Synergistic properties of linezolid against Enterococcus spp. isolates: a systematic review from in vitro studies

PURPOSE

Vancomycin-resistant enterococci (VRE) are a leading cause of hospital-acquired infections with limited therapeutic options. Combination of at least two antimicrobials is a possible strategy to obtain rapid and sustained bactericidal effects and overcome the emergence of resistance. We revised the literature on linezolid synergistic properties from in vitro studies to assess its activity in combination with molecules belonging to other antibiotic classes against Enterococcus spp.

METHODS

We performed a systematic review of the literature from three peer-reviewed databases including papers evaluating linezolid synergistic properties in vitro against Enterococcus spp. isolates.

RESULTS

We included 206 Enterococcus spp. isolates (92 E. faecalis, 90 E. faecium, 2 E. gallinarum, 3 E. casseliflavus, 19 Enterococcus spp.) from 24 studies. When an isolate was tested with different combinations, each combination was considered independently for further analysis. The most frequent interaction was indifferent effect (247/343, 72% of total interactions). The highest synergism rates were observed when linezolid was tested in combination with rifampin (10/49, 20.4% of interactions) and fosfomycin (16/84, 19.0%, of interactions). Antagonistic effect accounted for 7/343 (2.0%) of total interactions.

CONCLUSION

Our study reported overall limited synergistic in vitro properties of linezolid with other antibiotics when tested against Enterococcus spp. The clinical choice of linezolid in combination with other antibiotics should be guided by reasoned empiric therapy in the suspicion of a polymicrobial infection or targeted therapy on microbiological results, rather than on an intended synergistic effect of the linezolid-based combination.

Antibiotic versus cranberry in the treatment of uncomplicated urinary infection: a randomized controlled trial

OBJECTIVE

This study was designed to determine the effect of cranberry extract used in patients with single urinary tract infections.

METHODS

Patients with simple-type urinary tract infections were divided into two groups. Treatment with fosfomycin or cranberry tablet was started. On days 1, 3, and 7 of the treatment, whether there was a decrease in the complaints was evaluated with a Likert-type scale. The recovery status of urinary tract infections and the well-being of patients were compared via antibiotic and cranberry groups.

RESULTS

After the treatment, the leukocyte levels of the cranberry users were at the same level as those of the other group, and the rate of well-being and the portion of patients that reported to be "very well" on days 3 and 7 in the cranberry group was significantly higher compared with the fosfomycin group (p<0.05).

CONCLUSION

Considering the results of this study, it was determined that the patient's complaints decreased from day 3 and their well-being increased with the use of cranberry only. Specifically, on day 7, the well-being of the cranberry group was higher than that of the fosfomycin group. For this reason, cranberry is a favorable alternative to antibiotics in uncomplicated and simple urinary tract infections.

Efficacy of fosfomycin compared to second generation cephalosporin flumarin as antimicrobial prophylaxis for transrectal ultrasound-guided prostate biopsy: a single center retrospective study

BACKGROUND

Fluoroquinolone has been the historic choice of antimicrobial prophylaxis for transrectal ultrasound (TRUS) guided prostate biopsy. However, increased fluoroquinolone resistance and recent restrictions of its use for antimicrobial prophylaxis has led to the emergence of alternative agents for antimicrobial prophylaxis for TRUS guided prostate biopsy including fosfomycin and cephalosporins. This study aimed to compare the efficacy of fosfomycin and a second-generation cephalosporin flumarin as alternative antimicrobials for TRUS-guided prostate biopsy in terms of the incidence of infectious complications after TRUS-guided prostate biopsy.

METHODS

A retrospective chart review of all patients who underwent TRUS-guided prostate biopsy between November 2009 to January 2023 was undertaken. Comparison of baseline characteristics and the incidence of infectious complications was done between those who received fosfomycin as antimicrobial prophylaxis for TRUS-guided prostate biopsy and those who received flumarin. Multivariate logistic regression analysis was conducted to identify risk factors for infectious complications after TRUS-guided prostate biopsy.

RESULTS

Of 2,900 patients identified as eligible candidates for analysis, 333 (11.5%) received fosfomycin and 2,567 (88.5%) received flumarin. The overall rate of infectious complications was approximately 3% lower in patients who received fosfomycin, although such difference did not reach statistical significance (5.7% vs. 8.6%, p = 0.074). Multivariate logistic regression analysis showed that history of operation done under general anaesthesia within six months of the biopsy (odds ratio [OR]: 2.216; 95% confidence interval [CI]: 1.042-4.713; p = 0.039) and history of prior antimicrobial use within six months (OR: 1.457; 95% CI: 1.049-2.024; p = 0.025) were significant risk factors for infectious complications after TRUS-guided prostate biopsy.

CONCLUSION

Fosfomycin was comparable to second-generation cephalosporin flumarin in preventing infectious complications after TRUS-guided prostate biopsy. Coupled with its properties such as ease of administration, low adverse effects, low resistance rate, and low collateral damage, fosfomycin might be an attractive alternative antimicrobial prophylaxis for TRUS-guided prostate biopsy.

