Application of Monte Carlo simulation to optimise the dosage regimen of meropenem in patients with augmented renal clearance for Pseudomonas aeruginosa infection.

Objective: To optimise the dosing regimen of meropenem for treating Pseudomonas aeruginosa (PA) infections in critically ill patients with augmented renal clearance (ARC) using pharmacokinetic/pharmacodynamic (PK/PD) principles and Monte Carlo simulation (MCS). Methods: This research involves an MCS based on PK data from patients with ARC and a minimum inhibitory concentration (MIC) distribution of PA. This study simplifies the methods section, focusing on the critical aspects of simulation and target values for effective treatment. Results: The study highlights key findings and emphasises that tailored dosing based on bacterial MIC values is essential for patients with ARC. It also notes that empirical treatment in patients with ARC should consider the MIC distribution, with 2 g every (q) 6 h administered to achieve the PK/PD target, while 3 g q 6 h is effective in inhibiting resistance. Conclusion: Tailored dosing based on bacterial MIC values is crucial for patients with ARC. Prolonged infusion time alone does not enhance efficacy. Empirical treatment in patients with ARC should consider MIC distribution; a dosage of 2 g q 6 h achieves the PK/PD target, while 3 g q 6 h (≥12 g daily) inhibits resistance.

Development of an HPLC method using relative molar sensitivity for the measurement of blood concentrations of nine pharmaceutical compounds.

We developed a reliable high-performance liquid chromatographic analysis method using a relative molar sensitivity (RMS) technique that does not require an authentic, identical reference analyte material to quantify blood serum carbamazepine, phenytoin, voriconazole, lamotrigine, meropenem, mycophenolic acid, linezolid, vancomycin, and caffeine levels for routine blood concentration measurements. Carbamazepine and caffeine were also used as non-analyte reference materials to calculate the RMS of each analyte. The RMS was calculated from the ratio of the slope of the calibration equation (analyte/non-analyte reference material), then used to quantify analytes in control serum samples spiked with carbamazepine, phenytoin, voriconazole, meropenem, mycophenolic acid, linezolid or vancomycin. In addition, the concentrations of these six drugs in control serum samples determined by the proposed RMS method agreed well with that obtained using a conventional method. The proposed RMS method is a promising tool for the clinical determination of nine drugs, given the accuracy, precision, and efficiency of quantifying these analytes.

Does two-step infusion improve the pharmacokinetics/pharmacodynamics target attainment of meropenem in critically ill patients?

The optimal method for administering meropenem remains controversial. This study was conducted to explore the optimal two-step infusion strategy (TIT), and to investigate whether TIT is superior to intermittent infusion therapy (IIT) and prolonged infusion therapy (PIT). A physiologically based pharmacokinetics model for critically ill patients was established and evaluated. The validated model was utilized to evaluate the pharmacokinetics/pharmacodynamics (PK/PD) target attainment of meropenem. The PK/PD target attainment of different TITs varied greatly, and the total infusion duration and the first-step dose greatly affected these values. The optimal TIT was 0.25 g (30 min) + 0.75 g (150 min) at MICs of ≤2 mg/L, and 0.25 g (45 min) + 0.75 g (255 min) at MICs of 4-8 mg/L. The PK/PD target attainment of optimal TIT, PIT, and IIT were 100% at MICs of ≤1 mg/L. When MIC increased to 2-8 mg/L, the PK/PD target attainment of optimal TIT was similar to that of PIT and higher than IIT. In conclusion, TIT did not significantly improve the PK/PD target attainment of meropenem compared with PIT. IIT is adequate at MICs of ≤1 mg/L, and PIT may be the optimal meropenem infusion method in critically ill patients with MICs of 2-8 mg/L.

Genetic and phenotypic of Pseudomonas aeruginosa sensitive to meropenem antibiotics after exposure to meropenem.

