Antimicrobial Resistance of Escherichia coli Causing Uncomplicated Urinary Tract Infections: A European Update for 2014 and Comparison with 2000 and 2008

SIL-IS LC-ESI-MS/MS method for simultaneous quick detection of amoxicillin and clavulanic acid in human plasma: Development, validation and its application to a pharmacokinetics study

A liquid chromatography electrospray ionization tandem mass spectrometry method with amoxicillin-d4 as the stable isotope-labeled internal standard for simultaneous quick detection of amoxicillin and clavulanic acid in human plasma was developed and validated. Chromatographic separations were performed on a Hedera ODS-2 column (2.1 × 150 mm, 5 μm). The mobile phases for gradient elution were aqueous solution containing 0.2% acetic acid (AA) (mobile phase A) together with organic phase solution (acetonitrile and methanol mixed solution, mobile phase B). Mass spectrometry was performed using negative electrospray ionization in multiple reaction monitoring mode. The target fragment ion pairs of amoxicillin, clavulanic acid and amoxicillin-d4 were m/z 364.1 → 223.1, 198.1 → 135.9 and 368.1 → 227.1, respectively. The linear ranges of this method were 40-5,000 ng/ml for amoxicillin and 30-2,500 ng/ml for clavulanic acid, with coefficient of determination > 0.9900. This method validation included selectivity, standard curve, lower limit of quantitation, accuracy, precision, recovery, matrix effect (hemolytic matrix and hyperlipidemic matrix), carryover, stability, dilution reliability and incurred sample reanalysis study. A successful application of this method was realized in a pharmacokinetic study after administration of amoxicillin-clavulanic acid potassium granules.

Economic Burden of Community-Acquired Antibiotic-Resistant Urinary Tract Infections: Systematic Review and Meta-Analysis

Background

Antibiotic resistance (ABR) poses a major burden to global health and economic systems. ABR in community-acquired urinary tract infections (CA-UTIs) has become increasingly prevalent. Accurate estimates of ABR's clinical and economic burden are needed to support medical resource prioritization and cost-effectiveness evaluations of urinary tract infection (UTI) interventions.

Objective

This study aims to systematically synthesize the evidence on the economic costs associated with ABR in CA-UTIs, using published studies comparing the costs of antibiotic-susceptible and antibiotic-resistant cases.

Methods

We searched the PubMed, Ovid MEDLINE and Embase, Cochrane Review Library, and Scopus databases. Studies published in English from January 1, 2008, to January 31, 2023, reporting the economic costs of ABR in CA-UTI of any microbe were included. Independent screening of titles/abstracts and full texts was performed based on prespecified criteria. A quality assessment was performed using the Integrated Quality Criteria for Review of Multiple Study Designs (ICROMS) tool. Data in UTI diagnosis criteria, patient characteristics, perspectives, resource costs, and patient and health economic outcomes, including mortality, hospital length of stay (LOS), and costs, were extracted and analyzed. Monetary costs were converted into 2023 US dollars.

Results

This review included 15 studies with a total of 57,251 CA-UTI cases. All studies were from high- or upper-middle-income countries. A total of 14 (93%) studies took a health system perspective, 13 (87%) focused on hospitalized patients, and 14 (93%) reported UTI pathogens. Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa are the most prevalent organisms. A total of 12 (80%) studies reported mortality, of which, 7 reported increased mortality in the ABR group. Random effects meta-analyses estimated an odds ratio of 1.50 (95% CI 1.29-1.74) in the ABR CA-UTI cases. All 13 hospital-based studies reported LOS, of which, 11 reported significantly higher LOS in the ABR group. The meta-analysis of the reported median LOS estimated a pooled excess LOS ranging from 1.50 days (95% CI 0.71-4.00) to 2.00 days (95% CI 0.85-3.15). The meta-analysis of the reported mean LOS estimated a pooled excess LOS of 2.45 days (95% CI 0.51-4.39). A total of 8 (53%) studies reported costs in monetary terms-none discounted the costs. All 8 studies reported higher medical costs spent treating patients with ABR CA-UTI in hospitals. The highest excess cost was observed in UTIs caused by carbapenem-resistant Enterobacterales. No meta-analysis was performed for monetary costs due to heterogeneity.

Conclusions

ABR was attributed to increased mortality, hospital LOS, and economic costs among patients with CA-UTI. The findings of this review highlighted the scarcity of research in this area, particularly in patient morbidity and chronic sequelae and costs incurred in community health care. Future research calls for a cost-of-illness analysis of infections, standardizing therapy-pathogen combination comparators, medical resources, productivity loss, intangible costs to be captured, and data from community sectors and low-resource settings and countries.

Pharmacokinetic and pharmacodynamic evaluation of nitrofurantoin against Escherichia coli in a murine urinary tract infection model

The antimicrobial agent nitrofurantoin is becoming increasingly important for treatment of urinary tract infections (UTIs) due to widespread occurrence of multidrug-resistant Escherichia coli. Despite many years of use, little data on nitrofurantoin pharmacokinetics (PK) or -dynamics (PD) exist. The objective of this study was to (i) evaluate the pharmacokinetics of nitrofurantoin in a mouse model and (ii) use that data to design an in vivo dose fractionation study in an experimental model of UTI with E. coli for determination of the most predictive PK/PD index. Nitrofurantoin concentrations in urine were approximately 100-fold larger than concentrations in plasma after oral administration of 5, 10, and 20 mg/kg nitrofurantoin. The area under the curve over the minimum inhibitory concentration (AUC/MIC) was weakly correlated to bacterial reduction in urine (r2 = 0.24), while no such correlation was found for the time that nitrofurantoin stayed above the MIC (T > MIC). Increasing size of single-dose treatment was significantly correlated to eradication of bacteria in the urine, while this was not apparent when the same doses were divided in 2 or 3 doses 8 or 12 h apart. In conclusion, the results indicate that nitrofurantoin activity against E. coli in urine is driven by AUC/MIC.

Review of the In Vitro Microbiological Activity of Mecillinam Against Common Uropathogens in Uncomplicated Urinary Tract Infection: Focus on Resistant Pathogens

Antimicrobial resistance in uropathogens commonly causing urinary tract infections (UTIs) is a growing problem internationally. Pivmecillinam, the oral prodrug of mecillinam, has been used for over 40 years, primarily in Northern Europe and Canada. It is recommended in several countries as a first-line agent for the treatment of uncomplicated UTIs (uUTIs) and is now approved in the United States. We performed a structured literature search to review the available evidence on susceptibility of common uUTI-causing uropathogens to mecillinam. Among 38 studies included in this literature review, susceptibility rates for Escherichia coli to mecillinam-including resistant phenotypes such as extended-spectrum β-lactamase-producing E. coli-exceed 90% in most studies. High rates of susceptibility were also reported among many other uropathogens including Klebsiella spp., Enterobacter spp., and Citrobacter spp. In the current prescribing climate within the United States, pivmecillinam represents a viable first-line treatment option for patients with uUTI.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and lateral flow immunochromatography for rapid identification of β-lactamase-gene-harboring Enterobacterales in urine specimens: Performance and cost-benefit analyses

In this single-center prospective study, we evaluated the performance to the MALDI-ToF MS based method in conjunction with lateral flow immunochromatographic (LFIC) in urine specimens for rapid diagnosis of bacterial Urinary Tract Infection (UTI) and detection of carbapenemase and/or extended-spectrum β- lactamase (ESBL) enzymes produced by the involved bacteria, compared to standard culture, and antimicrobial susceptibility testing/genotypic resistance markers characterization performed on culture-grown colonies. In addition, a cost-benefit analysis comparing this approach against standard procedures was conducted. A total of 324 urines were included in the study, of which 288 (88.9 %) yielded concordant results by the MALDI-ToF MS and conventional culture (Kappa agreement, 0.82; P<0.001). Direct LFIC testing could be carried out in 249/324 urines. Bacterial species carrying β-lactam genotypic resistance markers were identified in 35 urines (35 CTX-M and 2 OXA-48). Two ESBL-producing Escherichia coli were missed by LFIC (Kappa agreement with standard procedures of 0.96; P<0.001). The cost-benefit analysis indicated that our novel approach resulted in an improvement of clinical outcomes (less need of outpatient care) with a marginal incremental cost (€2.59).

Urinary tract infections: a review of the current diagnostics landscape

Urinary tract infections are the most common bacterial infections worldwide. Infections can range from mild, recurrent (rUTI) to complicated (cUTIs), and are predominantly caused by uropathogenic Escherichia coli (UPEC). Antibiotic therapy is important to tackle infection; however, with the continued emergence of antibiotic resistance there is an urgent need to monitor the use of effective antibiotics through better stewardship measures. Currently, clinical diagnosis of UTIs relies on empiric methods supported by laboratory testing including cellular analysis (of both human and bacterial cells), dipstick analysis and phenotypic culture. Therefore, development of novel, sensitive and specific diagnostics is an important means to rationalise antibiotic therapy in patients. This review discusses the current diagnostic landscape and highlights promising novel diagnostic technologies in development that could aid in treatment and management of antibiotic-resistant UTIs.

