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The emergence of bacteria resistant to beta-lactam/beta-lactamase inhibitor combinations is insufficiently studied, wherein the role of the inoculum effect (IE) in decreased efficacy is unclear. To address these issues, 5-day treatments with doripenem and doripenem/relebactam combination at different ratios of the agents were simulated in a hollow-fiber dynamic model against carbapenemase-producing K. pneumoniae at standard and high inocula. Minimal inhibitory concentrations (MICs) of doripenem alone and in the presence of relebactam at two inocula were determined. Combination MICs were tested using traditional (fixed relebactam concentration) and pharmacokinetic-based approach (fixed doripenem-to-relebactam concentration ratio equal to the therapeutic 24-h area under the concentration-time curve (AUC) ratio). In all experiments, resistant subpopulations were noted, but combined simulations reduced their numbers. With doripenem, the IE was apparent for both K. pneumoniae isolates in combined treatments for one strain. The pharmacokinetic-based approach to combination MIC estimation compared to traditional showed stronger correlation between DOSE/MIC and emergence of resistance. These results support (1) the constraint of relebactam combined with doripenem against the emergence of resistance and IE; (2) the applicability of a pharmacokinetic-based approach to estimate carbapenem MICs in the presence of an inhibitor to predict the IE and to describe the patterns of resistance occurrence. [ABSTRACT FROM AUTHOR]

ABSTRACT: Objective: Both ertapenem and other carbapenems, including imipenem, meropenem, and doripenem, are recommended in the treatment of extended-spectrum-β-lactamase (ESBL)-producing Enterobacterales infection. However, whether ertapenem is as effective as other carbapenems for ESBL-producing Enterobacterales remains unclear. Therefore, this meta-analysis was conducted to compare the clinical efficacy of ertapenem versus other carbapenems in the treatment of ESBL-producing Enterobacterales infection. Methods: PubMed, Web of Science, and Cochrane Library were searched from their inception to 29 November 2022. Only studies comparing ertapenem and other carbapenems in the treatment of patients with ESBL-producing Enterobacterales infections were included. Results: A total of six studies meeting selection criteria were identified. Overall, ertapenem was associated with a significantly lower 30-d mortality when compared with other carbapenems (10.7% [46/431] vs. 17.7% [104/586]; risk ratio [RR], 0.61; 95% CI: 0.40–0.91). The ertapenem group exhibited a significantly shorter length of hospital stay than the other carbapenem groups (mean differences, -6.02 d; 95% CI, -9.39 to -2.64). No significant differences were noted between ertapenem and other carbapenem groups in terms of rates of clinical cure or improvement (RR, 1.11; 95% CI: 0.97–1.25) and microbiological eradication (RR, 1.01; 95% CI: 0.97–1.06). Conclusions: Ertapenem could be as effective as other carbapenems in the treatment of patients with ESBL-producing Enterobacterales infections.

In this study, we established a novel capillary electrophoresis method for monitoring the concentration of doripenem in human plasma. As a time-dependent antibiotic, doripenem maximizes its antibacterial effects and minimizes the potential for antibiotic resistance through careful therapeutic drug monitoring. Two online preconcentration techniques, field-enhanced sample stacking (FESS) and sweeping, were coupled to enhance the detection sensitivity. Briefly, an uncoated fused silica capillary (40 cm × 50 μm i.d) was rinsed with a high conductivity buffer (HCB) composed of 150 mM phosphate buffer (NaH2PO4, pH 2.5) and 20% methanol. A large sample plug prepared in a low-conductivity phosphate buffer (50 mM NaH2PO4, pH 2.5) was then hydrodynamically injected (5 psi, 80 s) into the capillary. Under an applied voltage of −30 kV, the analyte was accumulated at the FESS boundary and swept by the negatively charged micelles toward the UV detector. Plasma samples were pretreated by solid-phase extraction (SPE) to eliminate endogenous interferences. The validation results demonstrated a high coefficient of determination (r2 > 0.9995) for the regression curve with impressive precision and accuracy: relative standard deviation (RSD) <5.86% and relative error <4.63%. The limit of detection (LOD, S/N = 3) for doripenem was determined to be 0.4 μg/mL. Compared to the conventional micellar electrokinetic chromatography method, our developed method achieved a sensitivity enhancement of up to 488-fold for doripenem. Furthermore, the newly developed method successfully quantified doripenem concentrations in plasma samples obtained from patients accepting doripenem regimens, proving its application potential in the clinical realm. [ABSTRACT FROM AUTHOR]

The occurrence of antibiotic pollution has become a concerning issue to public health, where the adsorption of antibiotics on bentonite-based adsorbent represents an attractive solution to reduce the antibiotic residue in wastewater. In this work, the bentonite-chitosan composite was synthesised and the adsorption isotherms of amoxicillin, ampicillin, and doripenem were investigated experimentally at temperatures between 303.15 and 323.15 K. The bentonite-chitosan composite was characterised by scanning electron microscope, electron dispersive X-ray spectrophotometer, surface area and porosity analyser, powder X-ray diffractometer, Fourier transform infrared spectrometer, and thermogravimetric analyser to examine the structure of the synthesised adsorbent. The experimental data were also correlated with models of Langmuir, Freundlich, Toth, and Dubinin-Radushkevich. The experimental results showed an enhanced adsorption of all antibiotics on the bentonite-chitosan composite compared with raw bentonite despite having a much smaller BET surface area and pore volume. On the other hand, the Toth model provided the best estimates on the adsorption isotherms, though Langmuir constants were mostly recovered particularly in the lower temperature range. From the fitting results, the adsorptions of all antibiotics were implied to be endothermic and associated with monolayer formation. Within the tested temperatures, the adsorption capacities of the bentonite-chitosan composite computed by Toth model were found to be 51.9–86.1 mg g−1 for amoxicillin, 66.1–83.3 mg g−1 for ampicillin, and 78.4–96.0 mg g−1 for doripenem.

