Concentrations Of Ceftriaxone Research Articles

Characterisation of Neisseria gonorrhoeae strain differences in patients with multisite infection

BackgroundNeisseria gonorrhoeae, the aetiological agent of gonorrhoea, is an increasing global health priority due to high levels of antimicrobial resistance (AMR). It is estimated that up to 42% of patients...

Population pharmacokinetic modeling of ceftriaxone in cerebrospinal fluid in children: should we be using once- or twice-daily dosing for meningitis?

Guidelines for bacterial meningitis in children recommend intravenous ceftriaxone 50 mg/kg (max 2 g) twice daily (BD) or 100 mg/kg (max 4 g) once daily (OD), leaving the decision regarding the dose frequency to the prescriber. We investigated the cerebrospinal fluid (CSF) penetration of ceftriaxone to evaluate whether one dosing regimen is superior. Unbound ceftriaxone concentrations were measured in serum and CSF samples from children aged 0-18 years treated with ceftriaxone if there was a sample remaining after clinical tests were performed. A serum-CSF population pharmacokinetic model was developed using non-linear mixed-effects modeling. The once- and twice-daily dosing regimens were simulated, and the probability of target attainment (PTA) was determined for maintaining a CSF concentration above a minimum inhibitory concentration (MIC) of 1 mg/L for common meningitis pathogens and 4 mg/L for Staphylococcus aureus for 100% of the dosing interval. Sixteen serum and 87 CSF samples were collected from 98 children (age range 0.1-18.5 years). The final two-compartment serum-CSF model included a renal maturation function with weight scaling on clearance and volume of distribution. The estimated serum:CSF uptake was 20.1%. For MIC 1 mg/L, the 24 h PTA was higher for OD (88%) compared with BD (53%) dosing, although both achieved a 100% PTA at steady state. For S. aureus (MIC 4 mg/L), neither dosing regimen was sufficient. Our findings support the use of a 100 mg/kg once daily regimen for empirical treatment of bacterial meningitis due to earlier achievement of the pharmacodynamic target. Neither dosing regimen was adequate for S. aureus meningitis.

Synthesis and characterization of CuCoFe2O4@GA/AC as a bio-based matrix magnetic nano-heterogeneous photocatalyst for ceftriaxone degradation from aqueous media

Emerging contaminants such as ceftriaxone are a significant issue in the environment. They have led to a series of ecological, environmental, and health issues, and it is urgent to find a green and secure method to remove antibiotics from water effectively. In this research, the CuCoFe2O4@Gum Arabic (GA)/Activated Carbon (AC) as an innovative bio-based matrix magnetic nanocatalyst was synthesized for the efficient degradation of ceftriaxone from aqueous media. The structure of CuCoFe2O4@GA/AC was characterized via FESEM, EDS, Mapping, XRD, FTIR, VSM, and DRS analyses. The structural analysis of the catalyst revealed its synthesis at the nanometer scale (40–50 nm), exhibiting high magnetic strength (Ms: 5.38 emu/g) and favorable optical properties with a bandgap of 3.6 eV. Under optimized conditions, including a pH of 5, 60 min of irradiation time, 0.24 g/L photocatalyst dose, and ceftriaxone concentration of 5 mg/L, the removal efficiency from synthetic and real samples was 94.43% and 62.5%, respectively. The photocatalytic degradation process of ceftriaxone followed pseudo-first-order and Langmuir–Hinshelwood kinetic models. Furthermore, analysis of the process mechanism indicated a prominent role of the superoxide radical. The catalyst had a high recovery capability and chemical stability. The photocatalytic degradation of ceftriaxone by CuCoFe2O4@GA/AC showcased remarkable efficiency, indicating its potential utility in the treatment of wastewater contaminated with antibiotics.

A quantitative method for the analysis of total and unbound concentrations of amoxicillin, ampicillin, ceftazidime, ceftriaxone, ertapenem, fosfomycin and penicillin G in human plasma with liquid chromatography-tandem mass spectrometry assay.