Cystitis and Utipro® Plus: Real-World Evidence

BACKGROUND

The emergence of drug resistance in the etiological agents of uncomplicated urinary tract infections (UTIs) emphasizes the need to shift the paradigm towards alternative therapeutic strategies. The objective of the present study was to evaluate the use of a medical device containing xyloglucan, hibiscus, and propolis for reducing UTI symptomatic episodes, antibiotic prescription, and days of sick leave.

MATERIALS AND METHODS

It used retrospective, cross-sectional study data provided by office-based physicians from Germany (Disease Analyzer, IQVIA database), including those on 3586 patients with a diagnosis of UTI treated with Utipro® Plus (Noventure, Barcelona, Spain) from January 2015 to December 2020.

RESULTS

The majority of patients were women (94.2%) and had a mean age (standard deviation, SD) of 57.7 years (19.0). Within 12 months after the prescription and compared to the 12 months before, it was observed that there was a reduction in the proportion of patients with at least one UTI diagnosis (from 79.4% to 36.4%, p < 0.001), in antibiotic prescriptions (from 33.5% to 22.1%, p < 0.001), and in the proportion of patients with at least one day of sick leave (from 4.1% to 2.7%).

CONCLUSIONS

The use of Utipro® Plus is able to decrease UTI recurrence and can lead to the reduction of antibiotic prescriptions and disease burden in individuals affected by uncomplicated cystitis.

Association Between Uropathogenic Escherichia coli Virulence Genes and Severity of Infection and Resistance to Antibiotics

Purpose

Urinary tract infection (UTI) is the most frequent bacterial infection. Some uropathogenic Escherichia coli (UPEC) genes have been associated with disease severity and antibiotic resistance. The aim was to determine the association of nine UPEC virulence genes with UTI severity and antibiotic resistance of strains collected from adults with community-acquired UTI.

Patients and Methods

A case-control study (1:3) (38 urosepsis/pyelonephritis and 114 cystitis/urethritis) was conducted. The fimH, sfa/foc, cvaC, hlyA, iroN, fyuA, ireA, iutA, and aer (the last five are siderophore genes) virulence genes were determined by PCR. The information of antibiotic susceptibility pattern of the strains was collected from medical records. This pattern was determined using an automated system for antimicrobial susceptibility testing. Multidrug-resistant (MDR) was defined as resistance to three or more antibiotic families.

Results

fimH was the most frequently detected virulence gene (94.7%), and sfa/foc was the least frequently detected (9.2%); 55.3% (83/150) of the strains were MDR. The evaluated genes were not associated with UTI severity. Associations were found between the presence of hlyA and carbapenem resistance (Odds ratio [OR] = 7.58, 95% confidence interval [CI], 1.50-35.42), iutA and fluoroquinolone resistance (OR = 2.35, 95% CI, 1.15-4.84, and aer (OR = 2.8, 95% CI, 1.20-6.48) and iutA (OR = 2.95, 95% CI, 1.33-6.69) with penicillin resistance. In addition, iutA was the only gene associated with MDR (OR = 2.09, 95% CI,1.03-4.26).

Conclusion

There was no association among virulence genes and UTI severity. Three of the five iron uptake genes were associated with resistance to at least one antibiotic family. Regarding the other four non-siderophore genes, only hlyA was associated with antibiotic resistance to carbapenems. It is essential to continue studying bacterial genetic characteristics that cause the generation of pathogenic and multidrug-resistant phenotypes of UPEC strains.

Risk Factors and the Impact of Multidrug-Resistant Bacteria on Community-Acquired Urinary Sepsis

Risk factors for multidrug-resistant bacteria (MDRB) in nosocomial urinary tract infection (UTI) have been widely studied. However, these risk factors have not been analyzed in community-acquired urinary sepsis (US), nor have its outcomes been studied. The aim of our study is to determine risk factors for MDRB in community-acquired US and its influence on outcomes. Prospective observational study of patients with community-acquired US admitted to a university hospital. We compared epidemiological and clinical variables and outcomes of US due to MDRB and non-MDRB. Independent risk factors for MDRB were analyzed using logistic regression. A total of 193 patients were included, 33.7% of them with US due to MDRB. The median age of patients was 82 years. Hospital mortality was 17.6%, with no difference between the MDRB and non-MDRB groups. The length of hospital stay was 5 (4-8) days, with a non-significant tendency to longer hospital stays in the MDRB group (6 (4-10) vs. 5 (4-8) days, p = 0.051). Healthcare-associated US was found to be an independent risk factor for MDR bacteria by multivariate analysis. In conclusion, the impact of MDR bacteria on the outcomes of community-acquired urinary sepsis was mild. Healthcare-associated US was an independent risk factor for MDR bacteria.

Antimicrobial activity of ceftibuten-avibactam against a global collection of Enterobacterales from patients with urinary tract infections (2021)

We evaluated the in vitro activity of ceftibuten-avibactam against Enterobacterales causing urinary tract infection (UTI). A total of 3216 isolates (1/patient) were consecutively collected from patients with UTI in 72 hospitals from 25 countries in 2021 then susceptibility tested by CLSI broth microdilution. Ceftibuten-susceptible breakpoints currently published by EUCAST (≤ 1 mg/L) and CLSI (≤ 8 mg/L) were applied to ceftibuten-avibactam for comparison. The most active agents were ceftibuten-avibactam (98.4%/99.6% inhibited at ≤ 1/ ≤ 8 mg/L), ceftazidime-avibactam (99.6% susceptible [S]), amikacin (99.1%S), and meropenem (98.2%S). Ceftibuten-avibactam (MIC_50/90, 0.03/0.06 mg/L) was fourfold more potent than ceftazidime-avibactam (MIC_50/90, 0.12/0.25 mg/L) based on MIC_50/90 values. The most active oral agents were ceftibuten (89.3%S; 79.5% inhibited at ≤ 1 mg/L), levofloxacin (75.4%S), and trimethoprim-sulfamethoxazole (TMP-SMX; 73.4%S). Ceftibuten-avibactam inhibited 97.6% of isolates with an extended-spectrum β-lactamase phenotype, 92.1% of multidrug-resistant isolates, and 73.7% of carbapenem-resistant Enterobacterales (CRE) at ≤ 1 mg/L. The second most active oral agent against CRE was TMP-SMX (24.6%S). Ceftazidime-avibactam was active against 77.2% of CRE isolates. In conclusion, ceftibuten-avibactam was highly active against a large collection of contemporary Enterobacterales isolated from patients with UTI and exhibited a similar spectrum to ceftazidime-avibactam. Ceftibuten-avibactam may represent a valuable option for oral treatment of UTI caused by multidrug-resistant Enterobacterales.

Fluoroquinolones Are Useful as Directed Treatment for Complicated UTI in a Setting with a High Prevalence of Quinolone-Resistant Microorganisms

Fluoroquinolones (FQs) have been widely used for treating urinary tract infections (UTIs); however, the increasing emergence of resistant strains has compromised their use. We aimed to know the usefulness of FQs for the treatment of community-acquired UTI in a setting with a high prevalence of fluoroquinolone-resistant microorganisms. A prospective observational study of patients diagnosed with community-acquired UTI was conducted, in which their outcomes according to whether they had FQs or not in their empirical and directed treatments were compared. A multivariate analysis was performed to identify risk factors for UTIs due to ciprofloxacin-resistant microorganisms. A total of 419 patients were included; 162 (38.7%) patients were treated with FQs, as empirical treatment in 27 (6.4%), and as directed treatment in 135 (32.2%). In-hospital mortality (2.2% vs. 6.6%, p 0.044) and 30-day mortality (4.4 vs. 11%, p 0.028) were both lower in the group of patients directly treated with FQ, while there were no differences when FQs were used as empirical treatment. A total of 37.2% of the cases were resistant to ciprofloxacin, which was associated with healthcare-associated UTI (OR 2.7, 95% CI 2-3.7) and prior exposure to FQs (OR 2.7, 95 % CI 1.9-3.7). In conclusion, our findings show that in a setting with a high prevalence of community-acquired UTI caused by quinolone-resistant microorganisms, FQs as directed treatment for community-acquired UTI were associated with better outcomes than other antibiotics, but their use as empirical treatment is not indicated, even in those cases without risk factors for quinolones resistance.

Antibiotic Resistance in Proteus mirabilis: Mechanism, Status, and Public Health Significance

Proteus mirabilis is a specific opportunistic pathogen of many infections including urinary tract infections (UTIs). Risk factors are linked with the acquisition of multidrug-resistant (MDR) to 3 or more classes of antimicrobials) strains. The resistance in extended-spectrum alpha-lactamase is rare, but the rising resistance in extended-spectrum beta-lactamase (ESBL) producing strains is a matter of concern. β-lactamases and antibiotic modifying enzymes mainly constitute the ESBLs resistance mechanism by hydrolyzing the antibiotics. Mutation or Porin loss could lead to the reduced permeability of antibiotics, enhanced efflux pump activity hindering the antibiotic access to the target site, antibiotic failure to bind at the target site because of the target modification, and lipopolysaccharide mutation causing the resistance against polymyxin antibiotics. This review aimed to explore various antimicrobial resistance mechanisms in Proteus mirabilis and their impact on public health status.