Information regarding carbapenem-induced liver injury is limited, and the rate of liver injury caused by meropenem (MEPM) and doripenem (DRPM) remains unknown. Decision tree (DT) analysis, a machine learning method, has a flowchart-like model where users can easily predict the risk of liver injury. Thus, we aimed to compare the rate of liver injury between MEPM and DRPM and construct a flowchart that can be used to predict carbapenem-induced liver injury. We investigated patients treated with MEPM (n = 310) or DRPM (n = 320) and confirmed liver injury as the primary outcome. We used a chi-square automatic interaction detection algorithm to construct DT models. The dependent variable was set as liver injury from a carbapenem (MEPM or DRPM), and factors including alanine aminotransferase (ALT), albumin-bilirubin (ALBI) score, and concomitant use of acetaminophen were used as explanatory variables. The rates of liver injury were 22.9% (71/310) and 17.5% (56/320) in the MEPM and DRPM groups, respectively; no significant differences in the rate were observed (95% confidence interval: 0.710–1.017). Although the DT model of MEPM could not be constructed, DT analysis showed that the incidence of introducing DRPM in patients with ALT >22 IU/L and ALBI scores > −1.87 might be high-risk. The risk of developing liver injury did not differ significantly between the MEPM and DRPM groups. Since ALT and ALBI score are evaluated in clinical settings, this DT model is convenient and potentially useful for medical staff in assessing liver injury before DRPM administration. [ABSTRACT FROM AUTHOR]

The dataset reported in this article describes the adsorption isotherms of amoxicillin, ampicillin, and doripenem onto bentonite. Batch adsorption experiments were carried out on single antibiotic solutions with various dosage of bentonite across temperatures from 30 to 50 °C. The adsorbent loading dataset was later obtained by measuring the concentration of antibiotic solution at adsorption equilibrium via UV-Vis spectrophotometer. The dataset was also fitted using various isotherm models including Freundlich, Langmuir, Toth, Hill, and Dubinin-Radushkevich models to further analyze the adsorption behavior. On top of that, orthogonal regression was applied to avoid fitting biasness, whereby the fitting results revealed the highest adsorption capacities of 82.259 mg g−1 for amoxicillin, 78.851 mg g−1 for ampicillin, and 93.278 mg g−1 for doripenem using Langmuir model, which gave an accurate representation of the adsorption isotherm dataset that was consistent with the results of Toth and Hill model.

The emergence of bacteria resistant to beta-lactam/beta-lactamase inhibitor combinations is insufficiently studied, wherein the role of the inoculum effect (IE) in decreased efficacy is unclear. To address these issues, 5-day treatments with doripenem and doripenem/relebactam combination at different ratios of the agents were simulated in a hollow-fiber dynamic model against carbapenemase-producing K. pneumoniae at standard and high inocula. Minimal inhibitory concentrations (MICs) of doripenem alone and in the presence of relebactam at two inocula were determined. Combination MICs were tested using traditional (fixed relebactam concentration) and pharmacokinetic-based approach (fixed doripenem-to-relebactam concentration ratio equal to the therapeutic 24-h area under the concentration-time curve (AUC) ratio). In all experiments, resistant subpopulations were noted, but combined simulations reduced their numbers. With doripenem, the IE was apparent for both K. pneumoniae isolates in combined treatments for one strain. The pharmacokinetic-based approach to combination MIC estimation compared to traditional showed stronger correlation between DOSE/MIC and emergence of resistance. These results support (1) the constraint of relebactam combined with doripenem against the emergence of resistance and IE; (2) the applicability of a pharmacokinetic-based approach to estimate carbapenem MICs in the presence of an inhibitor to predict the IE and to describe the patterns of resistance occurrence.

The aim of the study was to determine the efficacy of carbapenem-only combination treatments derived from four approved drugs (meropenem, doripenem, ertapenem and imipenem) against a MDR strain of P. aeruginosa in a Galleria mellonella larvae infection model. G. mellonella larvae were infected with P. aeruginosa NCTC 13437 (carrying the VIM 10 carbapenamase) and the efficacy of the six possible dual, four triple, and one quadruple carbapenem combination(s) were compared to their constituent monotherapies. Four of these combinations showed significantly enhanced survival compared to monotherapies and reduced the bacterial burden inside infected larvae but without complete elimination. Bacteria that survived combination therapy were slower growing, less virulent but with unchanged carbapenem MICs—observations that are consistent with a persister phenotype. In vitro time-kill assays confirmed that the combinations were bactericidal and confirmed that a low number of bacteria survived exposure. Mass spectrometry was used to quantify changes in the concentration of carbapenems in the presence of carbapenemase-carrying P. aeruginosa. The rate of degradation of individual carbapenems was altered, and often significantly reduced, when the drugs were in combinations compared with the drugs alone. These differences may account for the enhanced inhibitory effects of the combinations against carbapenem-resistant P. aeruginosa and are consistent with a 'shielding' hypothesis. In conclusion, carbapenem combinations show promise in combating MDR P. aeruginosa and are worthy of additional study and development. [ABSTRACT FROM AUTHOR]

