Association of Fluoroquinolone Prescribing Rates With Black Box Warnings from the US Food and Drug Administration

Association of outpatient fluoroquinolone prescribing with the National Medical Products Administration announcements of label changes in China

BACKGROUND

In 2017 and 2021, the National Medical Products Administration (NMPA) announced to revise the drug label of fluoroquinolones. We aimed to evaluate the association of fluoroquinolone prescribing with the NMPA announcements of label changes.

RESEARCH DESIGN AND METHODS

Monthly prevalence of fluoroquinolone prescriptions for uncomplicated urinary tract infections (uUTI), acute exacerbation of chronic bronchitis (AECB), and acute sinusitis (AS) between 2016 and 2022 was calculated, and interrupted time series analysis was applied to assess the impacts of NMPA label changes on fluoroquinolone use.

RESULTS

Prevalence of fluoroquinolone prescriptions decreased by 2.39% (95% CI, -4.72% to -0.07%) for uUTI but increased by 3.02% (95% CI, 1.71% to 4.34%) for AS immediately after the 2017 label change. Moreover, after the 2021 label change, fluoroquinolone use decreased shortly in all the three indications. However, a significant increasing trend was observed in fluoroquinolone use for AECB episodes, and fluoroquinolons were used for 61.4% of treated uUTI, 31.6% of treated AECB, and 5.42% of treated AS at the end of 2022, respectively.

CONCLUSIONS

The label changes issued by the NMPA had no substantial impacts on fluoroquinolone prescribing in the study region in China. Fluoroquinolone prescribing was still highly prevalent for uUTI and AECB and thus requiring further antimicrobial stewardship.

Antibiotic Use in Hospital Urinary Tract Infections After FDA Regulation

BACKGROUND

The FDA issued a "black box" warning regarding risks of fluoroquinolones in 2008 with updates in 2011, 2013, and 2016.

OBJECTIVE

To examine antimicrobial use in hospital-treated UTIs from 2000 to 2020.

DESIGN

Cross-sectional study with interrupted time series analysis.

PARTICIPANTS

Patient encounters with a diagnosis of UTI from January 2000 to March 2020, excluding diagnoses of renal abscess, chronic cystitis, and infection of the gastrointestinal tract, lungs, or prostate.

MAIN MEASURES

Monthly use of fluoroquinolone and non-fluoroquinolone antibiotics were assessed. Fluoroquinolone resistance was assessed in available cultures. Interrupted time series analysis examined level and trend changes of antimicrobial use with each FDA label change.

KEY RESULTS

A total of 9,950,790 patient encounters were included. From July 2008 to March 2020, fluoroquinolone use declined from 61.7% to 11.7%, with similar negative trends observed in inpatients and outpatients, age ≥ 60 and < 60 years, males and females, patients with and without pyelonephritis, and across physician specialties. Ceftriaxone use increased from 26.4% encounters in July 2008 to 63.6% of encounters in March 2020. Among encounters with available culture data, fluoroquinolone resistance declined by 28.9% from 2009 to 2020. On interrupted time series analysis, the July 2008 FDA warning was associated with a trend change (-0.32%, < 0.001) and level change (-5.02%, p < 0.001) in monthly fluoroquinolone use.

CONCLUSIONS

During this era of "black box" warnings, there was a decline in fluoroquinolone use for hospital-treated UTI with a concomitant decline in fluoroquinolone resistance and rise in ceftriaxone use. Efforts to restrict use of a medication class may lead to compensatory increases in use of a single alternative agent with changes in antimicrobial resistance profiles.

The devil's in the defaults: An interrupted time-series analysis of the impact of default duration elimination on exposure to fluoroquinolone therapy

OBJECTIVE

To determine whether removal of default duration, embedded in electronic prescription (e-script), influenced antibiotic days of therapy.

DESIGN

Interrupted time-series analysis.

SETTING

The study was conducted across 2 community hospitals, 1 academic hospital, 3 emergency departments, and 86 ambulatory clinics.

PATIENTS

Adults prescribed a fluoroquinolone with a duration <31 days.

INTERVENTIONS

Removal of standard 10-day fluoroquinolone default duration and addition of literature-based duration guidance in the order entry on December 19, 2017. The study period included data for 12 months before and after the intervention.