Fluoroquinolones and Other Antibiotics Redeemed for Cystitis—A Swedish Nationwide Cohort Follow-Up Study (2006–2018)

Background: Antibiotics are commonly prescribed for outpatient management of cystitis. Previous evidence suggests that certain factors likely beyond the infection seem to influence the choice of antimicrobial treatment. However, studies on the specific antibiotic treatments for cystitis are lacking. This study aimed to explore the antibiotic treatments for cystitis using nationwide primary healthcare data and investigate if factors beyond the infection could be associated with fluoroquinolone treatment. Methods: This nationwide follow-up cohort study consisted of 352,507 women with cystitis. The primary aim was to investigate what specific classes of antibiotics were redeemed by patients within five days from the cystitis diagnosis. Each patient could only be included once. Logistic regression models were also used to examine the relationship between fluoroquinolone (FQ) treatment, parity, and sociodemographic factors. Results: In total, 192,065 antibiotic prescriptions were redeemed. Pivmecillinam (58.4%) followed by nitrofurantoin (22.2%), trimethoprim (12.0%), fluoroquinolone (5.6%), and cephalosporins (1.5%) were the most redeemed antibiotics. Sociodemographic factors were weakly associated with fluoroquinolone treatment; young age was inversely associated with fluoroquinolone treatment. Parity and cervical cancer history were not associated with fluoroquinolone treatment. The proportion of fluoroquinolone and trimethoprim treatments decreased over time, while pivmecillinam and nitrofurantoin increased. Conclusions: The treatment trends of antibiotics redeemed within five days from a cystitis diagnosis were similar to the national surveillance program of these antibiotics (not diagnosis linked). Fluoroquinolones were weakly associated with sociodemographic factors, which likely is only of historical relevance.

US-Focused Conceptual Health Care Decision-Analytic Models Examining the Value of Pivmecillinam Relative to Current Standard-of-Care Agents Among Adult Patients With Uncomplicated Urinary Tract Infections due to Enterobacterales

Background

Pivmecillinam is approved for the treatment of adults with uncomplicated urinary tract infection (uUTI) in Canada and Europe and is pending United States (US) Food and Drug Administration submission for consideration for approval. US-focused health care decision-analytics were developed to define the value of an agent like pivmecillinam relative to current standard-of-care (SOC) agents among adult patients with Enterobacterales uUTIs based on its improved microbiologic activity against common Enterobacterales.

Methods

The model population was 100 theoretical adult outpatients with Enterobacterales uUTIs under 4 different uUTI first-line empiric treatment scenarios (ie, pivmecillinam, nitrofurantoin, trimethoprim-sulfamethoxazole [SXT], or fluoroquinolones). The total mean uUTI-related 30-day costs, including inappropriate treatment costs, were calculated for each regimen. The range of pivmecillinam regimen costs that conferred cost savings relative to the current SOC agents based on its potentially improved microbiologic activity against common Enterobacterales was determined.

Results

The 30-day uUTI-related costs associated with nitrofurantoin, SXT, and fluoroquinolones were $655.61, $687.57, and $659.69, respectively. The pivmecillinam neutral regimen cost thresholds that resulted in the same uUTI-related 30-day per-patient costs for nitrofurantoin, SXT, and fluoroquinolones were $83.50, $115.45, and $87.58, respectively. The overall antimicrobial susceptibility improvement required with pivmecillinam fixed at $200/regimen, for it to be cost savings relative to SOC agents, was 28%.

Conclusions

The analyses suggests that an agent like pivmecillinam, if approved in the US, has the potential to reduce the economic burden associated with inappropriate treatment of adult outpatients with uUTIs, especially in patients at high risk for an Enterobacterales uUTI that is resistant to SOC agents.

Resistance Trend Estimation Using Regression Analysis to Enhance Antimicrobial Surveillance: A Multi-Centre Study in London 2009-2016

In the last years, there has been an increase of antimicrobial resistance rates around the world with the misuse and overuse of antimicrobials as one of the main leading drivers. In response to this threat, a variety of initiatives have arisen to promote the efficient use of antimicrobials. These initiatives rely on antimicrobial surveillance systems to promote appropriate prescription practices and are provided by national or global health care institutions with limited consideration of the variations within hospitals. As a consequence, physicians' adherence to these generic guidelines is still limited. To fill this gap, this work presents an automated approach to performing local antimicrobial surveillance from microbiology data. Moreover, in addition to the commonly reported resistance rates, this work estimates secular resistance trends through regression analysis to provide a single value that effectively communicates the resistance trend to a wider audience. The methods considered for trend estimation were ordinary least squares regression, weighted least squares regression with weights inversely proportional to the number of microbiology records available and autoregressive integrated moving average. Among these, weighted least squares regression was found to be the most robust against changes in the granularity of the time series and presented the best performance. To validate the results, three case studies have been thoroughly compared with the existing literature: (i) Escherichia coli in urine cultures; (ii) Escherichia coli in blood cultures; and (iii) Staphylococcus aureus in wound cultures. The benefits of providing local rather than general antimicrobial surveillance data of a higher quality is two fold. Firstly, it has the potential to stimulate engagement among physicians to strengthen their knowledge and awareness on antimicrobial resistance which might encourage prescribers to change their prescription habits more willingly. Moreover, it provides fundamental knowledge to the wide range of stakeholders to revise and potentially tailor existing guidelines to the specific needs of each hospital.

Repeated exposure of nosocomial pathogens to silver does not select for silver resistance but does impact ciprofloxacin susceptibility

The rise of antimicrobial resistant bacteria coupled with a void in antibiotic development marks Antimicrobial Resistance as one of the biggest current threats to modern medicine. Antimicrobial metals are being developed and used as alternative anti-infectives, however, the existence of known resistance mechanisms and limited data regarding bacterial responses to long-term metal exposure are barriers to widespread implementation. In this study, a panel of reference and clinical strains of major nosocomial pathogens were subjected to serial dosage cycles of silver and ciprofloxacin. Populations exposed to silver initially showed no change in sensitivity, however, increasingly susceptibility was observed after the 25th cycle. A control experiment with ciprofloxacin revealed a selection for resistance over time, with silver treated bacteria showing faster adaptation. Morphological analysis revealed filamentation in Gram negative species suggesting membrane perturbation, while sequencing of isolated strains identified mutations in numerous genes. These included those encoding for efflux systems, chemosensory systems, stress responses, biofilm formation and respiratory chain processes, although no consistent locus was identified that correlated with silver sensitivity. These results suggest that de novo silver resistance is hard to select in a range of nosocomial pathogens, although silver exposure may detrimentally impact sensitivity to antibiotics in the long term. STATEMENT OF SIGNIFICANCE: The adaptability of microbial life continuously calls for the development of novel antibiotic molecules, however, the cost and risk associated with their discovery have led to a drying up in the pipeline, causing antimicrobial resistance (AMR) to be a major threat to healthcare. From all available strategies, antimicrobial metals and, more specifically, silver showcase large bactericidal spectrum and limited toxic effect which coupled with a large range of processes available for their delivery made these materials as a clear candidate to tackle AMR. Previous reports have shown the ability of this metal to enact a synergistic effect with other antimicrobial therapies, nevertheless, the discovery of Ag resistance mechanisms since the early 70s and limited knowledge on the long term influence of silver on AMR poses a threat to their applicability. The present study provides quantitative data on the influence of silver based therapies on AMR development for a panel of reference and clinical strains of major nosocomial pathogens, revealing that prolonged silver exposure may detrimentally impact sensitivity to antibiotics.

Consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in the community, European Union/European Economic Area, 1997-2017

Objectives

Data on consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials were collected from 30 EU/European Economic Area (EEA) countries over two decades. This article reviews temporal trends, seasonal variation, presence of change-points and changes in the composition of main subgroups of tetracyclines, sulphonamides and trimethoprim and other antibacterials.

Methods

For the period 1997–2017, data on consumption of tetracyclines (ATC group J01A), sulphonamides and trimethoprim (ATC group J01E), and other antibacterials (ATC group J01X) in the community and aggregated at the level of the active substance, were collected using the WHO ATC/DDD methodology (ATC/DDD index 2019). Consumption was expressed in DDD per 1000 inhabitants per day and in packages per 1000 inhabitants per day. Consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials was analysed based on ATC-4 subgroups and presented as trends, seasonal variation, presence of change-points and compositional changes.

Results

In 2017, consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in the community expressed in DDD per 1000 inhabitants per day varied considerably between countries. Between 1997 and 2017, consumption of tetracyclines did not change significantly, while its seasonal variation significantly decreased over time. Consumption of sulphonamides and trimethoprim significantly decreased until 2006, and its seasonal variation significantly decreased over time. The consumption of other antibacterials showed no significant change over time or in seasonal variation.

