Unitary Tract Infection Treatment: When to Use What Agents including Beta-lactam Combination Agents

In this study, the authors review antibiotic treatment options for both acute uncomplicated and complicated urinary tract infection (UTI). In addition, they also review regimens used in the setting of drug-resistant pathogens including vancomycin resistant Enterococcus, extended spectrum beta-lactamase (ESBL) producing Enterobacterals, carbapenem-resistant Enterobacterals and carbapenem-resistant Pseudomonas, which are encountered with increasing frequency.

Antibiotics efficacy in clinical and microbiological cure of uncomplicated urinary tract infection: a systematic review and network meta-analysis

PURPOSE

Fosfomycin has been used more frequently in managing uncomplicated urinary tract infections (UTIs) due to decreased compliance and increased multidrug-resistant bacteria. The aim of this network meta-analysis was to assess the efficacy of Fosfomycin compared to Nitrofurantoin, Trimethoprim-Sulfamethoxazole (TMP-SMX), and Ciprofloxacin in terms of clinical and microbiological cure alongside with other measurements.

MATERIALS AND METHODS

We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL). We included randomized control trials (RCTs) with uncomplicated UTI patients who received Fosfomycin, Nitrofurantoin, TMP-SMX, or Ciprofloxacin and reported the clinical or microbiological cure. We used Cochrane Risk of Bias Assessment Tool to assess the included studies' quality. R-software was used for all statistical analysis. We ranked all antibiotics using the netrank function which yielded P scores. Frequentist network meta-analysis was used to assess the efficacy of all outcomes.

RESULTS

We included 13 RCTs with a total number of 3856 patients that showed Fosfomycin ranked the highest among the other antibiotics with respect to clinical cure (P-score = 0.99) and microbiological cure (P-score = 0.99) while Ciprofloxacin ranked the lowest (P-score = 0.11 and 0.02, respectively). Moreover, Ciprofloxacin yielded the highest relapse rate (P-score = 1), whereas TMP-SMX had the lowest relapse rate (P-score = 0.07). As for the adverse events, Ciprofloxacin demonstrated the highest adverse events as opposed to Fosfomycin (P-score = 0.98 and 0.05, respectively).

CONCLUSION

The network meta-analysis demonstrated that Fosfomycin is the most effective antibiotic in treating uncomplicated UTIs with respect to clinical cure, microbiological cure, and adverse events profile.

Nitrofurantoin: what is the evidence for current UK guidance?

Three days of nitrofurantoin at 100 mg twice daily is recommended as first-line treatment for uncomplicated urinary tract infection (UTI) in evidence-based guidelines across the UK. A review of international guidelines shows that the evidence base has been interpreted in very different ways. UK guidelines are unusual in promoting short (3 day) courses, and we find little direct evidence to support this. Although 'short' courses of antibiotics for other agents may provide optimum balance between providing effective treatment whilst reducing selective pressure driving resistance amongst colonizing microbial flora, it remains unclear that course lengths can be extrapolated to nitrofurantoin. Three days of nitrofurantoin may indeed be a useful intervention in a large group of patients. However, without supporting evidence and because clinical response should be expected to vary widely, it is unclear that establishing and promoting an antibiotic duration for UTI is the best approach to optimizing prescribing in this important area.

Antibiotic Myths for the Infectious Diseases Clinician

Antimicrobials are commonly prescribed and often misunderstood. With more than 50% of hospitalized patients receiving an antimicrobial agent at any point in time, judicious and optimal use of these drugs is paramount to advancing patient care. This narrative will focus on myths relevant to nuanced consultation from infectious diseases specialists, particularly surrounding specific considerations for a variety of antibiotics.

Why D-Mannose May Be as Efficient as Antibiotics in the Treatment of Acute Uncomplicated Lower Urinary Tract Infections—Preliminary Considerations and Conclusions from a Non-Interventional Study

Urinary tract infections (UTIs) are very frequent in women and can be caused by a range of pathogens. High recurrence rates and increasing antibiotic resistance of uropathogens make UTIs a severe public health problem. d-mannose is a monosaccharide that can inhibit bacterial adhesion to the urothelium after oral intake. Several clinical studies have shown the efficacy of d-mannose in the prevention of recurrent UTIs; these also provided limited evidence for the efficacy of d-mannose in acute therapy. A recent prospective, non-interventional study in female patients with acute cystitis reported good success rates for treatment with d-mannose. Here, we present data from a post hoc analysis of this study to compare the cure rate of d-mannose monotherapy with that of antibiotics. The results show that d-mannose is a promising alternative to antibiotics in the treatment of acute uncomplicated UTIs in women.

OUP accepted manuscript

Background

Uncomplicated urinary tract infections (UTIs) are amongst the most frequent infections presenting in the outpatient setting. A growing number of clinical trials are assessing the most effective treatment interventions for uncomplicated UTI. Due to the heterogeneity of the outcomes reported in these trials, however, comparing these outcomes is challenging.

Objectives

Identify the core outcomes that have been reported in trials and systematic reviews of interventions treating uncomplicated UTI in adults.

Methods

We conducted a systematic search for core outcomes used to evaluate treatments of UTIs. We searched the Cochrane Database of Systematic Reviews, PubMed and Embase. One researcher independently screened each article for inclusion, and the Core Outcome Set for treatment of Urinary Tract Infections (COSUTI) team acted as second reviewers. All included articles were screened by two reviewers. All outcomes were extracted verbatim, and similar outcomes were grouped into domains and subdomains.

Results

In total, 334 outcomes were reported across 41 papers, the average number of outcomes reported being 8. Outcomes were categorized across 18 domains, the majority of which were related to clinical cure outcomes. Many outcomes varied in the timepoints within which the outcome was measured and reported.

Conclusions

Comparing the outcomes of trials investigating uncomplicated UTI treatment remains challenging due to the difference in outcomes currently reported. Consistency of reporting of outcomes would be improved by developing a minimum number of consistent outcomes that should be reported in all trials.

The Five Ds of Outpatient Antibiotic Stewardship for Urinary Tract Infections

Urinary tract infections (UTI) are one of the most common indications for antibiotic prescriptions in the outpatient setting. Given rising rates of antibiotic resistance among uropathogens, antibiotic stewardship is critically needed to improve outpatient antibiotic use, including in outpatient clinics (primary care and specialty clinics) and emergency departments. Outpatient clinics are in general a neglected practice area in antibiotic stewardship programs, yet most antibiotic use in the United States is in the outpatient setting. This article provides a comprehensive review of antibiotic stewardship strategies for outpatient UTI in the adult population, with a focus on the "five Ds" of stewardship for UTI, including right diagnosis, right drug, right dose, right duration, and de-escalation. Stewardship interventions that have shown success for improving prescribing for outpatient UTI are discussed, including diagnostic stewardship strategies, such as reflex urine cultures, computerized decision support systems, and modified reporting of urine culture results. Among the many challenges to achieving stewardship for UTI in the outpatient setting, some of the most important are diagnostic uncertainty, increasing antibiotic resistance, limitations of guidelines, and time constraints of stewardship personnel and front-line providers. This article presents a stewardship framework, built on current evidence and expert opinion, that clinicians can use to guide their own outpatient management of UTI.

A global perspective on improving patient care in uncomplicated urinary tract infection: Expert consensus and practical guidance

BACKGROUND

Uncomplicated urinary tract infections (uUTIs) are a common problem in women. Management is mainly based on empirical prescribing, but there are concerns about overtreatment and antimicrobial resistance (AMR), especially in patients with recurrent uUTIs.

