of asymptomatic womenwithcath-
eter-acquired bacteriuria that persists 48 h after catheter
Short-term catheters.
cility patients with short-term (!30 days) indwelling urethralcatheters receive antimicrobial therapy, usually for an indicationother than urinary infection [90, 91]. This high frequency of
Urologic Interventions
concurrent antimicrobial use makes assessment of outcomes
Patients with asymptomatic bacteriuria who undergo traumatic
unique to treatment of asymptomatic bacteriuria problematic.
genitourinary procedures associated with mucosal bleeding have
A prospective, cohort study of 235 catheter-acquired infections
a high rate of postprocedure bacteremia and sepsis. Bacteremia
among 1497 patients, 90% of whom were asymptomatic, re-
occurs in up to 60% of bacteriuric patients who undergo tran-
ported only 1 secondary bloodstream infection [92]. A case-
surethral prostatic resection, and there is clinical evidence of
control study reported that acquisition of bacteriuria with in-
sepsis in 6%–10% of these persons [98]. Retrospective analysis
dwelling urethral catheterization increased mortality 3-fold, but
[99] and prospective, randomized clinical trials [100–103] sup-
the explanation for this association was not clear, and multi-
port the effectiveness of antimicrobial treatment in preventing
variate analysis found that antimicrobial therapy did not alter
these complications in bacteriuric men undergoing transurethral
the association with mortality [93]. A prospective, randomized,
resection of the prostate. In one comparative trial, the efficacy
placebo-controlled trial of treatment of funguria in 313 pa-
of cefotaxime was superior to that of methenamine mandelate
tients, more than one-half of whom had indwelling urethral
[101]. There is little information relevant to other procedures,
catheters in place, showed no differences in eradication of fun-
but any intervention with a high probability of mucosal bleeding
650 • CID 2005:40 (1 March) • Nicolle et al.
should be considered a risk [104]. Pretreatment of asymptomatic
rather than bacteriuria [113]. Thus, with current management
bacteriuria is not beneficial for all invasive procedures. For in-
strategies, screening for bacteriuria is unlikely to provide a ben-
stance, replacement of a long–term indwelling foley catheter is
efit. Some experts do recommend screening for bacteriuria, at
associated with a low risk of bacteremia, and antimicrobial treat-
least for the first 6 months after renal transplantation [114].
Recent guidelines for outpatient surveillance of renal transplant
The appropriate timing for initiation of antimicrobial ther-
recipients, however, make no recommendation for screening
apy is not well defined. Although 72 h before the intervention
has been suggested [107], this is likely to be excessive and allows
Screening for or treatment of bacteriuria has not been eval-
the opportunity for superinfection before the procedure. Ini-
uated for other solid organ transplant recipients. Guidelines
tiation of therapy the night before or immediately before the
for infection prevention in bone marrow transplant recipients
procedure is effective [99, 103]. The optimal time to obtain a
make no recommendation for screening for bacteriuria [117].
sample for culture before the procedure and the duration of
A small study of women with primary biliary cirrhosis and
antimicrobial therapy are also not addressed in clinical trials.
bacteriuria randomized to receive either antimicrobial therapy
In the absence of an indwelling catheter, antimicrobial therapy
or no antimicrobial therapy reported no differences in the time
can likely be discontinued immediately after the procedure [99,
to reinfection or the number of reinfections in the 2 groups
102, 103]. When an indwelling catheter remains in place after
[118]. Limited studies involving HIV-infected patients have re-
a prostatic resection, it has been recommended by some in-
ported no association between asymptomatic bacteriuria and
vestigators that antimicrobial therapy be continued until the
HIV infection in women, but there was an increased prevalence
of bacteriuria among HIV-infected men that was inversely cor-
Recommendation.
related with CD4+ cell counts [30]. Adverse clinical outcomes
tomatic bacteriuria before transurethral resection of the pros-
associated with bacteriuria in these populations have not been
Recommendations.
