Antimicrobial resistance among uropathogens that cause community-acquired urinary tract infections in women: a nationwide analysis

Extended-release ciprofloxacin (Cipro XR) for treatment of urinary tract infections

Symptomatic urinary tract infections (UTIs) constitute a major health problem throughout the Western world. In the USA, UTIs are responsible for 7-8 million outpatient visits each year and for over one-third of all hospital-acquired infections. Empiric antimicrobial therapy for UTIs, which are primarily caused by Escherichia coli, is increasingly being complicated by the emergence of resistance to the most widely used agents. Recent studies indicate that the prevalence of E. coli resistance to trimethoprim/sulphamethoxazole (TMP/SMX), the current first-line therapy for UTIs, exceeds 20% in many North American regions. Importantly, antibiotic resistance often translates into clinical failure. The use of antibiotics with favourable pharmacokinetic/pharmacodynamic profiles and convenient dosing schedules, which effectively increase bacterial eradication and patient compliance, can help to curb the current epidemic of resistance and reduce the rate of clinical failure associated with resistance. Fluoroquinolones have well-established efficacy in the treatment of multiple bacterial infections and, over the years, the rates of resistance to these antibiotics have remained very low. Fluoroquinolones are currently recommended for therapy of uncomplicated UTIs when the local incidence of TMP/SMX resistance is >or=10-20%, as well as for the treatment of complicated UTIs and acute pyelonephritis. Ciprofloxacin, one of the most widely used fluoroquinolones, has a potent bactericidal effect across the full spectrum of uropathogens, as well as a long and excellent efficacy and safety record in the management of UTI and other infections. A recently developed extended (modified)-release formulation of ciprofloxacin (Cipro XR or Cipro XL) provides higher maximum plasma concentrations with lower inter-patient variability than the conventional, immediate-release, twice-daily formulation. Additionally, therapeutic drug levels with extended-release ciprofloxacin are achieved rapidly and maintained over the course of 24 h, allowing once-daily dosing. Clinical trials in patients with cystitis and those with complicated UTIs or acute uncomplicated pyelonephritis indicate that extended-release ciprofloxacin is at least as effective as the immediate-release formulation. These studies have also confirmed good tolerability and safety of extended-release ciprofloxacin, similar to the immediate-release formulation. Therefore, extended-release ciprofloxacin is a convenient, well-tolerated and effective therapy for UTIs that may improve patients' compliance with treatment and thus decrease the risk of treatment failure and the spread of antibiotic resistance.

Resistance of uropathogens in symptomatic urinary tract infections in León, Nicaragua

Management of urinary tract infections (UTI) in Central America and especially Nicaragua, is complicated by the lack of knowledge about the antibiotic resistance of uropathogens. We conducted a prevalence study to gain more insight into the aetiology, bacterial resistance and risk factors for symptomatic UTI in the region of León, Nicaragua. In 2002, all consecutive patients with UTI symptoms and pyuria >/=10 WBC/hpf were admitted to the study. Positive cultures from midstream urine specimens were defined as >/=10(5) cfu/ml of a single uropathogen. Susceptibility tests were performed with disc diffusion tests using the Kirby-Bauer method and broth microdilution using National Committee for Clinical Laboratory Standards criteria both in León and a reference laboratory in Utrecht. A positive culture was present in 62 of 208 study subjects (30%). Escherichia coli (56%), Klebsiella spp. (18%) and Enterobacter spp. (11%) were the most frequent pathogens isolated. Presence of cystocele, incontinence and increasing age were risk factors for bacterial UTI. E. coli was least resistant to ceftriaxone, amikacin and nitrofurantoin (>90% susceptible). We observed high resistance rates in E. coli to amoxicillin (82%, MIC(90) 128 mg/l), trimethoprim-sulphamethoxazole (TMP-SMX) (64%, MIC(90) 32 mg/l), cephalothin (58%, MIC(90), 32 mg/l), ciprofloxacin (30%; MIC(90), 32 mg/l), amoxicillin/clavulanate (21%, MIC(90) 8 mg/l) and gentamicin (12%, MIC(90) 2 mg/l). Our results suggests that community acquired uropathogens in Nicaragua are highly resistant to many antimicrobial agents. The use of amoxicillin, trimethoprim-sulphamethoxazole and cephalothin against uropathogens needs to be reconsidered. High quinolone resistance rates among E. coli in Nicaragua gives cause for great concern.

All dysuria is local. A cost-effectiveness model for designing site-specific management algorithms

OBJECTIVE

To determine the cost-effectiveness of management strategies for dysuria in different office settings.

DESIGN

Decision and cost-effectiveness analyses, assuming the payer's perspective. Data on disease prevalence, test characteristics, treatment efficacy, and adverse effects were drawn from the English language literature using medline searches and bibliographies.

SETTING

Hypothetical primary care practice.

PATIENTS

Otherwise healthy, nonpregnant women with symptoms of dysuria, urgency, and frequency.

INTERVENTIONS

All reasonable combinations of urinalysis, urine culture, pelvic examination, chlamydia and gonorrhea cultures, and empiric treatment with trimethoprim-sulfamethoxazole.

RESULTS

The cost-effectiveness of strategies varied substantially among different patient settings. In all settings, empiric trimethoprim-sulfamethoxazole for all patients was least expensive and least effective. Most testing increased both cost and effectiveness. Compared to empiric antibiotics, performing pelvic examination and urine culture for women with normal urinalyses had a marginal cost-effectiveness ratio of $4 to $32 per symptom-day avoided (SDA). Adding urine culture for patients with pyuria had a marginal cost of $34 to $107 per SDA, which fell to $40/SDA when the prevalence of resistance to trimethoprim-sulfamethoxazole exceeded 40%. Pelvic examination and urine culture for all patients regardless of urinalysis results achieved the greatest benefit but at the highest cost (>$300 per SDA).

CONCLUSIONS

In otherwise healthy women with symptoms of dysuria and no vaginal complaints, performing pelvic exam and urine culture based on urinalysis offers a reasonable alternative to empiric therapy. Other testing may be warranted, depending on antibiotic resistance and the value of avoiding a day of dysuria.