METHODS

A multidisciplinary panel of experts met to discuss diagnosis, treatment, prevention, guidelines, AMR, clinical trial design, and the impact of COVID-19 on clinical practice.

RESULTS

Symptoms remain the cornerstone of uUTI diagnosis, and urine culture is necessary only when empirical treatment fails, or rapid recurrence of symptoms or AMR is suspected. Specific antimicrobials are first-line therapy (typically nitrofurantoin, fosfomycin, trimethoprim-sulfamethoxazole, and pivmecillinam; dependent on availability and local resistance data). Fluoroquinolones are not first-line options for uUTIs due primarily to safety concerns, but also rising resistance rates. High-quality data to support most non-antimicrobial approaches are lacking. Local AMR data specific to community-acquired uUTIs are needed, but representative information is difficult to obtain; instead, identification of risk factors for AMR can provide a basis to guide empirical antimicrobial prescribing. The COVID-19 pandemic has impacted management of uUTIs in some countries and may have long-lasting implications for future models of care.

CONCLUSIONS

The management of uUTIs in women can be improved without increasing complexity, including simplified diagnosis, and empirical antimicrobial prescribing based on patient characteristics, including review of recent antimicrobial use and past pathogen resistance profiles, drug availability, and guidelines. Current data for non-antimicrobial approaches are limited. The influence of COVID-19 on telehealth could provide an opportunity to enhance patient care in the long term.

First Detection of Klebsiella pneumoniae Isolate Co-Harboring Fosfomycin Resistance Gene fosA3 and blactx-m Among Gram Negative Urine Isolates in a Turkish Hospital

The most common gram-negative pathogens in urinary tract infections are Escherichia coli and Klebsiella pneumoniae. Therapy that is often empirical relies on local antibiotic resistance data, hence monitorization of antimicrobial resistance periodically in each hospital is a requirement. In this study, antibiotic susceptibility profiles of consecutive urinary isolates (E. coli [n = 235] and K. pneumoniae [n = 56]) of adult patients collected between February 2018 and February 2019 from inpatients in Hacettepe University Hospital were assessed. Isolates resistant to fosfomycin (minimum inhibitory concentration >32 mg/L) were further investigated for the presence of fosA, fosA3, and fosC2. Fosfomycin susceptibility was determined by agar dilution method. Broth microdilution method was performed for amikacin, gentamicin, ceftazidime, ceftriaxone, meropenem, ciprofloxacin, tigecycline, trimethoprim/sulfamethoxazole (TMP/SMX), colistin, and piperacillin/tazobactam (PIP/TAZ). PCR method was employed to investigate fosA, fosA3, fosC2, and bla_CTX-M. Existence of fosA3 gene was confirmed by sequencing. Resistance rates to amikacin, gentamicin, ceftazidime, ceftriaxone, meropenem, ciprofloxacin, tigecycline, TMP/SMX, colistin, and PIP/TAZ were 2.7%, 18.5%, 25.4%, 33.0%, 3.4%, 45.4%, 2.4%, 43.6%, 6.2%, and 23.7%, respectively. Sixteen isolates (5.5%) were resistant to fosfomycin. Resistance was most frequently observed in K. pneumoniae (n = 9). fosA3 gene was detected in one fosfomycin-resistant K. pneumoniae isolate. This isolate also carried bla_CTX-M. fosC2 and fosA genes could not be detected in any of the isolates. In this study, we report for the first time the existence of fosA3 in Turkey and its association with the bla_CTX-M gene. As a result of increasing bla_CTX-M producing Enterobacterales isolates globally, increase in fosfomycin resistance may be expected in near future.

Oral fosfomycin for treating lower urinary tract infections due to multidrug-resistant Escherichia coli in female adolescents

Fosfomycin trometamol (FT) has shown promising in vitro activity against multidrug-resistant (MDR) uropathogens; however, clinical data are limited in pediatric patients. We conducted a retrospective study to describe the clinical and microbiological outcomes of uncomplicated lower urinary tract infections (LUTIs) due to MDR Escherichia coli treated with oral FT in female adolescents. A total of 70 outpatients, with a median age of 13 years (range 12-16 years), were included. FT was initiated as definitive treatment of UTIs in all patients due to documented resistance against alternative oral agents. All patients received a single dose of 3 g oral FT. The post-treatment clinical and microbiological cure rates were 97% (68/70) and 94% (66/70), respectively. Only two (3%) patients reported mild, self-limited diarrhea. UTI relapse occurred in two (3%) patients. Our results suggest that oral FT might be an alternative option for outpatient treatment of uncomplicated LUTIs due to MDR E. coli in female adolescents.

Evaluation of efficacy and safety of fosfomycin versus nitrofurantoin for the treatment of uncomplicated lower urinary tract infection (UTI) in women - A systematic review and meta-analysis

Urinary tract infections (UTI) are among the most frequent medical conditions requiring outpatient treatment. Single dose oral fosfomycin (300 mg) and the older nitrofurantoin (100 mg for 5 days) have been found to be more effective than other first-line drugs in multiple studies. This systematic review and meta-analysis were carried out with the objective of evaluating their comparative efficacy and safety in the management of uncomplicated UTI. Two authors independently searched PubMed, Cochrane Central, Embase, and Google Scholar till Nov 2020 using MeSH terms and free text. Randomized controlled trials (RCTs) comparing both drugs for efficacy and safety in uncomplicated UTI in adult women were included. The primary outcome measures were microbiological and clinical cure rates. The search resulted in n = 663 studies out of which only four studies (three for treatment of uncomplicated UTI in women and one for asymptomatic bacteriuria in pregnancy) satisfied the selection criteria. No significant differences in clinical, (RR 0.95, 95% CI - 0.81, 1.12) and microbiological cure, (RR 0.96, 95% CI - 0.84, 1.08) were found within 4 weeks of treatment. The incidence of adverse events was found to be more in fosfomycin relative to the nitrofurantoin group (RR 1.05, 95% CI - 0.59, 1.87). Hence, single-dose fosfomycin presents a potentially useful and safe treatment option for the treatment of uncomplicated UTI in women and asymptomatic bacteriuria in pregnancy.

Zidovudine in synergistic combination with fosfomycin: an in vitro and in vivo evaluation against multidrug-resistant Enterobacterales

Multidrug-resistant (MDR) Enterobacterales are a priority health issue with few treatment options. Recently, fosfomycin has been reconsidered for MDR bacterial infections. Zidovudine, licensed for the treatment of human immunodeficiency virus (HIV), has unexploited antibacterial properties and has been considered for drug repurposing. The aim of this study was to assess the effect of the combination of fosfomycin plus zidovudine against clinical MDR Enterobacterales isolates. Minimum inhibitory concentration (MIC) determination and checkerboard assays for 36 MDR Enterobacterales strains were performed. In addition, fosfomycin-resistant strains were evaluated using time-kill assay and in an in vivo Galleria mellonella infection model. Zidovudine and fosfomycin MICs ranged between 0.06 to >64 mg/L and 0.125 to >512 mg/L, respectively. A synergistic effect [fractional inhibitory concentration index (FICI) ≤0.5] was observed in 25 isolates and no antagonistic effect was observed in the remaining isolates. For 7 of 8 fosfomycin-resistant strains (MIC > 32 mg/L), zidovudine combination was able to restore fosfomycin susceptibility. These results were confirmed by time-kill assays. Fosfomycin + zidovudine presented greater larval survival (20-50%) than monotherapy. Synergistic activity was observed for fosfomycin + zidovudine in 69.4% of the tested strains. In vivo experiments confirmed the enhanced effectiveness of the combination. The zidovudine concentrations tested here can be reached in human serum using the actual licensed dosage, therefore this combination deserves further clinical investigation.