Susceptibility to Fosfomycin and Nitrofurantoin of ESBL-Positive Escherichia coli and Klebsiella pneumoniae Isolated From Urine of Pediatric Patients

BACKGROUND

Pediatric urinary tract infection (UTI) caused by extended-spectrum β-lactamase (ESBL)-positive gram-negative bacilli (GNB) has limited options for oral antibiotic treatment. The purpose of this study was to investigate the susceptibility of ESBL-positive Escherichia coli and Klebsiella pneumoniae isolates from pediatric urine samples to two oral antibiotics (fosfomycin and nitrofurantoin).

METHODS

From November 2020 to April 2022, ESBL-positive E. coli and K. pneumoniae isolates from urine samples were collected at Samsung Medical Center, Seoul, Korea. Patients over 18 years of age or with malignancy were excluded. For repeated isolates from the same patient, only the first isolate was tested. Minimum inhibitory concentrations (MICs) were measured using agar (fosfomycin) or broth (nitrofurantoin) dilution methods. MIC50 and MIC90 were measured for fosfomycin and nitrofurantoin in both E. coli and K. pneumoniae.

RESULTS

There were 117 isolates from 117 patients, with a median age of 7 months (range, 0.0-18.5 years). Among 117 isolates, 92.3% (108/117) were E. coli and 7.7% (9/117) were K. pneumoniae. Isolates from the pediatric intensive care unit (PICU) and general ward (GW) was 11.1% (13/117) and 88.9% (104/117), respectively. Among 108 E. coli isolates, MIC50 and MIC90 for fosfomycin were 0.5 μg/mL and 2 μg/mL, respectively. Fosfomycin susceptibility rate was 97.2% (105/108) with a breakpoint of 128 μg/mL. Fosfomycin susceptibility rate was significantly lower in PICU isolates than in GW isolates (81.8% vs. 99.0%, P = 0.027). For nitrofurantoin, both the MIC50 and MIC90 were 16 μg/mL. Nitrofurantoin susceptibility rate was 96.3% (104/108) with a breakpoint of 64 μg/mL based on Clinical and Laboratory Standards Institute guidelines. Among the nine K. pneumoniae isolates, the MIC50 and MIC90 for fosfomycin was 2 μg/mL and 32 μg/mL, respectively. MIC50 and MIC90 for nitrofurantoin were 64 μg/mL and 128 μg/mL, respectively.

CONCLUSION

For uncomplicated UTI caused by ESBL-positive GNB in Korean children, treatment with fosfomycin and nitrofurantoin for E. coli infections can be considered as an effective oral therapy option.

[Optimization of prevention of infectious complications during prostate biopsy]

Prostate cancer (PCa) is one of the most common malignant neoplasms in middle-aged and elderly men. Transrectal ultrasound guided prostate biopsy is the standard method for diagnosing prostate cancer but is associated with a high incidence of infectious compli-cations. A review of the literature on optimizing the prevention of infectious complications when performing transrectal prostate biopsy is presented. The main risk factors and the common measures to prevent the development of complications are discussed, including a study of using fosfomycin trometamol as the preferred drug for antibacterial prophylaxis. Fosfomycin meets the requirements for empirical prophylaxis, but further clinical studies are needed.

Rediscovering the value of fosfomycin trometamol in the era of antimicrobial resistance: A systematic review and expert opinion

The worldwide prevalence of uncomplicated lower urinary tract infections (uUTIs) caused by multidrug-resistant Escherichia coli is increasing. To address this emergency, international guidelines recommend reducing administration of fluoroquinolones, in the context of growing resistance and the long-lasting and potentially disabling side effects of these drugs. The favoured drug to replace fluoroquinolones is fosfomycin trometamol (FT), a well-known derivate of phosphonic acid with broad-spectrum activity against Gram-negative and Gram-positive bacteria, including multidrug-resistant (MDR) strains. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) recently reduced the susceptibility breakpoint for E. coli from 32 mg/L to 8 mg/L regarding FT used for uUTIs. This might lead to increased appropriate use of oral fosfomycin target therapy against E. coli and other microorganisms, and may be associated with a high likelihood of success. For species such as Klebsiella spp, particularly MDR strains, the absence of clinical breakpoints might lead to reduced use of oral fosfomycin, particularly if minimum inhibitory concentration is not available. To address this issue, this review presents an overview of the preclinical evidence on the activity of FT, and a systematic review of the clinical activity of FT in uUTIs in women, and in the prevention of infectious complications after prostate biopsy. The findings indicate that the safety and microbiological and clinical effectiveness of a single oral dose of FT are similar to that for comparator regimens with longer treatment schedules in women with uUTI, and FT can be considered a viable alternative to fluoroquinolones for antimicrobial prophylaxis in prostate biopsy. These observations and a broad clinical experience support the empirical use of FT for treating uUTI and indicate that FT is a promising candidate to effectively counteract antibiotic-resistant uUTIs throughout Europe.