Conclusions

Consumption and composition of tetracyclines, sulphonamides and trimethoprim, and other antibacterials showed wide variations between EU/EEA countries and over time. This represents an opportunity to further reduce consumption of these groups in some countries and improve the quality of their prescription.

A non-pharmacological approach to the treatment of urinary tract infections: case reports with Utipro® Plus

Recurrent urinary tract infections (UTIs) can profoundly impair patients’ quality of life and carry a substantial health resource burden. Although antibiotics are the mainstay of treatment, interest is growing in identifying antibiotic-sparing alternatives. Utipro^® Plus is a medical device that acts as a mechanical barrier to protect the intestinal lumen against the adherence and invasion of uropathogenic strains of Escherichia coli. It is intended for the control and prevention of UTIs caused by E. coli and other Gram-negative uropathogens. Using illustrative case reports, this review documents outcomes in three women with recurrent UTIs who were treated with Utipro^® Plus in clinical practice.

Intravenous mecillinam compared with other β-lactams as targeted treatment for Escherichia coli or Klebsiella spp. bacteraemia with urinary tract focus

BACKGROUND

Mecillinam (amdinocillin) is active against Gram-negative bacteria. Clinical data on the efficacy of IV mecillinam for severe urinary tract infections is sparse.

OBJECTIVES

To assess the effectiveness of targeted IV mecillinam compared with other β-lactams for bacteraemia with Escherichia coli and Klebsiella spp. and a urinary tract focus.

PATIENTS AND METHODS

We performed a retrospective cohort study at five university hospitals in the Capital Region of Denmark from 1 January 2012 to 31 December 2017. We used Cox proportional hazard regression to compare the primary composite endpoint (all-cause mortality or bacteraemia recurrence within 30 days) between patients treated with mecillinam versus ampicillin, cefuroxime, piperacillin/tazobactam and meropenem.

RESULTS

We included 1129 patients in the primary analysis, of which 146 were given IV mecillinam as targeted treatment. We found no significant difference in the primary endpoint between patients treated with mecillinam versus ampicillin and cefuroxime, but found a higher risk for the primary endpoint in the piperacillin/tazobactam and meropenem groups, with adjusted HRs of 2.22 (95% CI 1.24-3.97, P < 0.01) and 2.48 (95% CI 1.04-5.93, P = 0.04), respectively, compared with mecillinam.

CONCLUSIONS

The results of this study suggest that IV mecillinam may be a suitable targeted treatment for bacteraemia with a urinary tract focus. However, these results need confirmation by randomized controlled studies.

Selective concentrations for trimethoprim resistance in aquatic environments

Antibiotic resistance presents a serious and still growing threat to human health. Environmental exposure levels required to select for resistance are unknown for most antibiotics. Here, we evaluated different experimental approaches and ways to interpret effect measures, in order to identify what concentration of trimethoprim that are likely to select for resistance in aquatic environments. When grown in complex biofilms, selection for resistant E. coli increased at 100 µg/L, whereas there was only a non-significant trend with regards to changes in taxonomic composition within the tested range (0-100 µg/L). Planktonic co-culturing of 149 different E. coli strains isolated from sewage again confirmed selection at 100 µg/L. Finally, pairwise competition experiments were performed with engineered E. coli strains carrying different trimethoprim resistance genes (dfr) and their sensitive counterparts. While strains with introduced resistance genes grew slower than the sensitive ones at 0 and 10 µg/L, a significant reduction in cost was found already at 10 µg/L. Defining lowest effect concentrations by comparing proportion of resistant strains to sensitive ones at the same time point, rather than to their initial ratios, will reflect the advantage a resistance factor can bring, while ignoring exposure-independent fitness costs. As costs are likely to be highly dependent on the specific environmental and genetic contexts, the former approach might be more suitable as a basis for defining exposure limits with the intention to prevent selection for resistance. Based on the present and other studies, we propose that 1 µg/L would be a reasonably protective exposure limit for trimethoprim in aquatic environments.

Whole-genome analysis of extraintestinal Escherichia coli sequence type 73 from a single hospital over a 2 year period identified different circulating clonal groups

Sequence type (ST)73 has emerged as one of the most frequently isolated extraintestinal pathogenic Escherichia coli. To examine the localized diversity of ST73 clonal groups, including their mobile genetic element profile, we sequenced the genomes of 16 multiple-drug resistant ST73 isolates from patients with urinary tract infection from a single hospital in Sydney, Australia, between 2009 and 2011. Genome sequences were used to generate a SNP-based phylogenetic tree to determine the relationship of these isolates in a global context with ST73 sequences (n=210) from public databases. There was no evidence of a dominant outbreak strain of ST73 in patients from this hospital, rather we identified at least eight separate groups, several of which reoccurred, over a 2 year period. The inferred phylogeny of all ST73 strains (n=226) including the ST73 clone D i2 reference genome shows high bootstrap support and clusters into four major groups that correlate with serotype. The Sydney ST73 strains carry a wide variety of virulence-associated genes, but the presence of iss, pic and several iron-acquisition operons was notable.

In vitro and in vivo antibacterial activity of nitrofurantoin against clinical isolates of E. coli in Japan and evaluation of biological cost of nitrofurantoin resistant strains using a mouse urinary tract infection model

INTRODUCTION

Nitrofurantoin is a well-established antibiotic, and is an important first-line oral treatment for uncomplicated urinary tract infections. However, little information is available with respect to its antibacterial activity in Japan, in vivo efficacy, or the in vivo biological cost of resistant strains.

METHODS

We compared the susceptibility of six representative antibacterial agents-nitrofurantoin, sulfamethoxazole/trimethoprim, fosfomycin, mecillinam, ciprofloxacin, and cefdinir-against E. coli clinically isolated in Japan during 2017. We evaluated the in vivo efficacy of nitrofurantoin using a model of mouse urinary tract infection caused by ciprofloxacin resistant E. coli. We obtained nitrofurantoin resistant isolates through tests generating spontaneous mutations, and assessed the in vivo fitness of nitrofurantoin resistant isolates.

RESULTS

The MIC₉₀ of nitrofurantoin was 16 μg/mL, and was the lowest among the drugs tested. It was found that, in the mouse urinary tract infection model, 30 mg/kg and 100 mg/kg of nitrofurantoin reduced the count of viable bacterial cells in the kidney, while 100 mg/kg of ciprofloxacin did not. All spontaneous bacterial mutants resistant to nitrofurantoin had deletions in the nfsA gene, and we found that the resistant strain had lower growth in the mouse urinary tract infection model than in the parent strain.

CONCLUSIONS

We demonstrated promising in vitro and in vivo activity of nitrofurantoin against E. coli clinical isolates in Japan, and lower in vivo fitness of the resistant strain of nitrofurantoin.

Escherichia coli Resistance to Fluoroquinolones in Community-Acquired Uncomplicated Urinary Tract Infection in Women: a Systematic Review

Antibiotic resistance is a threat to public health, and uncomplicated urinary tract infections (uUTIs) are an example of this concern. This systematic review (International Prospective Register of Systematic Reviews [PROSPERO] ID: CRD42020156674) is the first to determine the prevalence of Escherichia coli resistance to fluoroquinolones in women with community-acquired uUTI. PubMed and Embase searches were conducted; 38 studies fulfilled eligibility criteria and were included in the systematic review. Within Europe, ciprofloxacin resistance in E. coli isolates varied between countries and increased in some from 2006 to 2008 and 2014 to 2016, specifically in the United Kingdom (0.5% to 15.3%), Germany (8.7% to 15.1%), and Spain (22.9% to 30.8%), although methodologies and settings were often not comparable. In Asia, there was a substantial increase in ciprofloxacin resistance during 2008 to 2014 from 25% to more than 40%. In North America, resistance to ciprofloxacin also increased between 2008 and 2017, from 4% to 12%. Data exploring different age groups did not show a consistent relationship with resistance, whereas two studies found that fluoroquinolone resistance was higher in postmenopausal women than premenopausal women. One study indicated a link between fluoroquinolone resistance and uUTI recurrence. These findings may have implications for the empirical treatment of uUTI with fluoroquinolones globally, but more data are needed to fully understand regional situations and impact patient management.

Spectrum and Antibiotic Resistance of Uropathogens in Romanian Females

Urinary tract infections (UTIs) in women represent a common bacteriological finding, with negligible recent and consistent research on antimicrobial resistance (AMR) in the female population. We designed a retrospective study to observe the incidence of frequent uropathogens and their resistance rates to common antibiotics. We elaborated multicenter research in three different teaching hospitals in Romania, analyzing 13,081 urine samples, of which 1588 met the criteria of inclusion. Escherichia coli (58.37%) was the most frequent Gram-negative uropathogen, presenting high resistance rates to levofloxacin (R = 29.66%), amoxicillin–clavulanic ac. (R = 14.13%), and ceftazidime (R = 6.68%). We found good sensitivity to imipenem and meropenem (both 98.16%), amikacin (S = 96.0%), and fosfomycin (S = 90.39%). The second most prevalent uropathogen was Klebsiella (16.93%), with the highest resistance quota to amoxicillin–clavulanic ac. (R = 28.62%), levofloxacin and nitrofurantoin (both R = 15.61%), and ceftazidime (R = 15.24%), and good sensitivity to imipenem (S = 93.93%), meropenem (S = 91.91%), and amikacin (S = 88.47%). Enterococcus (13.35%) was the most encountered Gram-positive pathogen. It proved the highest resistance to levofloxacin (R = 32.07%), penicillin (R = 32.07%), and ampicillin (R = 14.62%) and good sensitivity to vancomycin (S = 91.98%), fosfomycin (S = 94.4%), and nitrofurantoin (S = 89.15%). Considering the lack of recent and consistent data on this topic, we find our survey a valuable starting research study in this area with high significance for an accurate clinical approach.