In the context of difficult-to-treat carbapenem-resistant Pseudomonas aeruginosa infections, we evaluated imipenem, meropenem, and doripenem combinations against eleven carbapenemase-producing P. aeruginosa isolates. According to the widespread global distribution of high-risk clones and carbapenemases, four representative isolates were selected: ST175 (OXA-2/VIM-20), ST175 (VIM-2), ST235 (GES-5), and ST111 (IMP-33), for efficacy studies using a sepsis murine model. Minimum inhibitory concentration (mg/L) ranges were 64–256 for imipenem and 16–128 for meropenem and doripenem. In vitro, imipenem plus meropenem was synergistic against 72% of isolates and doripenem plus meropenem or imipenem against 55% and 45%, respectively. All combinations were synergistic against the ST175, ST235, and ST155 clones. In vivo, meropenem diminished the spleen and blood bacterial concentrations of four and three isolates, respectively, with better efficacy than imipenem or doripenem. The combinations did not show efficacy compared with the more active monotherapies, except for imipenem plus meropenem, which reduced the ST235 bacterial spleen concentration. Mortality decreased with imipenem plus meropenem or doripenem for the ST175 isolate. Results suggest that carbapenem combinations are not an alternative for severe infections by carbapenemase-producing P. aeruginosa. Meropenem monotherapy showed in vivo efficacy despite its high MIC, probably because its dosage allowed a sufficient antimicrobial exposure at the infection sites. [ABSTRACT FROM AUTHOR]

Relevance. The tendency to a decrease in sensitivity of bacterial agents to old antibiotics, as well as the slowdown in creation of new medications, dictate the need to develop effective approaches to combat bacterial resistance.Aim. Evaluation of the applicability of a pharmacokinetically-based approach to predicting anti-mutant effectiveness of combined therapy with doripenem and levofloxacin against gram-negative bacteria Pseudomonas aeruginosa.Material and methods. A collection strain of Pseudomonas aeruginosa was used in the study. The values of MPC (mutant prevention concentration) of the combination of doripenem and levofloxacin were evaluated at a ratio of their concentrations equal to therapeutic ratios of the area under the pharmacokinetic curve in the in vitro dynamic model. 5-day treatments with clinical doses of doripenem and levofloxacin individually and in combination were simulated. Bacteria-containing medium was sampled during the experiments and plated on agar media containing 2MIC of each antibiotic.Results. The MPCs of doripenem and levofloxacin decreased 4 times when used in combination compared to MPC values when used separately. P.aeruginosa population was enriched with resistant mutants during monotherapy with each medication; the number of the bacteria did not decrease or even increased by the end of observation period. The use of doripenem/levofloxacin combination completely prevented development of resistance to both drugs in P.aeruginosa. The observed anti-mutant effect of antibiotic combination was consistent with higher (compared to monotherapy) values of the time during which the concentration of the antibiotic exceeded MPC (T>MPC).Conclusion. The anti-mutant effectiveness of combined therapy with doripenem and levofloxacin increased with the decrease in the values of MPC of antibiotics when used simultaneously, which consequently led to the increase in the values of T>MPC. Obtained results confirm the applicability of a pharmacokinetically-based approach to the estimation of MPC of combined antibiotics for predicting anti-mutant effectiveness of combination therapy in the treatment of infections caused by gram-negative bacteria.

The aim of this study was to determine whether fingolimod could synergize the antibacterial activity of doripenem against carbapenem-resistant Escherichia coli (CREC) and its potential as an antibiotic adjuvant for doripenem. The E. coli used in this study had the blaKPC gene and became resistant to many classes of antibiotics, particularly carbapenems. The minimum inhibitory concentrations (MICs) of fingolimod and doripenem were determined. To investigate the synergistic action between fingolimod and doripenem, synergy checkerboard, growth curve, and time-kill analyses were performed. A motility test was also performed using a semi-solid medium to determine whether fingolimod could inhibit the motility of E. coli, one of its virulence mechanisms. The expression levels of carbapenemase-, motility-, and efflux pump-related genes suppressed by fingolimod were analyzed by quantitative polymerase chain reaction (qPCR). Our study demonstrated that the combination of fingolimod and doripenem inhibited carbapenemase, biological activity and other CREC virulence factors. This study findings suggest the potential of fingolimod as an adjuvant to prevent antibiotic resistance in CREC. [ABSTRACT FROM AUTHOR]