Efficacy of antibiotic combinations in an experimental sepsis model with Pseudomonas aeruginosa

This study aimed to compare the efficacy of fosfomycin, colistin, tobramycin and their dual combinations in an experimental sepsis model. After sepsis was established with a Pseudomonas aeruginosa isolate (P1), antibiotic-administered rats were divided into six groups: Fosfomycin, tobramycin, colistin and their dual combinations were administered by the intravenous or intraperitoneal route to the groups. The brain, heart, lung, liver, spleen and kidney tissues of rats were cultured to investigate bacterial translocation caused by P1. Given the antibiotics and their combinations, bacterial colony counts in liver tissues were decreased in colistin alone and colistin plus tobramycin groups compared with control group, but there were no significant differences. In addition, a non-statistical decrease was found in the spleen tissues of rats in the colistin plus tobramycin group. There was a > 2 log10 CFU/ml decrease in the number of bacterial colonies in the kidney tissues of the rats in the fosfomycin group alone, but the decrease was not statistically significant. However, there was an increase in the number of bacterial colonies in the spleen and kidney samples in the group treated with colistin as monotherapy compared to the control group. The number of bacterial colonies in the spleen samples in fosfomycin plus tobramycin groups increased compared to the control group. Bacterial colony numbers in all tissue samples in the fosfomycin plus colistin group were found to be close to those in the control group. Colistin plus tobramycin combinations are effective against P. aeruginosa in experimental sepsis, and clinical success may be achieved. New in vivo studies demonstrating the ability of P. aeruginosa to biofilm formation in tissues other than the lung are warranted in future.

Antibiotic Resistance Patterns Among Uropathogens in Female Outpatients Affected by Uncomplicated Cystitis: Focus on Fosfomycin Trometamol

OBJECTIVES

To report the resistance rate against fosfomycin trometamol among outpatient women with symptoms related to urinary tract infections over a 6-year period in a multicentre, cross-sectional study.

METHODS

Urinary samples were collected from three high-volume laboratories from January 2015 to December 2020. The pattern of resistance to fosfomycin was analysed by using the Vitek II automated system.

RESULTS

A total of 7289 urinary samples were collected and 8321 strains were analysed during the study period. The most commonly isolated uropathogen was Escherichia coli (n = 6583, 79.1%). The mean resistance rate against fosfomycin was 9.7% (range 7.1-11.3). No statistically significant difference was found between the three laboratories (P = 0.53). There was no significant increase in resistance rate during the study period. The mean resistance rate against fosfomycin was higher among extended-spectrum β-lactamase (ESBL)-producing bacteria when compared with non-ESBL-producing strains (10.8% vs. 7.9%; P < 0.001).

CONCLUSION

Uropathogens isolated from women affected by cystitis remained highly susceptible to fosfomycin. These findings confirm recommendations in international guidelines that advocate fosfomycin trometamol for empirical treatment of uncomplicated cystitis in women.

The efficacy of mesenchymal stem cell treatment and colistin-fosfomycin combination on colistin-resistant Acinetobacter baumannii sepsis model

INTRODUCTION

This study examines the role of mesenchymal stem cells (MSCs) in an experimental sepsis model developed with colistin-resistant Acinetobacter baumannii (CRAB).

MATERIALS AND METHODS

BALB-c mice were divided into treatment groups (MSC, MSC + colistin (C)-fosfomycin (F), and C-F and control groups (positive and negative)). CRAB was administered to mice through intraperitoneal injection. Three hours later, C, F, and MSC were given intraperitoneally to the treatment groups. Colistin administration was repeated every 12 h, F administration was done every 4 h, and the second dose of MSC was administered after 48 h. Mice were sacrificed at 24 and 72 h. The bacterial load was determined as colony-forming units per gram (cfu/g). Histopathological examination was conducted on the left lung, liver, and both kidneys. IL-6 and C-reactive protein (CRP) levels in mouse sera were determined by enzyme-linked immunosorbent assay.

RESULTS

Among the treatment groups, the C-F group had the lowest colony count in the lung (1.24 ± 1.66 cfu/g) and liver (1.03 ± 1.08 cfu/g). The highest bacterial clearance was observed at 72 h compared to 24 h in the MSC-treated groups (p = 0.008). The MSC + C-F group showed the lowest histopathological score in the liver and kidney (p = 0.009). In the negative control group, the IL-6 level at the 24th hour was the lowest (p < 0.001). Among the treatment groups, the CRP level was the lowest in the MSC + C-F group at 24 and 72 h.

CONCLUSION

In a CRAB sepsis model, adding MSCs to a colistin-fosfomycin treatment may be beneficial in terms of reducing bacterial loads and preventing histopathological damage.

Daily fosfomycin versus levofloxacin for complicated urinary tract infections

IMPORTANCE

Concerns over resistance and safety have been identified in the current treatment regimen for complicated urinary tract infections. Fosfomycin is a drug that is routinely used for the treatment of uncomplicated cystitis. This study shows that fosfomycin could be an oral alternative as step-down therapy for the treatment of complicated urinary tract infections, with a clinical cure rate comparable to levofloxacin but a lower microbiological success rate 3 weeks from start of antibiotics.