Laboratory diagnosis of urinary tract infections in adult patients

Urinary tract infections (UTIs) are among the most common bacterial infections and account for a significant part of the workload in clinical microbiology laboratories. Enteric bacteria (in particular, Escherichia coli) remain the most frequent cause of UTIs, although the distribution of pathogens that cause UTIs is changing. More important is the increase in resistance to some antimicrobial agents, particularly the resistance to trimethoprim-sulfamethoxazole seen in E. coli. Physicians distinguish UTIs from other diseases that have similar clinical presentations with use of a small number of tests, none of which, if used individually, have adequate sensitivity and specificity. Among the diagnostic tests, urinalysis is useful mainly for excluding bacteriuria. Urine culture may not be necessary as part of the evaluation of outpatients with uncomplicated UTIs, but it is necessary for outpatients who have recurrent UTIs, experience treatment failures, or have complicated UTIs, as well as for inpatients who develop UTIs.

Once daily, extended release ciprofloxacin for complicated urinary tract infections and acute uncomplicated pyelonephritis

PURPOSE

We assessed the efficacy and safety of 1,000 mg extended release ciprofloxacin orally once daily vs conventional 500 mg ciprofloxacin orally twice daily, each for 7 to 14 days, in patients with a complicated urinary tract infection (cUTI) or acute uncomplicated pyelonephritis (AUP).

MATERIALS AND METHODS

In this prospective, randomized, double-blind, North American multicenter clinical trial adults were stratified based on clinical presentation of cUTI or AUP and randomized to extended release ciprofloxacin or ciprofloxacin twice daily. Efficacy valid patients had positive pretherapy urine cultures (105 or greater cFU/ml) and pyuria within 48 hours of study entry. Bacteriological and clinical outcomes were assessed at the test of cure visit (5 to 11 days after therapy) and the late followup visit (28 to 42 days after therapy).

RESULTS

The intent to treat population comprised 1,035 patients (extended release ciprofloxacin in 517 and twice daily in 518), of whom 435 were efficacy valid (cUTI in 343 and AUP in 92). For efficacy valid patients (cUTI and AUP combined) bacteriological eradication rates at test of cure were 89% (183 of 206) vs 85% (195 of 229) (95% CI -2.4%, 10.3%) and clinical cure rates were 97% (198 of 205) vs 94% (211 of 225) (95% CI -1.2%, 6.9%) for extended release vs twice daily ciprofloxacin. Late followup outcomes were consistent with test of cure findings. Eradication rates for Escherichia coli, which accounted for 58% of pathogens, were 97% or greater per group. Drug related adverse event rates were similar for extended release and twice daily ciprofloxacin (13% and 14%, respectively).

CONCLUSIONS

Extended release ciprofloxacin at a dose of 1,000 mg once daily was as safe and effective as conventional treatment with 500 mg ciprofloxacin twice daily, each given orally for 7 to 14 days in adults with cUTI or AUP. It provides a convenient, once daily, empirical treatment option.

Multidrug-resistant Escherichia coli clonal groups causing community-acquired pyelonephritis

From October 1999 through January 2000, an Escherichia coli clonal group (designated "CgA") was isolated from the urine of nearly one-half of all women with urinary tract infections (UTIs) caused by trimethoprim-sulfamethoxazole (TMP-SMZ)-resistant E. coli in a California community. This study describes the prevalence of pyelonephritis caused by CgA in the same community. E. coli isolates were characterized by enterobacterial repetitive intergenic consensus (ERIC2) polymerase chain reaction (PCR), serogrouping, and pulsed-field gel electrophoresis. Fourteen (11%) of 130 women with UTIs received a diagnosis of pyelonephritis. CgA was associated with 4 (57%) of the 7 pyelonephritis cases caused by TMP-SMZ-resistant E. coli and was associated with none of the cases caused by TMP-SMZ-susceptible E. coli (P<.02). Six (86%) of these TMP-SMZ-resistant E. coli isolates belonged to 2 distinct ERIC2 PCR-defined clonal groups, whereas all of the TMP-SMZ-susceptible E. coli strains had unique fingerprints (P<.001). The prevalence of antimicrobial-resistant pyelonephritis in a community may be affected by a limited number of E. coli clonal groups.

[Acute pyelonephritis: bacteriological data and general course of germ resistance]

Recent bacteriological data concerning pyelonephritis mainly focus on sensitivity to antibiotics and virulence factors. Epidemiologically, and regardless of age and sex of the patients, E. coli remains the most often isolated pathogen. Only 55% of E. coli strains (43% if isolated during a nosocomial infection) are sensitive to amoxicillin. Resistance to parenterally administered third generation cephalosporins remain exceptional. Fluoroquinolones remain very active, particularly in community-acquired infections (>95% sensitive strains). P. aeruginosa, S. aureus and enterococci are mainly isolated during nosocomial infections or in patients with a history of previous hospital admissions. Adhesion factors to urothelial cells are of uppermost importance in the pathogenesis of urinary infection. Adhesins G borne by fimbriae P are mainly concerned. Also, hemolysin is very often present in strains responsible for pyelonephritis. As to the search for these factors in the diagnosis of pyelonephritis, particularly in children, further studies are needed. The choice of antibiotherapy not only rests upon antibiogram data, but also upon pharmacological characteristics of the antibiotic.