• An assessment for the presence of bacteriuria should be
screening for or treatment of asymptomatic bacteriuria in renal
obtained, so results will be available to direct antimicrobial
transplant or other solid organ transplant recipients (C-III).
therapy prior to the procedure (A-III).
• Antimicrobial therapy should be initiated shortly before the
Asymptomatic bacteriuria is common. Pregnant women with
Antimicrobial therapy should not be continued beyond the
asymptomatic bacteriuria are at an increased risk for adverse
procedure, unless an indwelling catheter remains in place
outcomes, and these can be prevented with antimicrobial treat-
ment of asymptomatic bacteriuria. Thus, pregnant women
Screening for and treatment of asymptomatic bacteriuria is
should be screened for bacteriuria and treated if test results are
recommended before other urologic procedures in which mu-
positive. Asymptomatic bacteriuria is also a risk for patients
cosal bleeding is anticipated (A-III).
who undergo traumatic urologic interventions with mucosalbleeding, and such patients should be treated prior to such
Immunocompromised Patients and Other Patients
interventions. For all other adult populations, asymptomatic
Cohort studies performed early in the transplantation era re-
bacteriuria has not been shown to be harmful. Although per-
ported a high prevalence of asymptomatic bacteriuria among
sons with bacteriuria are at an increased risk of symptomatic
renal transplant recipients, especially in the first 6 months after
urinary infection, treatment of asymptomatic bacteriuria does
transplantation [108, 109]. Evolution in management of trans-
not decrease the frequency of symptomatic infection or improve
plantation has introduced routine perioperative prophylaxis,
other outcomes. Thus, in populations other than those for
minimization of use of indwelling urethral catheters, and long-
whom treatment has been documented to be beneficial, screen-
term antimicrobial prophylaxis to prevent pneumonia and
ing for or treatment of asymptomatic bacteriuria is not ap-
other infections. These interventions also prevent both asymp-
propriate and should be discouraged.
tomatic bacteriuria and symptomatic urinary infection [110,
RESEARCH PRIORITIES
111]. Recent studies, including a retrospective chart review[112] and a prospective cohort study [113], have not reported
Many issues relevant to asymptomatic bacteriuria require fur-
an association between asymptomatic bacteriuria and graft sur-
ther research and evaluation in appropriately conducted clinical
vival. Transplant recipients with urinary infection and poor
graft outcome are also characterized by urologic abnormalitiesand are identified by episodes of symptomatic urinary infection,
• Exploration of the clinical and microbiologic implications,
IDSA Guidelines for Asymptomatic Bacteriuria • CID 2005:40 (1 March) • 651
if any, of pyuria in selected populations, such as pregnant
teriuria. In: Guide to clinical preventive services. 2nd edition. 1996. Available at: http://www.ahcpr.gov/clinic/uspstfix.htm. Accessed May
• The utility of obtaining a second urine specimen to confirm
3. Rubin RH, Shapiro ED, Andriole VT, Davis RJ, Stamm WE. Evalu-
asymptomatic bacteriuria prior to treatment after an initial
ation of new anti-infective drugs for the treatment of urinary tract
positive screening specimen in pregnant women.
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The optimal duration of antimicrobial therapy for treatment
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of asymptomatic bacteriuria in pregnant women requires
5. Nicolle LE. A practical approach to the management of complicated
evaluation in appropriate clinical trials.
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Further characterization of symptomatic presentations of
Am J Med 1983; 75(Suppl 1B):53–58.
urinary infection in elderly institutionalized populations
7. Moher D, Schulz KF, Altman DG. The CONSORT statement: revised
with a high prevalence of bacteriuria.
recommendations for improving the quality of reports of parallel-
• Management of asymptomatic bacteriuria in subjects with
group randomized trials. CONSORT Group (Consolidated Standards of Reporting Trials). Ann Intern Med 2001; 134:657–62.
