Antimicrobial Susceptibility Patterns of Contemporary Pathogens from Uncomplicated Urinary Tract Infections Isolated in a Multicenter Italian Survey: Possible Impact on Guidelines

Therapies in preclinical and in early clinical development for the treatment of urinary tract infections: from pathogens to therapies

INTRODUCTION

Urinary tract infections (UTIs) are a prevalent health challenge characterized by the invasion and multiplication of microorganisms in the urinary system. The continuous exploration of novel therapeutic interventions is imperative. Advances in research offer hope for revolutionizing the management of UTIs and improving the overall health outcomes for individuals affected by these infections.

AREAS COVERED

This review aimed to provide an overview of existing treatments for UTIs, highlighting their strengths and limitations. Moreover, we explored and analyzed the latest therapeutic modalities under clinical development. Finally, the review offered a picture into the potential implications of these therapies on the future landscape of UTIs treatment, discussing possible advancements and challenges for further research.

EXPERT OPINION

Comprehensions into the pathogenesis of UTIs have been gleaned from foundational basic science studies, laying the groundwork for the exploration of novel therapeutic interventions. The primary source of evidence originates predominantly from animal studies conducted on murine models. Nevertheless, the lack of clinical trials interferes the acquisition of robust evidence in humans. The challenges presented by the heterogeneity and virulence of uropathogens add an additional layer of complexity, posing an obstacle that scientists and clinicians are actively grappling with in their pursuit of effective solutions.

Cost-Effectiveness of Targeted Prophylaxis among Allogenic Stem Cell Transplant Recipients

Bloodstream infections (BSI) are life-threatening complications for onco-hematologic patients. Fluoroquinolones prophylaxis (FQP) was recommended for patients with neutropenia. Later, it was correlated with increased resistance rates among this population and its role became debated. While the role of FQ prophylaxis is still being studied, its cost-effectiveness is also unknown. The objective of this study was to evaluate the costs and effects associated with two alternative strategies (FQP vs. no prophylaxis) for patients with hematological malignancies undergoing allogenic stem cell transplant (HSCT). A decision-tree model was built integrating retrospectively collected data from a single transplant center, part of a tertiary teaching hospital in Northern Italy. Probabilities, costs and effects were considered in the assessment of the two alternative strategies. Probabilities of colonization, BSIs, extended-spectrum beta lactamase (ESBL) and Klebsiella pneumoniae carbapenemase (KPC) BSIs and mortality associated with infection, as well as median duration of length of stay (LOS) were calculated based on data collected between 2013 and 2021. The center applied the strategy of FQP between 2013 and 2016, and of no prophylaxis between 2016 and 2021. Data on 326 patients were collected during the considered time period. Overall, the rates of colonization, BSI, KPC/ESBL BSI, and mortality were 6.8% (95% confidence interval (CI) 2.7-13.5), 42% (9.9-81.4) and 20.72 (16.67-25.26), respectively. A mean bed-day cost of 132€ was estimated. Considering no prophylaxis vs. prophylaxis, the difference in costs ranged between additional 33.61 and 80.59€ per patient, whereas the difference in effects ranged between 0.11 and 0.03 life-years (LYs) lost (around 40 and 11 days). Given the small differences in terms of costs and effects between the two strategies, no prophylaxis seems an appropriate choice. Furthermore, this analysis did not consider the broader effect on hospital ecology of multiple doses of FQP, which could provide further support for the strategy of no prophylaxis. Our results suggest that the necessity for FQP in onco-hematologic setting should be determined based on local antibiotic resistance patterns.

Polymicrobial interactions in the urinary tract: is the enemy of my enemy my friend?

The vast majority of research pertaining to urinary tract infection has focused on a single pathogen in isolation, and predominantly Escherichia coli. However, polymicrobial urine colonization and infection are prevalent in several patient populations, including individuals with urinary catheters. The progression from asymptomatic colonization to symptomatic infection and severe disease is likely shaped by interactions between traditional pathogens as well as constituents of the normal urinary microbiota. Recent studies have begun to experimentally dissect the contribution of polymicrobial interactions to disease outcomes in the urinary tract, including their role in development of antimicrobial-resistant biofilm communities, modulating the innate immune response, tissue damage, and sepsis. This review aims to summarize the epidemiology of polymicrobial urine colonization, provide an overview of common urinary tract pathogens, and present key microbe-microbe and host-microbe interactions that influence infection progression, persistence, and severity.