Current Issues in the Management of Urinary Tract Infections

Symptomatic urinary tract infections (UTIs) are a major public health concern in the developed world, accounting for almost 8 million annual outpatient and emergency department visits in the US alone, while also representing one of the most common hospital-acquired infections. The vast majority of uncomplicated UTIs are caused by the Gram-negative bacillus Escherichia coli, with other pathogens including enterococci, Staphylococcus saprophyticus, Klebsiella spp. and Proteus mirabilis. Effective management of UTIs in both the inpatient and outpatient settings has been complicated by the fact that many uropathogenic strains have developed resistance to antimicrobials, including cotrimoxazole (trimethoprim/sulfamethoxazole), the current first-line treatment for uncomplicated UTIs in the US and many other countries. In some countries, other antimicrobial therapies, such as trimethoprim and nitrofurantoin, are also used for treatment of uncomplicated UTIs. Antimicrobial resistance has been associated with an increased rate of clinical failure, and reports from Canada and the US indicate that the prevalence of cotrimoxazole resistance exceeds 15% and can be as high as 25%.The emergence and dissemination of antimicrobial resistance can be reduced with the use of agents that have favourable pharmacokinetic/pharmacodynamic profiles and convenient dose administration regimens that facilitate patient adherence and, therefore, pathogen eradication. Fluoroquinolones have been used successfully to treat a wide range of community- and hospital-acquired infections, and the rates of fluoroquinolone resistance have remained low. Use of fluoroquinolones is recommended for uncomplicated UTIs in areas where the incidence of cotrimoxazole resistance exceeds 10%, as well as for the treatment of complicated UTIs and acute pyelonephritis. Ciprofloxacin is a widely used fluoroquinolone with high bactericidal activity against uropathogens and well established clinical efficacy in the treatment of UTIs. A new, extended-release formulation of ciprofloxacin (Cipro XR) provides systemic drug exposure comparable with that achieved with twice-daily administration of conventional, immediate-release ciprofloxacin, while also attaining higher maximum plasma concentrations with less interpatient variability. Therapeutic drug concentrations with extended-release ciprofloxacin are established immediately after dose administration and maintained throughout the 24-hour dosage interval, permitting convenient, once-daily treatment. Clinical trial results confirm that extended-release ciprofloxacin is as safely used and effective as the conventional, immediate-release formulation of ciprofloxacin in patients with uncomplicated UTIs, complicated UTIs or acute uncomplicated pyelonephritis. These findings support the use of extended-release ciprofloxacin as a well tolerated, effective and convenient therapy for UTIs, which may improve patients' adherence to therapy and, thereby, reduce the risk of infection recurrence and emergence of antimicrobial resistance.

Impact of Changing Patterns of Antimicrobial Resistance in Uropathogens: Emerging Treatment and Strategies

Urinary tract infection (UTI) is common, especially in women, and the microbiology of UTI is predictable. Over the past decade, numerous reports have documented increasing resistance among uropathogens to first-line agents for the treatment of UTI, especially trimethoprim/sulfamethoxazole (TMP/SMX). It is recommended that TMP/SMX should not be administered as empiric therapy for UTI in communities where resistance rates exceed 20%. However, reliable data regarding the true prevalence of resistance in a community are often lacking. Preliminary work has suggested that recent antimicrobial use is an important risk factor for infection with a TMP/SMX-resistant isolate. A better understanding of the epidemiology of resistance is needed to aid therapeutic decisions and devise interventions to reduce or slow emerging resistance.

Molecular Epidemiology of Acute, Uncomplicated Urinary Tract Infections in Young Women

Molecular biological methods, a relatively new addition to the epidemiologist's tool chest, are now applied to the study of urinary tract infection (UTI). By combining sound epidemiologic methods and the ability to genetically stratify UTI-causing Escherichia coli, recent studies have added to our understanding of UTI. These advancements include the possible identification of outbreaks of community-acquired UTI, the contribution of person-to-person transmission of E. coli to the risk for UTI in young women, and changes in the community prevalence and distribution of UTI caused by drug-resistant organisms. The application of molecular methods to future UTI research studies may yield novel approaches to UTI prevention.

Phase 2 clinical trial of a vaginal mucosal vaccine for urinary tract infections

PURPOSE

Recurrent urinary tract infections (UTIs) in susceptible women remain a common urological condition. With an increasing number of UTIs being caused by antibiotic resistant bacteria there is a need for alternatives to antibiotics. We determined whether multiple doses of a vaginal mucosal vaccine are effective for increasing long-term resistance to recurrent UTIs.

MATERIALS AND METHODS

A total of 54 women were entered into a double-blind, placebo controlled, phase 2 clinical trial using a vaginal vaccine containing 10 heat killed uropathogenic bacteria. Patients were withdrawn from prophylactic antibiotics and randomly assigned to 1 of 3 treatment groups, namely placebo only, primary immunization or primary plus booster immunizations. Subjects received treatments at 0, 1, 2, 6, 10 and 14 weeks. Placebo treated patients received suppositories without bacteria. The primary immunization group received vaccine suppositories, followed by 3 doses of placebo. Patients receiving booster immunizations were given 6 vaccine suppositories. All women were followed for 6 months to determine the time until first recurrence, number of infections and adverse reactions.

RESULTS

Women receiving 6 vaccine doses remained free of infections for a significantly longer period than those receiving placebo or primary immunizations. Of patients receiving 6 immunizations 55% did not experience an infection, whereas 89% of placebo treated women had UTIs. No women had significant adverse effects.

CONCLUSIONS

This study demonstrates that vaginal mucosal vaccine given for a 14-week period increased the time to re-infection in UTI susceptible women. The infrequent, minimal adverse reactions confirm previous observations on the safety of this vaginal mucosal immunization regimen.

Antibiotic prescribing for cystitis: how well does it match published guidelines?

PURPOSE

Cystitis is one of the most common bacterial infections seen by physicians in outpatient settings. Published clinical guidelines by the Infectious Disease Society of America and other organizations have been established to enable effective treatment, while attempting to decrease cost and limit antibiotic resistance.

METHODS

Insurance claims data for employees and dependents of a single Midwest corporation, with Preferred Provider Organization coverage, diagnosed with cystitis between 1996 and 1999 were matched to prescription drug claims for those who filled an antibiotic prescription within 3 days of diagnosis.

RESULTS

For acute and recurrent cystitis physicians prescribed trimethoprim-sulfamethoxazole 37% and 18% respectively. The other most common antibiotics prescribed were the broad-spectrum flouroquinolones, and nitrofurantoin. The mean duration for these prescriptions was 10 days regardless of whether the infection was acute or recurrent.

CONCLUSIONS

The first line recommended antibiotic, trimethoprim-sulfamethoxazole, was prescribed in 37% of acute infections, and for considerably longer than the suggested 3-day course of therapy. Steps should be taken to educate physicians and patients on the choice and dosage of antibiotics for cystitis to minimize emergence of antibiotic resistance.

Emerging antibiotic resistance in urinary tract pathogens

In vitro antimicrobial resistance is an evolving and growing problem in UTI. Much of the increase is occurring in acute uncomplicated cystitis, an infection that has traditionally been simple to treat. The current trend of rising TMP-SMX and beta-lactam resistance rates is worrisome. Of more concern, however, are the emerging issues of fluoroquinolone resistance and MDR among community-acquired urinary isolates. Judicious use of antibiotics and development of novel nonantimicrobial-based methods of prevention of UTI are important strategies to help slow the progression of resistance. In the meantime, ongoing surveillance of resistance trends and enhanced understanding of the determinants of resistance are crucial for optimal management of UTIs.