Antimicrobial Susceptibility Patterns of Escherichia coli among Tunisian Outpatients with Community-Acquired Urinary Tract Infection (2012-2018)

Introduction

Community-acquired urinary tract infection is one of the most common reasons for consultation in everyday practice; it represents a major source of antibiotic consumption. Escherichia coli (E. coli) is the main pathogen incriminated.

Objective

The aim of this study was to evaluate antimicrobial susceptibility patterns of community-acquired uropathogenic E coli throughout a 7-year period.

Methodology

All strains of E. coli isolated from urine samples between January 1st 2012 and December 31st 2018 were included. Presence of ≥ 10³ CFU/ml in urine culture media was considered as significant for urinary tract infection. The identification of E. coli strains was realized using standard laboratory techniques. Antibiotic susceptibility testing was performed using the disk diffusion method according to the CA-SFM/ EUCAST criteria.

Results

A total of 1,335 E. coli strains were isolated. Overall susceptibility rates to antimicrobial agents were as follows: ampicillin 39.1%, amoxicillin-clavulanic acid 64.9%, cefotaxime 94.9%, trimethoprim/sulfamethox-azole 67.6%, ciprofloxacin 89.2%, ofloxacin 86.9%, amikacin 98.6%, gentamicin 93.9%, nitrofurantoin 97.6% and fosfomycin 99.3%. All isolates were susceptible to carbapenems. The frequency of extended spectrum beta-lactamases-producing E. coli strains was 4.7%. Susceptibility rates of E. coli for ampicillin, trimethoprim/sulfamethoxazole and amikacin remained relatively stable over the study period, whereas susceptibility to amoxicillin-clavulanic acid, cefotaxime and fluoroquinolones showed a 2-phase pattern. As for gentamicin, a continuous decrease in susceptibility rates was observed.

Conclusion

Antimicrobial susceptibility profiles of uropathogenic E. coli are constantly changing, due to modifications in the antibiogram interpretation criteria and antibiotic prescription habits. Rigorous surveillance of resistance rate is necessary to determine appropriate empirical treatment and limit the spread of multiresistant strains.

Multidrug-resistant organisms in urinary tract infections in children

The global spread of multidrug-resistant organisms has led to an increase in urinary tract infections (UTIs) in children that are difficult to treat. This review explores the current literature regarding multidrug-resistant UTIs in childhood and proposes an approach to management. Multidrug-resistant organisms include a wide range of potential urinary tract pathogens and, while most literature on drug resistance in UTIs during childhood has focused on extended-spectrum beta-lactamase producing organisms, in this review, we have included a discussion of multidrug resistance including and beyond beta-lactamase production. We provide definitions for multidrug-resistant organisms in line with current consensus guidelines and summarise clinically relevant mechanisms of resistance. Additionally, in this review, we outline the global epidemiology of multidrug-resistant UTIs in children, summarising published prevalence rates, which range from 5 to 90% in different settings. Finally, we also critically review the evidence on risk factors for colonisation and infection of the urinary tract with multidrug-resistant organisms, including prior antibiotic use, hospitalisation and underlying urological malformations. We also highlight multidrug-resistant UTI occurring in children without any identifiable risk factors, reflecting an increasing prevalence of colonisation with these organisms in the general community. Taken as a whole, this emphasises a need for careful and evidence-based use of antibiotics when treating UTIs in children and, to aide clinicians, we have outlined here potential management strategies for when infection with a multidrug-resistant organism is suspected or confirmed.

A Critical Review of Cephalexin and Cefadroxil for the Treatment of Acute Uncomplicated Lower Urinary Tract Infection in the Era of "Bad Bugs, Few Drugs"

First-generation oral cephalosporins (cephalexin and cefadroxil) have traditionally been considered second-line treatment options for uncomplicated lower urinary tract infections (uLUTIs).  However, in the current age of "bad bugs, few drugs", where there are increasingly limited oral options against resistant Enterobacteriaceae, there is an urgent need to rethink how best to utilize the available antibiotic armamentarium.  This review examines the historical clinical trials and experimental studies of cephalexin and cefadroxil, particularly through the modern lens of pharmacokinetics/pharmacodynamics (PK/PD), to better appreciate the efficacy of these drugs in uLUTIs.  Furthermore, newer cefazolin-cephalexin surrogate testing, as recommended by the Clinical and Laboratory Standards Institute (CLSI) and the United States Committee on Antimicrobial Susceptibility Testing (USCAST), has recategorized cephalexin in many instances from resistant to susceptible.  We conclude that cephalexin and cefadroxil have very good early bacteriological and clinical cures in uLUTIs due to non-extended-spectrum beta-lactamase-producing (ESBL) Enterobacteriaceae comparable to many traditionally first-line agents.  Cephalexin can be conveniently administered as 500 mg twice or thrice daily, similar to cefadroxil (500 mg twice daily); therefore, either agent may be used as a fluoroquinolone-sparing alternative. Cephalexin may be the more practical choice for many clinicians because reliable antimicrobial susceptibility test interpretative criteria (STIC) are provided by CLSI, USCAST, and the European Committee on Antimicrobial Susceptibility Testing (EUCAST), whereas direct cefadroxil STIC is offered only by EUCAST.

New strategies and structural considerations in development of therapeutics for carbapenem-resistant Enterobacteriaceae

Antimicrobial resistance poses a significant threat to our ability to treat infections. Especially concerning is the emergence of carbapenem-resistant Enterobacteriaceae (CRE). In the new 2019 United States Centers for Disease Control and Prevention Antibiotic Resistance Report, CRE remain in the most urgent antimicrobial resistance threat category. There is good reason for this concerning designation. In particular, the combination of several resistance elements in CRE can make these pathogens untreatable or effectively untreatable with our current armamentarium of anti-infective agents. This article reviews recently approved agents with activity against CRE and a range of modalities in the pipeline, from early academic investigation to those in clinical trials, with a focus on structural aspects of new antibiotics. Another article in this series addresses the need to incentive pharmaceutical companies to invest in CRE antimicrobial development and to encourage hospitals to make these agents available in their formularies. This article will also consider the need for change in requirements for antimicrobial susceptibility testing implementation in clinical laboratories to address practical roadblocks that impede our efforts to provide even existing CRE antibiotics to our patients.

Potential of fosfomycin in treating multidrug-resistant infections in children

In an era of increasing antimicrobial resistance, there are limited treatment options available to treat multidrug-resistant organisms in paediatric patients. Fosfomycin is an antibiotic defined as 'critically important' by The World Health Organization due to its potential efficacy against multidrug-resistant bacteria and is increasingly cited in the international literature as a promising antimicrobial for combating sepsis in an era of increasing antimicrobial resistance. With broad-spectrum cover that includes both Gram-positive and Gram-negative organisms and both parenteral and oral formulations available, fosfomycin provides a promising treatment option for paediatric patients. This review summarises fosfomycin's spectrum of activity, published efficacy in paediatric patients, safety considerations and pharmacokinetic data, as well as identifying current clinical trials delineating pharmacokinetic parameters and safety parameters in neonatal sepsis which will provide further information regarding the use of fosfomycin in neonatal and paediatric infections. Limitations regarding the current standards for fosfomycin susceptibility definitions, variations in dosing regimens and the potential mechanisms for resistance are also discussed.