Monitoring antibiotic plasma levels is critical in populations with altered pharmacokinetics, such as critically ill patients in neonatal or adult intensive care units. This study aimed to develop and validate a rapid, reproducible and sensitive liquid chromatography-tandem mass spectrometry assay (LC-MS/MS) for measuring total and unbound concentrations of amoxicillin, ampicillin, ceftazidime, ceftriaxone, ertapenem, fosfomycin and penicillin G in human plasma. The method required 20 and 250 μl sample volumes for measuring total and unbound concentrations, respectively. Sample preparation involved protein precipitation and the addition of an internal standard. Ultrafiltration separated unbound drugs. Method validation covered selectivity, carryover, linearity, accuracy, precision, dilution effects, matrix effects and stability. The LC-MS/MS was performed within a run time of 7.5min. Calibration curves were linear for ceftazidime and ertapenem (ranges 0.1-50 and 0.05-100 mg/l, respectively) and quadratic for other analytes (0.1-50 mg/l, except for ampicillin: 0.1-20 mg/l; R2 > 0.990). Accuracy was within ±15% of the nominal concentration, and precision did not exceed ±15% (relative standard deviation). Samples showed no significant degradation at the tested temperatures and time points. Clinical applicability was demonstrated in a critically ill neonate. This method with minimal sample volume and short analysis time enables the measurement of total and unbound concentrations of selected antibiotics, and is suitable for routine clinical care and studies.

Ceftriaxone photodegradation in wastewater using AgCuFe2O4/ZnO Almond-like heterogeneous nanocatalyst anchored on multi walled carbon nanotubes: Synthesis, characterization, mechanism study, and bioassay effluent

This study investigated the Ceftriaxone (CFT) degradation by photocatalytic process using AgCuFe2O4@MWCNT/ZnO as novel nanophotocatalyst. Firstly, the catalyst was prepared by microwave-assisted chemical coprecipitation method as a simple, fast, and green procedure with high efficiency. FESEM, EDS, Mapping, Line scan, FTIR, XRD, BET, DRS, PL, TGA, and VSM analyzes was carried out to identify the characteristics of the AgCuFe2O4@MWCNT/ZnO. The effect of key operational parameters for CFT photodegradation including solution pH, catalyst dosage, CFT concentration, and irradiation time was elaborated. Under optimal photocatalytic conditions (pH 7, 5 mg/L of CFT concentration, catalyst dosage of 0.24 g/L, and 60 minutes of irradiation) removal efficiency reached 90.1 % in synthetic samples and 75 % in real wastewater samples. •OH and •O2– are the dominant generated reactive oxygen species in the process. The kinetic study of the process revealed that the CFT degradation process followed the pseudo-first-order kinetic and Langmuir-Hinshelwood models with kc = 0.412 mg/L.min and kL-H =0.053 L/mg. Photocatalytic process indicated a powerful ability for mineralization of CFT (85.31 % of COD degradation). After four catalyst recovery cycles, the CFT degradation efficiency was achieved by 58.14 %, demonstrating the catalyst's recovery capability and chemical stability. The results of toxicity assessment using lettuce and basil seeds germination indicated a significant detoxification of CFT-containing effluent compared to the untreated CFT-containing wastewater. This study offers AgCuFe2O4@MWCNT/ZnO as effective, stable, and competitive catalyst for hastening and enhancing the photocatalytic process to mitigate environmentally related pollutants of high concern.

An analytical method using salting-out assisted liquid-liquid extraction to quantify ceftriaxone from micro volumes of human serum.

Ceftriaxone (CTRX) is a commonly used cephalosporin antibiotic. It is suggested that monitoring plasma/serum concentrations is helpful for its safe use. This study aimed to develop and validate an analytical method for measuring CTRX concentrations in human serum according to International Conference on Harmonization guideline M10. Ten microliters of serum sample was purified using a salting-out assisted liquid-liquid extraction procedure with magnesium sulfate. The upper layer was then diluted threefold and analyzed using a liquid chromatography-tandem mass spectrometry-based method with a total run time of 12 min. The linear calibration curve was obtained over the concentration range 5-500 μg/ml. The within-run accuracy varied from 0.2 to 6.5%, and the precision was ≤8.0%. The between-run accuracy and precision ranged from 0.7% to 5.6% and ≤6.4%, respectively. Significant carryover was resolved by injecting four blanks after high-concentration CTRX samples. The recovery rates from spiked serum at low and high concentrations were 44.4 and 43.4%, respectively. Other factors, including selectivity, matrix effects, stability, dilution integrity and reinjection reproducibility also met the acceptance criteria. Serum concentrations in 14 samples obtained from two participants receiving 2 g/day of CTRX were successfully determined using this method.