The current management strategies for community-acquired urinary tract infection

Acute uncomplicated UTI is one of the most common problems for which young women seek medical attention and accounts for considerable morbidity and health care costs. Acute cystitis or pyelonephritis in the adult patient should be considered uncomplicated if the patient is not pregnant or elderly, if there has been no recent instrumentation or antimicrobial treatment, and if there are no known functional or anatomic abnormalities of the genitourinary tract. Most of these infections are caused by E. coli, which are susceptible to many oral antimicrobials, although resistance is increasing to some of the commonly used agents, especially TMP-SMX. In women with risk factors for infection with resistant bacteria, or in the setting of a high prevalence of TMP-SMX-resistant uropathogens, a case can be made for using a fluoroquinolone or nitrofurantoin. Use of nitrofurantoin for the empiric treatment of mild cystitis is supportable from a public health perspective in an attempt to decrease uropathogen resistance because it does not share cross-resistance with more commonly prescribed antimicrobials. Beta-lactams and fosfomycin should be considered second-line agents for empiric treatment of cystitis. Acute pyelonephritis in an otherwise healthy woman may be considered an uncomplicated infection. Fluoroquinolone regimens are superior to TMP-SMX for empiric therapy because of the relatively high prevalence of TMP-SMX resistance among uropathogens causing pyelonephritis. TMP-SMX, effective for patients with mild to moderate disease, is an appropriate drug if the uropathogen is known to be susceptible. It is reasonable to use a 7- to 10-day oral fluoroquinolone regimen for outpatient management of mild to moderate pyelonephritis in the setting of a susceptible causative pathogen and rapid clinical response to therapy. Most women with acute uncomplicated pyelonephritis are now managed safely and effectively as outpatients. Acute uncomplicated cystitis or pyelonephritis in healthy adult men is very uncommon but is generally caused by the same spectrum of uropathogens with the same antimicrobial susceptibility profile as that seen in women. The choice of antimicrobials is similar to that recommended for cystitis in women except that nitrofurantoin is not considered a good choice. Treatment duration should generally be longer than that recommended for women.

Empirical management of urinary tract infections complicating transrectal ultrasound guided prostate biopsy

PURPOSE

Although urinary tract infection is a recognized complication of transrectal ultrasound guided prostate biopsy, to our knowledge there are no recommendations in the literature for its management. We studied the unique features of this infection and provide management recommendations.

MATERIALS AND METHODS

A prospective design was used. The study group was composed of patients admitted to the emergency department from 2000 to 2001 with complaints suggestive of urinary tract infection after transrectal ultrasound guided prostate biopsy. The indication for biopsy, prophylactic regimen used and clinical manifestations were documented. Urine and blood cultures were obtained at hospital admission and bacterial susceptibility was examined for all positive cultures.

RESULTS

All 23 patients enrolled in the study underwent biopsy for acceptable indications and 95.7% had received antibiotic prophylaxis, including 69.5% with fluoroquinolones. Infection was typically accompanied by high fever (mean +/- SD 39.1 +/- 0.6C), chills in 78.3% of cases and leukocytosis in 56.5%. All positive blood cultures and 92.9% of positive urine cultures yielded Escherichia coli. Bacterial isolates showed high resistance to fluoroquinolones and trimethoprim-sulfamethoxazole, and 100% susceptibility to second and third generation cephalosporins, amikacin and carbapenems.

CONCLUSIONS

The successful management of urinary tract infection complicating transrectal prostate biopsy depends on the recognition of its unique features, the pathogens involved and their antimicrobial susceptibility. The recommended empirical treatment is a second or third generation cephalosporin, amikacin or a carbapenem.

[Quinolones]

Quinolones act by inhibiting enzymes (topoisomerases), which are indispensable to DNA synthesis. Their bactericidal activity is concentration-dependent. Their spectrum has become broader, especially since the introduction of a fluorine atom at position 6 (fluoroquinolones). They are used as the treatment of choice or as alternative therapy in a wide variety of infections, both in the hospital and non-hospital setting. Depending on the compound, they are used in urinary tract infections, sexually transmitted diseases, chronic osteomyelitis, respiratory tract infections, and severe systemic infections, among others. The upsurge and extent of quinolone resistance has limited the use of these agents in some cases and in future may determine their use in others. There are strategies to minimize the spread of resistance. Quinolones are safe and well tolerated. The most frequent adverse effects are gastrointestinal and those affecting the central nervous system.

Best pharmacological practice: urinary tract infections

Urinary tract infection is the most frequent bacterial infection. Acute uncomplicated urinary infection and acute non-obstructive pyelonephritis occur in young women with normal genitourinary tracts. Empirical short-course therapy is preferred for the management of acute cystitis, but evolving resistance requires continuing reassessment of optimal antimicrobial selection. Empirical trimethoprim or trimethoprim/sulfamethoxazole has been recommended, but increasing resistance to these agents suggests that pivmecillinam, nitrofurantoin and perhaps fosfomycin trometamol should be considered. Although flouroquinolones are effective as short-course therapy, widespread empirical use of these agents should be discouraged because of potential promotion of resistance. For acute non-obstructive pyelonephritis, flouroquinolones are the empirical oral treatment of choice, although urine culture results should direct continuing therapy. Complicated urinary tract infection occurs in men or women of all ages with underlying abnormalities of the genitourinary tract. Treatment of complicated urinary infection is individualised, taking into consideration the underlying abnormality and susceptibilities of the infecting organism. Asymptomatic bacteriuria should not be treated except in pregnant women, in patients prior to undergoing an invasive surgical procedure, or renal transplant recipients in the early postrenal transplant period.