Antibiotic resistance in childhood urinary tract infections: A single-center experience

Aim

Urinary tract infections are the most common genitourinary tract disease in children, and inappropriate antibiotic and/or dose selection increase the likelihood of resistance. The aim of this study was to determine the prevalence of urinary tract infection pathogens, patterns of resistance to antibiotics, and empirical treatment options.

Material and Methods

Between January 2013 and December 2017, urine culture and antibiogram results of pediatric patients aged 0 days to 16 years were analyzed retrospectively. Antibiotic susceptibilities were determined using disc diffusion according to methods of the Clinical and Laboratory Standards Institute.

Results

Of the 1326 children with culture growth, 1070 (80.6%) were female and 256 (19.3%) were male. The most common microorganism found was (1138, 85.8%) E. Coli, followed by Klebsiella spp. (71, 5.3%), Enterobacter spp. (44, 3.3%), and Proteus spp. (28, 2.1%). High frequency of resistance to ampicillin, ampicillin-sulbactam, amoxicillin-clavulanate, cefuroxime axetil, as TMP-SMX was detected in all microorganisms, whereas resistance to amikacin, meropenem, imipenem, ertapenem, fosfomycin, and nitrofurantoin was low.

Conclusion

E. coli was the most common causative agent of urinary tract infections in childhood. High resistance to ampicillin, ampicillin-sulbactam, amoxicillin-clavulanate, cefuroxime axetil, and TMP-SMX was detected in all agents in our center.

Fluoroquinolone prophylaxis in haematological cancer patients with neutropenia: ECIL critical appraisal of previous guidelines

OBJECTIVES

Fluoroquinolone (FQ) prophylaxis was recommended in 2005 by European Conference on Infections in Leukemia (ECIL) for patients with prolonged neutropenia. In consideration of a worldwide increase in antibiotic resistance, the issue of FQ prophylaxis during neutropenia was re-evaluated.

METHODS

Literature review of randomised controlled trials (RCT) and observational studies published in years 2006-2014 was performed. Their results were analysed in meta-analysis. Meta-regression model was applied to evaluate whether the rates of FQ resistance in community and hospital settings influenced the efficacy of FQ prophylaxis. The impact of FQ prophylaxis on colonisation and infection with resistant bacteria was reviewed.

RESULTS

Two RCTs and 12 observational studies were identified. FQ prophylaxis did not have effect on mortality (pooled OR 1.01, 95%CI 0.73-1.41), but was associated with lower rate of bloodstream infections (BSI) (pooled OR 0.57, 95%CI 0.43-0.74) and episodes of fever during neutropenia (pooled OR 0.32, 95%CI 0.20-0.50). No effect of the background rate of FQ resistance on the efficacy of FQ prophylaxis was observed. In few studies, FQ prophylaxis resulted in an increased colonisation or infection with FQ- or multi-drug resistant strains.

CONCLUSIONS

The possible benefits of FQ prophylaxis on BSI rate, but not on overall mortality, should be weighed against its impact in terms of toxicity and changes in local ecology in single centres.

Origin and Dissemination of Antimicrobial Resistance among Uropathogenic Escherichia coli

Antimicrobial agents of various types have important bearing on the outcomes of microbial infections. These agents may be bacteriostatic or –cidal, exert their impact via various means, originate from a living organism or a laboratory, and appropriately be used in or on living tissue or not. Though the primary focus of this chapter is on resistance to the antimicrobial agents used to treat uropathogenic Escherichia coli (UPEC)-caused urinary tract infections (UTIs), some attention will be given to UPEC’s resistance to silver-containing antiseptics, which may be incorporated into catheters to prevent foreign body-associated UTIs.

Role of Old Antibiotics in the Era of Antibiotic Resistance. Highlighted Nitrofurantoin for the Treatment of Lower Urinary Tract Infections

Bacterial infections caused by antibiotic-resistant isolates have become a major health problem in recent years, since they are very difficult to treat, leading to an increase in morbidity and mortality. Nitrofurantoin is a broad-spectrum bactericidal antibiotic that, through a complex mode of action which is not completely understood, affects both Gram-negative and Gram-positive bacteria. Nitrofurantoin has been used successfully for a long time for the prophylaxis and treatment of acute lower urinary tract infections in adults, children and pregnant women, but the increased emergence of antibiotic resistance has made nitrofurantoin a suitable candidate for the treatment of infections caused by multidrug-resistant pathogens. Here, we review the mechanism of action, antimicrobial spectrum, pharmacology and safety profile of nitrofurantoin. We also investigate the therapeutic use of nitrofurantoin, including recent data which highlight its role in the management of community urinary tract infection, especially in cases of multidrug-resistant isolates, in which oral active antimicrobials are limited resources nowadays.