Background and Objectives: Pseudomonas aeruginosa, drug-resistant, causes health infections. Resistance to the preferred therapy meropenem is a serious threat. This study aimed to analyze changes in meropenem minimum inhibitory concentration (MIC), changes in ampC, mexA, and oprD gene expression, and the correlation between MIC and ampC, mexA, and oprD gene expression after meropenem exposure. Materials and Methods: Ten isolates of P. aeruginosa from the Clinical Microbiology Department, Faculty of Medicine, Universitas Indonesia were used. After the bacteria were shown to be sensitive to meropenem phenotypically, intrinsic resistance genes were detected using PCR. After meropenem exposure on Days 5 and 12, sensitivity testing was carried out with the concentration gradient method and RNA was detected using real-time RT-PCR. Results: All P. aeruginosa isolates that were phenotypically sensitive to meropenem had the ampC, mexA, and oprD genes. An increase in MIC, an increase in ampC and mexA gene expression, and a decrease in oprD gene expression were observed after meropenem exposure. There was a very strong and significant correlation (p ≤ 0.05) between MIC and oprD gene expression after Day 12 of meropenem exposure. Conclusion: Although there were no significant differences in MIC and ampC, mexA, and oprD gene expression between Day 5 and Day 12, there was a very strong and significant correlation between MIC and oprD gene expression on Day 12 (p ≤ 0.05). This indicates that decreasing oprD gene expression has the potential to increase meropenem resistance in Pseudomonas aeruginosa.

Effects of meropenem supply restriction: A multicenter retrospective study.

BACKGROUND: In Japan, the supply of one generic meropenem product was restricted from August 2022 to March 2023. OBJECTIVE: To determine the effects of meropenem (MEPM) restriction. METHODS: We conducted a multicenter retrospective study comparing antimicrobial use, bacteremia mortality, and drug-resistant bacteria detected before the restriction of MEPM (control period), from September 2021 to February 2022, and after the restriction of MEPM (MEPM supply restriction period), from September 2022 to February 2023, in five institutions. RESULTS: The number of carbapenem days of therapy (DOTs) were decreased in all five institutions. Fourth-generation cephalosporin DOTs increased in all facilities, and piperacillin/tazobactam DOTs increased in four facilities. The 30-day and 90-day mortality rates were significantly higher during the MEPM supply restriction period than those during the control period. Moreover, survival time was significantly shorter during the MEPM supply restriction period than that during the control period. Multivariable analysis revealed that MEPM supply restriction, age >80 years, Pitt Bacteremia Score ≥4, platelet count <10 × 104/µL, serum albumin level <2.5 g/dL, and methicillin-resistant Staphylococcus aureus bloodstream infection were independent risk factors for 30-day mortality. The detection rates of carbapenem-resistant Pseudomonas aeruginosa and Enterobacteriaceae did not differ significantly between the two periods. CONCLUSIONS: MEPM supply restriction decreased the use of carbapenems and increased the use of other broad-spectrum antimicrobial agents, which worsened the prognosis of bacteremia. Overall, carbapenems are important drugs for the treatment of infectious diseases and are difficult to replace in unforeseen situations such as drug supply outages.

Neutropenia Induced by Ceftriaxone and Meropenem.

Neutropenia by non-chemotherapy drugs is an extremely rare idiosyncratic life-threatening drug reaction. Ceftriaxone and meropenem are widely used broad-spectrum antibiotics and are generally safe and well tolerated. The authors present a case of neutropenia induced by ceftriaxone and meropenem in an adult patient. The resolution of neutropenia occurred within 48 hours of ceftriaxone and meropenem being discontinued. Although antibiotic-induced neutropenia is uncommon, clinicians should be mindful of this adverse drug effect because of its potential development of severe neutropenia, septicaemia, septic shock, deep-seated infections and even death. Therefore, neutropenic sepsis treatment should be initiated without delay, particularly if the patient becomes septic and febrile. Granulocyte-colony stimulation factor (G-CSF) may be administered to facilitate the recovery process with daily monitoring of neutrophil count. Mortalities from antibiotic-induced neutropenia remain rare, with a range of 2.5-5%. LEARNING POINTS: Beta-lactam antibiotics and cabapenem are widely prescribed antibiotics for the treatment of various infections, but they can uncommonly cause neutropenia as adverse effects.Severe neutropenia may lead to severe life-threatening sepsis, shock and even death.Drug-induced neutropenia typically improves with the cessation of offending agents, supportive treatment and granulocyte-colony stimulating factor (G-CSF) which may shorten the recovery time.

The impact of meropenem shortage and post-prescription review and feedback on broad-spectrum antimicrobial use: An interrupted time-series analysis.