Susceptibility patterns of orally administered antimicrobials among urinary tract infection pathogens from hospitalized patients in North America: comparison report to Europe and Latin America. Results from the SENTRY Antimicrobial Surveillance Program (2000)

Urinary tract infections (UTIs) remain a worldwide nosocomial infection problem. Geographic variations in pathogen occurrence and susceptibility profiles require monitoring to provide information to guide new (garenoxacin [BMS284756]) therapeutic options. Two thousand seven hundred-eighty UTI isolates from Europe (n = 783), Latin America (531), and North America (1,466) were tested and compared against 44 agents by reference methods in the SENTRY Antimicrobial Surveillance Program. The top seven pathogens accounted for 90% of all isolates and the rank order for all regions was: Escherichia coli (1,316; 47%), Enterococcus spp. (351; 13%), Klebsiella spp. (306; 11%), Pseudomonas aeruginosa (210; 8%), Proteus mirabilis (145; 5%), Enterobacter spp. (97; 4%), and Citrobacter spp. (78; 3%). The pathogen rank order was similar among regions except for the rarer occurrence of Enterococcus spp. (Rank #6, 4%) in Latin America. E. coli ampicillin resistance was highest in Europe and Latin America (51-55%). Ampicillin (37%), ciprofloxacin or garenoxacin (4%), and trimethoprim/sulfamethoxazole (23%) resistance remained lowest in North America. Nitrofurantoin susceptibility in E. coli was still at acceptable levels and ranged from 91 to 96% across regions. The regional ciprofloxacin-resistant rank order for P. aeruginosa by region was: Latin America (55%) > Europe (41%) > North America (29%). Vancomycin-resistant enterococci (VRE) were only detected in North America (7%). Garenoxacin possessed a 34 to 44% wider spectrum compared to ciprofloxacin against enterococci UTI isolates. Extended spectrum beta-lactamase rates for E. coli and Klebsiella spp. were 4 and 19%, respectively. These results emphasized the need to assess the often striking differences in pathogen occurrence and resistance rates among the commonly encountered UTI pathogens.

Addressing antibiotic resistance

Management of uncomplicated urinary tract infections (UTIs) has traditionally been based on 2 important principles: the spectrum of organisms causing acute UTI is highly predictable (Escherichia coli accounts for 75% to 90% and Staphylococcus saprophyticus accounts for 5% to 15% of isolates), and the susceptibility patterns of these organisms have also been relatively predictable. As a result, empiric therapy with short-course trimethoprim-sulfamethoxazole (TMP-SMX) has been a standard management approach for uncomplicated cystitis.However, antibiotic resistance is now becoming a major factor not only in nosocomial complicated UTIs, but also in uncomplicated community-acquired UTIs. Resistance to TMP-SMX now approaches 18% to 22% in some regions of the United States, and nearly 1 in 3 bacterial strains causing cystitis or pyelonephritis demonstrate resistance to amoxicillin. Fortunately, resistance to other agents, such as nitrofurantoin and the fluoroquinolones, has remained low, at approximately 2%. Preliminary data suggest that the increase in TMP-SMX resistance is associated with poorer bacteriologic and clinical outcomes when TMP-SMX is used for therapy. As a result, these trends have necessitated a change in the management approach to community-acquired UTI. The use of TMP-SMX as a first-line agent for empiric therapy of uncomplicated cystitis is only appropriate in areas where TMP-SMX resistance prevalence is <10% to 20%. In areas where resistance to TMP-SMX exceeds this rate, alternative agents need to be considered.

The expanding role of fluoroquinolones

There has been a growing rate of resistance among common urinary tract pathogens, such as Escherichia coli, to traditional antimicrobial therapies including the "gold standard" trimethoprim-sulfamethoxazole (TMP-SMX). Consequently, fluoroquinolone antimicrobial agents have taken on an expanding management role for UTIs. In fact, the recent Infectious Diseases Society of America clinical management guidelines for UTI recommend fluoroquinolones as first-line therapy for uncomplicated UTI in areas where resistance is likely to be of concern. Fluoroquinolones have demonstrated high bacteriologic and clinical cure rates, as well as low rates of resistance, among most common uropathogens. There are currently 7 fluoroquinolones with indications for UTI in the United States. However, only 3 are commonly used: levofloxacin, ciprofloxacin, and, to a lesser extent, gatifloxacin. Many of the fluoroquinolone agents have once-daily dosing regimens, enhancing patient adherence. In addition, levofloxacin and gatifloxacin have same-dose bioequivalency between their intravenous and oral formulations, allowing for "switch" or step-down therapy from parenteral to oral formulations of the same agent at the same dose. Fluoroquinolones are indicated for the management of acute uncomplicated UTIs, as well as complicated and severe UTI and pyelonephritis, in adults. They are the first-line treatment of acute uncomplicated cystitis in patients who cannot tolerate sulfonamides or TMP, who live in geographic areas with known resistance >10% to 20% to TMP-SMX, or who have risk factors for such resistance. Fluoroquinolone properties include a broad spectrum of coverage, low rates of resistance, and good safety profiles.

Urinary tract infection: traditional pharmacologic therapies

Urinary tract infections (UTIs) are common bacterial infections, particularly in women. Antimicrobial therapy is seldom indicated for asymptomatic infection, but antimicrobial therapy is usually indicated for amelioration of symptoms. Management of acute uncomplicated UTI (cystitis) is generally straightforward, with a predictable distribution of uropathogens isolated. First-line treatment of acute uncomplicated UTI has traditionally involved a 3-day regimen of trimethoprim-sulfamethoxazole (TMP-SMX) or TMP alone for patients with sulfa allergies. Increasing resistance among community-acquired Escherichia coli to TMP-SMX worldwide has led to a reassessment of the most appropriate empiric therapy for these infections. Alternative first-line agents include the fluoroquinolones, nitrofurantoin, and fosfomycin. Factors to be considered in the selection of appropriate antimicrobial therapy include pharmacokinetics, spectrum of activity of the antimicrobial agent, resistance prevalence for the community, potential for adverse effects, and duration of therapy. Ideal antimicrobial agents for UTI management have primary excretion routes through the urinary tract to achieve high urinary drug levels. In addition, there are special considerations in the management of UTI among selected populations, including postmenopausal and pregnant women, and for women with frequent recurrent UTIs.

