Isolation of fluoroquinolone-resistant rectal Escherichia coli after treatment of acute uncomplicated cystitis

OBJECTIVES: Given increasing rates of co-trimoxazole resistance among uropathogens causing acute uncomplicated cystitis, fluoroquinolones, nitrofurantoin and fosfomycin are often considered as alternative empirical therapy. The choice between these drugs should depend in part on whether they are associated with the isolation of drug-resistant microbial flora. We conducted a randomized treatment trial to assess the effects of ciprofloxacin, nitrofurantoin and fosfomycin on the rectal microbial flora of women with acute uncomplicated cystitis, including isolation of fluoroquinolone-resistant strains. METHODS: Pre-menopausal women presenting with acute uncomplicated cystitis were randomized to treatment with 3 days of ciprofloxacin, 7 days of nitrofurantoin, or a single dose of fosfomycin. Women were followed for 1 month for evaluation of clinical and microbiological responses as well as for isolation of resistant rectal E. coli. RESULTS: Sixty-two women (25 ciprofloxacin, 17 nitrofurantoin, 20 fosfomycin) were enrolled and eligible for analysis. All three regimens were well tolerated and resulted in >90% clinical and bacteriological cure. The prevalence of rectal E. coli was markedly decreased by ciprofloxacin and fosfomycin, but not by nitrofurantoin. One woman treated with ciprofloxacin had emergence of two ciprofloxacin-resistant rectal E. coli strains within 10 days of completing therapy. No emergence of resistance was observed in the other two treatment groups. CONCLUSIONS: This study demonstrates that fluoroquinolone-resistant E. coli remain infrequent in the rectal flora of women with uncomplicated cystitis in Seattle. However, a 3 day course of a fluoroquinolone for treatment of uncomplicated cystitis was followed by isolation of fluoroquinolone-resistant rectal E. coli in one patient.     

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.     

Risk factors for trimethoprim-sulfamethoxazole resistance in patients with acute uncomplicated cystitis

Emerging antimicrobial resistance among uropathogens makes the management of acute uncomplicated cystitis increasingly challenging. Few prospective data are available on the risk factors for resistance to trimethoprim-sulfamethoxazole (TMP-SMX), the drug of choice in most settings. In order to evaluate this, we prospectively enrolled women 18 to 50 years of age presenting to an urban primary care practice with symptoms of cystitis. Potentially eligible women provided a urine sample for culture and completed a questionnaire regarding putative risk factors for TMP-SMX resistance. Escherichia coli isolates were tested for clonal group A (CGA) membership by a fumC-specific PCR. Of 165 women with cystitis symptoms, 103 had a positive urine culture and were eligible for participation. E. coli was the predominant uropathogen (86%). Fifteen (14.6%) women had a TMP-SMX-resistant (TMP-SMX r) organism (all of which were E. coli). Compared with the women who had a TMP-SMX-susceptible organism, women in the TMP-SMX r group were more likely to have traveled (odds ratio [OR], 15.4; 95% confidence interval [CI], 4.4 to 54.3; P < 0.001) and to be Asian (OR, 6.1; 95% CI, 1.0 to 36.4; P = 0.048). CGA was also independently associated with TMP-SMX resistance (OR, 105; 95% CI, 6.3 to 1,777.6; P = 0.001). No association with TMP-SMX resistance was demonstrated for the use of either TMP-SMX or another antibiotic in the past 3 months or with having a child in day care. Among these women with acute uncomplicated cystitis, Asian race and recent travel were independently associated with TMP-SMX resistance. TMP-SMX r isolates were more likely to belong to CGA. Knowledge of these risk factors for TMP-SMX resistance could facilitate the accurate selection of empirical therapy.     

Treatment of uncomplicated urinary tract infections in an era of increasing antimicrobial resistance

In the past few years, notable advances have occurred in our understanding of the epidemiology and clinical importance of drug resistance among uropathogens that cause uncomplicated urinary tract infections (UTIs) or cystitis. Guidelines recommend trimethoprim-sulfamethoxazole for empirical treatment of uncomplicated UTI unless trimethoprim-sulfamethoxazole resistance in a community exceeds 10% to 20%. The rationale for this 10% to 20% cutoff appears to be related to clinical and economical considerations and to concerns about the emergence of fluoroquinolone-resistant bacteria. In patients with uncomplicated UTIs caused by uropathogens resistant to trimethoprim-sulfamethoxazole who were treated with this drug combination, clinical outcomes were clarified recently and found to be suboptimal (<60% clinical cure). Following guidelines for empirical treatment of uncomplicated UTIs is problematic. Surveillance of antimicrobial resistance among uropathogens that cause uncomplicated UTIs is performed rarely. Hospital antibiograms provide data on resistance among bacteria that cause community-associated UTIs; however, antibiograms overestimate drug resistance among uropathogens that cause UTIs and may mislead clinicians about the prevalence of local resistance. We review options for management of uncomplicated UTIs in light of these considerations.     