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.

Fluoroquinolone resistance in Escherichia coli isolates after exposure to non-fluoroquinolone antibiotics: a retrospective case-control study

OBJECTIVES

To investigate whether prior exposure to non-fluoroquinolone antibiotics increases the risk of fluoroquinolone resistance in Escherichia coli.

METHODS

This was a secondary analysis of data collected retrospectively in a case-control study linking microbiological test results (isolated bacteria and their susceptibility) of urine samples routinely collected from primary, secondary and tertiary care patients in Belgium with information on prior antibiotic use at the patient level up to 1 year previously.

RESULTS

In urine samples from 6125 patients, 7204 E. coli isolates were retrieved [1949 fluoroquinolone-resistant isolates (cases) and 5255 fluoroquinolone-susceptible isolates (controls)]. After adjusting for potential confounders (including fluoroquinolone use) and correcting for multiple testing there were lower odds of fluoroquinolone resistance in E. coli isolates after exposure to cefazolin (OR = 0.65; 95% CI = 0.52-0.81; P = 0.00014) and higher odds after exposure to trimethoprim/sulfamethoxazole (OR = 1.56; 95% CI = 1.23-1.97; P =0.00020) or nitrofurantoin (OR = 1.50; 95% CI = 1.23-1.84; P =0.000083). A sensitivity analysis excluding samples with antibiotic use during the 6 months prior to the sampling date confirmed the higher odds of fluoroquinolone resistance after exposure to trimethoprim/sulfamethoxazole and nitrofurantoin.

CONCLUSIONS

Assuming no residual confounding or other biases, this study suggests that exposure to non-fluoroquinolone antibiotics, i.e. trimethoprim/sulfamethoxazole and nitrofurantoin, might be causally related to fluoroquinolone resistance in E. coli isolates from urinary samples. Future prospective research is needed to confirm non-fluoroquinolone antibiotics as potential drivers of fluoroquinolone resistance.

Fluoroquinolone resistant bacterial isolates from the urinary tract among patients attending hospitals in Bushenyi District, Uganda

Introduction

bacterial resistance to fluoroquinolones is on the rise globally, bacteria causing urinary tract infections (UTIs) are no exception to this fact. Judicious use of the current antibiotics by clinicians is therefore deemed necessary to combat development of resistance. This study determined fluoroquinolone resistant profiles, multiple antibiotic resistance indices (MARI), factors associated with fluoroquinolone resistance and their strength among patients attending hospitals in Bushenyi District, Uganda.

Methods

this was a cross-sectional study in which a total of 86 bacterial uropathogens isolated previously by standard microbiological methods were subjected to antibiotic susceptibility testing using Kirby Bauer disk diffusion method. Data for factors suspected to be associated with fluoroquinolone resistant UTI were obtained by use of questionnaires.

Results

the most resisted fluoroquinolone was ofloxacin with 29/83 (34.9%), followed by moxifloxacin 27/83 (32.5%), levofloxacin 24/86 (27.9%) and ciprofloxacin 23/86 (26.7%). The bacterial uropathogens that exhibited the highest frequency of fluoroquinolone resistant strains were P. mirabilis with 2/3 (66.7%) and E. faecalis with 2/3 (66.7%), followed by E. coli 19/36 (52.8%), S. aureus 13/27 (48.1%), K. oxytoca 2/6 (33.3%), K. pneumoniae 2/10 (20.0%) and P. vulgaris 0/1 (0.0%). All the bacterial uropathogens tested showed MARI of ≥ 0.2. Hospitalization, history of fluoroquinolones use in the last 12 months and wrong prescription of antibiotics were found to bear statistically significant relationships (p < 0.05) with fluoroquinolone resistant UTI.

Conclusion

antibiotic susceptibility testing of the first generation quinolones such as nalidixic acid in hospitalized patients, patients with history of fluoroquinolones' use in the last 12 months and wrong prescription of antibiotics should be adopted to avoid fluoroquinolone abuse. For empiric treatment of UTIs in Bushenyi District, ciprofloxacin still remains the first line of choice among the fluoroquinolone class of antibiotics.

Routine laboratory surveillance of antimicrobial resistance in community-acquired urinary tract infections adequately informs prescribing policy in England

Objectives

To assess whether resistance estimates obtained from sentinel surveillance for antimicrobial resistance (AMR) in community-acquired urinary tract infections (UTIs) differ from routinely collected laboratory community UTI data.

Methods

All patients aged ≥18 years presenting to four sentinel general practices with a suspected UTI, from 13 November 2017 to 12 February 2018, were asked to provide urine specimens for culture and susceptibility. Specimens were processed at the local diagnostic laboratory. Antibiotic susceptibility testing was conducted using automated methods. We calculated the proportion of Escherichia coli isolates that were non-susceptible (according to contemporaneous EUCAST guidelines) to trimethoprim, nitrofurantoin, cefalexin, ciprofloxacin and amoxicillin/clavulanic acid, overall and by age group and sex, and compared this with routine estimates.

Results

Sentinel practices submitted 740 eligible specimens. The specimen submission rate had increased by 28 specimens per 1000 population per year (95% CI 21-35). Uropathogens were isolated from 23% (169/740) of specimens; 67% were E. coli (113/169). Non-susceptibility of E. coli to trimethoprim was 28.2% (95% CI 20.2-37.7) on sentinel surveillance (33.4%; 95% CI 29.5-37.6 on routine data) and to nitrofurantoin was 0.9% (95% CI 0-5.7) (1.5%; 95% CI 0.7-3.0 on routine data).

Conclusions

Routine laboratory data resulted in a small overestimation in resistance (although the difference was not statistically significant) and our findings suggest that it provides an adequate estimate of non-susceptibility to key antimicrobials in community-acquired UTIs in England. This study does not support the need for ongoing local sentinel surveillance.

Evaluation of multiplex tandem PCR (MT-PCR) assays for the detection of bacterial resistance genes among Enterobacteriaceae in clinical urines

Background

Increasing resistance drives empirical use of less potent and previously reserved antibiotics, including for urinary tract infections (UTIs). Molecular profiling, without culture, might better guide early therapy.

Objectives

To explore the potential of AusDiagnostics multiplex tandem (MT) PCR UTI assays.

Methods

Two MT-PCR assays were developed successively, seeking 8 or 16 resistance genes. Amplification was tracked in real time, with melting temperatures used to confirm product identity. Assays were variously performed on: (i) extracted DNA; (ii) cultured bacteria; (iii) urine spiked with reference strains; and (iv) bacteria harvested from clinical urines. Results were compared with those from sequencing, real-time SybrGreen PCR or phenotypic susceptibility.

Results

Performance was similar irrespective of whether DNA, cultures or urines were used, with >90% sensitivity and specificity with respect to common β-lactamases, dfr genes and aminoglycoside resistance determinants except aadA1/A2/A3, for which carriage correlated poorly with streptomycin resistance. Fluoroquinolone-susceptible and -resistant Escherichia coli (but not other species) were distinguished by the melting temperatures of their gyrA PCR products. The time from urine to results was <3 h.

Conclusions

The MT-PCR assays rapidly identified resistance genes from Gram-negative bacteria in urines as well as from cultivated bacteria. Used directly on urines, this assay has the potential to guide early therapy.

Design and Fabrication of a Conductometry System for Fast Detection of Pathogenic Bacteria in Human Urine

Background: Common methods for identifying the infectious bacteria in human urine are mainly time-consuming and costly. Therefore, the most reliable method for detecting the urinary tract infections is the urine culture, which requires at least 48 hours to identify infectious factors. Objectives: It is important to detect the bacteria in urine rapidly, simply, and accurately. Materials and Methods: In this work, the variations in the electrical conductivity and dielectric coefficient of the urine sample due to changes in the concentration of infectious bacteria have been studied. Furthermore, an appropriate measurement system was prepared for impedancemetry and conductometry. Results: We showed that the detection time was reduced to about an hour. Finally, the accuracy of the device for diagnosis and precision of measurement were evaluated and compared by the detection method for bacterial culture. Conclusion: In this work, the detection time was reduced to about 1 hour.

[Current state of resistance of E. coli to trimethoprim in uncomplicated urinary tract infections in France]

OBJECTIVE

The objective of this study was to assess the level of resistance of trimethoprim alone (TMP) with respect to E. coli strains isolated from the urines of women with simple acute cystitis in community.