Susceptibility of antimicrobial-resistant urinary Escherichia coli isolates to fluoroquinolones and nitrofurantoin

In vitro surveillance data from across the United States indicate that approximately 10%-20% of urinary Escherichia coli isolates from female outpatients are resistant to trimethoprim-sulfamethoxazole (TMP-SMX). Alternative therapies for uncomplicated urinary tract infections in women include fluoroquinolones and nitrofurantoin, but the activities of these agents against TMP-SMX-resistant isolates are rarely reported. Among TMP-SMX-resistant urinary E. coli isolates tested in US laboratories from 1998 through 2001, 9.5% (5767 of 60,414) were resistant to ciprofloxacin and 1.9% (1214 of 63,817) were resistant to nitrofurantoin; 10.4% of ciprofloxacin-resistant isolates (683 of 6560) were resistant to nitrofurantoin. An association between resistance to fluoroquinolones and nitrofurantoin in E. coli has not been previously reported and warrants further study.

Comparison of once-daily extended-release ciprofloxacin and conventional twice-daily ciprofloxacin for the treatment of uncomplicated urinary tract infection in women

BACKGROUND

Trimethoprim/sulfamethoxazole (TMP/SMX) is currently the first choice for empiric therapy of acute uncomplicated urinary tract infection (UTI) in women. In areas where resistance to TMP/SMX is known to be high, ciprofloxacin and other fluoroquinolones are recommended as first-line choices for the empiric therapy of UTI.

OBJECTIVE

This study compared the efficacy and safety profile of once-daily extended-release ciprofloxacin 500 mg (referred to hereafter as ciprofloxacin QD) with those of conventional ciprofloxacin 250 mg BID, each administered orally for 3 days, in the treatment of uncomplicated UTI in women.

METHODS

In this multicenter, prospective, randomized, double-blind, double-dummy, Phase III trial, adult women with clinical signs and symptoms of acute uncomplicated UTI, pyuria, and a positive pretherapy urine culture (>/=10(5) colony-forming units/mL) received ciprofloxacin QD or ciprofloxacin BID. Bacteriologic and clinical outcomes were assessed at the test-of-cure visit (4-11 days after completion of therapy) and the late follow-up visit (25-50 days after completion of therapy).

RESULTS

The intent-to-treat population consisted of 891 patients (444 ciprofloxacin QD, 447 ciprofloxacin BID); 422 patients were evaluable for efficacy (199 ciprofloxacin QD, 223 ciprofloxacin BID). At the test-of-cure visit, bacteriologic eradication was achieved in 94.5% (188/199) of the ciprofloxacin QD group and 93.7% (209/223) of the ciprofloxacin BID group (95% CI, -3.5 to 5.1). Clinical cure was achieved in 95.5% (189/198) of the ciprofloxacin QD group and 92.7% (204/220) of the ciprofloxacin BID group (95% CI, -1.6 to 7.1). Bacteriologic and clinical outcomes at the late follow-up visit were consistent with the test-of-cure findings. The rate of eradication of Escherichia coli, the most prevalent organism, was >97% in each treatment group. Rates of drug-related adverse events were similar with the once- and twice-daily ciprofloxacin regimens (10% and 9%, respectively).

CONCLUSION

Extended-release ciprofloxacin 500 mg given once daily for 3 days was as effective and well tolerated as conventional ciprofloxacin 250 mg given twice daily for 3 days in the treatment of acute uncomplicated UTI in women.

Urinary tract infections: what's new?

PURPOSE

This review provides practicing urologists with important basic information about urinary tract infections (UTIs) that can be applied to everyday clinical problems.

MATERIALS AND METHODS

A review is presented of provocative and controversial concepts in the current literature.

RESULTS

Bacterial virulence mechanisms are critical for overcoming the normal host defenses. Increasing antimicrobial resistance of uropathogens has led to reconsideration of traditional treatment recommendations in many areas. For effective patient management the first issue is to define complicating urological factors. Managing complicated urinary tract infections, particularly in urology, is determined by clinical experience to define the pertinent anatomy and to determine the optimal interventions. New clinical data are summarized on UTIs in long-term care patients, behavioral risks for UTI in healthy women and anatomical differences associated with an increased risk for UTI. The rationale is presented for UTI prophylaxis using cranberry juice, immunization and bacterial interference. Current treatment trends for UTI include empiric therapy (without urine culture and sensitivity testing), short-course therapy, patient-administered (self-start) therapy and outpatient therapy for uncomplicated pyelonephritis.

CONCLUSIONS

Recommendations for treating patients with UTIs have changed based on basic science and clinical experience.

Antibiotic prescribing and urinary tract infection

The aim of this study was to evaluate the diagnostic and therapeutic approach to urinary tract infections (UTIs) by primary care physicians, in Samsun, Turkey. Data were obtained from the records of 2083 visits at eight primary care areas. Trained research students were stationed on site at each of the eight primary care centres between 1 June, 1999 and 1 July, 1999. Patients who had acute cystitis, recurrent UTIs, acute pyelonephritis and acute urethritis were included in the study. A total of 2083 office visits were recorded and 419 (20.1%) of the patients had UTIs and acute urethritis. Antibiotics were prescribed for 94.7% of the patients with UTIs and urethritis. Some 74% of prescriptions were consistent with current recommendation, but only 41% of the antibiotic prescriptions were rational according to dosage, dosage interval and duration of therapy. Urinary antiseptic agents were prescribed to 75% of patients with UTIs. These data indicate that polypharmacy is widespread in our region; primary care physicians need to review their knowledge about the diagnosis and treatment of UTIs and acute urethritis.

Vaccine Development for the Prevention of Urinary Tract Infections

The effectiveness of antibiotic prophylaxis for recurrent urinary tract infections is being compromised as increasing numbers of uropathogens develop resistance to conventional antibiotics. Because one alternative to antibiotic therapy is immunization of susceptible patients to increase innate resistance, several different vaccines are currently being developed. Four of the vaccines contain a mixture of whole bacteria or an antigenic extract and are administered as a vaginal suppository or oral tablet. A parenteral route is being used in clinical trials of the Escherichia coli type 1 fimbrial adhesin and its chaperone protein. The safety of both the mucosal and parenteral vaccines has been demonstrated in phase 1 clinical trials. Phase 2 trials have shown the efficacy of a vaginal mucosal vaccine containing whole bacteria and an oral vaccine prepared from bacterial lysates. Further clinical trials will allow comparisons of the various vaccines and evaluation of their effectiveness relative to prophylactic antibiotic therapy.