Comparison of single-dose fosfomycin tromethamine and other antibiotics for lower uncomplicated urinary tract infection in women and asymptomatic bacteriuria in pregnant women: A systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis investigated the efficacy and safety of single-dose fosfomycin tromethamine (FT) versus other antibiotic agents in women suffering from lower uncomplicated urinary tract infection (uUTI) and pregnant women with uUTI or asymptomatic bacteriuria (ASB).

METHODS

MEDLINE, EMBASE and the Cochrane library were searched to identify relevant literature. Twenty-one studies were identified. Nine of the 21 studies enrolled 21 22 patients and were used to compare the clinical resolution of uUTI between non-pregnant and pregnant women. Given that uUTI and ASB are assessed using similar microbiological evaluation methods, all 3103 patients in the identified 21 studies were pooled to determine microbiological resolution between uUTI or ASB patients. Safety outcomes of the treatments were analysed in 15 studies.

RESULTS

The results showed that single-dose FT was comparable with other antibiotic agents in clinical resolution of uUTI (OR 0.89; 95% CI 0.71-1.10; P = 0.41) in non-pregnant (P = 0.32) and pregnant women (P = 0.64). Moreover, single-dose FT was equal to other antibiotics in microbiological resolution, and there was no difference in overall microbiological resolution (OR 1.11; 95% CI 0.92-1.34; P = 0.29) among non-pregnant women with uUTI (P = 0.48), pregnant women with uUTI (P = 0.81) and pregnant women with ASB (P = 0.30). There were no serious fosfomycin-related adverse events and most frequent adverse events were mainly gastrointestinal.

CONCLUSION

This meta-analysis suggests that single-dose fosfomycin tromethamine produces equivalent clinical outcomes to comparator antibiotics in terms of clinical efficacy and microbiological efficacy. It is therefore clinically effective and safe for women with uUTI and pregnant women with uUTI or ASB, and has higher patient compliance.

Office-based approach to urinary tract infections in 50 000 patients: results from the REWIND study

OBJECTIVES

The REWIND study sought to describe the real-world clinical and prescribing practices for the management of urinary tract infection (UTI) in Italy, Belgium, Russia and Brazil in order to compare current practices with international, European and national guidelines.

METHODS

An integrated mixed-methods approach was adopted that used information from primary care electronic medical records in longitudinal patient databases available in Italy and Belgium, and surveys of physicians in Russia (general practitioners) and Brazil (gynaecologists).

RESULTS

In total, 49 548 female patients were included in the study. Antibiotics were the most common management option for UTI in Italy (71.1%, n=27 600), Belgium (92.4%, n=7703), Russia (81.9%, n=1231) and Brazil (82.4%, n=740). Fosfomycin trometamol was the first-choice antibiotic for the treatment of UTI in all countries. Ciprofloxacin was also commonly prescribed in Italy (24.6%, n=6796), Belgium (17.8%, n=1373), Russia (14.9%, n=184) and Brazil (9.6%, n=71), while prescription of nitrofurantoin was common in Belgium (24.5%, n=1890) alone.

CONCLUSIONS

Despite differences in study designs and data sources, fosfomycin trometamol was found to be the most commonly prescribed treatment for UTI in all participating countries. In Belgium, real-world prescribing practices for UTI adhered more closely to European guidelines than national guidelines. Although not recommended in international and European guidelines for lower UTI management, the use of fluoroquinolones was still widespread.

X-ray crystallographic structure of BshB, the zinc-dependent deacetylase involved in bacillithiol biosynthesis

Many gram-positive bacteria produce bacillithiol to aid in the maintenance of redox homeostasis and degradation of toxic compounds, including the antibiotic fosfomycin. Bacillithiol is produced via a three-enzyme pathway that includes the action of the zinc-dependent deacetylase BshB. Previous studies identified conserved aspartate and histidine residues within the active site that are involved in metal binding and catalysis, but the enzymatic mechanism is not fully understood. Here we report two X-ray crystallographic structures of BshB from Bacillus subtilis that provide insight into the BshB catalytic mechanism.

Characterization of the genomically encoded fosfomycin resistance enzyme from Mycobacterium abscessus

Mycobacterium abscessus belongs to a group of rapidly growing mycobacteria (RGM) and accounts for approximately 65-80% of lung disease caused by RGM. It is highly pathogenic and is considered the prominent Mycobacterium involved in pulmonary infection in patients with cystic fibrosis and chronic pulmonary disease (CPD). FosM is a putative 134 amino acid fosfomycin resistance enzyme from M. abscessus subsp. bolletii that shares approximately 30-55% sequence identity with other vicinal oxygen chelate (VOC) fosfomycin resistance enzymes and represents the first of its type found in any Mycobacterium species. Genes encoding VOC fosfomycin resistance enzymes have been found in both Gram-positive and Gram-negative pathogens. Given that FosA enzymes from Gram-negative bacteria have evolved optimum activity towards glutathione (GSH) and FosB enzymes from Gram-positive bacteria have evolved optimum activity towards bacillithiol (BSH), it was originally suggested that FosM might represent a fourth class of enzyme that has evolved to utilize mycothiol (MSH). However, a sequence similarity network (SSN) analysis identifies FosM as a member of the FosX subfamily, indicating that it may utilize water as a substrate. Here we have synthesized MSH and characterized FosM with respect to divalent metal ion activation and nucleophile selectivity. Our results indicate that FosM is a Mn2+-dependent FosX-type hydrase with no selectivity toward MSH or other thiols as analyzed by NMR and mass spectroscopy.

The etiology and management of recurrent urinary tract infections in postmenopausal women

Urinary tract infections (UTIs) are one of the most common infections and affect up to 50% of women in their lifetime, with almost half of these women experiencing a recurrence in 6-12 months. Menopause predisposes women to recurrent UTI (rUTI), as normally lower levels of estrogen lead to changes in the urogenital epithelium and subsequently urogenital microbiome. The recently discovered urobiome is now known to have different compositions in both healthy and unhealthy bladders, including a role in the pathophysiology of rUTI, and may be a therapeutic target for prevention and treatment options for rUTI. In postmenopausal women with frequent UTI, the diagnosis of acute UTI should be made using a combination of the symptom assessment and urine diagnostic studies. The choice of UTI antibiotic should include consideration of efficacy, collateral effects, and side-effects. Some women may be candidates for self-start therapy, in which the patient accurately recognizes her UTI symptoms and then starts previously prescribed antibiotics. A large component of the management of women with rUTI is prevention. Urobiome research for bladder health and disease is a young field of investigation with significant potential to improve care for postmenopausal women affected by rUTI through novel, evidence-based prevention and treatment strategies.

The IOU Consensus Recommendations for Empirical Therapy of Cystitis in Nursing Home Residents

OBJECTIVE

To establish consensus recommendations for empirical treatment of uncomplicated cystitis with anti-infectives in noncatheterized older nursing home residents to be implemented in the Improving Outcomes of UTI Management in Long-Term Care Project (IOU) funded by the Agency for Healthcare Research and Quality.