Increasing Resistance According to Patient's Age and Sex inEscherichia coliIsolated from Urine in Italy

The prevalence of Escherichia coli among the uropathogens routinely isolated in non-hospital laboratories (Labs) and its susceptibility profiles were investigated. Thirty-three Labs were selected throughout Italy. In vitro assays were performed by means of disk diffusion according to the CLSI. Females were prevalent (79.9%) and the mean patient age was 58.6 (sd 20.4) years. Overall, the prevalence of E. coli was 55.3% (1375 strains), with Enterococcus spp 10.2 %, Proteus mirabilis 4.8%, coagulase-negative staphylococci 4.3% and Klebsiella 3.8% being the next most frequently encountered species. High compliance with quality control program was observed. Susceptibility figures in E. coli were consistently low for many antimicrobial agents such as ampicillin (51.3%) and co-trimoxazole (74.6%) and higher for others such as gentamicin (87.9%) and ceftazidime (95.1%). Resistance rates were higher among male patients and increased according to the patient's age.

Prulifloxacin versus Levofloxacin in the Treatment of Chronic Bacterial Prostatitis: a Prospective, Randomized, Double-Blind Trial

Ninety-six patients with chronic bacterial prostatitis (CBP) and evidence of infection were randomized to receive a 4-week oral course of either prulifloxacin (a new fluoroquinolone) 600 mg or levofloxacin 500 mg once daily. They were evaluated with the Meares-Stamey test and the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) at baseline and one week after therapy completion. Patients with microbiological eradication were evaluated again with the Meares-Stamey test 6 months after therapy completion. The microbiological eradication rate was 72.73% for prulifloxacin and 71.11% for levofloxacin (p=0.86) and the reduction in the NIH-CPSI was 10.75 and 10.73, respectively (p=0.98). Safety was comparable, with 18.18% adverse events for prulifloxacin and 22.22% for levofloxacin (p=0.79). Thus, a 4-week course of prulifloxacin 600 mg once daily is at least as effective and safe as levofloxacin 500 mg once daily in the treatment of CBP.

Can we improve adherence to guidelines for the treatment of lower urinary tract infection? A simple, multifaceted intervention in out-of-hours services

OBJECTIVES

To improve antimicrobial prescribing behaviour of general practitioners in large-scale out-of-hours services for uncomplicated lower urinary tract infection (LUTI) in females aged 20-80 years, which is regarded as one of the most prevalent bacterial infections in primary care.

METHODS

A quasi-experimental design was used in two regional large-scale out-of-hours services. A simple, multifaceted intervention was offered in a 16 week period in one region (the intervention region). During the two washout periods, at 5 and 17 months, we observed diagnoses and prescriptions. The main outcome measure was the share of appropriate and inappropriate prescriptions.

RESULTS

The proportion of patients with LUTI ranged from 1.0% to 2.1%. The relative proportion of appropriate prescriptions in the intervention region increased from 26.9% to 69.4%, but decreased afterwards to 40.8%.

CONCLUSIONS

A simple, multifaceted intervention for treatment of LUTI during out-of-hours care may improve the quality of antimicrobial prescribing, although the improvement may not be sustained in the longer term.

Extended-spectrum β-lactamase-producing Enterobacteriaceae: in vitro susceptibility to fosfomycin, nitrofurantoin and tigecycline

OBJECTIVE

To assess the susceptibility trends of community-acquired extended-spectrum β-Iactamase (ESBL)-producing urinary isolates with particular reference to fosfomycin, nitrofurantoin and tigecycline.

MATERIALS AND METHODS

Seven hospitals across the United Arab Emirates participated in this study from June 2008 to March 2010. The antibiotic sensitivity of ESBL-producing uropathogens to a panel of antibiotics including tigecycline, fosfomycin and nitrofurantoin was assessed. The Hyplex ESBL identification system (h-ES-ID) was used for genotypic identification.