RESULTS

The study included 35,609 fluoroquinolone e-scripts from the preintervention period and 31,303 fluoroquinolone e-scripts from the postintervention period, accounting for 520,388 cumulative fluoroquinolone DOT. Mean durations before and after the intervention were 7.8 (SD, 4.3) and 7.7 (SD, 4.5), a nonsignificant change. E-scripts with a 10-day duration decreased prior to and after the default removal. The inpatient setting showed a significant 8% drop in 10-day e-scripts after default removal and a reduced median duration by 1 day; 10-day scripts declined nonsignificantly in ED and ambulatory settings. In the ambulatory settings, both 7- and 14-day e-script durations increased after default removal.

CONCLUSION

Removal of default 10-day antibiotic durations did not affect overall mean duration but did shift patterns in prescribing, depending on practice setting. Stewardship interventions must be studied in the context of practice setting. Ambulatory stewardship efforts separate from inpatient programs are needed because interventions cannot be assumed to have similar effects.

The Diagnosis and Treatment of Adult Urinary Tract Infections in the Emergency Department

Emergency medicine has been called the art of "making complicated clinical decisions with limited information." This description is particularly relevant in the case of diagnosis and treatment of urinary tract infections (UTIs). Although common, UTIs are often challenging to diagnose given the presence of non-specific signs and symptoms and over-reliance on laboratory findings. This review provides an interdisciplinary interpretation of the primary literature and practice guidelines, with a focus on diagnostic and antimicrobial stewardship in the emergency department.

Gyrase and Topoisomerase IV: Recycling Old Targets for New Antibacterials to Combat Fluoroquinolone Resistance

Beyond their requisite functions in many critical DNA processes, the bacterial type II topoisomerases, gyrase and topoisomerase IV, are the targets of fluoroquinolone antibacterials. These drugs act by stabilizing gyrase/topoisomerase IV-generated DNA strand breaks and by robbing the cell of the catalytic activities of these essential enzymes. Since their clinical approval in the mid-1980s, fluoroquinolones have been used to treat a broad spectrum of infectious diseases and are listed among the five "highest priority" critically important antimicrobial classes by the World Health Organization. Unfortunately, the widespread use of fluoroquinolones has been accompanied by a rise in target-mediated resistance caused by specific mutations in gyrase and topoisomerase IV, which has curtailed the medical efficacy of this drug class. As a result, efforts are underway to identify novel antibacterials that target the bacterial type II topoisomerases. Several new classes of gyrase/topoisomerase IV-targeted antibacterials have emerged, including novel bacterial topoisomerase inhibitors, Mycobacterium tuberculosis gyrase inhibitors, triazaacenaphthylenes, spiropyrimidinetriones, and thiophenes. Phase III clinical trials that utilized two members of these classes, gepotidacin (triazaacenaphthylene) and zoliflodacin (spiropyrimidinetrione), have been completed with positive outcomes, underscoring the potential of these compounds to become the first new classes of antibacterials introduced into the clinic in decades. Because gyrase and topoisomerase IV are validated targets for established and emerging antibacterials, this review will describe the catalytic mechanism and cellular activities of the bacterial type II topoisomerases, their interactions with fluoroquinolones, the mechanism of target-mediated fluoroquinolone resistance, and the actions of novel antibacterials against wild-type and fluoroquinolone-resistant gyrase and topoisomerase IV.

Utilization of broad- versus narrow-spectrum antibiotics for the treatment of outpatient community-acquired pneumonia among adults in the United States

PURPOSE

To characterize antibiotic utilization for outpatient community-acquired pneumonia (CAP) in the United States.

METHODS

We conducted a cohort study among adults 18-64 years diagnosed with outpatient CAP and a same-day guideline-recommended oral antibiotic fill in the MarketScan® Commercial Database (2008-2019). We excluded patients coded for chronic lung disease or immunosuppressive disease; recent hospitalization or frequent healthcare exposure (e.g., home wound care, patients with cancer); recent antibiotics; or recent infection. We characterized utilization of broad-spectrum antibiotics (respiratory fluoroquinolone, β-lactam + macrolide, β-lactam + doxycycline) versus narrow-spectrum antibiotics (macrolide, doxycycline) overall and by patient- and provider-level characteristics. Per 2007 IDSA/ATS guidelines, we stratified analyses by otherwise healthy patients and patients with comorbidities (coded for diabetes; chronic heart, liver, or renal disease; etc.).