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.     

The etiology of urinary tract infection: traditional and emerging pathogens

The microbial etiology of urinary infections has been regarded as well established and reasonably consistent. Escherichia coli remains the predominant uropathogen (80%) isolated in acute community-acquired uncomplicated infections, followed by Staphylococcus saprophyticus (10% to 15%). Klebsiella, Enterobacter, and Proteus species, and enterococci infrequently cause uncomplicated cystitis and pyelonephritis.The pathogens traditionally associated with UTI are changing many of their features, particularly because of antimicrobial resistance. The etiology of UTI is also affected by underlying host factors that complicate UTI, such as age, diabetes, spinal cord injury, or catheterization. Consequently, complicated UTI has a more diverse etiology than uncomplicated UTI, and organisms that rarely cause disease in healthy patients can cause significant disease in hosts with anatomic, metabolic, or immunologic underlying disease. The majority of community-acquired symptomatic UTIs in elderly women are caused by E coli. However, gram-positive organisms are common, and polymicrobial infections account for up to 1 in 3 infections in the elderly. In comparison, the most common organisms isolated in children with uncomplicated UTI are Enterobacteriaceae. Etiologic pathogens associated with UTI among patients with diabetes include Klebsiella spp., Group B streptococci, and Enterococcus spp., as well as E coli. Patients with spinal cord injuries commonly have E coli infections. Other common uropathogens include Pseudomonas and Proteus mirabilis.Recent advances in molecular biology may facilitate the identification of new etiologic agents for UTI. The need for accurate and updated population surveillance data is apparent, particularly in light of concerns regarding antimicrobial resistance. This information will directly affect selection of empiric therapy for UTI.     

Antimicrobial resistance among uropathogens that cause acute uncomplicated cystitis in women in Hong Kong: a prospective multicenter study in 2006 to 2008

A prospective multicenter study was conducted to assess the epidemiology of antimicrobial resistance among uropathogens causing uncomplicated cystitis. Adult women with clinical diagnosis of uncomplicated cystitis were enrolled from 54 participating centers distributed all over Hong Kong during 2006 to 2008. A positive urine culture was found in 59.5% (352/592) patients. The patients had mean age of 44.9 years, and most (89.2%) were otherwise healthy. The most prevalent causative organism was Escherichia coli (77%), followed by other Enterobacteriaceae (14.2%), staphylococci (5.1%), and other Gram-positive bacteria (3.7%). The resistance rates of E. coli to co-trimoxazole and ciprofloxacin were 29.5% and 12.9%, respectively, and 14 isolates (5.2%) were confirmed as extended-spectrum β-lactamase (ESBL) producers. Of the ESBL producers, molecular studies showed CTX-M-14, CTX-M-24, or CTX-M-9. Nitrofurantoin and fosfomycin were active against >90% of the isolates, regardless of resistance phenotypes for other drugs. Pulsed-field gel electrophoresis of representative isolates showed that the antibiotic-resistant strains were genetically diverse. Patients with history of recent antibiotic use were significantly more likely to have infection by E. coli with co-trimoxazole resistance (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.4–5.7; P = 0.003) and ciprofloxacin resistance (OR, 2.5; 95% CI, 1.1–5.8; P = 0.03). Knowledge of the resistance data and risk factors could inform better use of antibiotics for empiric therapy for acute uncomplicated cystitis.     

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.     

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.     