RESULTS

Two hundred and ninety-two ESBL-producing Enterobacteriaceae isolates were identified during the study period. Of these, 182 (62%) were urinary isolates and comprised of Escherichia coli: 149 (81.9%), Klebsiella pneumoniae: 30 (16.5%) and Proteus mirabilis: 3 (1.6%). Of the 182 urinary isolates, 179 (98.3%) were from patients with community onset urinary tract infections. The h-ES-ID system identified 172 (94.5%) of the urinary isolates as CTX-M positive. All isolates were susceptible to imipenem and meropenem. Over half of the isolates showed resistance to gentamicin (98; 53.8%), trimethoprim-sulfamethoxazole (139; 76.4%) and ciprofloxacin (143; 78.6%). Sensitivity to nitrofurantoin and fosfomycin was 90 and 100%, respectively. Two CTX-M-positive K. pneumoniae isolates with tigecycline resistance (MIC >4 µg/ml) were identified.

CONCLUSION

There is dissemination of CTX-M ESBL-producing urinary pathogens into the community. Fosfomycin and nitrofurantoin were active against ESBL-positive uropathogens, and emergence of tigecycline resistance needs close monitoring.

Antimicrobial prophylaxis in women with recurrent urinary tract infections

Recurrent urinary tract infections (UTIs) in women are common, result in considerable morbidity and expense, and can be a management problem for clinicians. Behavioural changes can be useful antimicrobial-sparing measures in the prevention of recurrent UTIs, but antimicrobial prophylaxis may be necessary in those who continue to have recurrences. Continuous prophylaxis, post-coital prophylaxis and intermittent self-treatment with antimicrobials have all been demonstrated to be effective in the prevention of recurrent uncomplicated UTIs. The decision as to which approach to use depends upon the frequency and pattern of recurrences and willingness of the patient to commit to a specific regimen. The risk of adverse events, including antimicrobial resistance, patient's lifestyle and compliance and plans for a pregnancy also need to be considered. The choice of antimicrobial should be based upon the susceptibility pattern of the organisms causing the patient's previous UTIs and history of drug allergies.

Antibiotic treatment of uncomplicated urinary tract infection in premenopausal women

Uncomplicated urinary tract infections (UTIs) in otherwise healthy premenopausal women are one of the most frequent infections in the community. Therefore any improvement in management will have a high impact not only on the quality of life of the individual patient but also on the health system. In placebo-controlled studies antimicrobial treatment was significantly more effective than placebo, but on the other hand showed more adverse events. The choice of antibiotic depends on the spectrum and susceptibility patterns of the uropathogens, its effectiveness for this indication, its tolerability, its collateral effects and cost. After a systematic literature search, recommendations for empiric treatment of acute uncomplicated cystitis and acute uncomplicated pyelonephritis and for follow-up strategies were developed.

Comparison of single-dose and multiple-dose antibiotics for lower urinary tract infection in pregnancy

OBJECTIVE

To compare the efficacy of fosfomycin trometamol, cefuroxime axetil, and amoxicillin clavulanate antibiotics, and to assess the difference in patient compliance, in the treatment of urinary tract infections during pregnancy.

METHODS

Between September 2007 and May 2008, 90 out of 324 pregnant women with complaints of lower urinary tract infection, who were followed at the outpatient clinic or referred to the emergency department of Vakif Gureba Education and Research Hospital, were enrolled in a prospective study. Patients were randomized into 3 equal groups for treatment with single-dose fosfomycin trometamol, or 5-day courses of amoxicillin clavulanate or cefuroxime axetil. After follow-up, study data were obtained for 28, 27, and 29 patients, respectively.

RESULTS

The treatment groups did not differ significantly in terms of demographics, clinical success rate, microbiological cure rate, or adverse effects. Significantly higher drug compliance was observed in the fosfomycin trometamol group than in the other 2 groups (P<0.05).

CONCLUSION

Treatment with a single dose of fosfomycin trometamol was as effective for UTI as the standard course of treatment with amoxicillin clavulanate or cefuroxime axetil. Fosfomycin trometamol may be a preferable treatment for UTI because of its simpler use and better rates of compliance.

[Etiology and sensitivity of uropathogens identified in uncomplicated lower urinary tract infections in women (ARESC Study): implications on empiric therapy]

BACKGROUND AND OBJECTIVE

To determine the etiology and susceptibility of uropathogens identified in women with uncomplicated lower urinary tract infections (UTI).

PATIENTS AND METHODS

In a multicenter study (ARESC) in 9 Spanish hospitals, 803 female patients with uncomplicated cystitis were consecutively enrolled and evaluated to identify the uropathogens and their susceptibility to 9 antimicrobials.