CRISPR Interference-Mediated Silencing of the mmpL3 Gene in Mycobacterium smegmatis and Its Impact on Antimicrobial Susceptibility.

The discovery of novel therapeutic agents, especially those targeting mycobacterial membrane protein large 3 (mmpL3), has shown promise. In this study, the CRISPR interference-Streptococcus thermophilus nuclease-deactivated Cas9 (CRISPRi-dCas9Sth1) system was utilized to suppress mmpL3 expression in Mycobacterium smegmatis, and its impacts on susceptibility to antimicrobial agents were evaluated. The repression of the mmpL3 gene was confirmed by RT-qPCR. The essentiality, growth curve, viability, and antimicrobial susceptibility of the mmpL3 knockdown strain were investigated. mmpL3 silencing was achieved by utilizing 0.5 and 1 ng/mL anhydrotetracycline (ATc), resulting in reductions in the expression of 60.4% and 74.4%, respectively. mmpL3 silencing led to a significant decrease in bacterial viability when combined with one-half of the minimal inhibitory concentrations (MICs) of rifampicin, rifabutin, ceftriaxone, or isoniazid, along with 0.1 or 0.5 ng/mL ATc (p < 0.05). However, no significant difference was observed for clarithromycin or amikacin. The downregulation of the mmpL3 gene in mycobacteria was achieved through the use of CRISPRi-dCas9Sth1, resulting in growth deficiencies and resensitization to certain antimicrobial agents. The impact was dependent upon the level of gene expression.

Evaluating the antimicrobial efficacy of ceftriaxone regimens: 1 g twice daily versus 2 g once daily in a murine model of Streptococcus pneumoniae pneumonia.

Ceftriaxone is administered in regimens of either 2 g once-daily or 1 g twice-daily for the treatment of pneumonia caused by Streptococcus pneumoniae. Previous clinical study suggests the 2 g once-daily regimen is more effective, but comparison of antimicrobial efficacy between are lacking. To assess the antimicrobial efficacy of these two ceftriaxone regimens against S. pneumoniae using a murine model of pneumonia. The study employed three S. pneumoniae isolates with ceftriaxone MICs of 1, 2 and 4 mg/L and two human-simulated regimens based on the blood concentration of ceftriaxone (1 g twice-daily and 2 g once-daily). Antimicrobial activity was quantified based on the change in bacterial counts (Δlog10 cfu/lungs) observed in treated mice after 24 h, relative to the control mice at 0 h. The human-simulated 2 g once-daily regimen of ceftriaxone exhibited significantly higher antimicrobial activity against S. pneumoniae isolates with MICs of 1 and 2 mg/L compared with the 1 g twice-daily regimen (1 mg/L, -5.14 ± 0.19 Δlog10 cfu/lungs versus -3.47 ± 0.17 Δlog10 cfu/lungs, P < 0.001; 2 mg/L, -3.41 ± 0.31 Δ log10 cfu/lungs versus -2.71 ± 0.37 Δlog10 cfu/lungs, P = 0.027). No significant difference in antimicrobial activity was observed against the S. pneumoniae isolate with a MIC of 4 mg/L between the two regimens (-0.33 ± 0.18 Δlog10 cfu/lungs versus -0.42 ± 0.37 Δlog10 cfu/lungs, P = 0.684). 2 g once-daily regimen of ceftriaxone is more effective for treating pneumonia caused by S. pneumoniae, with MICs of ≤2 mg/L.

Ceftriaxone Pharmacokinetics and Pharmacodynamic Target Attainment for Three Pediatric Patients Receiving Continuous Kidney Replacement Therapy.