Background: Meropenem (MEPM) holds significance in treating severe infections and drug-resistant bacteria. There are concerns that antimicrobial shortages may lead to the use of alternative antimicrobials that are less effective and safer. We have responded to the MEPM shortage with post-prescription monitoring and feedback (PPRF) with no restrictions on MEPM initiation. We aimed to assess the impact of the MEPM shortage and the PPRF on broad-spectrum antimicrobial use and mortality. Methods: This retrospective study was conducted in a single hospital in Japan. The period from October 2021 to August 2022 was defined as the period before the MEPM shortage, and the period from September 2022 to March 2023 was defined as the period during the MEPM shortage. To support the appropriate use of antimicrobials during MEPM shortages, the antimicrobial stewardship team (AST) developed a list of alternatives to MEPM. An interrupted time series analysis was used to assess changes in use and mortality among patients receiving broad-spectrum antimicrobials over the study period. Discussion: The shortage of MEPM and PPRF temporarily increased the use of alternative cefepime; however, the subsequent change in days of therapy and days of coverage of broad-spectrum antimicrobials suggests a decrease in the use of these antimicrobials. Despite these shifts, the mortality rates remained stable, suggesting that the response to the shortage did not adversely affect treatment outcomes. Conclusion: In the context of antimicrobial shortages, AST support plays an important role in enabling physicians to make optimal use of antimicrobials.

Susceptibility evaluation of novel beta-lactam/beta-lactamase inhibitor combinations against carbapenem-resistant Klebsiella pneumoniae from bloodstream infections in hospitalized patients in Brazil.

Novel beta-lactams/beta-lactamase inhibitors (BIBLI) combinations are commercially available and they have been used for treating carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. Continuous surveillance of susceptibility profile and resistance mechanisms identification are necessary to monitor the evolution of resistance as these agents are used. The purpose of this study was to evaluate susceptibility rates to ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam in CRKP isolates from patients with bloodstream infection screened for a randomized clinical trial in Brazil. Minimum inhibitory concentration (MIC) was determined by gradient diffusion strip method for meropenem, ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam. Carbapenemase genes were detected by multiplex qPCR. KPC-producing isolates showing resistance to any BLBLI and NDM-producing isolates showing susceptibility to any BLBLI were further submitted to whole genome sequencing. From a total of 69 CRKP isolates, 39 were positive for blaKPC, 19 for blaNDM and 11 for blaKPC and blaNDM. KPC-producing isolates demonstrated susceptibility rates above 94% for all BLBLI. Two isolates with resistance to meropenem/vaborbactam showed a Gly and Asp duplication at OmpK36 protein and truncated ompK35 genes. All NDM-producing isolates, including KPC and NDM coproducers, demonstrated susceptibility rates for ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam of 0%, 9.1 to 21.1% and 9.1 to 26.3%, respectively. Five NDM-producing isolates that presented susceptibility to BLBLI also demonstrated alterations in porins. This study demonstrated that, although high susceptibility rates to the BLBLI were found, KPC-2 isolates can also demonstrate resistance due to porin mutations. Additionally, NDM-1 isolates can demonstrate susceptibility in vitro to the BLBLI.

Impact of continuous-infusion meropenem degradation and infusion bag changes on bacterial killing of Pseudomonas aeruginosa based on model-informed translation.

BACKGROUND: Continuous infusion of meropenem has been proposed to increase target attainment in critically ill patients, although stability might limit its practical use. This study investigated the impact of meropenem degradation and infusion bag changes on the concentration-time profiles and bacterial growth and killing of P. aeruginosa given different continuous-infusion solutions. METHODS: A semi-mechanistic pharmacokinetic-pharmacodynamic (PK-PD) model quantifying meropenem concentrations (CMEM) and bacterial counts of a resistant P. aeruginosa strain (ARU552, MIC = 16 mg/L) over 24 h was used to translate in vitro antibiotic effects to patients with severe infections. Concentration-dependent drug degradation of saline infusion solutions was considered using an additional compartment in the population PK model. CMEM, fT>MIC (time that concentrations exceed the MIC) and total bacterial load (BTOT) after 24 h were simulated for different scenarios (n = 144), considering low- and high-dose regimens (3000/6000 mg/day±loading dose), clinically relevant infusion solutions (20/40/50 mg/mL), different intervals of infusion bag changes (every 8/24 h, q8/24 h), and varied renal function (creatinine clearance 40/80/120 mL/min) and MIC values (8/16 mg/L). RESULTS: Highest deviations between changing infusion bags q8h and q24h were observed for 50 mg/mL solutions and scenarios with CMEM_24h close to the MIC, with differences (Δ) in CMEM_24h up to 4.9 mg/L, ΔfT>MIC≤65.7%, and ΔBTOT_24h≤1.1 log10 CFU/mL, thus affecting conclusions on whether bacteriostasis was reached. CONCLUSIONS: In summary, this study indicated that for continuous infusion of meropenem, eight-hourly infusion bag changes improved PK/PD target attainment and might be beneficial particularly for high meropenem concentrations of saline infusion solutions and for plasma concentrations in close proximity to the MIC.