PATIENTS AND METHODS

Prospective study realized for 9 months in 2017-18. A total of 351 urine samples were analyzed. Culture has been made according to the usual techniques and antibiogram was carried out according to the recommendations of the CA-SFM.

RESULTS

The rate of resistance to TMP was 16.5% (58/351). Only 11 strains of E. coli (3%) producing ESBL were found, 5 of which were sensitive to TMP.

CONCLUSION

The resistance rate of E. coli to TMP remains below 20%, the threshold for choosing a probabilistic treatment of a non-serious infection. Considering the good tolerance of TMP and its weak effect on the microbiota during a short treatment, one can propose TMP alone in the probabilistic treatment of simple acute cystitis.

Microbial risk factors for treatment failure of pivmecillinam in community-acquired urinary tract infections caused by ESBL-producing Escherichia coli

The aim of this study was to identify microbial risk factors for treatment failure of pivmecillinam in community-acquired urinary tract infections (ca-UTIs) caused by ESBL-producing Escherichia coli. Eighty-nine ESBL-producing E. coli isolated from women suffering from ca-UTIs were included. The susceptibilities to mecillinam were determined using MIC gradient strip. Whole genome sequencing was performed on a MiSeq platform, and genome assembly was performed using SPAdes v3.11.0. Neither mecillinam MICs nor ESBL genotypes were associated with treatment outcome of patients treated with pivmecillinam. Specific STs, however, showed significant differences in treatment outcome. Patients infected with ST131 were more likely to experience treatment failure compared to patients infected with non-ST131 (p 0.02) when adjusted for pivmecillinam dose, mecillinam MIC and severity of infection. Patients infected with ST69 were more often successfully treated compared to patients infected with non-ST69 (p 0.04). Patients infected with bla_CTX-M-15 ST131 strains were more likely to experience treatment failure than those infected with non-bla_CTX-M-15 ST131 strains (p 0.02). The results suggest that specific STs are associated with the clinical efficacy of pivmecillinam. Further studies with a larger number of strains, including a larger number of mecillinam resistant strains, are needed to confirm these results.

Antimicrobial susceptibility among urinary Escherichia coli isolates from female outpatients: age-related differences

OBJECTIVES

Urinary tract infections (UTIs) are common problems in women, and important reason for visiting primary care physicians, resulting in substantial financial burden to community. The aim of this study was to determine the resistance rates of E. coli to commonly prescribed antimicrobial drugs for community-acquired UTIs in women and to establish the association between age and resistance to antibiotics among isolates of E. coli from urine.

METHODS

The study was designed as a retrospective cross-sectional study during the 5-years period. It was conducted on a sample of urinary tract isolates of E. coli taken from women with community-acquired UTIs. After prevalence of E. coli resistance to antibiotics was established, the analysis of risk factors for emergence of resistance was conducted.

RESULTS

There were 10,734 isolates of E. coli, comprising 70.62% of all samples analyzed. E. coli was the most frequently resistant to ampicillin (54.68%), followed by trimethoprim-sulphamethoxazole (37.46%), first and second generation cephalosporins (cephalexin and cefaclor) (29.53% both), and ciprofloxacin (23.80%). Less than 50% of E. coli isolates was sensitive to all three tested antibiotics, and nearly 13% acquired triple-resistance. Prevalence of isolates resistant to two or three agents was higher in the subgroup of women older than 65 years.

CONCLUSIONS

Empirical choice of antimicrobial agent for community-acquired non-complicated UTIs in women should be individualized on the basis of the patient's age, prevalence of resistance in the local community, and compliance history of the patient.

Antibiotic resistance of Escherichia coli isolated from uncomplicated UTI in general practice patients over a 10-year period

Recommendations of first choice antibiotic therapy need to be based on actual antibiotic susceptibility data. We determined the antibiotic susceptibility of E. coli in uncomplicated UTI among women and compared the results with 2004 and 2009. In 30 sentinel general practitioner practices of Nivel Primary Care database, urine samples were collected from women with symptoms of uncomplicated UTI. Patient characteristics, E. coli susceptibility, and ESBL production were analyzed. Six hundred eighty-nine urine samples were collected; E. coli was the most isolated uropathogen (83%). Antibiotic susceptibility was stable over time except for ciprofloxacin (96% in 2004, 97% in 2009, and 94% in 2014; P < 0.05). The susceptibility to co-amoxiclav was 88%, 87%, and 92% in 2004, 2009, and 2014, respectively. The prevalence of ESBL-producing E. coli increased from 0.1% in 2004 to 2.2% in 2014 (P < 0.05). Regional differences in antibiotic susceptibility for co-trimoxazole were found being the highest in the west (88%) and the lowest in the north (72%, P = 0.021). Ciprofloxacin susceptibility was related to antibiotic use in the past 3 months (97% no use versus 90% use, P = 0.002) and age > 70 years (P = 0.005). In 2014, prescription of fosfomycin increased compared to 2009 (14.3% versus 5.6%) at the expense of co-amoxiclav, co-trimoxazole, and fluoroquinolones (P < 0.05). The susceptibility percentages to most antimicrobial agents tested were stable over 10 years’ period although the prevalence of E. coli and ESBLs significantly increased. Performance of a survey with regular intervals is warranted.

Pivmecillinam compared to other antimicrobials for community-acquired urinary tract infections with Escherichia coli, ESBL-producing or not - a retrospective cohort study

Objectives

To compare the therapeutic effect of pivmecillinam and other common oral antibiotics for community-acquired urinary tract infections (UTIs) caused by Extended Spectrum Beta-Lactamase (ESBL)- or non-ESBL-producing Escherichia coli.

Methods

Retrospective cohort study from 2010 to mid-2016 with data from the regional Laboratory Database and three national databases on antibiotic prescriptions, hospital admission, and mortality, respectively. Primary care patients (≥18 years) empirically treated for UTI caused by non-ESBL- or ESBL-producing E. coli (non-ESBL and ESBL E. coli) were included. Seven antibiotics, commonly used empirically for UTI, were investigated. Treatment failure measured as the redemption of a new antibiotic prescription or admission to hospital due to UTI. Cox proportional hazard ratios and adjusted risk differences along with 95% confidence intervals were calculated for 14 and 30 days, respectively.

Results

Thirty-six thousand two hundred and ninety-three (95.7%) and 1624 (4.3%) cases were included in the non-ESBL and ESBL groups, respectively. Male sex, high age, ESBL production, and resistance to empirical therapy were found to independently increase the risk of treatment failure. Compared to pivmecillinam, ciprofloxacin had significantly lower treatment failure for non-ESBL E. coli, but significantly higher treatment failure in ESBL E. coli. There was no significant difference between nitrofurantoin and pivmecillinam.

Conclusion

All antibiotics seem to have a higher risk of treatment failure for UTI caused by ESBL-producing E. coli as compared to non-ESBL-producing E. coli. At present, nitrofurantoin and pivmecillinam seem to be the most relevant orally available therapies for E. coli UTI. Local resistance data should guide which of the two that should be the contemporary first-line option.

Pivmecillinam for Uncomplicated Lower Urinary Tract Infections Caused by Staphylococcus saprophyticus-Cumulative Observational Data from Four Recent Clinical Studies

Objectives: To investigate pivmecillinam´s efficacy in uncomplicated lower urinary tract infection (UTI) caused by Staphylococcus saprophyticus-considered non-susceptible to mecillinam. Methods: Participants with confirmed UTIs caused by S. saprophyticus from four randomized controlled trials, where pivmecillinam was empirically given to females with symptoms of UTIs. The primary outcome was defined as a cumulative clinical effect-symptom resolution during the first eight days of therapy, without a recurrence of UTI symptoms in the long-term follow-up (approximately four weeks). Secondary outcomes included the bacteriological effect-elimination of the causative agent, with or without new uropathogenic bacteria present in the first control urine sample. Significant bacteriuria was defined as ≥103 bacteria/mL. The antibiotic susceptibility testing was done by disc diffusion methodology, according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Results: Seventy-four females (18-55 years) were empirically treated with pivmecillinam for UTIs caused by S. saphrophyticus (mean age 25 years; standard deviation (SD) 5.8). The cumulative clinical effect was 53/74 (72%), and the bacteriological effect was 51/59 (86%). Conclusion: Pivmecillinam showed a high clinical and bacteriological effect in UTIs caused by S. saprophyticus in these four clinical trials. The characterization of non-susceptibility for mecillinam regarding the treatment of UTIs caused by this common pathogen may need to be revised.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Second nationwide surveillance of bacterial pathogens in patients with acute uncomplicated cystitis conducted by Japanese Surveillance Committee from 2015 to 2016: antimicrobial susceptibility of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus saprophyticus

The Japanese Surveillance Committee conducted a second nationwide surveillance of antimicrobial susceptibility patterns of uropathogens responsible for acute uncomplicated cystitis (AUC) in premenopausal patients aged 16-40 years old at 31 hospitals throughout Japan from March 2015 to February 2016. In this study, the susceptibility of causative bacteria (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus) for various antimicrobial agents was investigated by isolation and culturing of organisms obtained from urine samples. In total, 324 strains were isolated from 361 patients, including E. coli (n = 220, 67.9%), S. saprophyticus (n = 36, 11.1%), and K. pneumoniae (n = 7, 2.2%). The minimum inhibitory concentrations (MICs) of 20 antibacterial agents for these strains were determined according to the Clinical and Laboratory Standards Institute (CLSI) manual. At least 93% of the E. coli isolates showed susceptibility to fluoroquinolones and cephalosporins, whereas 100% of the S. saprophyticus isolates showed susceptibility to fluoroquinolones and aminoglycosides. The proportions of fluoroquinolone-resistant and extended-spectrum β-lactamase (ESBL)-producing E. coli strains were 6.4% (13/220) and 4.1% (9/220), respectively. The antimicrobial susceptibility of K. pneumoniae was retained during the surveillance period, while no multidrug-resistant strains were identified. In summary, antimicrobial susceptibility results of our second nationwide surveillance did not differ significantly from those of the first surveillance. Especially the numbers of fluoroquinolone-resistant and ESBL-producing E. coli strains were not increased in premenopausal patients with AUC in Japan.