Introduction: Clinically, doripenem therapy for nosocomial pneumonia remains a serious concern. The purpose of this meta-analysis was to explore the efficacy and the safety of doripenem therapy for nosocomial pneumonia in comparison with other antimicrobial agents. Methods: Studies were eligible for inclusion only if they directly compared the clinical effectiveness of doripenem and other antimicrobial agent therapies for nosocomial pneumonia in adult patients between 1 January 2000 and 30 April 2022. All studies were included if they reported one or more of the following outcomes: clinical cure rate, microbiological cure rate, all-cause mortality, and adverse events. Results: Six randomized controlled trials and three retrospective studies were included in the meta-analysis. There were 952 patients in the doripenem group and 1183 patients in the comparator group. The comparator antimicrobial agents included imipenem/cilastatin, meropenem, and piperacillin/tazobactam. Seven studies had a high risk of bias. Doripenem therapy for nosocomial pneumonia had a microbiological cure rate, a clinical cure rate, an all-cause mortality, and adverse events similar to those of comparators. Conclusions: The efficacy and the safety of doripenem therapy for nosocomial pneumonia were comparable with those of comparators. Randomized controlled trials are needed to confirm the role of doripenem in nosocomial pneumonia therapy. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the pharmacokinetics (PK) of doripenem in healthy Chinese subjects and evaluate the optimal dosage regimens of doripenem. A randomized, single-dose, three-period, self-crossover controlled extended-infusion clinical trial was conducted with 12 healthy Chinese subjects. Plasma and urine samples were collected to determine doripenem concentrations. Non-compartmental and population PK analysis were performed to characterize the PK of doripenem. The Monte Carlo simulation was employed to optimize dosing regimens based on the probability of target attainment of doripenem against pathogens with different minimum inhibitory concentrations (MIC). All 12 healthy Chinese subjects completed the study, and the doripenem was well tolerated. The study showed linearity relationships in the peak plasma concentration and the area under the concentration-time curve after intravenous infusion of doripenem from 0.25 g to 1.0 g. The cumulative urinary recovery rate of doripenem was 68.1–72.0% within 24 h. PPK modeling showed a two-compartmental model, with first-order elimination presenting the best fit for doripenem PK. Monte Carlo simulation results showed that 1.0 g q12h or 0.5 g q8h was an optimal regimen for pathogens susceptible to doripenem (MIC ≤ 1 mg/L); while high dose and extended infusion (1 g, q8h, 4 h infusion) was proposed for unsusceptible pathogens (2 ≤ MIC ≤ 8 mg/L). In the dose range of 0.25 to 1.0 g, doripenem showed linear pharmacokinetics. Doripenem at 1.0 g with a prolonged infusion time of 4 h was predicted to be effective against pathogens with MICs as high as 8 mg/L. [ABSTRACT FROM AUTHOR]

The inoculum effect (IE) is a well-known phenomenon with beta-lactams. At the same time, the IE has not been extensively studied with carbapenem/carbapenemase inhibitor combinations. The antibiotic-to-inhibitor concentration ratio used in susceptibility testing can influence the in vitro activity of the combination. To explore the role of these factors, imipenem/relebactam and doripenem/relebactam MICs were estimated against six Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae strains at standard inocula (SI) and high inocula (HI) by two methods: with a fixed relebactam concentration and with a fixed, pharmacokinetic-based carbapenem-to-relebactam concentration ratio. The combination MICs at HI, compared to SI, increased with most of the tested strains. However, the IE occurred with only two K. pneumoniae strains regardless of the MIC testing method. The relationship between the MICs at SI and the respective inoculum-induced MIC changes was observed when the MICs were estimated at pharmacokinetic-based carbapenem-to-relebactam concentration ratios. Thus, (1) IE was observed with both carbapenem/relebactam combinations regardless of the MIC testing method; however, IE was not observed frequently among tested K. pneumoniae strains. (2) At HI, carbapenem/relebactam combination MICs increased to levels associated with carbapenem resistance. (3) Combination MICs determined at pharmacokinetic-based carbapenem-to-inhibitor concentration ratios predict susceptibility elevations at HI in KPC-producing K. pneumoniae. [ABSTRACT FROM AUTHOR]

Abstract Background Yersinia pseudotuberculosis infection can occur in an immunocompromised host. Although rare, bacteremia due to Y. pseudotuberculosis may also occur in immunocompetent hosts. The prognosis and therapeutic strategy, especially for immunocompetent patients with Y. pseudotuberculosis bacteremia, however, remains unknown. Case presentation A 38-year-old Japanese man with a mood disorder presented to our hospital with fever and diarrhea. Chest computed tomography revealed consolidation in the right upper lobe with air bronchograms. He was diagnosed with pneumonia, and treatment with intravenous ceftriaxone and azithromycin was initiated. The ceftriaxone was replaced with doripenem and the azithromycin was discontinued following the detection of Gram-negative rod bacteria in 2 sets of blood culture tests. The isolated Gram-negative rod bacteria were confirmed to be Y. pseudotuberculosis. Thereafter, he developed septic shock. Doripenem was switched to cefmetazole, which was continued for 14 days. He recovered without relapse. Conclusions We herein report a case of septic shock due to Y. pseudotuberculosis infection in an adult immunocompetent patient. The appropriate microorganism tests and antibiotic therapy are necessary to treat patients with Y. pseudotuberculosis bacteremia.