RESULTS

Among 263 914 otherwise healthy CAP patients, 35% received broad-spectrum antibiotics (not recommended); among 37 161 CAP patients with comorbidities, 44% received broad-spectrum antibiotics (recommended). Ten-day antibiotic treatment durations were the most common for all antibiotic classes except macrolides. From 2008 to 2019, broad-spectrum antibiotic use substantially decreased from 45% to 19% in otherwise healthy patients (average annual percentage change [AAPC], -7.5% [95% CI -9.2%, -5.9%]), and from 55% to 29% in patients with comorbidities (AAPC, -5.8% [95% CI -8.8%, -2.6%]). In subgroup analyses, broad-spectrum antibiotic use varied by age, geographic region, provider specialty, and provider location.

CONCLUSIONS

Real-world use of broad-spectrum antibiotics for outpatient CAP declined over time but remained common, irrespective of comorbidity status. Prolonged duration of therapy was common. Antimicrobial stewardship is needed to aid selection according to comorbidity status and to promote shorter courses.

Evaluation of healthcare professionals' understanding of fluoroquinolones' safety profile, usage, and boxed warnings in Pakistan

INTRODUCTION

Fluoroquinolones (FQs) is a distinct class of antibiotics which are prescribed and used quite frequently worldwide, despite the box warnings (BW) issued by Food and Drug Administration (FDA). Literature has shown in spite of BWs related to FQs there is minimal impact on health care professionals (HCPs) prescribing habits, potentially attributing towards limited and insufficient awareness. In Pakistan, FQs are mostly prescribed antibiotics for microbial treatments, therefore the purpose of this study was to determine the level of knowledge about the safety profile, use, and BW of FQs among HCPs working in Pakistan.

METHODS

A cross-sectional study was undertaken among the HCPs of Khyber Pakhtunkhwa province of Pakistan from October 2022 to December 2022. A validated questionnaire was used to assess the knowledge of HCPs regarding FQs, its safety profile and BW. A random convenient sample technique was used while recruiting HCPs in this study. As the HCPs comprised physicians, dentists, pharmacist and nurses, all were approached in person and the study objective was fully elaborated and explained to them. The statistic test like: one-way ANOVA, independent-t test, multivariate logistic regression were used keeping the p-value < 0.05 as statistically significant.

RESULTS

A total of n = 250 HCPs were approached, of which n = 186 HCPs completed the questionnaire with a response rate of 74.4%. FQs prescribing pattern was only assessed among the prescribers, i.e., physicians and dentists (39/186). The mean knowledge score for indications was 5.29 ± 3.05, while for the adverse effects was 7.70 ± 2.61. The highest score for knowledge for indications and adverse effect score was achieved by physicians followed by dentist. The mean knowledge score for the BW was 3.46 ± 2.93 and among the HCPs for the BW of FQs, 20.4% of the HCPs had appropriate knowledge score (score ≥ 50%). The knowledge score was significantly higher in males (p = 0.039), dentists (p = 0.001), HCPs having master/specialization level of education (p = 0.003), HCPs working in government sector hospitals (p = 0.010) and secondary care hospitals (p = 0.001) while the multivariate logistic regression analysis showed that HCPs working in primary care hospital (OR: 6.2) and secondary care hospital (OR: 20.3) were associated with the tendency to achieve 50% or above knowledge score.

CONCLUSION

 Findings of this study reveals the unsatisfactory knowledge of HCPs regarding the safety profile, use, and BW of FQs putting patients at heightened risks of FQs associated AEs. Therefore, it is crucial to implement a national antimicrobial stewardship program, seminars and lectures aimed at continuously updating the knowledge of HCPs, regardless of their specialties, and effectively restrict the misuse of antimicrobial and disseminate FDA BWs in clinical practice.

Longitudinal Patterns in Testosterone Prescribing After US FDA Safety Communication in 2014

BACKGROUND

The objective of this study was to describe changes in testosterone prescribing following a 2014 US Food and Drug Administration (FDA) safety communication and how changes varied by physician characteristics.