RESULTS

Of 803 patients with uncomplicated cystitis, 784 patients were included. A positive urine culture was found in 87.7% of the samples. Of the 650 pathogens isolated, Escherichia coli (E. coli) was the most frequent (79.2%) followed by Staphylococcus saprophyticus (4.4%), Proteus mirabilis (4.3%), Enterococcus faecalis (3.2%) and Klebsiella pneumoniae (2.3%). E. coli showed a high rate of susceptibility to phosphomycin (97.2%), nitrofurantoin (94.1%) and somewhat lower to ciprofloxacin (88.1%). Fluorquinolone resistance rates were higher among postmenopausal women (17 versus 10%). E. coli was highly resistant to ampicillin (65%) and cotrimoxazole (34%) and 25% of the strains were resistant to amoxicillin/clavulanalic acid and cefuroxime.

CONCLUSIONS

In Spain, E. coli shows high resistance rates to widely used antimicrobial antibiotics. Phosphomycin and nitrofurantoin have a high in vitro activity. Taking into account practical aspects such as convenience (only one dose), and the influence of the amount of fluorquinolone use on enterobacteriaceae and other microorganisms resistance levels, phosphomycin trometamol represents the option of first choice for the empirical treatment of uncomplicated cystitis in women.

[Antimicrobial and clinical efficacy of nitrofurantoin in the treatment of acute lower urinary tract infections in adults]

BACKGROUND AND PURPOSE

In the light of increasing resistance to antibiotics used for the treatment of acute urinary tract infections, nitrofurantoin currently experiences a renaissance. Nitrofurantoin shows good efficacy against most bacteria expected in urinary tract infection, and the development of resistance is low. A study on the antimicrobial and clinical efficacy of nitrofurantoin in the treatment of acute lower urinary tract infections was conducted in Mexico City, an area where resistance rates of uropathogens to trimethoprim/sulfamethoxazole (cotrimoxazole) are high.

PATIENTS AND METHODS

In this open-label, single-arm study 20 adult patients (18 females, 2 males) with positive urine culture were treated orally with nitrofurantoin sustained release 100 mg twice daily for 7 days. Urinary nitrofurantoin concentrations were determined at baseline and day 4 of the study. Primary endpoint was the antimicrobial efficacy of nitrofurantoin at 12 to 16 days after baseline, assessed by changes in urine culture results.

RESULTS

In the patient population treated per protocol, primary endpoint analysis revealed a microbial eradication rate of 92.3%. At 35 to 42 days, the eradication rate was 83.3%. At these times, all patients in the per protocol population were free of symptoms. In patients with complicating factors, e.g. diabetic polyneuropathy, both antimicrobial and clinical efficacy appeared to be reduced. Urinary nitrofurantoin concentrations were mostly above minimum inhibitory concentrations of the isolated uropathogens. The study drug was generally well tolerated. Most frequent drug-related adverse event was mild headache, occurring in 10.8% of patients. Two patients discontinued the study due to rash.

CONCLUSION

The results of the present study indicate good antimicrobial and clinical efficacy of nitrofurantoin in the treatment of acute uncomplicated urinary tract infections as well as acceptable tolerability in adults.

14-day prulifloxacin treatment of acute uncomplicated cystitis in women with recurrent urinary tract infections: a prospective, open-label, pilot trial with 6-month follow-up

Recurrent urinary tract infections (UTI) are very common in otherwise healthy young women, and can have a very negative social and economic impact. In order to evaluate the tolerability and efficacy of a 14-day course of prulifloxacin orally administered once daily, 51 young female patients, attending the same STD center between may and June 2007 for symptoms of cystitis, with a history of recurrent UTI and urine culture positive for uropathogens, were enrolled in this prospective study. Microbiological and clinical efficacy was tested over three follow-up visits at 1, 3 and 6 months. Quality of life (QoL) was measured and the impact of prulifloxacin in modifying the Lactobacillus vaginal flora was also evaluated. At baseline, the pathogens most commonly isolated were Enterococcus faecalis (43.2%) and Escherichia coli (27.5%). 41 of the 51 women, (80.3%) had Lactobacillus spp. in vaginal samples at baseline. microbiological results at follow-up examinations were as follows: after 1 month, 47 patients were recurrence-free and 4 had recurrence; after 3 months, 41 were recurrence-free, while 6 reported recurrence; finally, after 6 months, 36 were recurrence-free and 5 had recurrence. A statistically significant difference was reported between the QoL questionnaire mean scores at baseline (0.63), 1 (0.77), 3 (0.77) and 6 months (0.78) after treatment (all p<0.001). the vaginal swab cultures demonstrated that Lactobacillus spp. flora was maintained in 38 out of the 41 (92.6%) patients who had positive vaginal swab sample at baseline. in conclusion, a 14-day administration of prulifloxacin 600 mg is a safe, well tolerated and effective treatment for the management of UTI in young women.