OBJECTIVE: This study aimed to evaluate the penetration of moxifloxacin and doripenem into the pleural fluid (PF) using a rabbit model of empyema. METHODS: An empyema was induced using the intrapleural injection of turpentine (1 mL), followed 24 h later by instillation of 5 mL Klebsiella Pneumoniae (ATCC 33495), Fusobacterium nucleatum (ATCC 25586) and Streptokok Pneumoniae (ATCC 6305) into the pleural space. After an empyema was corroborated, Moxifloxacin (25 mg/kg-1) and Doripenem (20 mg/kg-1) were administered intraperitoneally. To determine the levels of antibiotics measured by High-Performance Liquid Chromatography in pleural and blood samples were obtained serially at 8, 24, 48 and 72nd hour. RESULTS: The penetration of both antibiotics into the PF was very good. The penetration rate of doripenem (area under the curve (AUC) for PF/blood (AUCPF/AUCblood) ratio=1.68) was better than moxifloxacin (ratio=0.78). Equalization time between the PF and blood concentration of doripenem was more quickly than moxifloxacin. Peak PF concentration of moxifloxacin was 0,81 μg/mL-1 and occurred 8 h after infusion and then gradually decreased; at the beginning of the blood and pleural fluid concentrations of doripenem were equal. While the pleura concentration was increasing, blood concentration was almost the same. Doripenem reached a peak concentration (0.54 μg/ml) 24 h post-administration. CONCLUSION: Differences were found in the penetration of the two antibiotics. Doripenem had convenient penetration PF compared to moxifloxacin. Due to the differences between human and rabbit pleural thickness, doripenem's pleural penetration should be examined in infection models in animals with equal pleura thickness and clinical trials.

Background Salmonella Typhi ( S. Typhi) is increasingly resistant to multiple antibiotics, posing a challenge in treatment, particularly in multidrug-resistant (MDR) cases. Carbapenems, including doripenem, ertapenem, and meropenem, have been considered last-resort options. This study evaluates the effectiveness of these carbapenems against S. Typhi isolates in a clinical setting in Peshawar, Pakistan. Objective To assess the effectiveness of the carbapenem antibiotics, doripenem, ertapenem, and meropenem, against S. Typhi. Methods This study collected data from blood cultures of patients diagnosed with S. Typhi infections at the Hayatabad Medical Complex in Peshawar, Pakistan for two years: from January 1, 2022, to December 31, 2023. Sensitivity testing was performed using the disk diffusion method in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. The analysis examined the sensitivity rates of the three antibiotics and compared their effectiveness. Results A total of 626 S. Typhi isolates were tested. Only 11.98% of the isolates were sensitive to doripenem, while 88.02% were resistant to it. In contrast, 35.5% of the isolates responded to ertapenem, with 64.5% being resistant. Meropenem showed the highest efficacy, with 42.7% of the isolates demonstrating sensitivity. These findings highlight the growing challenge of managing multidrug-resistant (MDR) S. Typhi infections, especially in regions where resistance to carbapenems is becoming prevalent. Conclusion Meropenem proved to be more effective against S. Typhi compared to doripenem and ertapenem. The study emphasizes the need for ongoing monitoring of resistance patterns and the exploration of alternative or combination treatment options. These findings have immediate clinical implications for empiric therapy choices and highlight the urgent need for antibiotic stewardship programs in endemic regions., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Medical Teaching Institution (MTI), Hayatabad Medical Complex, Peshawar, Pakistan issued approval 2222, dated December 8, 2021. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Shah et al.)

Abstract Background Despite the high mortality of patients with sepsis and carbapenem-resistant bacteria infection, appropriate antimicrobial therapies are yet to be established. Here, we have reported the case of a patient with pneumonia that subsequently developed by carbapenem-resistant Pseudomonas aeruginosa infection and was treated with a continuous high-dose infusion of doripenem. Case presentation We started a continuous intravenous infusion of doripenem 3 g/day although the 59-year-old woman (body weight, 45 kg) had developed septic acute kidney injury, followed by continuous renal replacement therapy (the effluent flow rate was 650 mL/h). The minimum inhibitory concentration (MIC) of doripenem was 8 mg/L. The concentration of unbound doripenem in the serum was measured by using high-performance liquid chromatography. Twenty hours after the initial dose, the patient’s serum level of doripenem was 47.8 μg/mL; the level decreased to 33.6 μg/mL at 111 h after initial dosing. The unbound doripenem concentration in the serum was maintained four times above the MIC throughout the treatment. After the completion of 11 days of dosing, the patient was discharged from the intensive care unit. During the treatment period, the MIC remained at 8 mg/L. Conclusions A continuous high-dose infusion of doripenem is a potentially efficient strategy for the treatment of antimicrobial-resistant bacteria. Moreover, therapeutic drug monitoring may be useful for patients displaying variable pharmacokinetics, because the MIC is generally high in resistant bacteria.

The aim of the study was to determine the efficacy of carbapenem-only combination treatments derived from four approved drugs (meropenem, doripenem, ertapenem and imipenem) against a MDR strain of P. aeruginosa in a Galleria mellonella larvae infection model. G. mellonella larvae were infected with P. aeruginosa NCTC 13437 (carrying the VIM 10 carbapenamase) and the efficacy of the six possible dual, four triple, and one quadruple carbapenem combination(s) were compared to their constituent monotherapies. Four of these combinations showed significantly enhanced survival compared to monotherapies and reduced the bacterial burden inside infected larvae but without complete elimination. Bacteria that survived combination therapy were slower growing, less virulent but with unchanged carbapenem MICs—observations that are consistent with a persister phenotype. In vitro time-kill assays confirmed that the combinations were bactericidal and confirmed that a low number of bacteria survived exposure. Mass spectrometry was used to quantify changes in the concentration of carbapenems in the presence of carbapenemase-carrying P. aeruginosa. The rate of degradation of individual carbapenems was altered, and often significantly reduced, when the drugs were in combinations compared with the drugs alone. These differences may account for the enhanced inhibitory effects of the combinations against carbapenem-resistant P. aeruginosa and are consistent with a ‘shielding’ hypothesis. In conclusion, carbapenem combinations show promise in combating MDR P. aeruginosa and are worthy of additional study and development.