In vitro activity of cefiderocol against European Enterobacterales, including isolates resistant to meropenem and recentß-lactam/ß-lactamase inhibitor combinations.

Carbapenem-resistant Enterobacterales represent a major health threat and have few approved therapeutic options. Enterobacterales isolates were collected from hospitalized inpatients from 49 sites in six European countries (1 January-31 December 2020) and underwent susceptibility testing to cefiderocol and ß-lactam/ß-lactamase inhibitor combinations. Meropenem-resistant (MIC >8 mg/L) and cefiderocol-susceptible isolates were analyzed by PCR, and cefiderocol-|resistant isolates by whole-genome sequencing, to identify resistance mechanisms. Overall, 1,909 isolates (including 970 Klebsiella spp., 382 Escherichia coli, and 244 Enterobacter spp.) were collected, commonly from bloodstream infections (43.6%). Cefiderocol susceptibility was higher than approved ß-lactam/ß-lactamase inhibitor combinations and largely comparable to cefepime-taniborbactam and aztreonam-avibactam against all Enterobacterales (98.1% vs 78.1%-|97.4% and 98.7%-99.1%, respectively) and Enterobacterales resistant to meropenem (n = 148, including 125 Klebsiella spp.; 87.8% vs 0%-71.6% and 93.2%-98.6%, respectively), ß-lactam/ß-lactamase inhibitor combinations (66.7%-|92.1% vs 0%-|88.1% and 66.7%-97.9%, respectively), and to both meropenem and ß-|lactam/ß-lactamase inhibitor combinations (61.9%-65.9% vs 0%-|20.5% and 76.2%-97.7%, respectively). Susceptibilities to approved and developmental ß-lactam/ß-lactamase inhibitor combinations against cefiderocol-resistant Enterobacterales (n = 37) were 10.8%-|56.8% and 78.4%-94.6%, respectively. Most meropenem-resistant Enterobacterales harbored Klebsiella pneumoniae carbapenemase (110/148) genes, although metallo-ß-lactamase (35/148) and oxacillinase (OXA) carbapenemase (6/148) genes were less common; cefiderocol susceptibility was retained in ß-lactamase producers, other than NDM, AmpC, and non-carbapenemase OXA producers. Most cefiderocol-resistant Enterobacterales had multiple resistance mechanisms, including ≥1 iron uptake-related mutation (37/37), carbapenemase gene (33/37), and ftsI mutation (24/37). The susceptibility to cefiderocol was higher than approved ß-lac|tam/ß-lactamase inhibitor combinations against European Enterobacterales, including meropenem- and ß-lactam/ß-lactamase inhibitor combination-resistant isolates. IMPORTANCE: This study collected a notably large number of Enterobacterales isolates from Europe, including meropenem- and ß-lactam/ß-lactamase inhibitor combination-resistant isolates against which the in vitro activities of cefiderocol and developmental ß-lactam/ß-lactamase inhibitor combinations were directly compared for the first time. The MIC breakpoint for high-dose meropenem was used to define meropenem resistance, so isolates that would remain meropenem resistant with doses clinically available to patients were included in the data. Susceptibility to cefiderocol, as a single active compound, was high against Enterobacterales and was higher than or comparable to available ß-lactam/ß-lactamase inhibitor combinations. These results provide insights into the treatment options for infections due to Enterobacterales with resistant phenotypes. Early susceptibility testing of cefiderocol in parallel with ß-lactam/ß-lactamase inhibitor combinations will allow patients to receive the most appropriate treatment option(s) available in a timely manner. This is particularly important when options are more limited, such as against metallo-ß-lactamase-producing Enterobacterales.

Glycine restores the sensitivity to antibiotics in multidrug-resistant bacteria.