FOVOCIP study: a multicenter randomized trial of fosfomycin versus ciprofloxacin for febrile neutropenia in hematologic patients-efficacy and microbiologic safety

BACKGROUND

Multidrug-resistant Gram-negative bacterial (MRGNB) infections represent a major public health threat. Cancer patients and, among them, hematological patients are most vulnerable to these infections. Gut colonization by MRGNB is a common phenomenon occurring during hospitalization and chemotherapy exposure. In the neutropenic phase that occurs after chemotherapy, MRGNB translocation occurs increasing patient's mortality. Fluoroquinolone prophylaxis with ciprofloxacin or levofloxacin efficacy is now being questioned due to the increase of incidence in MRGNB.

METHODS

A phase III randomized, controlled, clinical trial, open-label parallel-group with a 1:1 ratio, aimed to demonstrate the non-inferiority of oral fosfomycin versus oral ciprofloxacin for febrile neutropenia prevention in patients with acute leukemia (AL) or hematopoietic cell transplant (HSC) receptors. Weekly surveillance cultures are planned to detect gut colonization. Changes in fecal microbiome at the beginning and end of prophylaxis will also be analyzed.

DISCUSSION

This trial will provide evidence of the efficacy of an alternative drug to ciprofloxacin for febrile neutropenia prevention in high-risk hematological patients. The battery of planned microbiological studies will allow us to evaluate prospectively the microbiological safety of both pharmacological strategies in terms of the selection of MRGNB occurring in each arm. In addition, valuable information on the way in which each drug changes the fecal microbiome of the patients throughout the treatment will be generated.

TRIAL REGISTRATION

Clinical trials NCT05311254, Registered on 5 April 2022, https://clinicaltrials.gov/ct2/show/NCT05311254?term=FOVOCIP&cntry=ES&draw=2&rank=1 .

PROTOCOL VERSION

3.0, dated 20 May 2022.

Population pharmacokinetic modeling of multiple-dose intravenous fosfomycin in critically ill patients during continuous venovenous hemodialysis

The aim of this study was to investigate the pharmacokinetics of multiple-dose intravenous (i.v.) fosfomycin in critically ill patients during continuous venovenous hemodialysis (CVVHD). Non-compartmental analysis and population pharmacokinetic modeling were used to simulate different dosing regimens. We evaluated 15 critically ill patients with renal insufficiency and CVVHD undergoing anti-infective treatment with fosfomycin in our ICU. Five grams of fosfomycin were administered for 120 min every 6 h. Plasma concentrations were determined with and without CVVHD. Pharmacokinetic analysis and simulations were performed using non-linear mixed effects modelling (NONMEM). A two-compartment model with renal and dialysis clearance was most accurate in describing the pharmacokinetics of i.v. fosfomycin during CVVHD. Population parameter estimates were 18.20 L and 20.80 L for the central and peripheral compartment volumes, and 0.26 L/h and 5.08 L/h for renal and intercompartmental clearance, respectively. Urinary creatinine clearance (CLCR) represented a considerable component of renal clearance. Central compartment volume increased over time after the first dose. For patients with CLCR > 50 (90) mL/min and CVVHD, dosage should be increased to ≥ 15 (16) grams of i.v. fosfomycin across three (four) daily doses. Individual CLCR must be considered when dosing i.v. fosfomycin in critically ill patients during CVVHD.

Effectiveness of implementing a locally-developed guideline for antibiotic treatment of lower urinary tract infection in adults in Thailand

Lower urinary tract infection (UTI) is still a major concern in clinical practice, but inappropriate antibiotics are commonly prescribed in Thailand. This study aimed to develop, implement, and evaluate the effectiveness of a clinical practice guideline (CPG) for antibiotic treatment of lower UTI in adults at Siriraj Hospital which is a university hospital in Thailand. This study comprised a retrospective cohort study development phase, and a prospective cohort study implementation phase. The outcomes of treatment were compared between phases. The development and implementation phases enrolled 220 and 151 patients, respectively. The CPG compliance rate was significantly increased from 17.3% during the development phase to 43.0% during the implementation phase (p = 0.001). The rates of fluoroquinolones and cotrimoxazole use were significantly lower during implementation than during development (p < 0.001 and p = 0.027, respectively). The rates of nitrofurantoin and fosfomycin use were significantly greater during implementation than during development (p = 0.009 and p = 0.005, respectively). The overall cure rate was not significantly different between the two study phases, but implementation group patients had significantly more unfavorable prognostic factors than development phase patients. CPG-compliance group patients had a significantly higher cure rate than CPG-non-compliance group patients (p = 0.011). The cost of the initial course of antibiotics per episode was significantly higher during the implementation phase because the cost of fosfomycin is more expensive and more fosfomycin was prescribed during implementation (p = 0.047). Implementation of the locally-developed CPG was found to be effective for increasing the appropriate use of empirical antibiotics and increasing the cure rate; however, measures to improve and reinforce CPG compliance are needed.