METHODS

Data were extracted from a 20% random sample of Medicare fee-for-service administrative claims data from 2011 through 2019. The sample included 1,544,604 unique male beneficiaries who received evaluation and management (E&M) services from 58,819 unique physicians that prescribed testosterone between 2011 and 2013. Patients were categorized based on presence of coronary artery disease (CAD) and non-age-related hypogonadism. Physician characteristics were identified in the OneKey database and included specialty and affiliations with teaching hospitals, for-profit hospitals, hospitals in integrated delivery networks, and hospitals in the top decile of case mix index. Linear segmented models described how testosterone prescriptions changed following a 2014 FDA safety communication and how changes were associated with physician and organizational characteristics.

RESULTS

Among 65,089,560 physician-patient-quarter-year observations, mean (standard deviation) age ranged from 72.16 (5.84) years for observations without CAD or non-age-related hypogonadism to 75.73 (6.92) years with CAD and without non-age-related hypogonadism. Following the safety communication, immediate changes in off-label testosterone prescription levels fell by 0.22 percentage points (pp) (95% confidence interval [CI] -0.33 to -0.11) for patients with CAD and by -0.16 pp (95% CI -0.19 to -0.16) for patients without CAD. A similar change was noticed in on-label prescribing levels. Off-label testosterone prescription quarterly trend, however, increased for patients with CAD and without CAD; on-label testosterone prescription trends declined for both groups. Declines in off-label prescribing were larger when treated by primary care physicians vs. non-primary care physicians, and physicians affiliated with teaching compared to nonteaching hospitals. Physician and organizational characteristics were not associated with changes in on-label prescribing.

CONCLUSION

On-label and off-label testosterone therapy declined following the FDA safety communication. Certain physician characteristics were associated with changes in off-label, but not on-label, prescribing.

Omadacycline in the treatment of community-acquired bacterial pneumonia in patients with comorbidities: a post-hoc analysis of the phase 3 OPTIC trial

Introduction

The 2019 American Thoracic Society/Infectious Disease Society of America guidelines recommend respiratory fluoroquinolones to treat community-acquired bacterial pneumonia (CABP) in adults with comorbidities. Fluoroquinolones are effective against both typical and atypical pathogens. However, fluoroquinolone treatment has a risk of adverse effects, and the Food and Drug Administration has issued black box safety warnings for their use. Inpatient use of fluoroquinolones has reduced as a result; however, most antibiotic courses are completed as outpatients and discharge prescriptions account for the majority of fluoroquinolone use. As such, a new treatment option is needed to replace fluoroquinolones. Omadacycline is an aminomethylcycline antibiotic with a broad spectrum of activity and is available as a once-daily intravenous or bioequivalent oral formulation.

Methods

This study assessed the safety and clinical efficacy of omadacycline compared with moxifloxacin for the treatment of adult CABP patients with Pneumonia Severity Index (PSI) risk class II/III and ≥1 comorbidity through a post-hoc analysis of the phase 3 OPTIC study (NCT02531438).

Results

In total, 239 omadacycline- and 222 moxifloxacin-treated patients were assessed. The median age was similar between groups (omadacycline: 57 years; moxifloxacin: 58 years), with 26.0% and 26.6%, respectively, ≥65 years of age. Early clinical response was 91.6% for patients with ≥1 comorbidity treated with omadacycline and 91.4% for those treated with moxifloxacin. Post-treatment evaluation results for overall response were 89.1% in the omadacycline group and 87.4% in the moxifloxacin group.

Conclusion

Safety warnings have reduced inpatient use of fluoroquinolones; however, outpatient and discharge prescriptions account for the majority of fluoroquinolone use. Outpatients with comorbidities need an efficacious alternative to fluoroquinolones. Omadacycline maintains the similar efficacy and benefits of fluoroquinolones as a once-daily, monotherapy, bioequivalent oral option with potent in vitro activity against the most common CABP pathogens, including S. pneumoniae and atypical pathogens, but offers a materially different safety profile consistent with its tetracycline heritage. In conclusion, both omadacycline and moxifloxacin exhibited similar efficacy in patients with PSI risk class II/III and comorbidities. Omadacycline fulfills an unmet need as an oral monotherapy treatment option for adult patients with CABP, which will further reduce the use of fluoroquinolones.

Clinical trial registration

https://www.clinicaltrials.gov/study/NCT02531438, identifer: NCT02531438; https://www.clinicaltrialsregister.eu/ctr-search/search?query=2013-004071-13, identifier: EudraCT #2013-004071-13.