The management of infections caused by multiresistant bacteria has become of fundamental importance for any medical practice. Glycine is the most common and the simplest non-essential amino acid in humans. Glycine is very effective in improving health and supporting growth and wellbeing of humans and animals. Instead, for many bacteria, high concentrations of glycine induce lysis or deep morphological alterations. The effect of glycine on multidrug resistant (MDR) microorganisms has not yet been extensively researched. The present study was conducted 1) to establish the effect of glycine on different nosocomial pathogens isolated during routine diagnostic investigations; 2) to determine the minimum inhibitory concentration of glycine and the type of activity performed (bacteriostatic or bactericidal) on representative isolates; 3) to test the interaction between glycine and meropenem, cefiderocol, or colistin. The data reported here show a dose-dependent activity of glycine on bacteria and its bactericidal activity on MDR bacteria. Furthermore, we found that the action of glycine restores in vitro the susceptibility of multiresistant nosocomial pathogens to the tested antibiotics.IMPORTANCEAntimicrobial resistance is a constantly growing concern throughout the world, and Italy is among the Western countries where antimicrobial resistance is most widespread. In Tuscany, carbapenemase-producing Enterobacterales are now even endemic. In this study, we challenged some resistant bacteria with a well-known molecule, glycine, the antibacterial properties of which have been known since the past century. This study could bring new insights into combining antibiotics with the simplest of all amino acids. The restoration of sensitivity to the aforementioned antibiotics by a natural compound, already used for clinical purposes, is of extreme importance in an era of proliferation of multiresistant bacteria. The in vivo use of this amino acid in evaluating its effectiveness against infections should be investigated. The low cost of this molecule can also make it easy to use even in low-income countries.

Dose rationale for the use of meropenem/vaborbactam combination in paediatric patients with Gram-negative bacterial infections.

AIMS: Meropenem/vaborbactam combination is approved in adults by FDA and EMA for complicated urinary tract infections and by EMA also for other Gram-negative infections. We aimed to characterise the pharmacokinetics of both moieties in an ongoing study in children and use a model-based approach to inform adequate dosing regimens in paediatric patients. METHODS: Over 4196 blood samples of meropenem and vaborbactam (n = 414 subjects) in adults, together with 114 blood samples (n = 39) in paediatric patients aged 3 months to 18 years were available for this analysis. Data were analysed using a population with prior information from a pharmacokinetic model in adults to inform parameter estimation in children. Simulations were performed to assess the suitability of different dosing regimens to achieve adequate probability of target attainment (PTA). RESULTS: Meropenem/vaborbactam PK was described with two-compartment models with first-order elimination. Body weight and CLcr were significant covariates on the disposition of both drugs. A maturation function was evaluated to explore changes in clearance in neonates. PTA ≥90% was derived for children aged ≥3 months after 3.5-h IV infusion of 40 mg/kg Q8h of both meropenem and vaborbactam and 2 g/2 g for those ≥50 kg. Extrapolation of disposition parameters suggest that adequate PTA is achieved after a 3.5-h IV infusion of 20 mg/kg for neonates and infants (3 months). CONCLUSIONS: An integrated analysis of adult and paediatric data allowed accurate description of sparsely sampled meropenem/vaborbactam PK in paediatric patients and provided recommendations for the dosing in neonates and infants (3 months).

Outcomes and Predictors of Mortality in Patients With KPC-Kp Infections Treated With Meropenem Vaborbactam: An Observational Multicenter Study.

Background: Meropenem-vaborbactam is a recent and promising option for the treatment of KPC-producing Klebsiella pneumoniae (KPC-Kp) infections, including those resistant to ceftazidime-avibactam. Methods: We conducted a retrospective analysis of observational data from 19 Italian hospitals on use and outcomes of patients treated with meropenem-vaborbactam for at least ≥24 hours for KPC-Kp infections. Crude and propensity-weighted multiple Cox regression models were performed to ascertain risk factors independently associated with 30-day mortality. Results: The cohort included 342 adults with bloodstream infections (n = 172) and nonbacteremic infections (n = 170), of which 107 were lower respiratory tract infections, 30 were complicated urinary tract infections, and 33 were infections involving other sites. Most infections (62.3%) were managed with meropenem-vaborbactam monotherapy, or in combination with at least 1 other active drug (usually fosfomycin, tigecycline, or gentamicin) (37.7%). The 30-day mortality rate was 31.6% (108/342). In multiple Cox regression model, 30-day mortality was independently associated with septic shock at infection onset, Charlson comorbidity index ≥ 3, dialysis, concomitant COVID-19, and INCREMENT score ≥ 8. Administration of meropenem-vaborbactam within 48 hours from infection onset was a negative predictor of mortality. All predictors, except administration of meropenem-vaborbactam within 48 hours, remained significant when the multiple Cox regression model was repeated after adjustment for the propensity score for receipt of combination therapy. Conclusions: Despite the limits of a retrospective study, the data derived from this multicenter cohort provide additional evidence on the efficacy of meropenem-vaborbactam in treating severe KPC-Kp infections, even when used as monotherapy.