Priorities and Progress in Gram-negative Bacterial Infection Research by the Antibacterial Resistance Leadership Group

Addressing the treatment and prevention of antibacterial-resistant gram-negative bacterial infections is a priority area of the Antibacterial Resistance Leadership Group (ARLG). The ARLG has conducted a series of observational studies to define the clinical and molecular global epidemiology of carbapenem-resistant and ceftriaxone-resistant Enterobacterales, carbapenem-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii, with the goal of optimizing the design and execution of interventional studies. One ongoing ARLG study aims to better understand the impact of fluoroquinolone-resistant gram-negative gut bacteria in neutropenic patients, which threatens to undermine the effectiveness of fluoroquinolone prophylaxis in these vulnerable patients. The ARLG has conducted pharmacokinetic studies to inform the optimal dosing of antibiotics that are important in the treatment of drug-resistant gram-negative bacteria, including oral fosfomycin, intravenous minocycline, and a combination of intravenous ceftazidime-avibactam and aztreonam. In addition, randomized clinical trials have assessed the safety and efficacy of step-down oral fosfomycin for complicated urinary tract infections and single-dose intravenous phage therapy for adult patients with cystic fibrosis who are chronically colonized with P. aeruginosa in their respiratory tract. Thus, the focus of investigation in the ARLG has evolved from improving understanding of drug-resistant gram-negative bacterial infections to positively affecting clinical care for affected patients through a combination of interventional pharmacokinetic and clinical studies, a focus that will be maintained moving forward.

Evaluation of the combination treatments with intravenous fosfomycin for carbapenem-resistant Klebsiella pneumoniae

OBJECTIVE

The aim of this study was to evaluate the combination treatments with intravenous fosfomycin for carbapenem-resistant Klebsiella pneumoniae infections in a tertiary-care center.

METHODS

Between December 24, 2018 and November 21, 2022, adult patients diagnosed with bloodstream infection or ventilator-associated pneumonia due to culture-confirmed carbapenem-resistant Klebsiella pneumoniae in the anesthesiology and reanimation intensive care units were investigated retrospectively.

RESULTS

There were a total of 62 patients fulfilling the study inclusion criteria. No significant difference was recorded in 14- and 30-day mortality among different types of combination regimens such as fosfomycin plus one or two antibiotic combinations. Hypokalemia (OR:5.651, 95%CI 1.019-31.330, p=0.048) was found to be a significant risk factor for 14-day mortality, whereas SOFA score at the time of diagnosis (OR:1.497, 95%CI 1.103-2.032, p=0.010) and CVVHF treatment (OR:6.409, 95%CI 1.395-29.433, p=0.017) were associated with 30-day mortality in multivariate analysis.

CONCLUSION

In our study, high mortality rates were found in patients with bloodstream infection or ventilator-associated pneumonia due to carbapenem-resistant Klebsiella pneumoniae, and no significant difference was recorded in 14- and 30-day mortality among different types of combination regimens such as fosfomycin plus one or two antibiotic combinations.

Cloxacillin plus fosfomycin versus cloxacillin alone for methicillin-susceptible Staphylococcus aureus bacteremia: a randomized trial

Treatment failure occurs in about 25% of patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. We assessed whether cloxacillin plus fosfomycin achieves better treatment success than cloxacillin alone in hospitalized adults with MSSA bacteremia. We conducted a multicenter, open-label, phase III-IV superiority randomized clinical trial. We randomly assigned patients (1:1) to receive 2 g of intravenous cloxacillin alone every 4 h or with 3 g of intravenous fosfomycin every 6 h for the initial 7 days. The primary endpoint was treatment success at day 7, a composite endpoint with the following criteria: patient alive, stable or with improved quick Sequential Organ Failure Assessment score, afebrile and with negative blood cultures for MSSA, adjudicated by an independent committee blinded to treatment allocation. We randomized 215 patients, of whom 105 received cloxacillin plus fosfomycin and 110 received cloxacillin alone. We analyzed the primary endpoint with the intention-to-treat approach in 214 patients who received at least 1 day of treatment. Treatment success at day 7 after randomization was achieved in 83 (79.8%) of 104 patients receiving combination treatment versus 82 (74.5%) of 110 patients receiving monotherapy (risk difference 5.3%; 95% confidence interval (CI), -5.95-16.48). Secondary endpoints, including mortality and adverse events, were similar in the two groups except for persistent bacteremia at day 3, which was less common in the combination arm. In a prespecified interim analysis, the independent committee recommended stopping recruitment for futility prior to meeting the planned randomization of 366 patients. Cloxacillin plus fosfomycin did not achieve better treatment success at day 7 of therapy than cloxacillin alone in MSSA bacteremia. Further trials should consider the intrinsic heterogeneity of the infection by using a more personalized approach. ClinicalTrials.gov registration: NCT03959345 .