In-Class Cross-Reactivity among Hospitalized Patients with Hypersensitivity Reactions to Fluoroquinolones

Results from this large, multicenter study suggest that patients with a confirmed ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction are likely to tolerate other fluoroquinolones. Avoiding different fluoroquinolones in patients labeled with a ciprofloxacin, moxifloxacin, or levofloxacin allergy may not always be mandatory. This was a study of patients with a ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction and a documented electronic medical record administration of a different fluoroquinolone. Numerically, the most common reaction risk occurred with a challenge to moxifloxacin (2/19; 9.5%), followed by ciprofloxacin (6/89; 6.3%), and levofloxacin (1/44; 2.2%).

Fluoroquinolone-Associated Movement Disorder: A Literature Review

BACKGROUND

Fluoroquinolones (FQNs) are related to several central nervous system side effects. This review aims to evaluate the clinical-epidemiological profile, pathophysiological mechanisms, and management of FQNs-associated movement disorders (MDs).

METHODS

Two reviewers identified and assessed relevant reports in six databases without language restriction between 1988 and 2022.

RESULTS

A total of 45 reports containing 51 cases who developed MDs secondary to FQNs were reported. The MDs included 25 myoclonus, 13 dyskinesias, 7 dystonias, 2 cerebellar syndromes, 1 ataxia, 1 tic, and 2 undefined cases. The FQNs reported were ciprofloxacin, ofloxacin, gatifloxacin, moxifloxacin, levofloxacin, gemifloxacin, and pefloxacin. The mean and median age were 64.54 (SD: 15.45) and 67 years (range: 25-87 years). The predominant sex was male (54.16%). The mean and median time of MD onset were 6.02 (SD: 10.87) and 3 days (range: 1-68 days). The mean and median recovery time after MD treatment was 5.71 (SD: 9.01) and 3 days (range: 1-56 days). A complete recovery was achieved within one week of drug withdrawal in 80.95% of the patients. Overall, 95.83% of the individuals fully recovered after management.

CONCLUSIONS

Future cases need to describe the long-term follow-up of the individuals. Additionally, FQN-induced myoclonus should include electrodiagnostic studies.

Impact of a Multifaceted Intervention on Antibiotic Prescribing for Cystitis and Asymptomatic Bacteriuria in 23 Community Hospital Emergency Departments

Background: Urinary tract infections (UTIs) are over-diagnosed and over-treated in the emergency department (ED) leading to unnecessary antibiotic exposure and avoidable side effects. However, data describing effective large-scale antimicrobial stewardship program (ASP) interventions to improve UTI and asymptomatic bacteriuria (ASB) management in the ED are lacking. Methods: We implemented a multifaceted intervention across 23 community hospital EDs in Utah and Idaho consisting of in-person education for ED prescribers, updated electronic order sets, and implementation/dissemination of UTI guidelines for our healthcare system. We compared ED UTI antibiotic prescribing in 2021 (post-intervention) to baseline data from 2017 (pre-intervention). The primary outcomes were the percent of cystitis patients prescribed fluoroquinolones or prolonged antibiotic durations (>7 days). Secondary outcomes included the percent of patients treated for UTI who met ASB criteria, and 14-day UTI-related readmissions. Results: There was a significant decrease in prolonged treatment duration for cystitis (29% vs 12%, P < .01) and treatment of cystitis with a fluoroquinolone (32% vs 7%, P < .01). The percent of patients treated for UTI who met ASB criteria did not change following the intervention (28% pre-intervention versus 29% post-intervention, P  = .97). A subgroup analysis indicated that ASB prescriptions were highly variable by facility (range 11%-53%) and provider (range 0%-71%) and were driven by a few high prescribers. Conclusions: The intervention was associated with improved antibiotic selection and duration for cystitis, but future interventions to improve urine testing and provide individualized prescriber feedback are likely needed to improve ASB prescribing practice.

Second-line levofloxacin-based quadruple therapy versus bismuth-based quadruple therapy for Helicobacter pylori eradication and long-term changes to the gut microbiota and antibiotic resistome: a multicentre, open-label, randomised controlled trial

BACKGROUND

Levofloxacin-based therapy or bismuth-based quadruple therapy are the recommended second-line regimens for Helicobacter pylori eradication after failure of clarithromycin-based therapy. However, resistance to levofloxacin has increased in the past decade. Furthermore, little is known about the long-term effects of H pylori eradication on the antibiotic resistome. In this study, we compared these second-line eradication therapies for efficacy, tolerability, and short-term and long-term effects on the gut microbiota, antibiotic resistome, and metabolic parameters.