Ceftriaxone is used commonly for sepsis, including in children requiring continuous kidney replacement therapy (CKRT). No reports exist of pharmacokinetic (PK) parameters for children receiving ceftriaxone on CKRT. We enrolled children admitted to our pediatric intensive care unit (PICU) who received CKRT for >24 hours and received >1 dose of ceftriaxone while on and off CKRT. We measured free ceftriaxone -concentrations from residual blood samples then used Bayesian estimation with PK modeling software to generate concentration-time profiles and determine PK parameters and the percentage of time free ceftriaxone concentrations were above 1× or 4× MIC (% fT >MIC). Three patients aged 2 to 17 years were included; all were anuric at CKRT initiation and received 50 mg/kg (max 2000 mg) ceftriaxone every 12 to 24 hours. Total ceftriaxone clearance (CL) was 0.50 to 3.67 L/hr while receiving CKRT and 0.29 to 2.71 L/hr while off, indicating CKRT provided 25% to 42% of total ceftriaxone CL. All achieved 100% fT >1× and 4× MIC using an estimated MIC (1 mg/L) for patients 1 to 2 (no culture data) and a measured MIC (0.016 mg/L) for patient 3. Therefore, CKRT contributed significantly to total ceftriaxone clearance in 3 children though the dosing strategies used in each patient attained PD targets.

Effects of antibiotics ceftriaxone and levofloxacin on the growth of Protophormia terraenovae (Diptera: Calliphoridae).

Protophormia terraenovae is a colonizer of decomposing bodies and is known to cause pre-mortem myiasis as the female flies lay eggs in uncleaned wounds. In this study the effects of different concentrations of antibiotics levofloxacin and ceftriaxone on maggot development, weight, length, and mortality were examined. The maggot length and weight were significantly increased by therapeutical doses of levofloxacin and ceftriaxone. The maggot development time was significantly decreased in every levofloxacin treatment compared to the control. The time to start pupation was significantly increased in the control compared to the antibiotic treatments. Levofloxacin significantly increased the survivability of the maggots. Every levofloxacin treatment significantly improved the rearing conditions for the maggots. Reaching the third instar was delayed by 24h in the control compared to the Levo 3.57 treatment. The Pupation in the control was delayed by an average of 48h compared to the Levo 3.57 treatment. The significantly reduced development time of the maggots in the antibiotic treatments might lead to an overestimation of the post-mortem interval and therefore an incorrect time of death determination. The improved rearing conditions may be an indication of the potential of a combined application of antibiotics and maggot therapy.

Risk of Ceftriaxone (Antibiotic) in the Tigris River Water, Iraq

There are several causes of hemolytic diseases, such as viral or bacterial contamination, enlarged spleen, and typhoid fever, which can be transmitted through contaminated water. Polluted wastewater samples were collected for the period of June-2022 to (May-2023) from five stations in Baghdad City such as Al- Gureat, Al-Ahdamyah, Bab Al-Muhadum, Bab Al-Sharqy and Al-Jadryah stations on the Tigris Riverbanks for the studying of Ceftriaxone antibiotic risk. The concentrations of ceftriaxone have been detected using high-performance liquid chromatography (HPLC). The results reveal that concentrations of ceftriaxone in the water fluctuated via sampling stations and seasons; so the highest concentration was 8 × 10-5 ppm in site 2 at Ahdamyah station, while the lowest concentrations was 1 × 10-7 ppm in site 5 sites at Al-Jadryah station during wet season 2023. The results of the statistical analysis showed that there were no significant differences between the study stations, except for the control station. The detection of ceftriaxone in raw surface water confirms that sewage from health institutions reaches the river without any effective treatment.

First Detection of Chimeric β-Lactamase CTX-M-64-Producing Salmonella Typhimurium from a Domestic Source in Japan.