DESIGN

Two-round modified Delphi survey.

PARTICIPANTS

Expert panel of 19 clinical pharmacists.

MEASUREMENTS

Comprehensive literature search and development/review/edit of draft survey by the investigative group (one geriatric clinical pharmacist, two geriatric medicine physicians, and one infectious disease physician). The expert panel members rated their agreement with each of 31 recommendations for drugs of choice, dosing medications at various levels of renal function, drug-drug interactions to avoid, and duration of therapy by sex on a 5-point Likert scale (1 = strongly disagree to 5 = strongly agree). Consensus agreement was defined as a lower 95% confidence limit of 4.0 or higher for the recommendation-specific mean score.

RESULTS

The response rate was 95% for the first round, and three recommendations achieved consensus (dosing for nitrofurantoin and trimethoprim/sulfamethoxazole in those without chronic kidney disease, and drug-drug interaction between trimethoprim/sulfamethoxazole and warfarin). In the second round, 90% responded and reached consensus on an additional eight recommendations (two for nitrofurantoin or trimethoprim/sulfamethoxazole as initial drugs of choice, three for dosing ciprofloxacin, nitrofurantoin, and trimethoprim/sulfamethoxazole at various levels of chronic kidney disease, and three drug-drug interactions to avoid: trimethoprim/sulfamethoxazole with phenytoin and ciprofloxacin with theophylline or with tizanidine).

CONCLUSION

An expert panel of clinical pharmacists was able to reach consensus on a set of recommendations for the empirical treatment of cystitis with oral anti-infective medications in older nursing home residents. The recommendations were incorporated into a treatment algorithm for uncomplicated cystitis in noncatheterized nursing home residents and used in educational materials for health professionals in an ongoing controlled intervention study. J Am Geriatr Soc 67:539-545, 2019.

Nitrofurantoin and fosfomycin for resistant urinary tract infections: old drugs for emerging problems

Uncomplicated urinary tract infection is one of the most common indications for antibiotic use in the community However the Gram-negative organisms that can cause the infection are becoming more resistant to antibiotics

Many multidrug resistant organisms retain susceptibility to two old antibiotics nitrofurantoin and fosfomycin Advantages over newer drugs include their high urinary concentrations and minimal toxicity

Fosfomycin is a potential treatment option for patients with uncomplicated urinary tract infection due to resistant organisms Nitrofurantoin may be more effective and can be used for urinary infections in pregnant women

Resistance to fosfomycin: Mechanisms, Frequency and Clinical Consequences

Fosfomycin has been used for the treatment of infections due to susceptible and multidrug-resistant (MDR) bacteria. It inhibits bacterial cell wall synthesis through a unique mechanism of action at a step prior to that inhibited by β-lactams. Fosfomycin enters the bacterium through membrane channels/transporters and inhibits MurA, which initiates peptidoglycan (PG) biosynthesis of the bacterial cell wall. Several bacteria display inherent resistance to fosfomycin mainly through MurA mutations. Acquired resistance involves, in order of decreasing frequency, modifications of membrane transporters that prevent fosfomycin from entering the bacterial cell, acquisition of plasmid-encoded genes that inactivate fosfomycin, and MurA mutations. Fosfomycin resistance develops readily in vitro but less so in vivo. Mutation frequency is higher among Pseudomonas aeruginosa and Klebsiella spp. compared with Escherichia coli and is associated with fosfomycin concentration. Mutations in cAMP regulators, fosfomycin transporters and MurA seem to be associated with higher biological cost in Enterobacteriaceae but not in Pseudomonas spp. The contribution of fosfomycin inactivating enzymes in emergence and spread of fosfomycin resistance currently seems low-to-moderate, but their presence in transferable plasmids may potentially provide the best means for the spread of fosfomycin resistance in the future. Their co-existence with genes conferring resistance to other antibiotic classes may increase the emergence of MDR strains. Although susceptibility rates vary, rates seem to increase in settings with higher fosfomycin use and among multidrug-resistant pathogens.

Phase I Study To Evaluate the Pharmacokinetics, Safety, and Tolerability of Two Dosing Regimens of Oral Fosfomycin Tromethamine in Healthy Adult Participants

The pharmacokinetics (PK), safety, and tolerability of two repeated dosing regimens of oral fosfomycin tromethamine were evaluated in 18 healthy adult subjects. Subjects received 3 g every other day (QOD) for 3 doses and then every day (QD) for 7 doses, or vice versa, in a phase I, randomized, open-label, two-period-crossover study. Serial blood (n = 11) and urine (n = 4 collection intervals) samples were collected before and up to 24 h after dosing on days 1 and 5, along with predose concentrations on days 3 and 7. PK parameters were similar between days 1 and 5 within and between dosing regimens. The mean (± standard deviation [SD]) PK parameters for fosfomycin in plasma on day 5 during the respective QOD and QD dosing regimens were as follows: maximum concentration of drug in serum (C_max) = 24.4 ± 6.2 versus 23.8 ± 5.6 μg/ml, time to C_max (T_max) = 2.2 ± 0.7 versus 2.0 ± 0.4 h, apparent volume of distribution (V/F) = 141 ± 67.9 versus 147 ± 67.6 liters, apparent clearance (CL/F) = 21.4 ± 8.0 versus 20.4 ± 5.3 liters/h, renal clearance (CL_R) = 7.5 ± 4.1 versus 7.3 ± 3.5 liters/h, area under the concentration-time curve from 0 to 24 h (AUC_0-24) = 151.6 ± 35.6 versus 156.6 ± 42.5 μg · h/ml, and elimination half-life (t_1/2) = 4.5 ± 1.1 versus 5.0 ± 1.7 h. Urine concentrations peaked at approximately 600 μg/ml through the 0- to 8-h urine collection intervals but displayed significant interindividual variability. Roughly 35 to 40% of the 3-g dose was excreted in the urine by 24 h postdose. No new safety concerns were identified during this study. The proportion of diarrhea-free days during the study was significantly lower with the QD regimen than with the QOD regimen (61% versus 77%; P < 0.0001). Further studies to establish the clinical benefit/risk ratio for repeated dosing regimens of oral fosfomycin tromethamine are warranted. (This trial is registered at ClinicalTrials.gov under registration no. NCT02570074.).

Factors associated with the duration of symptoms in adult women with suspected cystitis in primary care

Objective

The aim of this study was to identify factors associated to the duration of symptoms of cystitis.

Patients and methods

We conducted a nested survival study using Druti study data. Druti was a cross-sectional survey conducted in adult women visiting a general practitioner in France, for a suspected urinary tract infection between January 2012 and February 2013. For this study, urine cultures were systematically performed for all women. The evolution of symptoms were monitored daily for two weeks. This nested study considered only women with suspected cystitis from Druti; women with pyelonephritis were excluded. To identify independent predictors for duration of symptoms, a Cox proportional hazards regression model was performed.

Results

In Druti, 449 patients had a suspected cystitis. Among them, 440 had a follow up at two weeks. Out of the 440 patients, 424 had a prescription of antibiotic treatment (96.4%). The urine culture was positive for 326 patients (74.1%). The median duration of symptoms after consultation was two days (interquartile 1–3). The absence of urinary frequency (median two days versus three days, p = 0.008), age over 55 years (median two days versus three days, p<0.001) and patient’s bet about the presence of a urinary tract infection (median two days, p = 0.021) were associated to a longer duration of symptoms. Positive culture (p = 0.99) and presence of a multi-drug resistant organism (p = 0.38) did not influence the duration of symptoms.