The ARESC study: an international survey on the antimicrobial resistance of pathogens involved in uncomplicated urinary tract infections

The ARESC (Antimicrobial Resistance Epidemiological Survey on Cystitis) study is an international survey to investigate the prevalence and susceptibility of pathogens causing cystitis. Female patients (n=4264) aged 18-65 years with symptoms of uncomplicated cystitis were consecutively enrolled in nine European countries as well as Brazil during 2003-2006. Pathogens were identified and their susceptibility to nine antimicrobials was determined. Escherichia coli accounted for 76.7% of isolates. Among E. coli, 10.3% of the isolates were resistant to at last three different classes of antimicrobial agents. Resistance was most common to ampicillin (48.3%), trimethoprim/sulfamethoxazole (29.4%) and nalidixic acid (18.6%). Fosfomycin, mecillinam and nitrofurantoin were the most active drugs (98.1%, 95.8% and 95.2% susceptible strains, respectively) followed by ciprofloxacin, amoxicillin/clavulanic acid and cefuroxime (91.7%, 82.5% and 82.4%, respectively). Resistance to ciprofloxacin was >10% in Brazil, Spain, Italy and Russia. Overall, Proteus mirabilis were more susceptible to beta-lactams and less susceptible to non-beta-lactams than E. coli, whereas Klebsiella pneumoniae strains, which are intrinsically resistant to ampicillin, were less susceptible to mecillinam (88.8%), fosfomycin (87.9%), cefuroxime (78.6%) and nitrofurantoin (17.7%). Resistance was rare in Staphylococcus saprophyticus, with the exception of ampicillin (36.4%) and trimethoprim/sulfamethoxazole (10.2%). In Italy, Spain, Brazil and Russia, the countries most affected by antimicrobial resistance, extended-spectrum beta-lactamase (ESBL) enzymes (mainly CTX-M type) were detected in 48 strains (39 E. coli, 6 K. pneumoniae and 3 P. mirabilis). Despite wide intercountry variability in bacterial susceptibility rates to the other antimicrobials tested, fosfomycin and mecillinam have preserved their in vitro activity in all countries investigated against the most common uropathogens.

Antimicrobial resistance among uropathogens responsible for community-acquired urinary tract infections in an Italian community

This study aimed to establish the pattern of the antimicrobial resistance among the leading uropathogens causing community-acquired UTIs in an area of the region of Apulia, Southern Italy. Twenty-one thousand and two hundred outpatients, 6,893 males and 14,307 females, were enrolled. Urinary isolates were identified by conventional methods and the susceptibility to 18 antimicrobials determined. Recognized uropathogens Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were isolated from 3175 positive samples, E. coli accounting for 68.04% of positive cultures. Most overall resistance was to ampicillin, while the resistance rate to cephalothin was higher than that of third generation cephalosporins. Although to a different degree, all the bacteria had an overall good susceptibility rate to quinolones as well as to fosfomycin but increased resistance to sulfamethoxazole/trimethoprim. Our results confirm that E. coli is the leading uropathogen and provide information about the antimicrobial susceptibility patterns of the main pathogens causing community-acquired UTIs. These findings should be taken into account to help maintain the safety and efficacy of treatment for community-acquired UTIs.

European emergence of ciprofloxacin-resistant Escherichia coli clonal groups O25:H4-ST 131 and O15:K52:H1 causing community-acquired uncomplicated cystitis