Urinary tract infection trends in Latin American hospitals: report from the SENTRY antimicrobial surveillance program (1997-2000)

Urinary tract infections (UTI) are one of the most common infectious diseases diagnosed in outpatients as well as in hospitalized patients. The objective of this study was to report the frequency of occurrence and antimicrobial susceptibility of uropathogens collected in Latin America between 1997 to 2000 through the SENTRY Antimicrobial Surveillance Program. Antimicrobial susceptibility testing was performed and results interpreted using reference broth microdilution methods. In the 4 year period, a total of 1961 urine isolates from hospitalized patients were included. The patients' mean age was 51.3 years and most of the infections occurred among women (65.6%). Esherichia coli was the most frequent pathogen isolated followed by Klebsiella spp., Pseudomonas aeruginosa, and Proteus mirabilis. Among the E. coli isolates, piperacillin/tazobactam, aztreonam, extended-spectrum cephalosporins, carbapenems and amikacin constitute reasonable therapeutic options for treatment of serious UTI in Latin America (91.0-100.0% susceptible). High resistance rates to fluoroquinolones (17.5-18.9%) and trimethoprim/sulfamethoxazole (>45.0%) were observed among the E. coli. In contrast, nitrofurantoin displayed susceptibility rate of > 87.0%. Against Klebsiella spp. infections, the only effective therapeutic option would be the carbapenems due to the high number of isolates (>30.0%) producing extended-spectrum beta-lactamases (ESBL). Even the new fluoroquinolones showed limited activity against Klebsiella spp. (72.1-88.6% susceptible) and the P. aeruginosa isolates showed high resistance rates to most antimicrobial agents tested. The results of this survey endorse the importance of Enterobacteriaceae as cause of UTI in Latin America. Our results also demonstrate that the uropathogens isolated in the Latin American medical centers exhibit high resistance to various classes of antimicrobial agents. Carbapenem-resistant P. aeruginosa, ciprofloxacin-resistant E. coli, ESBL-producing K. pneumoniae constitute serious problem in this geographic region.

Trends in antimicrobial resistance among urinary tract infection isolates of Escherichia coli from female outpatients in the United States

The Infectious Diseases Society of America advocates trimethoprim-sulfamethoxazole (SXT) as initial therapy for females with acute uncomplicated bacterial cystitis in settings where the prevalence of SXT resistance does not exceed 10 to 20%. To determine trends in the activities of SXT, ampicillin, ciprofloxacin, and nitrofurantoin among urine isolates of Escherichia coli from female outpatients, susceptibility testing data from The Surveillance Network (TSN) Database-USA (n = 286,187) from 1995 to 2001 were analyzed. Resistance rates among E. coli isolates to ampicillin (range, 36.0 to 37.4% per year), SXT (range, 14.8 to 17.0%), ciprofloxacin (range, 0.7 to 2.5%), and nitrofurantoin (range, 0.4 to 0.8%) varied only slightly over this 7-year period. Ciprofloxacin was the only agent studied that demonstrated a consistent stepwise increase in resistance from 1995 (0.7%) to 2001 (2.5%). In 2001, SXT resistance among E. coli isolates was >10% in all nine U.S. Bureau of the Census regions. At institutions testing > or =100 urinary isolates of E. coli (n = 126) in 2001, ampicillin (range, 27.3 to 98.8%) and SXT (range, 7.5 to 47.1%) resistance rates varied widely while ciprofloxacin (range, 0 to 12.9%) and nitrofurantoin (range, 0 to 2.8%) resistance rates were more consistent. In 2001, the most frequent coresistant phenotypes were resistance to ampicillin and SXT (12.0% of all isolates; 82.3% of coresistant isolates) and resistance to ampicillin, ciprofloxacin, and SXT (1.4% of all isolates; 9.9% of coresistant isolates). Coresistance less frequently included resistance to nitrofurantoin (3.5% of coresistant isolates) than resistance to ciprofloxacin (15.8%), SXT (95.7%), and ampicillin (98.1%). In conclusion, among urinary isolates of E. coli from female outpatients in the United States, national resistance rates to SXT were relatively consistent (14.8 to 17.0%) from 1995 to 2001 but demonstrated considerable regional and institutional variation in 2001. Therapies other than SXT may need to be considered in some locations.

Urinary tract infection: traditional pharmacologic therapies

Urinary tract infections (UTIs) are common bacterial infections, particularly in women. Antimicrobial therapy is seldom indicated for asymptomatic infection, but antimicrobial therapy is usually indicated for amelioration of symptoms. Management of acute uncomplicated UTI (cystitis) is generally straightforward, with a predictable distribution of uropathogens isolated. First-line treatment of acute uncomplicated UTI has traditionally involved a 3-day regimen of trimethoprim-sulfamethoxazole (TMP-SMX) or TMP alone for patients with sulfa allergies. Increasing resistance among community-acquired Escherichia coli to TMP-SMX worldwide has led to a reassessment of the most appropriate empiric therapy for these infections. Alternative first-line agents include the fluoroquinolones, nitrofurantoin, and fosfomycin. Factors to be considered in the selection of appropriate antimicrobial therapy include pharmacokinetics, spectrum of activity of the antimicrobial agent, resistance prevalence for the community, potential for adverse effects, and duration of therapy. Ideal antimicrobial agents for UTI management have primary excretion routes through the urinary tract to achieve high urinary drug levels. In addition, there are special considerations in the management of UTI among selected populations, including postmenopausal and pregnant women, and for women with frequent recurrent UTIs.