In the context of difficult-to-treat carbapenem-resistant Pseudomonas aeruginosa infections, we evaluated imipenem, meropenem, and doripenem combinations against eleven carbapenemase-producing P. aeruginosa isolates. According to the widespread global distribution of high-risk clones and carbapenemases, four representative isolates were selected: ST175 (OXA-2/VIM-20), ST175 (VIM-2), ST235 (GES-5), and ST111 (IMP-33), for efficacy studies using a sepsis murine model. Minimum inhibitory concentration (mg/L) ranges were 64–256 for imipenem and 16–128 for meropenem and doripenem. In vitro, imipenem plus meropenem was synergistic against 72% of isolates and doripenem plus meropenem or imipenem against 55% and 45%, respectively. All combinations were synergistic against the ST175, ST235, and ST155 clones. In vivo, meropenem diminished the spleen and blood bacterial concentrations of four and three isolates, respectively, with better efficacy than imipenem or doripenem. The combinations did not show efficacy compared with the more active monotherapies, except for imipenem plus meropenem, which reduced the ST235 bacterial spleen concentration. Mortality decreased with imipenem plus meropenem or doripenem for the ST175 isolate. Results suggest that carbapenem combinations are not an alternative for severe infections by carbapenemase-producing P. aeruginosa. Meropenem monotherapy showed in vivo efficacy despite its high MIC, probably because its dosage allowed a sufficient antimicrobial exposure at the infection sites.

Carbapenem-resistant Klebsiella pneumoniae has emerged as one of the major multidrug-resistant bacterial pathogens worldwide. The international spread of this pathogen has been linked to a few high-risk clone group (CG) [...]

The aim of this study was to determine whether fingolimod could synergize the antibacterial activity of doripenem against carbapenem-resistant Escherichia coli (CREC) and its potential as an antibiotic adjuvant for doripenem. The E. coli used in this study had the blaKPC gene and became resistant to many classes of antibiotics, particularly carbapenems. The minimum inhibitory concentrations (MICs) of fingolimod and doripenem were determined. To investigate the synergistic action between fingolimod and doripenem, synergy checkerboard, growth curve, and time-kill analyses were performed. A motility test was also performed using a semi-solid medium to determine whether fingolimod could inhibit the motility of E. coli, one of its virulence mechanisms. The expression levels of carbapenemase-, motility-, and efflux pump-related genes suppressed by fingolimod were analyzed by quantitative polymerase chain reaction (qPCR). Our study demonstrated that the combination of fingolimod and doripenem inhibited carbapenemase, biological activity and other CREC virulence factors. This study findings suggest the potential of fingolimod as an adjuvant to prevent antibiotic resistance in CREC.

The aim of this study was to investigate the pharmacokinetics (PK) of doripenem in healthy Chinese subjects and evaluate the optimal dosage regimens of doripenem. A randomized, single-dose, three-period, self-crossover controlled extended-infusion clinical trial was conducted with 12 healthy Chinese subjects. Plasma and urine samples were collected to determine doripenem concentrations. Non-compartmental and population PK analysis were performed to characterize the PK of doripenem. The Monte Carlo simulation was employed to optimize dosing regimens based on the probability of target attainment of doripenem against pathogens with different minimum inhibitory concentrations (MIC). All 12 healthy Chinese subjects completed the study, and the doripenem was well tolerated. The study showed linearity relationships in the peak plasma concentration and the area under the concentration-time curve after intravenous infusion of doripenem from 0.25 g to 1.0 g. The cumulative urinary recovery rate of doripenem was 68.1–72.0% within 24 h. PPK modeling showed a two-compartmental model, with first-order elimination presenting the best fit for doripenem PK. Monte Carlo simulation results showed that 1.0 g q12h or 0.5 g q8h was an optimal regimen for pathogens susceptible to doripenem (MIC ≤ 1 mg/L); while high dose and extended infusion (1 g, q8h, 4 h infusion) was proposed for unsusceptible pathogens (2 ≤ MIC ≤ 8 mg/L). In the dose range of 0.25 to 1.0 g, doripenem showed linear pharmacokinetics. Doripenem at 1.0 g with a prolonged infusion time of 4 h was predicted to be effective against pathogens with MICs as high as 8 mg/L.

The inoculum effect (IE) is a well-known phenomenon with beta-lactams. At the same time, the IE has not been extensively studied with carbapenem/carbapenemase inhibitor combinations. The antibiotic-to-inhibitor concentration ratio used in susceptibility testing can influence the in vitro activity of the combination. To explore the role of these factors, imipenem/relebactam and doripenem/relebactam MICs were estimated against six Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae strains at standard inocula (SI) and high inocula (HI) by two methods: with a fixed relebactam concentration and with a fixed, pharmacokinetic-based carbapenem-to-relebactam concentration ratio. The combination MICs at HI, compared to SI, increased with most of the tested strains. However, the IE occurred with only two K. pneumoniae strains regardless of the MIC testing method. The relationship between the MICs at SI and the respective inoculum-induced MIC changes was observed when the MICs were estimated at pharmacokinetic-based carbapenem-to-relebactam concentration ratios. Thus, (1) IE was observed with both carbapenem/relebactam combinations regardless of the MIC testing method; however, IE was not observed frequently among tested K. pneumoniae strains. (2) At HI, carbapenem/relebactam combination MICs increased to levels associated with carbapenem resistance. (3) Combination MICs determined at pharmacokinetic-based carbapenem-to-inhibitor concentration ratios predict susceptibility elevations at HI in KPC-producing K. pneumoniae.