Conclusion

In a real-life study, factors influencing the duration of symptoms are clinical factors. The delay before re-evaluation in case of persistent symptoms after treatment could be adapted according to the initial clinical examination.

Antimicrobial resistance and treatment: an unmet clinical safety need

INTRODUCTION

Infections due to multidrug-resistant (MDR) bacteria are burdened by high mortality rates. The development of new compounds to face the global threat of resistance is urgently needed. Combination regimens including "old" high-dose antimicrobials are currently limited by the risk of toxicity, resistance selection, and reduced efficacy. Following the Infectious Diseases Society of America call to develop 10 new antibacterials by 2020, new molecules are currently under development or have become available for use in clinical practice.

AREAS COVERED

We have reviewed safety characteristics and tolerability of old antimicrobials that are currently employed in combination regimens as well as new antimicrobials, including beta-lactams/beta-lactamase inhibitors, new cephalosporins, quinolones, and aminoglycosides.

EXPERT OPINION

The availability of new compounds that show in vitro efficacy against MDR represents a unique opportunity to face the threat of resistance and to optimize the current use of antimicrobials, potentially reducing toxicity. Agents that are potentially active against MDR Gram-negatives are ceftozolane/tazobactam, new carbapenems and cephalosporins, the combination of avibactam with ceftazidime, and plazomicin. Further data from clinical trials and post-marketing studies for drugs targeting MDR pathogens are crucial to confirm their efficacy and safety.

Febrile urinary-tract infection due to extended-spectrum beta-lactamase-producing Enterobacteriaceae in children: A French prospective multicenter study

Objectives

To assess the management of febrile urinary-tract infection (FUTIs) due to extended-spectrum β-lactamase–producing Enterobacteriaceae (ESBL-E) in children, the Pediatric Infectious Diseases Group of the French Pediatric Society set up an active surveillance network in pediatric centers across France in 2014.

Materials and methods

We prospectively analysed data from 2014 to 2016 for all children < 18 years old who received antibiotic treatment for FUTI due to ESBL-E in 24 pediatric centers. Baseline demographic, clinical features, microbiological data and antimicrobials prescribed were collected.

Results

301 children were enrolled in this study. The median age was 1 year (IQR 0.02–17.9) and 44.5% were male. These infections occurred in children with history of UTIs (27.3%) and urinary malformations (32.6%). Recent antibiotic use was the main associated factor for FUTIs due to ESBL-E, followed by a previous hospitalization and travel history. Before drug susceptibility testing (DST), third-generation cephalosporins (3GC) PO/IV were the most-prescribed antibiotics (75.5%). Only 13% and 24% of children received amikacine alone for empirical or definitive therapy, respectively, whereas 88.7% of children had isolates susceptible to amikacin. In all, 23.2% of children received carbapenems in empirical and/or definitive therapy. Cotrimoxazole (24.5%), ciprofloxacin (15.6%) and non-orthodox clavulanate–cefixime combination (31.3%) were the most frequently prescribed oral options after obtaining the DST. The time to apyrexia and length of hospital stay did not differ with or without effective empirical therapy.

Conclusions

We believe that amikacin should increasingly take on a key role in the choice of definitive therapy of FUTI due to ESBL-E in children by avoiding the use of carbapenems.

Clinical Practice Guidelines for the Antibiotic Treatment of Community-Acquired Urinary Tract Infections

Urinary tract infections (UTIs) are infectious diseases that commonly occur in communities. Although several international guidelines for the management of UTIs have been available, clinical characteristics, etiology and antimicrobial susceptibility patterns may differ from country to country. This work represents an update of the 2011 Korean guideline for UTIs. The current guideline was developed by the update and adaptation method. This clinical practice guideline provides recommendations for the diagnosis and management of UTIs, including asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, complicated pyelonephritis related to urinary tract obstruction, and acute bacterial prostatitis. This guideline targets community-acquired UTIs occurring among adult patients. Healthcare-associated UTIs, catheter-associated UTIs, and infections in immunocompromised patients were not included in this guideline.

Uncomplicated Bacterial Community-Acquired Urinary Tract Infection in Adults

BACKGROUND

Uncomplicated bacterial community-acquired urinary tract infection is among the more common infections in outpatient practice. The resistance level of pathogens has risen markedly. This S3 guideline contains recommendations based on current evidence for the rational use of anti - microbial agents and for the prevention of inappropriate use of certain classes of antibiotics and thus of the resulting drug resistance. The prevention of recurrent urinary tract infection is considered in this guideline for the first time.

METHODS

The guideline was updated under the aegis of the German Urological Society (Deutsche Gesellschaft für Urologie). A systematic literature search (period: 2008-2015) concerning the diagnosis, treatment, and prevention of uncomplicated urinary tract infections was carried out in the Cochrane Library, MEDLINE, and Embase databases. Randomized, controlled trials and systemic reviews were included. Relevant guidelines were identified in a guideline synopsis.

RESULTS

Symptom-oriented diagnostic evaluation is highly valued. For the treatment of cystitis, fosfomycin-trometamol, nitrofurantoin, nitroxolin, pivmecillinam and trimethoprim are all equally recommended. Fluorquinolones and cephalosporins are not recommended. Uncomplicated pyelonephritis with a mild to moderate clinical course ought to be treated with oral cefpodoxime, ceftibuten, ciprofloxacin, or levofloxacin. For acute, uncomplicated cystitis, with mild to moderate symptoms, symptomatic treatment alone may be considered instead of antibiotics after discussion of the options with the patient. Mainly non-antibiotic measures are recommended for prophylaxis against recurrent urinary tract infection.

CONCLUSION

Physicians who treat uncomplicated urinary tract infections should familiarize themselves with the newly revised guideline's recommendations on the selection and dosage of antibiotic treatment so that they can responsibly evaluate and plan antibiotic treatment for their affected patients.

Fosfomycin Susceptibility in Multidrug-Resistant Enterobacteriaceae Species and Vancomycin-Resistant Enterococci Urinary Isolates

Background

Broad-spectrum antibiotics are often used to treat urinary tract infections (UTIs) due to drug-resistant species of Enterobacteriaceae and Enterococcus (e.g., organisms producing extended-spectrum β-lactamase [ESBL] or AmpC β-lactamase, as well as vancomycin-resistant enterococci [VRE]). However, this type of therapy can promote selection of resistant organisms and may necessitate venous access. Fosfomycin is an orally administered, single-dose antibiotic for the treatment of uncomplicated UTI. Little is known about its microbiologic activity against urinary isolates, including in southwestern Ontario, since fosfomycin susceptibility testing is not routinely performed.

Objective

To explore a cost-effective alternative for the treatment of lower UTIs caused by multidrug-resistant Enterobacteriaceae and VRE organisms resistant to usual first-line therapies by determining fosfomycin susceptibility rates.

Methods

Urinary isolates were collected prospectively from November 2015 to April 2016 at 3 hospitals in southwestern Ontario. Susceptibility testing was completed according to guidelines of the Clinical and Laboratory Standards Institute, with interpretation by zone of inhibition (as diameter in millimetres). Patients 18 years of age or older with isolation of multidrug-resistant Enterobacteriaceae or VRE were eligible for inclusion. Urinary isolates from these patients were subjected to susceptibility testing. The primary outcome was the rate of fosfomycin susceptibility of these isolates.