Antibacterial effect of seven days exposure to ceftolozane-tazobactam as monotherapy and in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa with ceftolozane-tazobactam MICs at or above 4 mg/l in an in vitro pharmacokinetic model

OBJECTIVES

To use a pre-clinical pharmacokinetic infection model to assess the antibacterial effect of ceftolozane/tazobactam alone or in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa strains with MICs at or higher than the clinical breakpoint (MIC ≥ 4 mg/L).

METHODS

An in vitro model was used to assess changes in bacterial load and population profiles after exposure to mean human serum concentrations of ceftolozane/tazobactam associated with doses of 2 g/1 g q8h, fosfomycin concentrations associated with doses of 8 g q8h or tobramycin at doses of 7 mg/kg q24 h over 168 h.

RESULTS

Simulations of ceftolozane/tazobactam at 2 g/1 g q8h alone produced 3.5-4.5 log reductions in count by 6 h post drug exposure for strains with MIC ≤32 mg/L. The antibacterial effect over the first 24 h was related to ceftolozane/tazobactam MIC. There was subsequent regrowth with most strains to bacterial densities of >106 CFU/mL. Addition of either fosfomycin or tobramycin resulted in suppression of regrowth and in the case of tobramycin more rapid initial bacterial killing up to 6 h. These effects could not be related to either fosfomycin or tobramycin MICs. Changes in population profiles were noted with ceftolozane/tazobactam alone often after 96 h exposure but such changes were suppressed by fosfomycin and almost abolished by the addition of tobramycin.

CONCLUSIONS

The addition of either fosfomycin or tobramycin to ceftolozane/tazobactam at simulated human clinically observed concentrations reduced P. aeruginosa bacterial loads and the risk of resistance to ceftolozane/tazobactam when strains had ceftolozane/tazobactam MIC values at or above the clinical breakpoint.

Urinary pH and antibiotics, choose carefully. A systematic review

Uncomplicated urinary tract infection (UTI) is the most common bacterial infection in women. Since 1948, the relationship between urinary pH and antibiotics (ABs) has been established. We aimed to search for the best urinary pH for each family of antibiotics and to assess whether pH changes bacterial susceptibility to them. We included in vitro research and in vivo studies including one or more bacterial species and tested the effect of one or more ABs at different pH values. We also included randomized controlled clinical trials (RCTs) in uncomplicated UTI (EAU guidelines 2019 definition), choosing the ABs based on urinary pH or using an antibiotic plus urinary pH modifiers (L-methionine, vitamin C…) vs. an antibiotic and a placebo. Quadas-2 tool was used as a quality assessment of the studies and PRISMA set of items for systematic reviews. Two authors independently screened and evaluated the papers, while two additional authors individually repeated the search. A fifth researcher acted as an arbiter, and another author collaborated as a hospital pharmaceutical consultant. Alkaline-friendly antibiotics are most fluoroquinolones, aminoglycosides, trimethoprim. Acidic-friendly antibiotics are fosfomycin, tetracycline, nitrofurantoin and some β-lactams. We suggest performing urine cultures with antibiogram tests, in both acidic and alkaline media, to define the bacterial susceptibility profile. There is insufficient in vivo evidence to support whether choosing an antibiotic based on a patient's urinary pH or adding urinary pH modifiers will lead to a higher cure rate.

Phytotherapy (BNO 1045) of Acute Lower Uncomplicated Urinary Tract Infection in Women Normalizes Local Host Responses

INTRODUCTION

Acute lower uncomplicated urinary tract infection (uUTI) affects a large proportion of women. Increased antimicrobial resistance has created an urgent need for novel therapeutics and the phytotherapeutic drug BNO 1045 (Canephron® N) has previously been shown to be noninferior to standard antimicrobial stewardship. This sub-analysis from a randomized, double-blind, controlled phase III noninferiority clinical trial using BNO 1045 versus fosfomycin to treat uUTI aimed to determine how urine cytokine levels are altered by the two different treatments.

METHODS

Urine samples from a predefined subset of women diagnosed with uUTI (18-70 years) and treated with BNO 1045 (n = 58) or fosfomycin (n = 69) were analyzed for urine levels of IL-6 and IL-8, using analyte-to-creatinine ratios.

RESULTS

BNO 1045 treatment showed similar effects to fosfomycin treatment in reducing both urine IL-6 and IL-8 levels. Mean IL-6 and IL-8 levels were markedly reduced in all patients regardless of treatment. BNO 1045 treatment decreased urine IL-8 significantly (p = 0.0142) and showed a trend toward reduction of urine IL-6 (p = 0.0551). Fosfomycin treatment reduced both IL-6 and IL-8 levels significantly (p = 0.0038, <0.0001 respectively).

CONCLUSION

BNO 1045 is, in addition to reducing symptoms, comparable to fosfomycin treatment in reducing the local inflammatory response associated with uUTI.