The adsorption of Doripenem (beta-lactam antibiotic belonging to the subgroup carbapenem) from aqueous solution using bentonite as the adsorbent was studied at various pH of the solution. The doripenem loaded in bentonite which called doripenem-bentonite composite was subsequently used as the antibacterial agent. The effect of pH on the adsorption of doripenem onto bentonite was studied at pH 2 to 10 at an initial concentration of 200 mg/L and temperature of 30oC. The kinetics of adsorption was also studied, and the results were adjusted by pseudo-first-order and pseudo-second-order models, and the result indicates that pseudo-first-order gave better performance in representing the kinetics data of adsorption of doripenem onto bentonite. The adsorption isotherm of doripenem onto bentonite could be described well by the Langmuir model. Buffer solution at pH 3 gave better release of doripenem from the surface of bentonite. The microbiological testing results indicate that doripenem-bentonite composite has potential application to inhibit the growth of Staphylococcus aureus and other bacteria.

Background: Yersinia pseudotuberculosis infection can occur in an immunocompromised host. Although rare, bacteremia due to Y. pseudotuberculosis may also occur in immunocompetent hosts. The prognosis and therapeutic strategy, especially for immunocompetent patients with Y. pseudotuberculosis bacteremia, however, remains unknown.Case Presentation: A 38-year-old Japanese man with a mood disorder presented to our hospital with fever and diarrhea. Chest computed tomography revealed consolidation in the right upper lobe with air bronchograms. He was diagnosed with pneumonia, and treatment with intravenous ceftriaxone and azithromycin was initiated. The ceftriaxone was replaced with doripenem and the azithromycin was discontinued following the detection of Gram-negative rod bacteria in 2 sets of blood culture tests. The isolated Gram-negative rod bacteria were confirmed to be Y. pseudotuberculosis. Thereafter, he developed septic shock. Doripenem was switched to cefmetazole, which was continued for 14 days. He recovered without relapse.Conclusions: We herein report a case of septic shock due to Y. pseudotuberculosis infection in an adult immunocompetent patient. The appropriate microorganism tests and antibiotic therapy are necessary to treat patients with Y. pseudotuberculosis bacteremia. [ABSTRACT FROM AUTHOR]

Purpose: Clearance via renal replacement therapy (RRT) can significantly alter the pharmacokinetic profile of drugs. The aim of this study was (i) to improve the use of clinical trial data and (ii) to provide a model that allows quantification of all aspects of drug elimination via RRT including adsorption to dialysis membranes and/or degradation of the drug in the dialysate. Methods: An integrated dialysis pharmacometric (IDP) model was developed to simultaneously incorporate all available RRT information. The sensitivity, accuracy and precision of the IDP model was compared to conventional approaches in clinical trial simulations and applied to clinical datasets of teicoplanin and doripenem. Results: The IDP model was more accurate, precise and sensitive than conventional plasma-concentration-based approaches when estimating the clearanceRRT (relative bias <1%). In contrast to conventional approaches, adsorption and degradation were quantifiable using the IDP model (relative bias: −1.1% and − 1.9%, respectively). Applied to clinical data, clearanceRRT, drug degradation (effluent-half-lifedoripenem: 13.5 h−1) and adsorption (polysulphone adsorption capacityteicoplanin: 31.2 mg) were assessed. Conclusion: The IDP model allows accurate, precise and sensitive characterization of clearanceRRT, adsorption and degradation. Successful quantification of all aspects of clearanceRRT in clinical data demonstrated the benefit of the IDP model as compared to conventional approaches. [ABSTRACT FROM AUTHOR]

Introduction: Valproic acid is a commonly used antiepileptic drug. Combining valproate derivatives with carbapenem antibiotics is associated with a potential drug interaction that decreases serum concentration of valproate and may expose the patient to uncontrolled seizure risk from valproate subtherapeutic concentration. Raising awareness of this drug interaction among health care providers including emergency department physicians, neurologists, and pharmacists is highly needed. The aim of this article was to review the current literature about the potential drug interaction resulting from combining valproate derivatives with carbapenem antibiotics and to establish therapeutic recommendations regarding their use together. Methods: A review of the literature was conducted using Medline (through PubMed), Ovid, Embase, Cochrane library using the following keywords: valproate, valproic acid, carbapenem, ertapenem, doripenem, meropenem, imipenem, and valproate drug interaction. In addition, a manual search through major journals for articles referenced in PubMed was performed. Related publications from January 1998 till November 2018 were included in the initial search. Relevant publications were reviewed, and data regarding patients, type of carbapenem used, valproic acid dosing and level, interaction severity, and clinical outcome were summarized. Results and Discussion: Few clinical trials and multiple case reports have shown that carbapenem antibiotics including meropenem, ertapenem, imipenem, and doripenem can decrease the serum concentration of valproate derivatives leading to a subtherapeutic serum concentration and seizures in some patients. Valproic acid serum concentration may be significantly decreased with addition of a carbapenem antibiotic but generally return toward normal shortly after discontinuation of the carbapenem antibiotic. Conclusions: Generally, the concurrent use of carbapenem antibiotics with valproate derivatives should be avoided due to the potential of drug-drug interaction that results in subtherapeutic valproate serum concentration. Other antimicrobial agents should be considered as alternatives to carbapenems but if a concurrent carbapenem is necessary, using an additional antiepileptic agent is recommended. Therapeutic drug monitoring of valproate serum concentrations is warranted when a carbapenem-valproic acid combination therapy is unavoidable. [ABSTRACT FROM AUTHOR]