Salmonella enterica subsp. enterica serovar Typhimurium has recently emerged worldwide as a producer of extended-spectrum β-lactamase (ESBL). However, drug-resistant clinical isolates are rare in Japan. The common types of ESBLs found are the CTX-M-type β-lactamases, including novel β-lactamases such as CTX-M-64. CTX-M-64 has a chimeric structure comprising a combination of the CTX-M-1 and CTX-M-9 groups. In 2017, S. Typhimurium was isolated from stool, blood, and urine cultures of an 82-year-old man. Herein, we describe the discovery of a clinical isolate of S. Typhimurium in Japan. Antimicrobial susceptibility testing revealed that the isolate was resistant to third- and fourth-generation cephalosporins, including ceftazidime and monobactam. The minimum inhibitory concentrations of ceftazidime and ceftriaxone were restored by administration of clavulanic acid. Whole-genome sequencing analysis revealed that the isolate harbored the blaCTX-M-64 gene on an IncHI2/IncHI2A-type plasmid, with an assembly length of 174,477 bp. The genetic structure of the region surrounding the blaCTX-M-64 gene, ISKpn26-ΔISEcp1-blaCTX-M-64-orf477, was shared only with the chromosome sequence of S. Typhimurium detected in food-producing chickens in Guangdong, China. Although rare, S. Typhimurium can induce bloodstream infections and produce ESBL. To our knowledge, this is the first report of a CTX-M-64-producing Enterobacterales clinical isolate of domestic origin in Japan.

Establishment and Evaluation of a Resazurin-Based Microdilution Assay for Microbial Sensitivity Test of Neisseria gonorrhoeae

To establish and evaluate a microbial sensitivity test method for Neisseria gonorrhoeae based on resazurin coloration. Based on the broth microdilution method, resazurin was added as a live bacteria indicator. WHO G, a WHO gonococcal reference strain, was used to optimize the incubation time for resazurin-stained bacteria and the color change was visually observed to obtain the results. Agar dilution method (the gold standard) and resazurin-based microdilution assay were used to determine the minimum inhibitory concentration (MIC) of azithromycin, ceftriaxone, and spectinomycin for 3 reference strains and 32 isolates of Neisseria gonorrhoeae. The results were analyzed based on essential agreement (EA), which reflected the consistency of the MIC values, category agreement (CA), which reflected the consistency in the determination of drug resistance, intermediary, and sensitivity, very major error (VME), which reflected false sensitivity, and major error (ME), which reflected pseudo drug resistance, to evaluate the accuracy of resazurin-based microdilution assay as a microbial sensitivity test of of Neisseria gonorrhoeae. CA and EA rates≥90% and VME and ME rates≤3% were found to be the acceptable performance rates. The results obtained 6 hours after resazurin was added were consistent with those of the agar dilution method and the resazurin-based microdilution assay was established accordingly based on this parameter. The EA of resazurin-based microdilution assay for measuring the MIC results of azithromycin, ceftriaxone, and spectinomycin was 97.1%, 91.5%, and 94.3%, respectively, and the CA was 88.6%, 94.3%, and 94.3%, respectively. The VME was 0% for all three antibiotics, while the ME was 11.4%, 5.7%, and 5.7%, respectively. The resazurin-based microdilution assay established in this study showed good agreement with agar dilution method for measuring the MIC of antibiotics against Neisseria gonorrhoeae. Moreover, the sensitivity results of this method were highly reliable and could be easily obtained through naked eye observation. Nonetheless, the results of drug resistance should be treated with caution and the optimization of parameters should be continued.

Effect of sub-minimum inhibitory concentrations of ceftriaxone on the Pseudomonas aeruginosa adhesion to human oral mucosal epithelial cells and biofilm formation to polystyrene in vitro

Effect of sub-minimum inhibitory concentrations of ceftriaxone on the Pseudomonas aeruginosa adhesion to human oral mucosal epithelial cells and biofilm formation to polystyrene in vitro

Divergent genetic landscapes drive lower levels of AmpC induction and stable de-repression in Serratia marcescens compared to Enterobacter cloacae.