Label-free detection of Escherichia coli bacteria by cascaded chirped long period gratings immunosensor

An optical fiber based immunosensing platform formed by two identical chirped long period gratings (CLPGs) for sensitive and label-free detection of Escherichia coli (E. coli) is presented. The proposed immunosensor having two CLPGs with an inter-grating space (IGS) works like a Mach-Zehnder interferometer. The important feature of this sensor is that by changing the refractive index (RI) induced phase at the IGS region, a corresponding shift in resonance wavelength can be realized without affecting the actual grating region. Additionally, the confining bandwidth of the interference fringes promotes greater resolution in the resonance wavelength analysis of the transmission spectrum. The main aim of this study was the specific and rapid detection of the E. coli bacteria in phosphate buffer saline (detection range: 10 cfu/ml to 60 cfu/ml) by using the bio-functionalized IGS region as a sensing probe of the dual CLPG structure. The observed detection limit was 7 cfu/ml. For specificity analysis, Salmonella typhimurium and Staphylococcus aureus were tested and no significant shift in resonance wavelength was observed. In addition, the proposed immunosensor has the ability to selectively detect E. coli in real samples including lake water. The high specificity, good sensitivity to ambient RI, and robustness of the developed sensing platform will open a new avenue in optical immunosensing technology, and cascaded long CLPG sensors can contribute significantly to the detection of pathogenic bacteria in water and food samples.

Antibiotic resistance of pathogens causing uncomplicated urinary tract infections in Russian Federation

Introduction.The choice of antibiotic for the treatment of uncomplicated urinary tract infections (UTI) is mainly carried out empirically. At the same time, it should correspond to local data on the sensitivity of uropathogens to antibacterial drugs. If the level of uropathogen resistance in the region is more than 10-20% to any antibiotic, its use should be limited to empirical therapy.

Purpose of research.Identify the structure of pathogens of uncomplicated UTIs and determine the dynamics of their sensitivity to the most commonly used antibacterial drugs.

Materials and methods.This article presents a summary data of Russian multicenter epidemiological on the etiology of uncomplicated UTIs and the resistance of pathogens to antibiotics. The study are included female outpatients meeting the following criteria: 1) non-pregnant women over 18; 2) the presence of lower UTIs (acute or exacerbation of chronic cystitis); 3) uropathogen isolation > 103 CFU/ml with a positive test results for the presence of leukocytes in the urine and >105 CFU/ml for any test results for the presence of leukocytes in the urine.

Results.The most frequent uropathogen causing uncomplicated UTI is E. coli, which is excreted in 72.4% - 90.6% of patients. Cephalosporins of the third generation (cefixime), Nitrofurantoin, Fosfomycin have a high microbiological activity against E. coli, the frequency of resistant strains to them is 0%, 0-1.9% and 0%, respectively. The persistently high resistance of E. coli strains is determined to Ampicillin (33.1% - 41.5%) and Co-trimoxazole (19.3% - 26.2%). For non-fluorinated and fluorinated quinolones, there is a tendency to increase the proportion of resistant strains during the study period.

Conclusions.High generation Cephalosporins (cefixime), Nitrofurantoin, Fosfomycin have high activity against uropathogens сausing uncomplicated UTI. Ampicillin and Co-trimoxazole cannot be considered the drugs of choice for the treatment of uncomplicated UTI according to currently established criteria.

Antimicrobial Resistance and Molecular Characterization of Extended-Spectrum β-Lactamases of Escherichia coli and Klebsiella spp. Isolates from Urinary Tract Infections in Southern Brazil

The objective of this study was to evaluate the frequency of different extended-spectrum β-lactamases (ESBL) as well as to associate these ESBL with antimicrobial (ATM) resistance in Escherichia coli and Klebsiella spp. isolates from outpatients and inpatients with urinary tract infections. The study included 435 consecutive nonduplicate clinical isolates, including 362 E. coli isolates, 62 Klebsiella pneumoniae isolates, and 11 K. oxytoca isolates. Isolates were obtained from patients who were treated in a University Hospital between August 2012 and July 2013. Three multiplex PCR were performed to identify the ESBL groups. A total of 48 (11%) ESBL-producing isolates were found. The risk for the ESBL presence was significantly higher in males (26.4%) than females (8%), from hospital-acquired infections (29.1%) than community-acquired infections (7.0%) and in Klebsiella spp. (27.4%) than in E. coli (7.7%). ESBL-producing isolates presented a significantly higher percentage of resistance in 21 of the 23 ATMs analyzed. The CTX-M-1 group was the most predominant ESBL identified. The bla_{CTX-M-1-group} gene was found in 56% of the total ESBL producers from community and in 42.4% from hospital origins; it was followed in frequency by the bla_{CTX-M-8/25-group}, also found in both environments. Klebsiella spp. presented the largest variety of β-lactamase enzyme combinations and a higher level of resistance to cefotaxime. These findings contribute to better knowledge of the epidemiology of ESBL enzymes and are alarming for the reduced therapeutic options available for the risk groups identified in the studied populations.

Antibiotic-Resistant E. coli in Uncomplicated Community-Acquired Urinary Tract Infection

BACKGROUND

Routine urine culture testing is not recommended for uncomplicated urinary tract infections (UTIs). As a result, the antibiotic resistance patterns or the organisms causing UTIs are not adequately reflected in routine data. We studied the sensitivity of Escherichia coli (E. coli) to trimethoprim (TMP) and to cotrimoxazole (i.e., trimethoprim/sulfamethoxazole, TMP/SMX) in community-acquired UTI and compared the findings with the resistance data of the Antimicrobial Resistance Surveillance System (ARS).

METHODS

General practitioners and internists in private practice prospectively recruited all of their adult patients with symptoms of a urinary tract infection from May 2015 to February 2016. Urine specimens from all patients were tested (including urine culture testing and antibiotic susceptibility) and infections were defined as uncomplicated or complicated UTIs.

RESULTS

1245 participants from 58 medical practices were enrolled in the study. Pathogenic organisms were found in the urine of 877 patients, of whom 74.5% had E. coli infections. Among the E.-coli-positive UTIs, 52.4% were classified as uncomplicated and 47.6% as complicated. The prevalence of E. coli that was resistant to TMP and to TMP/SMX in uncomplicated UTIs was 15.2% and 13.0%, respectively, compared to 25.3% and 24.4%, respectively, from all UTIs in ARS in 2015. Study participants who had previously taken antibiotics had the highest prevalence of E. coli resistance (30.9%), followed by those who had two or more UTIs within the past six months (28.9%).

CONCLUSION

E. coli with resistance to TMP was significantly less prevalent among the study patients with uncomplicated UTIs than in the routine data of the ARS. Accordingly, TMP should still be considered as an option for the treatment of uncomplicated UTIs. TMP/SMX is considered the agent of second choice because of its side effects. Surveillance systems based on routine data do not yield a representative sample for the evaluation of the resistance situation in patients with uncomplicated UTIs.

Synthesis and evaluation of thiomannosides, potent and orally active FimH inhibitors

FimH is a type I fimbrial lectin located at the tip of type-1 pili of Gram-negative uropathogenic Escherichia coli (UPEC) guiding its ability to adhere and infect urothelial cells. Accordingly, blocking FimH with small molecule inhibitor is considered as a promising new therapeutic alternative to treat urinary tract infections caused by UPEC. Herein, we report that compounds having the S-glycosidic bond (thiomannosides) had improved metabolic stability and plasma exposures when dosed orally. Especially compound 5h showed the potential to inhibit biofilm formation and also to disrupt the preformed biofilm. And compound 5h showed prophylactic effect in UTI model in mice.