METHODS

We did a multicentre, open-label, parallel group, randomised controlled trial at eight hospitals in Taiwan. Adult patients (age ≥20 years) with persistent H pylori infection after first-line clarithromycin-based therapy were randomly assigned (1:1, permuted block sizes of four) to receive levofloxacin-based sequential quadruple therapy for 14 days (EAML14; esomeprazole 40 mg and amoxicillin 1 g for 7 days, followed by esomeprazole 40 mg, metronidazole 500 mg, and levofloxacin 250 mg for 7 days, all twice-daily) or bismuth-based quadruple therapy for 10 days (BQ10; esomeprazole 40 mg twice daily, bismuth tripotassium dicitrate 300 mg four times a day, tetracycline 500 mg four times a day, and metronidazole 500 mg three times a day). All investigators were masked to the randomisation sequence. The primary endpoint was H pylori eradication rate measured by ¹³C urea breath test 6 weeks after second-line treatment according to both intention-to-treat (ITT) and per-protocol analysis. The microbiota composition and antibiotic resistome of faecal samples collected at baseline (before treatment) and at 2 weeks, 8 weeks, and 1 year after eradication therapy was profiled by shotgun metagenomic sequencing and 16S rRNA gene sequencing. The frequency of adverse effects and changes in the gut microbiota and antibiotic resistome were assessed in all participants with available data. The trial is complete and registered with ClinicalTrails.gov, NCT03148366.

FINDINGS

Between Feb 25, 2015, and Dec 11, 2020, 560 patients were randomly assigned to receive EAML14 or BQ10 (n=280 per group; 261 [47%] men and 299 [53%] women). Mean age was 55·9 years (SD 12·7) in the EAML14 group and 54·9 years (12·3) in the BQ10 group. Eradication of H pylori was achieved in 246 (88%) of 280 participants in the EAML14 group and 245 (88%) of 280 in the BQ10 group according to ITT analysis (risk difference -0·4%, 95% CI -5·8 to 5·1; p=0·90). In the per-protocol analysis, 246 (90%) of 273 participants in the EAML14 group and 245 (93%) of 264 participants in the BQ10 group achieved H pylori eradication (risk difference 2·7%, 95% CI -0·2 to 7·4; p=0·27). Transient perturbation of faecal microbiota diversity at week 2 was largely restored to basal state 1 year after EAML14 or BQ10. Diversity recovery was slower with BQ10, and recovery in species abundance was partial after both therapies. On shotgun sequencing, we observed significant increases in total resistome after EAML14 (p=0·0002) and BQ10 (p=4·3 × 10^-10) at week 2, which were restored to pretreatment level by week 8. The resistance rates of Escherichia coli and Klebsiella pneumonia to levofloxacin, ciprofloxacin, ampicillin (ampicillin-sulbactam for K pneumonia), and various cephalosporins were significantly increased in the EAML14 group compared with in the BQ10 group at week 2, which were restored to pretreatment levels and showed no significant differences at week 8 and 1 year. The frequency of any adverse effects was significantly higher after BQ10 therapy (211 [77%] of 273 participants) than after EAML14 therapy (134 [48%] of 277; p<0·0001).

INTERPRETATION

We found no evidence of superiority between levofloxacin-based quadruple therapy and bismuth-based quadruple therapy in the second-line treatment of H pylori infection. The transient increase in the antibiotic resistome and perturbation of faecal microbiota diversity were largely restored to pretreatment state from 2 months to 1 year after eradication therapy.