Fosfomycin for Antibiotic Prophylaxis in Men Undergoing a Transrectal Prostate Biopsy: A Systematic Review and Meta-Analysis

Background and Objectives: To assess the effects of fosfomycin compared with other antibiotics as a prophylaxis for urinary tract infections (UTIs) in men undergoing transrectal prostate biopsies. Materials and Methods: We searched multiple databases and trial registries without publication language or status restrictions until 4 January 2022. Parallel-group randomized controlled trials (RCTs) and non-randomized studies (NRS) were included. The primary outcomes were febrile UTI, afebrile UTI, and overall UTI. We used GRADE guidance to rate the certainty of evidence of RCTs and NRSs. The protocol was registered with PROSPERO (CRD42022302743). Results: We found data on five comparisons; however, this abstract focuses on the primary outcomes of the two most clinically relevant comparisons. Regarding fosfomycin versus fluoroquinolone, five RCTs and four NRSs with a one-month follow-up were included. Based on the RCT evidence, fosfomycin likely resulted in little to no difference in febrile UTIs compared with fluoroquinolone. This difference corresponded to four fewer febrile UTIs per 1000 patients. Fosfomycin likely resulted in little to no difference in afebrile UTIs compared with fluoroquinolone. This difference corresponded to 29 fewer afebrile UTIs per 1000 patients. Fosfomycin likely resulted in little to no difference in overall UTIs compared with fluoroquinolone. This difference corresponded to 35 fewer overall UTIs per 1000 patients. Regarding fosfomycin and fluoroquinolone combined versus fluoroquinolone, two NRSs with a one- to three-month follow-up were included. Based on the NRS evidence, fosfomycin and fluoroquinolone combined may result in little to no difference in febrile UTIs compared with fluoroquinolone. This difference corresponded to 16 fewer febrile UTIs per 1000 patients. Conclusions: Compared with fluoroquinolone, fosfomycin or fosfomycin and fluoroquinolone combined may have a similar prophylactic effect on UTIs after a transrectal prostate biopsy. Given the increasing fluoroquinolone resistance and its ease to use, fosfomycin may be a good option for antibiotic prophylaxis.

Comparison of amikacin with fosfomycin as an add-on to ciprofloxacin for antibiotic prophylaxis in transrectal prostate biopsy: A single-center retrospective study

PURPOSE

To assess the effect of ciprofloxacin (CP) and fosfomycin compared with CP and amikacin in patients with a fluoroquinolone (FQ)-resistant rectal flora who have undergone transrectal ultrasound-guided prostate biopsy (TRUSPB).

MATERIALS AND METHODS

In total, 516 patients with FQ-resistant rectal flora based on rectal swab cultures were divided into two groups according to prophylactic antibiotics. Patients in both groups were administered CP (400 mg, intravenous [IV], twice daily) on the same day as TRUSPB and 1 day after biopsy. The amikacin group (n=260) was administered a single injection of amikacin (1 g, IV) 1 hour before TRUSPB, whereas the fosfomycin group (n=256) was administered fosfomycin (3 g, orally) the night before the procedure. The primary endpoint was the rate of infectious complications in the two groups.

RESULTS

Overall, 13 patients (2.5%) reported infectious complications: 12 patients (4.62%) in the amikacin group compared with 1 patient (0.39%) in the fosfomycin group (risk ratio, 0.09; 95% confidence interval [CI], 0.01-0.65), respectively, which was a statistically significant difference (p=0.017). This corresponds to a number needed to treat of 24 patients (95% CI, 15-65) to prevent one infectious complication. In the multivariate analysis to assess variables related to infectious complications, prophylactic antibiotics with added fosfomycin was associated with infectious complications (odds ratio, 0.060; 95% CI, 0.008-0.459).

CONCLUSIONS

In the era of FQ resistance, CP and fosfomycin may reduce the rate of infectious complications compared with CP and amikacin prophylaxis.

The dienogest-related cystitis in women with endometriosis: a prospective, controlled, comparative study

The aim of the study was to examine the severity of clinical symptoms of acute cystitis and the level bacteriuria in female patients who underwent to laparoscopic surgery followed by a postoperative administration of dienogest 2 mg and combined oral contraceptives pills (COCP). One hundred and forty five women who had a laparoscopic surgery prospectively were enrolled. Criteria inclusions were the age from 30 to 45 years old; body mass index (BMI) absence of previous hormonal therapy at least 6 month and recent performed a laparoscopy surgery for endometriosis. The women (n = 35) who had uterine myoma, abnormal coagulation profile; concomitant neoplastic diseases; chronic pelvic inflammatory disease and chronic recurrent cystitis were excluded from study. The female patients were assigned into both groups treatment: group I (n = 54) and group II (control, n = 56) who received dienogest 2 mg once daily and COCP, respectively. During follow-up three female patients of group I were withdrawn due to prolonged genital bleedings. The final analysis included 105 women. The patients of both groups had a low level of bacteriuria <103 CFU/ml without clinical symptoms of acute cystitis before treatment. The level of bacteriuria in-group I significantly increased from 102 to 106 CFU/ml whereas in-group II did not exceed 102 CFU/ml during 4 weeks of hormonal treatment. The differences of values of acute cystitis symptom score (ACSS) for differential, typical, quality of life domains were statistically significant after 4, 8 and 12 weeks of therapy in-group I compared with group II. During 3 months of hormonal treatment with dienogest 2 mg in group I, the acute cystitis developed in 10 (18.5%), in 19 (38%) and in 34 (68%) women at 4, 8 and 12 weeks of follow-up, respectively. All cases of acute cystitis in-group I were successfully treated with fosfomycin trometamol 3 g single dose or nitrofurantoin 50 mg four times a day during 5 days. We concluded that the dienogest might increase the level bacteriuria and severity of clinical symptoms of acute cystitis during a postoperative prophylaxis of endometriosis.Impact statementWhat is already known on this subject? Dienogest is a 19-nortestosterone derivative progestogen that is highly selective for progesterone receptors with high efficacy for reducing endometriosis-related pelvic pain syndrome. The administration of dienogest is a standard treatment option after laparoscopic excision of endometrial heterotopic tissue with prophylactic purpose. However, there are some adverse events, which are a cause for discontinuation.What do the results of this study add? Despite the low incidence of urinary tract infection (1-5.4%) reported in different studies this study has shown that there was a significant increase of level bacteriuria and severity of clinical symptoms of cystitis in the dienogest group.What are the implications of these findings for clinical practice and/or further research? The implications of these findings are that the administration of dienogest may lead to enhancing of clinical symptoms of cystitis and increasing bacteriuria in some women after operative treatment of endometriosis.