Treatment options for acute uncomplicated cystitis in adults

Urinary tract infection (UTI) is classified as uncomplicated if it occurs in a patient with a structurally and functionally normal urinary tract. Acute uncomplicated cystitis is observed chiefly in women. It needs, however, to be differentiated depending on whether it occurs in premenopausal, postmenopausal or pregnant women. Only a small number of 15-50 year old, otherwise healthy men suffer acute uncomplicated cystitis. In premenopausal, non-pregnant women, single-dose antimicrobial therapy is generally less effective than the same antibiotic used for longer duration. However, most antimicrobial agents given for 3 days are as effective as those given for longer duration, and adverse events tend to be found more often with longer treatment. Trimethoprim (or co-trimoxazole) can be recommended as first-line empirical therapy only in communities with resistance rates of uropathogens to trimethoprim of < or =10-20%. Otherwise fluoroquinolones are recommended. Alternatives are fosfomycin trometamol or beta-lactams, such as second- or third-generation oral cephalosporins or pivmecillinam, especially when fluoroquinolones are contraindicated or a high proportion (>10%) of Escherichia coil strains in the community are already resistant to fluoroquinolones, as in Spain, for example. Recurrent UTIs are common among young, healthy women even though they generally have anatomically and physiologically normal urinary tracts. The following prophylactic antimicrobial regimens are recommended: (i) the use of long-term, low-dose prophylactic antimicrobials taken at bedtime; (ii) post-coital prophylaxis for women in whom episodes of infection are associated with sexual intercourse. Other prophylactic methods are not as yet as effective as antimicrobial prophylaxis.     

Diagnosis and treatment of acute uncomplicated cystitis

Urinary tract infections are the most common bacterial infections in women. Most urinary tract infections are acute uncomplicated cystitis. Identifiers of acute uncomplicated cystitis are frequency and dysuria in an immunocompetent woman of childbearing age who has no comorbidities or urologic abnormalities. Physical examination is typically normal or positive for suprapubic tenderness. A urinalysis, but not urine culture, is recommended in making the diagnosis. Guidelines recommend three options for first-line treatment of acute uncomplicated cystitis: fosfomycin, nitrofurantoin, and trimethoprim/sulfamethoxazole (in regions where the prevalence of Escherichia coli resistance does not exceed 20 percent). Beta-lactam antibiotics, amoxicillin/clavulanate, cefaclor, cefdinir, and cefpodoxime are not recommended for initial treatment because of concerns about resistance. Urine cultures are recommended in women with suspected pyelonephritis, women with symptoms that do not resolve or that recur within two to four weeks after completing treatment, and women who present with atypical symptoms.     

An observational study of empirical antibiotics for adult women with uncomplicated UTI in general practice

OBJECTIVES: Women presenting in primary care with symptoms suggestive of uncomplicated urinary tract infection (UTI) are commonly managed without urine culture. We therefore do not know how successful general practitioners (GPs) are at targeting antibiotic treatment to women who would have had a microbiologically confirmed UTI, or at avoiding antibiotics in those who would have had a negative culture, had all patients with a suspected UTI been sampled. We therefore explored the association between antibiotic prescribing and urine culture results when culture was performed in all symptomatic patients. METHODS: GPs in nine general practices in South Wales were asked to submit urine specimens from all women consulting with clinically suspected, uncomplicated UTI. Patients were followed up 2 weeks later by questionnaire. RESULTS AND CONCLUSIONS: One hundred and thirteen adult women with a median age of 54 years were included and 61% received empirical antibiotics. There was very low agreement between the decision to prescribe empirically and subsequent culture result (Kappa = 0.04), with 60% of those prescribed empirical antibiotics subsequently found to have a negative culture, and 25% of those found to have a positive culture not prescribed empirical antibiotics. Current strategies to target empirical antibiotic prescribing in clinically suspected, uncomplicated UTI require review.     

Single low-dose ofloxacin for the treatment of uncomplicated urinary tract infection in young women

Fifty premenopausal women with uncomplicated urinary tract infection (UTI) were treated with a single dose of 100 mg of ofloxacin. Duration of symptoms before the treatment, number of episodes of UTI during the last year, association with sexual activity, and the use of contraceptives were evaluated in relation to the clinical and microbiological response. Forty-seven women (94%) were cured clinically and microbiologically three days after treatment. Follow up at 28 days disclosed that 43 (86%) were free of symptoms and in 40 (80%) the urinary cultures were negative. Significantly higher rates of microbiological failure or reinfection were found among women with three or more episodes of UTI during the last year. This study shows that a single dose of ofloxacin is effective for therapy of uncomplicated UTI in young women.     