The chromosomally encoded AmpC beta-lactamase is widely distributed throughout the Enterobacterales. When expressed at high levels through transient induction or stable de-repression, resistance to ceftriaxone, a commonly used antibiotic, can develop. Recent clinical guidance suggests, based on limited evidence, that resistance may be less likely to develop in Serratia marcescens compared to the better-studied Enterobacter cloacae and recommends that ceftriaxone may be used if the clinical isolate tests susceptible. We sought to generate additional data relevant to this recommendation. AmpC de-repression occurs predominantly because of mutation in the ampD peptidoglycan amidohydrolase. We find that, in contrast to E. cloacae, where deletion of ampD results in high-level ceftriaxone resistance (with ceftriaxone MIC = 96 µg/mL), in S. marcescens deletion of two amidohydrolases (ampD and amiD2) is necessary for AmpC de-repression, and the resulting ceftriaxone MIC is 1 µg/mL. Two mechanisms for this difference were identified. We find both a higher relative increase in ampC transcript level in E. cloacae ΔampD compared to S. marcescens ΔampDΔamiD2, as well as higher in vivo efficiency of ceftriaxone hydrolysis by the E. cloacae AmpC enzyme compared to the S. marcescens AmpC enzyme. We also observed higher relative levels of transient AmpC induction in E. cloacae vs S. marcescens when exposed to ceftriaxone. In time-kill curves, this difference translates into the survival of E. cloacae but not S. marcescens at clinically relevant ceftriaxone concentrations. In summary, our findings can explain the decreased propensity for on-treatment ceftriaxone resistance development in S. marcescens, thereby supporting recently issued clinical guidance.

Non-pathogenic Neisseria species of the oropharynx as a reservoir of antimicrobial resistance: a cross-sectional study.

Commensal Neisseria species of the oropharynx represent a significant reservoir of antimicrobial resistance determinants that can be transferred to Neisseria gonorrhoeae. This aspect is particularly crucial in 'men having sex with men' (MSM), a key population in which pharyngeal co-colonization by N. gonorrhoeae and non-pathogenic Neisseria species is frequent and associated with the emergence of antimicrobial resistance. Here, we explored the antimicrobial susceptibility of a large panel of non-pathogenic Neisseria species isolated from the oropharynx of two populations: a group of MSM attending a 'sexually transmitted infection' clinic in Bologna (Italy) (n=108) and a group of males representing a 'general population' (n=119). We collected 246 strains, mainly belonging to N. subflava (60%) and N. flavescens (28%) species. Their antimicrobial susceptibility was evaluated assessing the minimum inhibitory concentrations (MICs) for azithromycin, ciprofloxacin, cefotaxime, and ceftriaxone using E-test strips. Overall, commensal Neisseria spp. showed high rates of resistance to azithromycin (90%; median MICs: 4.0 mg/L), and ciprofloxacin (58%; median MICs: 0.12 mg/L), whereas resistance to cephalosporins was far less common (<15%). Neisseria strains from MSM were found to have significantly higher MICs for azithromycin (p=0.0001) and ciprofloxacin (p<0.0001) compared to those from the general population. However, there was no significant difference in cephalosporin MICs between the two groups. The surveillance of the antimicrobial resistance of non-pathogenic Neisseria spp. could be instrumental in predicting the risk of the spread of multi-drug resistant gonorrhea. This information could be an early predictor of an excessive use of antimicrobials, paving the way to innovative screening and prevention policies.

Antimicrobial susceptibility profile of Neisseria gonorrhoeae from patients attending a medical laboratory, Institut Pasteur de Madagascar between 2014 and 2020: phenotypical and genomic characterisation in a subset of Neisseria gonorrhoeae isolates

ObjectivesAntimicrobial-resistant Neisseria gonorrhoeae (NG) is a concern. Little is known about antimicrobial susceptibility profiles and associated genetic resistance mechanisms of NG in Madagascar. We report susceptibility data of NG isolates...

Intra-operative drug level monitoring of pre-operative antibiotic for surgical prophylaxis inthe patients of elective spinal surgery.

Single dose prophylaxis is good enough for general surgery with low risk patients. However, the evidence for the effectiveness of single dose anti-microbial prophylaxis (AMP) is not conclusive in high risk patients andspinal surgeries requiring instrumentation or the use of implants in particular. No studies have explored the various concentration of ceftriaxone in plasma and tissue as well during an ongoing spinal surgery. Therefore, the objective of study was to correlate the serum and tissue concentrations of ceftriaxone with the SSI and identify patients with increased risk of SSI. It was an open label prospective study in 50 consecutive patients who underwent elective spine surgery under prophylactic cover of ceftriaxone. Serum and tissue concentration were estimated by high pressure liquid chromatography during the ongoing surgery. Subjects were observed for any post-operative complications including SSI. Serum (p=0.002) and tissue (p=0.012) concentrations of ceftriaxone at the closure of spinal surgery were associated with SSI. Duration of the surgery (p=0.04) and use of implants (p=0.02) were also important surgery related risk factors. Serum and tissue concentrations of ceftriaxone atthe closure and duration of surgery and instrumentation or use of implants in the spinal surgery are good predictors of SSI.