eaberry in the treatment of acute uncoplcated cystitis (BRUMI): protocol of a multicentre, randomised double-blind clinical trial

BACKGROUND

Bearberry (Arctostaphylos uva-ursi) leaf is available as a treatment of uncomplicated cystitis in several European countries. The antimicrobial activity of its extracts and some of its individual constituents has been observed in vitro; however, the efficacy of bearberry compared with standard antimicrobial therapy has not been assessed yet.

OBJECTIVE

The objective of the study is to assess the safety and non-inferiority of bearberry as an alternative therapy in the treatment of acute uncomplicated cystitis in comparison with standard antibiotic therapy (fosfomycin).

METHODS AND ANALYSIS

This is a randomised controlled double-blinded multicentre trial. Eligible patients will be premenopausal women with a sum score of ≥6 for the typical acute uncomplicated cystitis symptoms (frequency, urgency, painful urination, incomplete emptying, suprapubic pain and visible haematuria) reported on the Acute Cystitis Symptom Score (ACSS) typical domain and pyuria. Patients will be randomly assigned to receive 3 g single dose of fosfomycin powder and two placebo tablets three times a day for 7 days or B a single dose of placebo powder and two tablets containing a dry extract of Uvae ursi folium. At least 504 patients (allocated as 1:1) will need to be enrolled to access non-inferiority with a non-inferiority limit of 14% for the primary endpoint.Improvement of symptoms of uncomplicated cystitis (based on the ACSS score) at day 7 is defined as the primary endpoint, whereas several secondary endpoints such as the number and ratio of patients with bacteriuria at day 7, frequency and severity of side effects; recurrence of urinary tract infection, concurrent use of other over the counter (OTC) medications and food supplements will be determined to elucidate more detailed differences between the groups. The number of recurrences and medications taken for treatment will be monitored for a follow-up period of 90 days (80-100 days).

ETHICS AND DISSEMINATION

This study has been approved by the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (IV/4225-1/2021/EKU). The results will be disseminated by publication of peer-reviewed manuscripts.

TRIAL REGISTRATION NUMBER

NCT05055544.

Flomoxef and fosfomycin in combination for the treatment of neonatal sepsis in the setting of highly prevalent antimicrobial resistance

BACKGROUND

Neonatal sepsis is a serious bacterial infection of neonates, globally killing up to 680 000 babies annually. It is frequently complicated by antimicrobial resistance, particularly in low- and middle-income country (LMIC) settings with widespread resistance to the WHO's recommended empirical regimen of ampicillin and gentamicin.

OBJECTIVES

We assessed the utility of flomoxef and fosfomycin as a potential alternative empirical regimen for neonatal sepsis in these settings.

METHODS

We studied the combination in a 16-arm dose-ranged hollow-fibre infection model (HFIM) experiment and chequerboard assays. We further assessed the combination using clinically relevant regimens in the HFIM with six Enterobacterales strains with a range of flomoxef/fosfomycin MICs.

RESULTS

Pharmacokinetic/pharmacodynamic modelling of the HFIM experimental output, along with data from chequerboard assays, indicated synergy of this regimen in terms of bacterial killing and prevention of emergence of fosfomycin resistance. Flomoxef monotherapy was sufficient to kill 3/3 strains with flomoxef MICs ≤0.5 mg/L to sterility. Three of three strains with flomoxef MICs ≥8 mg/L were not killed by fosfomycin or flomoxef monotherapy; 2/3 of these were killed with the combination of the two agents.

CONCLUSIONS

These data suggest that flomoxef/fosfomycin could be an efficacious and synergistic regimen for the empirical treatment of neonatal sepsis in LMIC settings with prevalent antimicrobial resistance. Our HFIM results warrant further assessment of the flomoxef/fosfomycin combination in clinical trials.