Epidemiological Study on Case Definition of Methicillin-Resistant Staphylococcus aureus Enteritis.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) enteritis is a condition in which MRSA grows abnormally in the intestine after administration of antimicrobial agents, resulting in enteritis. Patients with MRSA detected in stool culture tests are often diagnosed with MSRA enteritis. However, uncertainty remains in the diagnostic criteria; therefore, we conducted epidemiological studies to define these cases. Patients and Methods: Patients who tested positive for MRSA by stool culture using selective media 48 h after admission to Kochi Medical School Hospital between April 1, 2012, and December 31, 2022, and did not meet the exclusion criteria were included. We defined MRSA enteritis (Group A) as cases that were responsive to treatment with vancomycin hydrochloride powder, had a Bristol Stool Scale of ≥ 5, and a stool frequency of at least three times per day; all others were MRSA carriers (Group B). Multivariate analysis was performed to risk factors associated with MRSA enteritis. Results: Groups A and B included 18 (25.4%) and 53 (74.6%) patients, respectively. Multivariate logistic regression analysis showed that a white blood cell count of > 10000/µL (odds ratio [OR], 5.50; 95% confidence interval [CI], 1.12-26.9), MRSA count of ≥ 2+ in stool cultures (OR, 8.91; 95% CI, 1.79-44.3), and meropenem administration within 1 month of stool specimen submission (OR, 7.47; 95% CI, 1.66-33.6) were risk factors of MRSA enteritis. Conclusion: The case definitions reviewed for MRSA enteritis may be useful as diagnostic criteria.

Usage of Meropenem Continuous Infusion for Treatment of Infectious Complications in Orthopedic Elderly Patients with Anemia: A Case Series.

Background and Objectives: The prolonged infusion of meropenem is recommended by guidelines for the treatment of sepsis. However, studies provide controversial data on the advantages of prolonged infusions over intermittent ones. In our opinion, this can be related to age, which possibly distorts the final data, as older people have age-related characteristics. In our study, we analyzed the ventilatory status, laboratory tests and vital signs of the patient and carried out microbiological cultures. Materials and Methods: This was a prospective single-center case series investigation conducted from June 2022 to June 2023. The objective of this study was to evaluate the effectiveness of continuous infusion in elderly patients with severe infectious complications after orthopedic interventions. The primary endpoints were 28-day survival and the emergence of new multidrug-resistant strains. Secondary endpoints were long-term mortality and length of stay in the ICU. Results: Three patients (median age 65, 100% female) received a continuous infusion of meropenem. Two patients were alive at hospital discharge, and one patient died on the 105th day of hospitalization. Multi-resistant bacteria were observed in one patient. Conclusions: The use of a continuous meropenem infusion in the complex treatment of purulent-septic complications in elderly patients with periprosthetic infection and anemia probably led to clinical improvement in these case reports. However, the emergence of new pan-resistant strains and overall mortality using this infusion technique remains unclear. Further, high-quality RCTs for the elderly are needed.

Meropenem/Vaborbactam-A Mechanistic Review for Insight into Future Development of Combinational Therapies.

Beta-lactam antibiotics have been a major climacteric in medicine for being the first bactericidal compound available for clinical use. They have continually been prescribed since their development in the 1940s, and their application has saved an immeasurable number of lives. With such immense use, the rise in antibiotic resistance has truncated the clinical efficacy of these compounds. Nevertheless, the synergism of combinational antibiotic therapy has allowed these drugs to burgeon once again. Here, the development of meropenem with vaborbactam-a recently FDA-approved beta-lactam combinational therapy-is reviewed in terms of structure rationale, activity gamut, pharmacodynamic/pharmacokinetic properties, and toxicity to provide insight into the future development of analogous therapies.