A total of 148 E. coli strains displaying reduced susceptibility to ciprofloxacin (MIC > or = 2 microg/ml) and causing uncomplicated urinary tract infections in eight European countries during 2003 to 2006 were studied. Their phylogenetic groups, biochemical profiles, and antibiotic susceptibilities were determined. Determination of the O:H serotype, pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA (RAPD) PCR, and multilocus sequence typing provided additional discrimination. The majority (82.4%) of the microorganisms (122/148) carried resistance to two or more additional drugs, with the pattern ciprofloxacin-trimethoprim-sufamethoxazole-tetracycline-ampicillin being the most represented (73 strains out of 148; 49.3%). Extended-spectrum beta-lactamase production was detected in 12/148 strains (8.1%), with CTX-M-15 being the most-common enzyme. Six strains out of the whole collection studied (4.0%) contained a qnrB-like gene. Overall, 55 different PFGE or RAPD PCR profiles could be distinguished, indicating a substantial heterogeneity. However, about one-third (51/148) of the strains belonged to two clonal groups: O15:K52:H1 (phylogenetic group B2, lactose-nonfermenting variant, ciprofloxacin MIC of 16 microg/ml) and O25:H4 sequence type 131 (ST-131) (phylogenetic group D, ciprofloxacin MIC of > or = 32 microg/ml). With the exception of Poland, strains of these two groups were isolated in samples from all participating countries but more frequently in samples from Spain and Italy. In some representative strains of the two main clonal groups, alterations in GyrA and ParC were the basic mechanism of fluoroquinolone resistance. In some members of the O25:H4 ST-131 group, displaying a ciprofloxacin MIC of > 32 microg/ml, additional OmpF loss or pump efflux overexpression was found. In the Mediterranean area, strains belonging to these two clonal groups played a major role in determining the high rate of fluoroquinolone-resistant E. coli strains observed in the community.

Surveillance study in Europe and Brazil on clinical aspects and Antimicrobial Resistance Epidemiology in Females with Cystitis (ARESC): implications for empiric therapy

BACKGROUND

Uncomplicated cystitis in females is among the most frequent infections in community.

OBJECTIVE

To determine clinical aspects, epidemiology, and antimicrobial susceptibility of uropathogens.

INTERVENTION

Patients were investigated clinically and with urinalysis and urine culture.

MEASUREMENTS

This survey started in 2003 and ended in 2006 including 68 centres in nine European countries and in Brazil. Female patients between 18 and 65 yr with symptoms of uncomplicated cystitis were consecutively enrolled and clinically evaluated. Uropathogens were identified and their susceptibility tested for nine antimicrobials.

RESULTS AND LIMITATIONS

Clinical data of 4264 eligible patients were analysed. A positive urine culture was found in 74.6%. Within the 3018 pathogens, Escherichia coli (E. coli) was most frequent (76.7%), followed by Enterococcus faecalis (4.0%), Staphylococcus saprophyticus (3.6%), Klebsiella pneumoniae (3.5%), and Proteus mirabilis (3.5%). E. coli showed the highest rate of susceptibility to fosfomycin (98.1%) followed by mecillinam (95.8%), nitrofurantoin (95.2%), and ciprofloxacin (91.8%). The lowest rate was found for ampicillin (45.1%). For the total spectrum the order was fosfomycin (96.4%), mecillinam (95.9%), ciprofloxacin (90.3%), and nitrofurantoin (87.0%). In all countries a susceptibility rate to E. coli above 90% was found only for fosfomycin, mecillinam, and nitrofurantoin. The susceptibility rates varied significantly from country to country (p<0.0001), except for fosfomycin, mecillinam, and nitrofurantoin.

CONCLUSIONS

Despite wide cross-country variability of bacterial susceptibility/resistance rates to the other antimicrobials tested, fosfomycin, mecillinam, and nitrofurantoin have preserved their in vitro activity in all countries investigated. They may represent good options for the empiric therapy of female patients with uncomplicated cystitis.

Risk factors for community-acquired urinary tract infection due to quinolone-resistant E. coli

BACKGROUND

Resistance to fluoroquinolone drugs is emerging among E. coli causing community acquired urinary tract infections (COMA-UTI).

OBJECTIVES

To evaluate demographic and clinical risk factors associated with COMA-UTI due to quinolone-resistant E. coli (QREc).

METHODS

In this case-control study, clinical and demographic data from 300 COMA-UTI due to E. coli (including 150 QREc) were analyzed.

RESULTS

By univariate analysis QREc was associated to males, older patients, nursing home residents, functionally dependent, dementia, diabetes, cardiovascular diseases, immunosupression, nephrolithiasis, recurrent UTI, invasive procedures, hospitalization, and antibiotic use within previous 6 months. By multivariate analysis, use of ciprofloxacin (OR 20.6 [CI 2.3-179.2], p=0.006) or ofloxacin (OR 7.5 [CI 2.9-19.4], p<0.0001), previous invasive procedure (OR 6.6 [CI 3.0-14.7], p<0.0001), recurrent UTI (OR 4.7 [CI 2.3-9.3], p<0.0001), and previous hospitalization (OR 2.9 [CI 1.4-6], p=0.003) were identified as independent risk factors for COMA-UTI due to QREc.