FUNDING

The Ministry of Science and Technology of Taiwan, the Ministry of Health and Welfare of Taiwan, National Taiwan University Hospital, Taipei Veteran General Hospital, and the Australian Federal Government through the St George and Sutherland Medical Research Foundation.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Developments in Non-Intercalating Bacterial Topoisomerase Inhibitors: Allosteric and ATPase Inhibitors of DNA Gyrase and Topoisomerase IV

Increases in antibiotic usage and antimicrobial resistance occurrence have caused a dramatic reduction in the effectiveness of many frontline antimicrobial treatments. Topoisomerase inhibitors including fluoroquinolones are broad-spectrum antibiotics used to treat a range of infections, which stabilise a topoisomerase-DNA cleavage complex via intercalation of the bound DNA. However, these are subject to bacterial resistance, predominantly in the form of single-nucleotide polymorphisms in the active site. Significant research has been undertaken searching for novel bioactive molecules capable of inhibiting bacterial topoisomerases at sites distal to the fluoroquinolone binding site. Notably, researchers have undertaken searches for anti-infective agents that can inhibit topoisomerases through alternate mechanisms. This review summarises work looking at the inhibition of topoisomerases predominantly through non-intercalating agents, including those acting at a novel allosteric site, ATPase domain inhibitors, and those offering unique binding modes and mechanisms of action.

Outpatient fluoroquinolone use in relation to European Medicines Agency's recommendation: An Estonian nationwide drug utilization study

PURPOSE

To determine possible changes in prescribing of fluoroquinolones in relation to the European Medicines Agency's (EMA) recommendation in October 2018.

METHODS

We conducted a nationwide time-series study on outpatient use of fluoroquinolones during January 2016-June 2021 in Estonia. Joinpoint regression was used to identify change points over time. Several subgroup analyses by prescriber specialty, indication group, risk factors for tendon injury, aortic aneurysm/dissection or heart valve regurgitation/incompetence and the prescribing of other antibiotics were performed.

RESULTS

During the study period 236 989 prescriptions of fluoroquinolones were dispensed to 142 659 persons. The number of episodes per month declined from 3780 (2.9/1000 inhabitants) to 2570 (1.9/1000 inhabitants). We identified three change points with four different trend segments: from January 2016 to November 2018 monthly percent change (MPC) -0.4%, from November 2018 to June 2019 MPC -2.5%, from June 2019 to July 2020 MPC 1.7% and from July 2020 to June 2021 MPC -3.3%. Prescribing for indications which were removed or restricted by EMA's recommendation comprised a small proportion of all fluoroquinolone episodes -2.8% and 6.3%, respectively. The risk factors for tendon injury and for cardiac disorders (aortic aneurysm/dissection or heart valve regurgitation/incompetence) were present in 46.4% and 57.8% episodes of fluoroquinolone users, respectively. No changes in the trend of prescribing to users with risk factors was detected.

CONCLUSIONS

The EMA's recommendation may have contributed to the greater decline in the use of fluoroquinolones. However, there is still a high proportion of users with predisposing factors for tendon injury and serious cardiac disorders.

Molecular mechanism of topoisomerase poisoning by the peptide antibiotic albicidin

The peptide antibiotic albicidin is a DNA topoisomerase inhibitor with low-nanomolar bactericidal activity towards fluoroquinolone-resistant Gram-negative pathogens. However, its mode of action is poorly understood. We determined a 2.6 Å resolution cryoelectron microscopy structure of a ternary complex between Escherichia coli topoisomerase DNA gyrase, a 217 bp double-stranded DNA fragment and albicidin. Albicidin employs a dual binding mechanism where one end of the molecule obstructs the crucial gyrase dimer interface, while the other intercalates between the fragments of cleaved DNA substrate. Thus, albicidin efficiently locks DNA gyrase, preventing it from religating DNA and completing its catalytic cycle. Two additional structures of this trapped state were determined using synthetic albicidin analogues that demonstrate improved solubility, and activity against a range of gyrase variants and E. coli topoisomerase IV. The extraordinary promiscuity of the DNA-intercalating region of albicidins and their excellent performance against fluoroquinolone-resistant bacteria holds great promise for the development of last-resort antibiotics.