Activity of Aztreonam/Avibactam and Recently Approved ß-Lactamase Inhibitor Combinations against Enterobacterales and Pseudomonas aeruginosa from Intensive Care Unit and Non-Intensive Care Unit Patients.

We evaluated the activities of aztreonam/avibactam and recently approved ß-lactamase inhibitor combinations (BLICs) to compare the antimicrobial susceptibility patterns of Enterobacterales and Pseudomonas aeruginosa isolated from intensive care unit (ICU) and non-ICU patients. Clinical isolates (1/patient) were consecutively collected from 72 United States medical centres in 2020-2022 and susceptibility tested by broth microdilution. The results for 5421 isolates from ICU patients were analysed and compared to those for 20,649 isolates from non-ICU patients. Isolates from ventilator-associated pneumonia patients were analysed separately. Aztreonam/avibactam inhibited 100.0%/>99.9% Enterobacterales and 100.0%/98.3% of carbapenem-resistant Enterobacterales (CRE) from ICU/non-ICU patients at ≤8 mg/L, respectively. The CRE susceptibility rates were 88.5%/82.9% for ceftazidime/avibactam, 82.1%/81.2% for meropenem/vaborbactam, and 78.2%/72.6% for imipenem/relebactam among ICU/non-ICU isolates. Among the P. aeruginosa isolates from ICU/non-ICU patients, the susceptibility rates were 96.3%/97.6% for ceftazidime/avibactam, 97.2/98.4% for ceftolozane/tazobactam, 97.1%/98.0% for imipenem/relebactam, 77.8%/84.6% for piperacillin/tazobactam, and 76.9%/85.8% for meropenem; aztreonam/avibactam inhibited 78.0%/81.9% of P. aeruginosa at ≤8 mg/L. In summary, lower susceptibility rates were observed among ICU than non-ICU isolates. Aztreonam/avibactam exhibited potent in vitro activity and broad-spectrum activity against Enterobacterales from ICU and non-ICU patients, including CRE and isolates non-susceptible to newer BLICs. Against P. aeruginosa, aztreonam/avibactam showed a spectrum of activity comparable to that of piperacillin/tazobactam, meropenem, and ceftazidime.

Patient outcomes by baseline pathogen resistance phenotype and genotype in CERTAIN-1, a Phase 3 study of cefepime-taniborbactam versus meropenem in adults with complicated urinary tract infection.

CERTAIN-1 was a Phase 3, double-blind, randomized, parallel group study of the efficacy and safety of cefepime-taniborbactam versus meropenem in the treatment of adults with complicated urinary tract infection (cUTI), including acute pyelonephritis. We determined susceptibility of Enterobacterales and Pseudomonas aeruginosa baseline pathogens to cefepime-taniborbactam and comparators and characterized ß-lactam resistance mechanisms. Microbiologic response and clinical response were assessed in patient subsets defined by baseline pathogens that were of cefepime-, multidrug-, or carbapenem-resistant phenotype or that carried ß-lactamase genes. Among Enterobacterales baseline pathogens, 26.8%, 4.1%, and 3.0% carried genes for extended-spectrum ß-lactamases (ESBLs), AmpC, and carbapenemases, respectively. Within each treatment group, while composite success rates at Test of Cure in resistant subsets by pathogen species were similar to those by pathogen overall, composite success rates in meropenem patients were numerically lower for cefepime-resistant Escherichia coli (9/19; 47.4%) and ESBL E. coli (13/25; 52.0%) compared with E. coli overall (62/100; 62.0%). Cefepime-taniborbactam achieved composite success in 7/8 (87.5%) patients with carbapenem-resistant Enterobacterales and 8/9 (88.9%) patients with Enterobacterales with a carbapenemase gene (5 OXA-48-group; 2 KPC-3; 2 NDM-1). Cefepime-taniborbactam also achieved composite success in 8/16 (50.0%) patients and clinical success in 13/16 (81.3%) patients with P. aeruginosa; corresponding rates were 4/7 (57.1%) and 6/7 (85.7%) for meropenem. Cefepime-taniborbactam demonstrated efficacy in adult cUTI patients with cefepime-, multidrug-, and carbapenem-resistant pathogens including pathogens with ESBL, AmpC, and carbapenemase genes. CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT03840148.