OBJECTIVE: This study aimed to evaluate the penetration of moxifloxacin and doripenem into the pleural fluid (PF) using a rabbit model of empyema. METHODS: An empyema was induced using the intrapleural injection of turpentine (1 mL), followed 24 h later by instillation of 5 mL Klebsiella Pneumoniae (ATCC 33495), Fusobacterium nucleatum (ATCC 25586) and Streptokok Pneumoniae (ATCC 6305) into the pleural space. After an empyema was corroborated, Moxifloxacin (25 mg/kg-1) and Doripenem (20 mg/kg-1) were administered intraperitoneally. To determine the levels of antibiotics measured by High-Performance Liquid Chromatography in pleural and blood samples were obtained serially at 8, 24, 48 and 72nd hour. RESULTS: The penetration of both antibiotics into the PF was very good. The penetration rate of doripenem (area under the curve (AUC) for PF/blood (AUCPF/AUCblood) ratio=1.68) was better than moxifloxacin (ratio=0.78). Equalization time between the PF and blood concentration of doripenem was more quickly than moxifloxacin. Peak PF concentration of moxifloxacin was 0,81 µg/mL-1 and occurred 8 h after infusion and then gradually decreased; at the beginning of the blood and pleural fluid concentrations of doripenem were equal. While the pleura concentration was increasing, blood concentration was almost the same. Doripenem reached a peak concentration (0.54 µg/ml) 24 h post-administration. CONCLUSION: Differences were found in the penetration of the two antibiotics. Doripenem had convenient penetration PF compared to moxifloxacin. Due to the differences between human and rabbit pleural thickness, doripenem's pleural penetration should be examined in infection models in animals with equal pleura thickness and clinical trials. [ABSTRACT FROM AUTHOR]

Introduction: Renal replacement therapy (RRT) is widely used in the treatment of septic acute kidney injury. However, little is known about how the adsorption properties of hemofilters used in RRT affect antibiotic concentration. Because a cytokine-adsorption membrane is frequently used in RRT, it is important to determine the antibiotic adsorption capacity of this membrane. Objective: The present study aimed to investigate the antibiotic adsorption capacity of different hemofilter membranes by in vitro experiments using 2 antibacterial agents (linezolid and doripenem). Methods: We performed experimental hemofiltration in vitro using polyacrylonitrile (AN69ST), polymethylmethacrylate (PMMA), and polysulfone (PS) hemofilters for 1,440 min. The test solution was a 1,000-mL substitution fluid containing 30 µg/mL linezolid and 120 µg/mL doripenem. We measured drug concentrations at the inlet, outlet, and filtrate ports of the hemofilters for 1,440 min and calculated the sieving coefficient (SC) and adsorption rate (Ra) of the drugs onto the hemofilters. Results: The amount of linezolid adsorbed onto AN69ST, PMMA, and PS membranes was decreased relative to that in the control group at 15 min (p < 0.05). However, no SC for linezolid was obtained thereafter. The Ra of linezolid onto AN69ST, PMMA, and PS membranes was higher than that in the control group (p < 0.05). In contrast, no significant differences were observed in the concentrations and Ra values of doripenem adsorbed onto AN69ST, PMMA, and PS membranes compared with those in the control group. Conclusions: Doripenem was not adsorbed onto PMMA, PS, and AN69ST membranes. Linezolid was adsorbed onto PMMA, PS, and AN69ST membranes, but only temporarily, and this did not affect drug bioavailability. [ABSTRACT FROM AUTHOR]

Traditionally, the antibacterial activity of β-lactam antibiotics in the presence of β-lactamase inhibitors is determined at the fixed inhibitor concentration. This traditional approach does not consider the ratio of antibiotic-to-inhibitor concentrations achieved in humans. To explore whether an alternative pharmacokinetically based approach to estimate MICs in combinations is predictive of antimicrobial efficacy, the effects of imipenem and doripenem alone and in combination with relebactam were studied in time-kill experiments against carbapenemase-producing Klebsiella pneumoniae. The carbapenem-to-relebactam concentration ratios in time-kill assays were equal to the therapeutic 24-h area under the concentration-time curve (AUC) ratios of the drugs (1.5/1). The simulated levels of carbapenem and relebactam were equal to their concentrations achieved in humans. When effects of combined regimens were plotted against respective C/MICs, a sigmoid relationship was obtained only with MICs determined by pharmacokinetically based method. The effectiveness of both carbapenems in the presence of relebactam was comparable by the results of time-kill experiments. These findings suggest that (1) antibiotic/inhibitor MICs determined at a pharmacokinetically based concentration ratio allow an adequate assessment of carbapenem susceptibility in carbapenemase-producing K. pneumoniae strains and can be used to predict antibacterial effects; (2) in time-kill experiments, the effects of imipenem and doripenem in the presence of relebactam are comparable.