Evaluating Empiric Therapy for Acute Uncomplicated Cystitis in the Outpatient Setting: A Retrospective Cohort Study

ObjectivesTo evaluate the empiric therapy prescribed for acute uncomplicated cystitis in the outpatient setting (emergency department and ambulatory care clinics) and to characterize uropathogens for discordance between the therapy prescribed and susceptibility.MethodsA retrospective review was conducted at an inner-city emergency department and multiple clinics to evaluate the empiric therapy prescribed and the uropathogens isolated from culture for patients with acute uncomplicated cystitis.ResultsA total of 144 urine cultures were included. Among the patients, 53.4% were empirically prescribed cephalexin, 20.1% ciprofloxacin, 11% nitrofurantoin, and 8.3% trimethoprim/sulfamethoxazole. The most common uropathogen was Escherichia coli (72.4%), followed by Streptococcus agalactiae (7.6%) and Klebsiella pneumoniae (4.8%). Of the 107 E. coli isolates, 9 were extended spectrum beta-lactamase–producing. E. coli antimicrobial susceptibilities were as follows: ceFAZolin (97%), nitrofurantoin (96%), cefTRIAXone (91%), ciprofloxacin (87%), and trimethoprim-sulfamethoxazole (59%). The concordance rates with the Infectious Diseases Society of America treatment guidelines for acute uncomplicated cystitis and local resistance patterns were as follows: empiric therapy prescribed (70%), dosing of empiric therapy (77%), and duration of empiric therapy (22%). For empiric therapy prescribed and susceptibility mismatch, 5.6% of the isolates were not susceptible to therapy, 76.4% were susceptible to therapy, 14% did not have susceptibilities, and 4.2% did not receive therapy.ConclusionsMost of the cases of acute uncomplicated cystitis at the subject institution can be managed safely and effectively with nitrofurantoin or first-generation cephalosporins. Institutions should use national guidelines in conjunction with local resistance and prescribing patterns to improve antibiotic prescribing in the outpatient setting.     

Pathogenesis of urinary tract infections: an update

The pathogenesis of uncomplicated urinary tract infection (UTI) is complex and influenced by many host biological and behavioural factors and by properties of the infecting uropathogens. Most uncomplicated UTIs in women are not associated with underlying functional or anatomical abnormalities of the urinary tract, whereas sexual intercourse, spermicide use, a history of recurrent UTI and recent antimicrobial chemotherapy are important risk factors. A maternal history of UTI and young age at first UTI, as well as sexual intercourse and spermicide use, are risk factors for recurrent UTI in young women. In some young healthy women, especially those with 'low UTI risk' behaviour, features of pelvic anatomy appear to be associated with UTI risk. In postmenopausal women, anatomical and functional characteristics of the genitourinary tract are more strongly associated with UTI risk than in younger women. A genetic predisposition to recurrent UTI is suggested by the association of recurrent UTI in certain age groups with the ABH blood group non-secretor phenotype, a maternal history of UTI and early age at onset of UTI. Virulence determinants of uropathogens are much more important in the normal host than in the host who has a functional or anatomical abnormality of the genitourinary tract.     

Clinical relevance of laboratory-reported antibiotic resistance in acute uncomplicated urinary tract infection in primary care

OBJECTIVES: To determine whether patients with an uncomplicated community-acquired urinary tract infection (UTI) and an isolate resistant to trimethoprim had worse clinical outcomes following empirical treatment with trimethoprim 200 mg twice daily for 3 days than did those with a susceptible isolate. PATIENTS AND METHODS: This was a prospective cohort study of clinical outcome. We enrolled 497 women (>or=18-70 years) presenting to general practitioner surgeries in Norwich and Gloucester with at least two symptoms of acute (<7 days) uncomplicated UTI. Significant bacteriuria was defined as >or=10(4) cfu/mL from a mid-stream urine (MSU). RESULTS: Of enrolled patients 75% (334/448) had significant bacteriuria, and trimethoprim resistance was present in 13.9% (44/317) of isolates. Patients with resistant isolates had a longer median time to symptom resolution (7 versus 4 days, P=0.0002), greater reconsultation to the practice (39% versus 6% in first week, P<0.0001), more subsequent antibiotics (36% versus 4% in first week, P<0.0001) and higher rates of significant bacteriuria at 1 month (42% versus 20% with susceptible isolate, P=0.04). Half of patients reconsulting in the first week had a resistant organism. CONCLUSIONS: Patients with uncomplicated UTI caused by trimethoprim-resistant organisms had significantly worse clinical outcomes than those with trimethoprim-susceptible organisms. Nevertheless, trimethoprim resistance was rarer than predicted from routine laboratory submissions and we calculate that 23 women require microbiological investigation to prevent one reconsultation arising from resistance-based treatment failure. We therefore suggest empirical antibiotic treatment in acute, uncomplicated UTIs. If patients reconsult in the first week, we suggest a change of antibiotic treatment with urine culture and susceptibility testing then done. More generally, laboratory resources should concentrate on resistance surveillance to inform empirical antibiotic choice.     