Results

A total of 137 urinary isolates were tested: 106 positive for ESBL-or AmpC β-lactamase-producing Enterobacteriaceae (95 Escherichia coli, 11 Klebsiella spp.) and 31 positive for vancomycin-resistant Enterococcus faecium. Susceptibility rates for ESBL- and AmpC β-lactamase-producing E. coli were 100% for ertapenem, 96% for fosfomycin, 83% for nitrofurantoin, 72% for gentamicin, 56% for trimethoprim-sulfamethoxazole, and 14% for ciprofloxacin. Susceptibility rates of vancomycin-resistant E. faecium urinary isolates were 100% for linezolid, 81% for fosfomycin, 68% for tetracycline, 6% for ampicillin, 3% for penicillin, and 0% for both nitrofurantoin and ciprofloxacin.

Conclusion

Given susceptibility rates at the study institutions, fosfomycin was deemed the most reliable oral option for the treatment of lower UTI in patients with suspected or documented multidrug-resistant uropathogens.

Prevalence of antimicrobial resistant Escherichia coli from patients with suspected urinary tract infection in primary care, Denmark

BACKGROUND

Escherichia coli is the most common pathogen causing Urinary Tract Infections (UTI). Data from the current National Surveillance program in Denmark (DANMAP) may not accurately represent the prevalence of resistant E. coli in primary care, because only urine samples from complicated cases may be forwarded to the microbiological departments at hospitals for diagnostic examination. The aim of this study was to assess the prevalence of resistant E. coli to the most commonly used antimicrobial agents in primary care in a consecutive sample of patients from general practice.

METHODS

Observational study carried out from December 2014 to December 2015. Thirty-nine general practices from The Capital Region of Denmark included adult patients with urinary tract symptoms and suspected UTI. All urine samples were sent to the central laboratory Statens Serum Institut (SSI). Significant bacteriuria was interpreted according to the European Urinalysis Standards. Susceptibility testing was performed and interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) standards.

RESULTS

From the 39 general practices 505 patients were recruited. Completed data were obtained from 485 (96%) patients. According to the European Urinalysis Standards, 261 (54%) patients had positive bacteriuria. The most common uropathogen in patients with uncomplicated (uUTI) and complicated (cUTI) urinary tract infection was E. coli 105 (69%) and 76 (70%), respectively. Eighty-two (45%) of 181 E. coli isolates were resistant to at least one of the tested antibiotics and 50 out of 82 isolates were resistant to two or more antimicrobial agents. The highest resistance-rate was found against ampicillin 34% (95% CI 24;42) in uUTI and 36% (24;46) in cUTI. There were no differences in the distribution of resistance between uncomplicated and complicated cases. The prevalence of resistance was similar to the one reported in DANMAP 2014.

CONCLUSION

In E. coli from uUTI there is high resistance rates to antimicrobial agents commonly used in primary care. There was no difference in the distribution of resistant E. coli in suspected uUTI vs cUTI. In Denmark, data from the National Surveillance program DANMAP can guide the decision for choice of antibiotic in patients with suspected UTI seeking care in primary care.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02249273 .

An update on new antibiotic prophylaxis and treatment for urinary tract infections in children

INTRODUCTION

This review focuses on the treatment of urinary tract infections (UTI) in children and in particular its recent changes. Areas covered: Acute pyelonephritis, acute cystitis and asymptomatic bacteriuria or asymptomatic infections have to be clearly distinguished. Prompt treatment is required in pyelonephritis and cystitis, but not in asymptomatic bacteriuria or infection, in order to avoid selection of more virulent strains. This concept should be considered even in immunocompromised or bedridden children. In case of pyelonephritis, there should be no delay in beginning the antibiotic treatment in order to decrease the risk of long term complication, such as renal scars. Predisposing conditions for UTI, such as voiding anomalies and urinary tract malformation should be carefully evaluated. Expert opinion: One major concern is the increasing resistance to 3^rd generation cephalosporins. Therefore overconsumption in low-risk settings should be absolutely avoided. The prevalence of infections with E. coli producing extended spectrum ß-lactamase (ESBL) is increasing and pediatricians should be aware about the specific treatment options. Any recommendation about (initial) antibiotic treatment should be regularly updated and adapted to local resistance profiles and to economic factors in different health systems.

High interindividual variability in urinary fosfomycin concentrations in healthy female volunteers

OBJECTIVES

Fosfomycin is increasingly being prescribed for treatment of uncomplicated urinary tract infections in an era of emerging drug resistance. Surprisingly, little is known of the urinary concentrations of fosfomycin and its interindividual variation after the standard single 3-g oral dose. We aimed to gain more insight into urinary fosfomycin pharmacokinetics to evaluate its effectiveness.

METHODS

Three grams of fosfomycin trometamol was administered to 40 healthy female volunteers with an estimated mean glomerular filtration rate of >90 mL/min/1.73m². Urine samples were collected from every urination during 48 hours, and then twice daily for up to 7 days. Time, volume, and pH were recorded. Concentrations were quantified with UPLC-MS/MS. Effectiveness was evaluated based on urinary concentrations and the target MIC of E. coli, the most common uropathogen.

RESULTS

A high interindividual variability was found. Peak concentration was 1982.0 ± 1257.4 mg/L, urinary half-life 12.4 ± 5.7 hours, and excretion rate over 48 hours 29.9 ± 7.1 mg/h. Recovery was 44.5 ± 12.6% after 48 hours and 47.0 ± 10.4% after 7 days. Concentrations remained above the EUCAST breakpoint of 32 mg/L in 100% of the volunteers over the first 24 hours, 67.5% for 48 hours, and 30% for 72 hours. A high urinary output was associated with low urinary concentrations and consequently reduced time > MIC, AUC_0-7days/MIC, and C_max/MIC values.

CONCLUSIONS

Considerable interindividual variability observed in the pharmacokinetics of fosfomycin signifies a risk for inadequate drug exposure in a significant proportion of the population. The current dosing regimen should therefore be reevaluated.

Pharmacokinetics, Safety, and Tolerability of Single-Dose Intravenous (ZTI-01) and Oral Fosfomycin in Healthy Volunteers

The pharmacokinetics, safety, and tolerability of intravenous (i.v.) fosfomycin disodium (ZTI-01) and oral fosfomycin tromethamine were evaluated after a single dose in 28 healthy adult subjects. Subjects received a single 1-h i.v. infusion of 1 g and 8 g fosfomycin disodium and a single dose of 3 g oral fosfomycin tromethamine in a phase I, randomized, open-label, three-period crossover study. Serial blood and urine samples were collected before and up to 48 h after dosing. The mean pharmacokinetic parameters ± standard deviations of fosfomycin in plasma after 1 g and 8 g i.v., respectively, were the following: maximum clearance of drug in serum (C_max), 44.3 ± 7.6 and 370 ± 61.9 μg/ml; time to maximum concentration of drug in serum (T_max), 1.1 ± 0.05 and 1.08 ± 0.01 h; volume of distribution (V), 29.7 ± 5.7 and 31.5 ± 10.4 liters; clearance (CL), 8.7 ± 1.7 and 7.8 ± 1.4 liters/h; renal clearance (CL_R), 6.6 ± 1.9 and 6.3 ± 1.6 liters/h; area under the concentration-time curve from 0 to infinity (AUC_0-∞), 120 ± 28.5 and 1,060 ± 192 μg·h/ml; and half-life (t_1/2), 2.4 ± 0.4 and 2.8 ± 0.6 h. After oral administration, the parameters were the following: C_max, 26.8 ± 6.4 μg/ml; T_max, 2.25 ± 0.4 h; V/F, 204 ± 70.7 liters; CL/F, 17 ± 4.7 liters/h; CL_R, 6.5 ± 1.8 liters/h; AUC_0-∞, 191 ± 57.6 μg · h/ml; and t_1/2, 9.04 ± 4.5 h. The percent relative bioavailability of orally administered fosfomycin was 52.8% in relation to the 1-g i.v. dose. Approximately 74% and 80% of the 1-g and 8-g i.v. doses were excreted unchanged in the urine by 48 h compared to 37% after oral administration, with the majority of this excretion occurring by 12 h regardless of dosage form. No new safety concerns were identified during this study. The results of this study support further investigation of i.v. fosfomycin in the target patient population, including patients with complicated urinary tract infections and pyelonephritis.