Mecillinam for the treatment of acute pyelonephritis and bacteremia caused by Enterobacteriaceae: a literature review

Purpose

The pharmacokinetic properties of mecillinam (MEC) for urinary tract infections are excellent, and the resistance rate in Enterobacteriaceae is low compared to other recommended antibiotics. The oral prodrug pivmecillinam (P-MEC) has been used successfully as first choice for cystitis in the Nordic countries for many years. Norwegian and Danish guidelines also recommend P-MEC for acute uncomplicated pyelonephritis (AUP) and intravenous (IV) MEC for suspected urosepsis (only in Denmark). Here, we wish to present an updated investigation on the clinical data behind these recommendations together with sparse but more current clinical data.

Methods

Prospective clinical trials evaluating MEC as monotherapy or in polytherapy with one other beta-lactam (mostly ampicillin [AMP]) for pyelonephritis or bacteremia were reviewed. Outcomes of primary interest were clinical and bacteriological success and relapse, respectively. Search databases used were PubMed, Cochrane Library, and Embase.

Results

Twelve clinical studies (1979-2015) were included in this integrated literature review. Clinical success was seen in 38/51 (75%) patients treated with MEC as monotherapy and in 152/164 (93%) patients treated with MEC and one other beta-lactam. Bacteriological success was seen in 35/47 (74%) and 117/167 (70%) patients treated with MEC alone and with one other beta-lactam, respectively. In complicated infections, bacteriological success was much lower. Clinical relapse rate was not well described. Several uropathogenic bacteremia cases were treated successfully with MEC alone (ie, 10/15 [67%] and 13/15 [87%] for clinical and bacteriological success, respectively) or with one other beta-lactam (ie, 57/65 [88%] and 53/63 [84%] for clinical and bacteriological success, respectively). However, data on bacteremia are very sparse. Adverse reactions were few and mild (73/406 [18%]) and primarily seen when AMP was co-administered (69/73 [95%]). No serious adverse reactions were reported.

Conclusion

IV MEC or oral P-MEC for 14 days may be suitable for the treatment of AUP and pediatric pyelonephritis. Randomized controlled trials using a single standardized dose of P-MEC compared to other current recommendations are warranted. Similarly, more evidence is required before MEC should be recommended for bacteremia or sepsis due to Enterobacteriaceae.

Stopping the effective non-fluoroquinolone antibiotics at day 7 vs continuing until day 14 in adults with acute pyelonephritis requiring hospitalization: A randomized non-inferiority trial

Objective

To evaluate whether stopping the effective antibiotic treatment following clinical improvement at Day 7 (Truncated treatment) would be non-inferior to continued treatment until Day 14 (Continued treatment) in patients with acute pyelonephritis (APN) requiring hospitalization treated with non-fluoroquinolone (non-FQ) antibiotics.

Methods

Hospitalized adult men and non-pregnant women with culture-confirmed APN were eligible for participation after they had clinically improved following empirical or culture-guided treatment with intravenous non-FQ antibiotic(s). We excluded patients with severe sepsis, abscesses, prostatitis, recurrent or catheter-associated urinary tract infection, or urinary tract obstruction. We randomized eligible patients on Day 7 of effective treatment and assessed them at Weeks 1 and 6 after treatment completion. The primary outcome was retreatment for recurrent urinary tract infection. The prespecified non-inferiority margin was 15%.

Results

Between March 17, 2015 and August 22, 2016, we randomly allocated 54 patients—27 patients in each arm. Twenty-four (44%) patients were male, and 26 (48%) had diabetes mellitus. Escherichia coli was the most common urinary isolate (47 [87%] patients); 36 (78%) were resistant to ciprofloxacin. In all, 41 (76%) patients received amikacin-based treatment. At the end of 6 weeks, no patient in the truncated treatment arm required retreatment, whereas 1 patient in the continued treatment arm was retreated. Difference (90% CI) in retreatment was −3.7% (−15.01% to 6.15%). Upper bound of the difference (6.15%) was below the prespecified limit, establishing non-inferiority of truncated treatment. Asymptomatic bacteriuria at Week 6 was similar between the two arms (3/24 vs. 3/26; P = 1.0). Patients in the truncated treatment arm had significantly shorter hospital stay (8 [7–10] vs. 14 [14–15] days; P < 0.001) and less antibiotic consumption per patient (8.4 ± 2.8 vs. 17.4 ± 8.3 DDDs; P < 0.001).

Conclusion

Stopping the effective non-FQ antibiotics following clinical improvement at Day 7 is non-inferior to continued treatment until Day 14 in selected patients with APN requiring hospitalization.

Trial registration

Clinical Trials Registry-India; CTRI/2016/04/006810.

Clonal relationships, antimicrobial susceptibilities, and molecular characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolates from urinary tract infections and fecal samples in Southeast Iran

INTRODUCTION

Multidrug-resistant (MDR) Escherichia coli, a species that is a leading cause of urinary tract infections (UTIs) and is a major global public health concern. This study was designed to detect the differences in antibiotic resistance patterns, the production and type of extended spectrum β-lactamases (ESBLs), and the clonal relationships among E. coli isolates from UTIs and fecal samples.

METHODS

Antibacterial resistance was determined by the disk diffusion method. ESBL, carbapenemase, and AmpC-producing isolates were detected phenotypically. Then, the ESBL genes were sequenced to detect the type. Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was performed on the ESBL-positive isolates.

RESULTS

The most common effective antibacterial agents were colistin, imipenem, and amikacin. Among the isolates, 204 (56.6%) were MDR. Of the 163 ESBL-positive isolates, 11 (6.7%) produced AmpC, and the frequencies of beta-lactamase-positive genes were as follows: bla CTX-Mgroup1, 76%; bla TEM1, 74.8%; bla SHV12, 1.2%; and bla OXA1, 12.88%. ERIC PCR showed a diverse pattern, suggesting that clonal spread of E. coli in this area is uncommon, and that most of the infecting strains are endogenous.

CONCLUSIONS

The high rates of antibacterial-resistant and MDR isolates are quite important since these strains can act as source of resistant bacteria that can be spread in the community. Controlling antibiotic use, against inappropriate use and abuse, in the community and continuous surveillance of emerging resistance traits are critical to controlling the spread of resistance.

High Prevalence of CTX-M-1-Like Enzymes in Urinary Isolates of Escherichia coli in Guayaquil, Ecuador

Escherichia coli is one of the major causes of urinary tract infections in primary healthcare, and treatment is more complicated due to the increase in antibiotic resistance. Extended-spectrum β-lactamases are the most common mechanism of resistance against third-generation cephalosporin, and CTX-M-like are among the most prevalent. The aim of our work is to investigate the prevalence of bla_CTX-M in isolates of E. coli obtained from samples of patients without previous known contact with the hospital. Ninety-four E. coli isolates with resistance to third-generation cephalosporin were collected between 2008 and 2013 in Guayaquil, Ecuador. Polymerase chain reaction, followed by sequencing, was performed to identify the type of bla_CTX-M-Like. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was carried out to determine the clonal relationship between isolates. These results show an increase in resistance to third-generation cephalosporin from 10.58% to 23.96%. CTX-M-15 was the most prevalent mechanism of resistance being that the isolates were not clonal. Overall, these results show an increase in antibiotic resistance in the community over time, suggesting that more precise antibiotic stewardship needs to be implemented to control the dissemination of antibiotic-resistant bacteria in this region.

Impact of Clinical and Laboratory Standards Institute breakpoint changes on susceptibility rates of cephalosporins in uncomplicated urinary tract infections caused by Enterobacteriaceae

Breakpoint changes may impact cephalosporin susceptibility rates in uncomplicated urinary tract infections (uUTIs). Applying the ≤16-mg/L breakpoint to urine cultures from adult women in an academic health system resulted in cefazolin being the most active uUTI antimicrobial, with 86.9% susceptibility, compared to levofloxacin (80%), nitrofurantoin (76.5%), and sulfamethoxazole-trimethoprim (72.6%).

Clinical isolates of Escherichia coli solely resistant to mecillinam: prevalence and epidemiology

In routine susceptibility testing of Gram-negative bacteria, a particular resistance phenotype was observed: an Escherichia coli isolate from a urine sample exhibited resistance solely to mecillinam (MEC) but was fully susceptible to other β-lactam antibiotics (MEC-R-BL-S). The objectives as this study were to determine the prevalence of this phenotype and to describe the phenotype, molecular epidemiology and genetic background. Between 1 January 2014 and 31 January 2016, MEC-R-BL-S E. coli isolates from urine were collected and genes previously reported as mostly involved in MEC resistance were analysed. The genetic relatedness among isolates was investigated by repetitive element sequence-based PCR (rep-PCR) and multilocus sequence typing (MLST). Ten MEC-R-BL-S isolates were collected, accounting for 0.4% (10/2547) of all E. coli obtained from urine samples, 0.9% (10/1135) of ampicillin-susceptible E. coli isolates and 9.6% (10/104) of MEC-R E. coli isolates. The isolates appeared as small colonies with round morphology and had impaired fitness. The isolates were not clonal and belonged to various extraintestinal or commensal E. coli phylogroups. Mutations in the cysB gene were evidenced in all clinical isolates. In conclusion, microbiologists should be aware of these isolates with a particular susceptibility phenotype, which is not due to error in disk diffusion but is a real non-enzymatic antibiotic resistance pattern.