Management of acute uncomplicated urinary tract infection in adults

Acute uncomplicated UTI is one of the most common problems for which young women seek medical attention, and it accounts for considerable morbidity and health care costs. Acute cystitis is a superficial infection of the bladder mucosa, whereas pyelonephritis involves tissue invasion of the upper urinary tract. Localization tests suggest that as many as one third of episodes of acute cystitis are associated with silent upper tract involvement. 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. Because of the superficial nature of cystitis, single-dose and 3-day regimens have gained wide acceptance as the preferred methods of treatment. Review of the published data suggests that a 3-day regimen is more effective than a single-dose regimen for all antimicrobials tested. Regimens with trimethoprim-sulfamethoxazole appear to be more effective than those with beta-lactams, regardless of the duration. Acute pyelonephritis does not necessarily imply a complicated infection. Upper tract infection with highly virulent uropathogens in an otherwise healthy woman may be considered an uncomplicated infection. The optimal treatment duration for acute uncomplicated pyelonephritis has not been established, and 14-day regimens are often used. We prefer to use antimicrobials that attain high renal tissue levels, such as trimethoprim-sulfamethoxazole or quinolones, for pyelonephritis. Women with frequently recurring infections can be successfully managed by continuous prophylaxis, either daily or thrice-weekly, by postcoital prophylaxis, or, in compliant patients, by early self-administration of single-dose or 3-day therapy as soon as typical symptoms are noted. Our drug of choice for all these regimens is trimethoprim-sulfamethoxazole. Acute uncomplicated cystitis in adult men is very uncommon, but it is occasionally noted in homosexual men who practice insertive and intercourse or in heterosexual men whose partners have vaginal colonization with E. coli.     

Antimicrobial resistance in community-acquired urinary tract infections: results from the Korean Antimicrobial Resistance Monitoring System

The Korean Antimicrobial Resistance Monitoring System was established and the first nationwide surveillance of bacterial uropathogens was conducted during the period from January 2008 to June 2009. With the cooperation of 34 medical centers throughout South Korea, a total of 1994 strains belonging to clinically relevant bacterial uropathogens were collected from patients with community-acquired urinary tract infections (UTIs). To compare with past data, understand a trend of antimicrobial resistance, and ultimately determine new regimens for empirical treatment of uncomplicated cystitis, the antimicrobial susceptibilities against Escherichia coli in uncomplicated cystitis to commonly prescribed drugs were investigated. In uncomplicated cystitis, the most prevalent causative organism was E. coli (72.7%), followed by Enterococcus faecalis (10.7%) and Klebsiella pneumoniae (3.5%). Among E. coli isolates from acute uncomplicated cystitis, 38.5% were susceptible to ampicillin, 80.7% to amoxicillin/clavulanate, 67.3% to trimethoprim/sulfamethoxazole, 74.6% to ciprofloxacin, 77.5% to levofloxacin, 86.0% to cefazolin, 86.1% to cefuroxime, 93.6% to cefpodoxime, 94.7% to ceftriaxone, 99.5% to amikacin, 80.9% to tobramycin, and 76.6% to gentamicin. An increasing tendency of resistance to ciprofloxacin (24.8%) has been observed compared with the similar studies in 2006 (23.4%) and 2002 (15.2%) from patients with uncomplicated cystitis. These data provide much needed information on the prevalence of antimicrobial resistance in community-acquired UTIs in South Korea and will be a useful reference for future periodic surveillance studies.     

Urinary tract infections in adults

Urinary tract infections remain a significant cause of morbidity in all age groups. Recent studies have helped to better define the population groups at risk for these infections, as well as the most cost-effective management strategies. Initially, a urinary tract infection should be categorized as complicated or uncomplicated. Further categorization of the infection by clinical syndrome and by host (i.e., acute cystitis in young women, acute pyelonephritis, catheter-related infection, infection in men, asymptomatic bacteriuria in the elderly) helps the physician determine the appropriate diagnostic and management strategies. Uncomplicated urinary tract infections are caused by a predictable group of susceptible organisms. These infections can be empirically treated without the need for urine cultures. The most effective therapy for an uncomplicated infection is a three-day course of trimethoprim-sulfamethoxazole. Complicated infections are diagnosed by quantitative urine cultures and require a more prolonged course of therapy. Asymptomatic bacteriuria rarely requires treatment and is not associated with increased morbidity in elderly patients.