Population pharmacokinetic/pharmacodynamic target attainment of ceftriaxone 2 g once daily in non-critically ill hospitalized adult patients during the acute phase of infection.

Pharmacokinetic/pharmacodynamic target attainment of ceftriaxone is compromised in intensive care unit (ICU) patients and non-ICU hospitalized patients in Beira, Mozambique. Whether this also accounts for non-ICU patients in a high-income setting is unknown. We therefore assessed the probability of target attainment (PTA) of the currently recommended dosing regimen of 2 g every 24 h (q24h) in this patient group. We performed a multicentre population pharmacokinetic study in hospitalized non-ICU adult patients empirically treated with intravenous ceftriaxone. During both the acute phase of infection (i.e. first 24 h of treatment) and convalescence, a maximum of 4 random blood samples were obtained per patient for ceftriaxone total and unbound concentration measurements. PTA was calculated using NONMEM and was defined as the percentage of patients of which the unbound ceftriaxone concentration exceeded the minimum inhibitory concentration (MIC) for >50% of the first dosing interval of 24 h. Monte Carlo simulations were performed to determine PTA for different estimated glomerular filtration rates (eGFR; CKD-EPI) and MICs. PTA >90% was considered adequate. Forty-one patients provided 252 ceftriaxone total and 253 unbound concentrations. The median eGFR was 65 mL/min/1.73 m2 (5th to 95th percentile 36-122). With the recommended dose of 2 g q24h, PTA >90% was achieved for bacteria with an MIC ≤2 mg/L. Simulations showed that PTA was insufficient for an MIC of 4 mg/L in case the eGFR was 122 mL/min/1.73 m2 (PTA 56.9%) and for an MIC of 8 mg/L regardless of eGFR. The PTA of 2 g q24h ceftriaxone dosing is adequate for common pathogens during the acute phase of infection in non-ICU patients.

Validating a novel three-times-weekly post-hemodialysis ceftriaxone regimen in infected Indigenous Australian patients-a population pharmacokinetic study.

To describe the total and unbound population pharmacokinetics of a 2 g three-times-weekly post-dialysis ceftriaxone regimen in Indigenous Australian patients requiring hemodialysis. A pharmacokinetic study was carried out in the dialysis unit of a remote Australian hospital. Adult Indigenous patients on intermittent hemodialysis (using a high-flux dialyzer) and treated with a 2 g three-times-weekly ceftriaxone regimen were recruited. Plasma samples were serially collected over two dosing intervals and assayed using validated methodology. Population pharmacokinetic analysis and Monte Carlo simulations were performed using Pmetrics in R. The probability of pharmacokinetic/pharmacodynamic target attainment (unbound trough concentrations ≥1 mg/L) and toxicity [trough concentrations (total) ≥100 mg/L] were simulated for various dosing strategies. Total and unbound concentrations were measured in 122 plasma samples collected from 16 patients (13 female) with median age 57 years. A two-compartment model including protein-binding adequately described the data, with serum bilirubin concentrations associated (inversely) with ceftriaxone clearance. The 2 g three-times-weekly regimen achieved 98% probability to maintain unbound ceftriaxone concentrations ≥1 mg/L for a serum bilirubin of 5 µmol/L. Incremental accumulation of ceftriaxone was observed in those with bilirubin concentrations >5 µmol/L. Three-times-weekly regimens were less probable to achieve toxic exposures compared with once-daily regimens. Ceftriaxone clearance was increased by >10-fold during dialysis. A novel 2 g three-times-weekly post-dialysis ceftriaxone regimen can be recommended for a bacterial infection with an MIC ≤1 mg/L. A 1 g three-times-weekly post-dialysis regimen is recommended for those with serum bilirubin ≥10 µmol/L. Administration of ceftriaxone during dialysis is not recommended.