CONCLUSION

In patients with one or more of the risk factors identified here, the empiric use of quinolones should be reconsidered.

Extraintestinal pathogenic Escherichia coli

Extraintestinal pathogenic Escherichia coli (ExPEC) possesses virulence traits that allow it to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgical site infections, as well as infections in other extraintestinal locations. ExPEC-induced diseases represent a large burden in terms of medical costs and productivity losses. In addition to human illnesses, ExPEC strains also cause extraintestinal infections in domestic animals and pets. A commonality of virulence factors has been demonstrated between human and animal ExPEC, suggesting that the organisms are zoonotic pathogens. ExPEC strains have been isolated from food products, in particular from raw meats and poultry, indicating that these organisms potentially represent a new class of foodborne pathogens. This review discusses various aspects of ExPEC, including its presence in food products, in animals used for food or as companion pets; the diseases ExPEC can cause; and the virulence factors and virulence mechanisms that cause disease.

[Uncomplicated urinary tract infections, what about fosfomycin and nitrofurantoin in 2006?]

Since 2000 to 2005 we assessed the prevalence of antimicrobial resistance among uropathogens causing acute uncomplicated urinary tract infections (UTI). A total of 19 618 bacteria were studied, fosfomycin, fluoroquinolones, nitrofurantoin were in vitro the most potent drugs with more than 80% of susceptibility. If we compare year 2000 to 2005 we observed a significant decrease of susceptibility for fluoroquinolones. For the same point of comparison, fosfomycin and nitrofurantoin showed a favourable evolution. Rationale and prudent use of antibiotics must now moved us to prescribe parsimoniously fluoroquinolones especially for some indications such as uncomplicated UTI though there are some others "old antibiotics" with a role may be underestimated for this specific indication.

Pharmacokinetic and pharmacodynamic aspects of antimicrobial agents for the treatment of uncomplicated urinary tract infections

Uncomplicated urinary tract infections (UTI) are treated with beta-lactams, co-trimoxazole, quinolones and fosfomycin tromethamine. Due to increasing resistance of causative pathogens, antibiotics should be used by considering their pharmacodynamic and pharmacokinetic characteristics. beta-lactams have time-dependent activity and should not be used once-daily. Co-trimoxazole should be restricted due to increasing chemoresistance. Fluoroquinolones play a primary role in the treatment of serious and complicated infections. Fosfomycin tromethamine is active against most urinary tract pathogens. In vitro time-kill kinetics of fosfomycin against Escherichia coli and Proteus mirabilis showed primarily concentration-dependent activity, with a prolonged post-antibiotic effect (3.4 to 4.7h). Based on these results a single 3g dose of fosfomycin guarantees optimal efficacy against common uropathogens with an AUC(urine)/MIC ratio of 500.

Antibiotic prophylaxis in neutropenic patients

New evidence shows that antibiotic prophylaxis in neutropenic patients reduces mortality, febrile episodes, and bacterial infections. For patients with acute leukemia or those who undergo bone marrow transplantation, prophylaxis with fluoroquinolones diminished the risk of death from any cause by 33% (95% confidence interval [95% CI], 2-54%). Thus, 55 patients who have acute leukemia or who undergo bone marrow transplantation must receive prophylaxis to prevent 1 death. In 4 studies that included patients with solid tumors or lymphoma, prophylaxis reduced the rate of death during the first month (relative risk, 0.51; 95% CI, 0.27-0.97), and 82 patients had to receive prophylaxis to prevent 1 death. The main argument brought against prophylaxis is the induction of resistance. Patients who received prophylaxis did not experience more infections caused by resistant strains than patients in the control group. The recent GIMEMA study was conducted in a population with a nearly 50% resistance to fluoroquinolones in all pathogens and 20% resistance in gram-negative isolates, thus indicating that prophylaxis should be offered in settings with similar or less resistance. Prophylaxis with fluoroquinolones was efficacious in reducing infections caused by gram-positive bacteria. Patients who are treated for acute leukemia should be offered prophylaxis with ciprofloxacin or levofloxacin. Prophylaxis to cover the expected period of neutropenia may be considered for the first cycle of treatment in patients with solid tumors or lymphoma who regularly receive regimens that cause severe neutropenia. Excessive local levels of resistance to fluoroquinolones or high local incidence of infections caused by Clostridium difficile and related to fluoroquinolones should prompt a reconsideration of this policy.