Microbial Spectrum and Antibiotic Resistance in Patients Suffering from Penetrating Crohn's Disease

Intraabdominal abscess formation occurs in up to 30% of patients suffering from Crohn´s disease (CD). While international guidelines recommend a step-up approach with a combination of empiric antibiotic therapy and percutaneous drainage to delay or even avoid surgery, evidence about microbial spectrum in penetrating ileitis is sparse. We retrospectively assessed outcomes of 46 patients with terminal penetrating Ileitis where microbial diagnostics have been performed and compared microbial spectrum and antibiotic resistance profile of CD patients with patients suffering from diverticulitis with intraabdominal abscess formation. In both groups, the most frequently isolated pathogen was the gram-negative bacterium E. coli belonging to the family of Enterobacterales. However, overall Enterobacterales were significantly more often verifiable in the control group than in CD patients. Furthermore, microbial analysis showed significant differences regarding isolation of anaerobic pathogens with decreased frequency in patients with CD. Subgroup analysis of CD patients to evaluate a potential influence of immunosuppressive therapy on microbial spectrum only revealed that Enterobacterales was less frequently detected in patients treated with steroids. Immunosuppressive therapy did not show any impact on all other groups of pathogens and did not change antibiotic resistance profile of CD patients. In conclusion, we were able to demonstrate that the microbial spectrum of CD patients does differ only for some pathogen species without increased rate of antibiotic resistance. However, the empiric antibiotic therapy for CD-associated intra-abdominal abscess remains challenging since different points such as local epidemiological and microbiological data, individual patient risk factors, severity of infection, and therapy algorithm including non-surgical and surgical therapy options should be considered before therapeutical decisions are made.

Time-Trends of Drug-Drug Interactions among Elderly Outpatients in the Piedmont Region (Italy): A Population-Based Study

Adverse drug reactions (ADRs) are a major health problem in the primary care setting, particularly among the elderly population. While the high frequency of ADRs in the elderly has several causes, a major and common determinant is polypharmacy, which can in turn increase the risk of drug-drug interactions (DDIs). In this paper, we analyzed the drugs prescriptions dispensed to elderly outpatients, to assess changes in the prevalence of selected DDIs in the period 2013−2019. Overall, about 15% of the patients aged >65 years were poly-treated. Among them, a decreasing trend in prevalence was observed for the majority of DDIs during the study period. This trend was particularly noticeable for DDIs involving fluoroquinolones and vitamin K antagonists, where a sharp reduction of over 40% was observed. On the opposite, a small increase in prevalence was observed for the association of antidiabetics and beta-blocking agents and for that of clopidogrel and PPIs. While the occurrence of most of the considered DDIs among poly-treated elderly decreased over time, the prevalence of some of them is still worrying. The complexity of the national drug formularies, as well as the increased number of prescribing actors that are involved, further urges the update of DDI lists to be used to monitor drug appropriateness and reduce avoidable ADRs.

Combined Training Intervention Targeting Medical and Nursing Staff Reduces Ciprofloxacin Use and Events of Urinary Tract Infection

Inappropriate diagnosis of urinary tract infections (UTI) contributes to antimicrobial overuse. A combined training intervention for medical and nursing staff mainly addressing the analytic process reduced UTI events (9.20 vs. 7.36 per 1000 PD, −20.0%, p = 0.003) and the utilization rate of ciprofloxacin (11.6 vs. 3.5, −69.6 p = 0.001) in a Bavarian University Hospital. Combined training intervention—as part of an antibiotic stewardship program—can be effective in avoiding unnecessary urinalysis and reducing antibiotic consumption.

ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment

Peritoneal dialysis (PD)-associated peritonitis is a serious complication of PD and prevention and treatment of such is important in reducing patient morbidity and mortality. The ISPD 2022 updated recommendations have revised and clarified definitions for refractory peritonitis, relapsing peritonitis, peritonitis-associated catheter removal, PD-associated haemodialysis transfer, peritonitis-associated death and peritonitis-associated hospitalisation. New peritonitis categories and outcomes including pre-PD peritonitis, enteric peritonitis, catheter-related peritonitis and medical cure are defined. The new targets recommended for overall peritonitis rate should be no more than 0.40 episodes per year at risk and the percentage of patients free of peritonitis per unit time should be targeted at >80% per year. Revised recommendations regarding management of contamination of PD systems, antibiotic prophylaxis for invasive procedures and PD training and reassessment are included. New recommendations regarding management of modifiable peritonitis risk factors like domestic pets, hypokalaemia and histamine-2 receptor antagonists are highlighted. Updated recommendations regarding empirical antibiotic selection and dosage of antibiotics and also treatment of peritonitis due to specific microorganisms are made with new recommendation regarding adjunctive oral N-acetylcysteine therapy for mitigating aminoglycoside ototoxicity. Areas for future research in prevention and treatment of PD-related peritonitis are suggested.