Long-term outcomes of inappropriate antibiotic therapy for upper urinary tract infections caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a retrospective cohort study

BACKGROUND

To evaluate the short- and long-term outcomes of different antimicrobial treatment options for upper urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae.

METHODS

We retrospectively analyzed patients with a first episode of febrile UTI and positive urine culture with ESBL-producing E. coli or K. pneumoniae during 2012-2015. We compared outcomes among patients who received: (1) definitive treatment with a carbapenem (CP), (2) a microbiologically appropriate intravenous non-carbapenem agent (NCA), (3) a non-appropriate antimicrobial (NAA), and (4) an intravenous NAA followed by an oral NCA (NAA-PO).

RESULTS

The majority of patients received empirical therapy with NAA (165/178, 93%), and definitive treatment with NCA (n=43), NAA (n=50), and NAA-PO (n=59). The NCA group had significantly higher SIRS score than the NAA-PO group (2.18 versus 1.76, P=0.018), but no differences were found between the NCA and NAA groups (2.18 and 1.92, P=0.15). Clinical cure at discharge from the index hospitalization was high (97-100%) in all 3 groups. The NCA group had longer length of stay as compared with the NAA-PO and NAA groups (8.7days versus 5.39 and 5.24days, P<0.0001) and a lower rate of early (48-72h) improvement (79% versus 96-100%, P=0.0002). Among re-admitted patients, re-admission with ESBL-related bloodstream infection was significantly higher in the NAA group as compared to the NAA-PO and NCA groups (33% versus 4% and 0%, respectively, P=0.02). Death rate within 60days was also higher in the NAA and NCA groups as compared with the NAA-PO group (P=0.048).

CONCLUSIONS

Inappropriate antimicrobial therapy for febrile non-bacteremic UTI with ESBL-producing enterobacteriaceae is associated with favorable short-term outcomes, but also with a long-term risk of relapsed bacteremic UTI. Definitive treatment with appropriate carbapenem-sparing antimicrobial agents effectively prevents late relapses.

Diagnosis, Treatment, and Prevention of Urinary Tract Infection

UTI may involve the lower or upper urinary tract and may be uncomplicated or complicated. The emphasis of this chapter is uncomplicated UTI. The diagnosis of uncomplicated cystitis (bladder infection) and pyelonephritis (kidney infection) is usually easily made based on the clinical presentation, whereas the diagnosis in patients with complicated UTI is often more complex. Thus uncomplicated cystitis is usually manifested by dysuria, frequency and/or urgency without fever, and pyelonephritis is usually manifested by fever and back pain/costovertebral angle tenderness. However, pyuria is usually present with UTI, regardless of location, and its absence suggests that another condition may be causing the patient's symptoms. Treatment of cystitis is usually straightforward with one of several effective short-course antimicrobial regimens, although antimicrobial resistance continues to increase and can complicate treatment choices in certain areas. Likewise, antimicrobial resistance has complicated our management of uncomplicated pyelonephritis since resistance of uropathogens to the fluoroquinolone class, the mainstay of oral treatment for pyelonephritis, is increasing worldwide, and some of the other agents used for cystitis are not recommended for pyelonephritis due to low tissue levels. The goal of prevention of recurrent cystitis is to minimize the use of antimicrobials and there are several research efforts in progress to develop effective and safe antimicrobial-sparing preventive approaches for this common condition.

Cost-Effectiveness Analysis of Fosfomycin for Treatment of Uncomplicated Urinary Tract Infections in Ontario

Background and Objective. Bacterial resistance to antibiotics traditionally used to treat uncomplicated urinary tract infections (uUTIs) is rising in Canada. We compared the cost-per-patient in Ontario of including fosfomycin (an antibiotic with a low resistance profile) as an option for first-line empirical treatment of uUTIs with current cost of treatment with sulfonamides, fluoroquinolones, and nitrofurantoin. Methods. A decision-tree model was used to perform a cost-minimization analysis. All possible outcomes of a uUTI caused by bacterial species treated with either sulfonamides, fluoroquinolones, nitrofurantoin, or fosfomycin were included. Results. In the base case analysis, the cost-per-patient for treating uUTI with fosfomycin was $105.12. This is similar to the cost-per-patient for each of the other currently reimbursed antibiotics (e.g., $96.19 for sulfonamides, $98.85 for fluoroquinolones, and $99.09 for nitrofurantoins). The weighted average cost-per-patient for treating uUTI was not substantially elevated with the inclusion of fosfomycin in the treatment landscape ($98.41 versus $98.29 with and without fosfomycin, resp.). The sensitivity analyses revealed that most (88.34%) of the potential variation in cost was associated with the probability of progressing to pyelonephritis and hospitalization for pyelonephritis. Conclusion. Fosfomycin in addition to being a safe and effective agent to treat uUTI has a low resistance profile, offers a single-dose treatment administration, and is similar in cost to other reimbursed antibiotics.

Characterization of Two Late-Stage Enzymes Involved in Fosfomycin Biosynthesis in Pseudomonads

The broad-spectrum phosphonate antibiotic fosfomycin is currently in use for clinical treatment of infections caused by both Gram-positive and Gram-negative uropathogens. The antibiotic is biosynthesized by various streptomycetes, as well as by pseudomonads. Notably, the biosynthetic strategies used by the two genera share only two steps: the first step in which primary metabolite phosphoenolpyruvate (PEP) is converted to phosphonopyruvate (PnPy) and the terminal step in which 2-hydroxypropylphosphonate (2-HPP) is converted to fosfomycin. Otherwise, distinct enzymatic paths are employed. Here, we biochemically confirm the last two steps in the fosfomycin biosynthetic pathway of Pseudomonas syringae PB-5123, showing that Psf3 performs the reduction of 2-oxopropylphosphonate (2-OPP) to (S)-2-HPP, followed by the Psf4-catalyzed epoxidation of (S)-2-HPP to fosfomycin. Psf4 can also accept (R)-2-HPP as a substrate but instead performs an oxidation to make 2-OPP. We show that the combined activities of Psf3 and Psf4 can be used to convert racemic 2-HPP to fosfomycin in an enantioconvergent process. X-ray structures of each enzyme with bound substrates provide insights into the stereospecificity of each conversion. These studies shed light on the reaction mechanisms of the two terminal enzymes in a distinct pathway employed by pseudomonads for the production of a potent antimicrobial agent.