Addressing antibiotic resistance

Management of uncomplicated urinary tract infections (UTIs) has traditionally been based on 2 important principles: the spectrum of organisms causing acute UTI is highly predictable (Escherichia coli accounts for 75% to 90% and Staphylococcus saprophyticus accounts for 5% to 15% of isolates), and the susceptibility patterns of these organisms have also been relatively predictable. As a result, empiric therapy with short-course trimethoprim-sulfamethoxazole (TMP-SMX) has been a standard management approach for uncomplicated cystitis.However, antibiotic resistance is now becoming a major factor not only in nosocomial complicated UTIs, but also in uncomplicated community-acquired UTIs. Resistance to TMP-SMX now approaches 18% to 22% in some regions of the United States, and nearly 1 in 3 bacterial strains causing cystitis or pyelonephritis demonstrate resistance to amoxicillin. Fortunately, resistance to other agents, such as nitrofurantoin and the fluoroquinolones, has remained low, at approximately 2%. Preliminary data suggest that the increase in TMP-SMX resistance is associated with poorer bacteriologic and clinical outcomes when TMP-SMX is used for therapy. As a result, these trends have necessitated a change in the management approach to community-acquired UTI. The use of TMP-SMX as a first-line agent for empiric therapy of uncomplicated cystitis is only appropriate in areas where TMP-SMX resistance prevalence is <10% to 20%. In areas where resistance to TMP-SMX exceeds this rate, alternative agents need to be considered.

The expanding role of fluoroquinolones

There has been a growing rate of resistance among common urinary tract pathogens, such as Escherichia coli, to traditional antimicrobial therapies including the "gold standard" trimethoprim-sulfamethoxazole (TMP-SMX). Consequently, fluoroquinolone antimicrobial agents have taken on an expanding management role for UTIs. In fact, the recent Infectious Diseases Society of America clinical management guidelines for UTI recommend fluoroquinolones as first-line therapy for uncomplicated UTI in areas where resistance is likely to be of concern. Fluoroquinolones have demonstrated high bacteriologic and clinical cure rates, as well as low rates of resistance, among most common uropathogens. There are currently 7 fluoroquinolones with indications for UTI in the United States. However, only 3 are commonly used: levofloxacin, ciprofloxacin, and, to a lesser extent, gatifloxacin. Many of the fluoroquinolone agents have once-daily dosing regimens, enhancing patient adherence. In addition, levofloxacin and gatifloxacin have same-dose bioequivalency between their intravenous and oral formulations, allowing for "switch" or step-down therapy from parenteral to oral formulations of the same agent at the same dose. Fluoroquinolones are indicated for the management of acute uncomplicated UTIs, as well as complicated and severe UTI and pyelonephritis, in adults. They are the first-line treatment of acute uncomplicated cystitis in patients who cannot tolerate sulfonamides or TMP, who live in geographic areas with known resistance >10% to 20% to TMP-SMX, or who have risk factors for such resistance. Fluoroquinolone properties include a broad spectrum of coverage, low rates of resistance, and good safety profiles.

Pathogen occurrence and antimicrobial resistance trends among urinary tract infection isolates in the Asia-Western Pacific Region: report from the SENTRY Antimicrobial Surveillance Program, 1998-1999

Worldwide surveillance of antimicrobial resistance among urinary tract pathogens is useful to determine important trends and geographical variation for common Gram-positive and -negative species. The most common causative uropathogens often have intrinsic or acquired resistance mechanisms which include ESBL production among enteric bacilli, multi-drug resistant staphylococci and non-fermentative Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter spp. and vancomycin-resistant Enterococcus spp. This study evaluates pathogen frequency and the resistance rates among urinary tract infection (UTI) pathogens in 14 medical centres in the Asia-Pacific region between 1998 and 1999. The isolates were referred to a central monitor for reference NCCLS broth microdilution testing, identification confirmation and patient demographic analysis. Over 50% of the 958 pathogens were Escherichia coli and Klebsiella spp. followed by P. aeruginosa, Enterococcus spp. and Enterobacter spp. Susceptibility for the three enteric bacilli was high for carbapenems (100%), 'fourth-generation' cephalosporins (cefepime 94.9-98.6%) and amikacin (> or = 93.0%). Beta-lactamase inhibitor compounds were more active against E. coli (piperacillin/tazobactam; > 90% susceptible) than the other two enteric species and all other tested agents had a narrower spectra of activity. The rank order of anti-pseudomonal agents was amikacin (91.5% susceptible)> imipenem > piperacillin/tazobactam > tobramycin > ceftazidime and cefepime (77.4 and 76.4% susceptible, respectively). Susceptibility to quinolones for the P. aeruginosa isolates was only 63.2-67.0%. Only one vancomycin-intermediate Enterococcus spp. (van C phenotype) was detected among the 103 strains tested. Newer fluoroquinolones (gatifloxacin; MIC(50), mg/l) were more potent against enterococci than ciprofloxacin (MIC(50), 2 mg/l) and high-level resistance to aminoglycosides was common (41.7%). The data presented are compared to studies of similar design from other areas which are part of the SENTRY surveillance network.

Outcomes associated with trimethoprim/sulphamethoxazole (TMP/SMX) therapy in TMP/SMX resistant community-acquired UTI

The increase in resistance rates to TMP/SMX among E. coli causing community-acquired UTI has resulted in consideration of alternative agents as first line therapy for these infections. However, there has been little study of the clinical significance of the in vitro trends in resistance which have been reported. We review studies that address the correlation between in vitro resistance to TMP/SMX and clinical outcome in uncomplicated UTI. From these data, it is clear that in vitro resistance does translate into therapeutic failure for 50-60% of patients with a TMP/SMX resistant uropathogen. Thus, it is reasonable to consider an agent other than TMP/SMX when the TMP/SMX resistance prevalence reaches 20%.

Spectrum and activity of three contemporary fluoroquinolones tested against Pseudomonas aeruginosa isolates from urinary tract infections in the SENTRY Antimicrobial Surveillance Program (Europe and the Americas; 2000): more alike than different!

The spectrum and potency of ciprofloxacin, gatifloxacin and levofloxacin was compared to that of 10 other agents against urinary tract isolates of Pseudomonas aeruginosa among patients in the year 2000 SENTRY Antimicrobial Surveillance Program (Europe, Latin America, North America). Dramatic differences were observed between isolates in geographic areas with the most fluoroquinolone-resistant strains detected in Latin America (54.5% resistance) compared to resistance rates of 40.8-43.7% and 28.3-29.2% for Europe and North America, respectively. Overall, no significant differences were observed between the spectrums of these fluoroquinolones (37.1-38.8% resistance) for therapy of P. aeruginosa urinary tract infections in hospitalized patients. Generally, in this world wide sample, aminoglycosides, carbapenems (imipenem, meropenem), cefepime, and piperacillin with or without tazobactam possessed a wider range of activity and spectrum versus current P. aeruginosa clinical isolates.