8. Kass EH. Bacteriuria and the diagnosis of infections of the urinary
• Characterization of the natural history and appropriate
tract. Arch Intern Med 1957; 100:709–14.
management of individuals with long-term indwelling uri-
9. Kass EH. Pyelonephritis and bacteriuria: a major problem in preven-
tive medicine. Ann Intern Med 1962; 56:46–53.
nary devices other than indwelling catheters (e.g., urinary
10. Kunin CM. Asymptomatic bacteriuria. Ann Rev Med 1966; 17:
• Whether individuals with asymptomatic bacteriuria with
11. Evans DA, Williams DN, Laughlin LW, et al. Bacteriuria in a popu-
urea-splitting organisms but without indwelling devices re-
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1968; 278:635–42.
neutropenia or who have undergone solid organ transplan-
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tation, require further characterization of the impacts, if
Med 2000; 343:992–7.
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• The optimal time to initiate therapy, duration of therapy,
may be considered a complication in women with diabetes. Diabetes
and antimicrobial choice for treatment of bacteriuria prior
Care 2000; 23:744–9.
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to invasive genitourinary procedures require evaluation in
prolonged intermittent colonization with E. coli. JAMA 1980; 243:
• Whether there are clinical benefits of screening for and treat-
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of urinary tract infection with sexual intercourse. J Infect Dis 1982;
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Acknowledgments
bacteriuria in men: specimen collection and culture interpretation. J Infect Dis 1987; 155:847–54.
We thank the following individuals for review and helpful suggestions
19. Ouslander JG, Greengold BA, Silverblatt FJ, Garcia JP. An accurate
in the development of this guideline: Elias Abrutyn, Diana Cardenas, Ste-
method to obtain urine for culture in men with external catheters.
phan Fihn, Kalpana Gupta, Jeremy Hamilton-Miller, Godfrey Harding,
Arch Intern Med 1987; 147:286–8.
Andy Hoepelman, James R. Johnson, Calvin Kunin, Leonard Leibovici,
20. Nicolle LE, Harding GKM, Kennedy J, McIntyre M, Aoki F, Murray
Benjamin Lipsky, Kurt G. Naber, Raul Raz, Allan Ronald, Thomas Russo,
D. Urine specimen collection with external devices for diagnosis of
Jack Sobel, Walter Stamm, Ann Stapleton, and John Warren. Expert sec-
bacteriuria in elderly incontinent men. J Clin Microbiol 1988; 26:
retarial assistance was provided by Brenda DesRosiers. Potential conflicts of interest.
from Ortho-McNeil. R.C. has received research funding from Ortho-
21. Saint SJ, Chenoweth CE. Biofilms and catheter-associated urinary tract
McNeil and has served on the speakers’ bureau for Bayer. A.S. has been a
infections. Infect Dis Clin North Am 2003; 17:411–32.
consultant for Ortho-McNeil, Proctor & Gamble, Gerson Lehrman Group,
22. Warren JW, Tenney JH, Hoopes JM, Muncie HL, Anthony WC. A
Urologix, DepoMed, Schwarz BioSciences GmbH, and SynerMed Com-
prospective microbiologic study of bacteriuria in patients with
munications. T.M.H. has been a consultant for Bayer and served on the
chronic-indwelling urethral catheters. J Infect Dis 1982; 146:719–23.
speakers’ bureau for Aventis, Bayer, Merck, and Pfizer.
23. Kass EH. Asymptomatic infections of the urinary tract. Trans Assoc
Amer Phys 1956; 69:56–64.
24. Zhanel GG, Nicolle LE, Harding GM. Prevalence of asymptomatic
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HiMedia Laboratories Cetrimide Agar Base Cetrimide Agar Base is used for the selective e isolation of Pseudomonas aeruginosa from clinical specimens. Composition** Ingredients **Formula adjusted, standardized to suit performance parameters Directions Suspend 46.7 grams in 1000 ml distilled water containing 10 ml glycerol. Heat, to boiling, to dissolve the medium completely. Steriliz